Horizontal transmission and measles vaccine: implications for
neo-pathogenesis, measles control, and measles eradication
Andrew J Wakefield MB.BS., FRCS., FRCPath,
Executive Director
Thoughtful House Center for Children
Austin, Texas 78746
[email protected]
Partick Tierney
Department of Latin American Studies
University of Pittsburgh
[email protected]
Stephen Walker Ph.D.
Assistant Professor
Department of Physiology and Pharmacology,
Wake Forest University School of Medicine.
Winston-Salem NC 27101
[email protected]
John Lednicky Ph.D.
Midwest Research Institute
425 Volker Blvd
Kansas City, MO 64110-2299
[email protected]
1
Arthur Krigsman M.D.
Associate Professor, New York university Medical School
Clincal Director, thoughtful House center for Children,
Austin, Texas, 78746
arthur.k@thoughtfulhouse,.org
Paul Ashwood Ph.D5.
Assistant Professor
Department of Medical Microbiology and Immunology and the M.I.N.D.
Institute, 2805 Wet Lab Building,
50th Street, Sacramento, CA 95817
[email protected]
Correspondence to:
Dr Andrew J Wakefield MB.BS., FRCS., FRCPath.
3001 Bee Caves Road, Suite 120
Austin, Texas, 78746
Tel: 512 732 8400
Fax No: 512 732 8353
www.thoughtfulhouse.org
[email protected]
2
Abstract
This review addresses the possibility of horizontal transmission of measles
vaccine virus in the context of evidence from recent molecular epidemiology
and the emergence of apparently novel, overlapping pathologic syndromes in
non-human primates and children. The review presents the evidence that age
of MMR vaccine exposure is associated with an increased risk of autistic
spectrum disorder. The syndrome of autistic enterocolitis is described and its
emergence in siblings of vaccinated children with this disorder, where these
siblings are unvaccinated and yet harbor measles vaccine-strain virus in their
intestinal lymphoid tissues, is presented as direct evidence of horizontal
transmission and its likely pathologic consequence. The implications of these
factors for the interpretation of current epidemiology, measles virus
surveillance, and global measles control and eradication, are discussed.
Introduction: measles virus vaccine and horizontal transmission
Measles virus vaccine is a live viral vaccine. All vaccines in widespread use
derive from the Edmonston virus first isolated by Enders and Peebles in 1954.
The passage history of this vaccine is shown in Figure 1.
3
Figure. 1. Passage history of the Edmonston virus. Temperature of passages
assumed to be at 37o C unless otherwise stated. HK, human kidney; HA, human
amnion; CE(am), intra-amniotic cavity of chick embryo; CEF, chick embryo
fibroblast; DK, dog kidney; WI-38, human diploid cells; SK, sheep kidney (Adapted
from 1).
The vaccine virus replicates within the host eliciting an immune response that
protects, to a variable degree, against subsequent exposure. The potential for
transmission from vaccinated to non-immune individuals is, therefore, an
important theoretical concern. Horizontal transmission refers to spread
between individuals unrelated as mother to child. Vertical transmission refers
to spread from mother to child, for example, in utero, intra partum or through
breast-feeding.
Millson first reported a possible case of brother-to-sister transmission of
measles after measles-mumps-rubella (MMR) immunization in 1989 (2). A 4-
4
year old boy had onset of clinical measles with Koplick spots 10 days after
MMR vaccination. His 8-month old sister developed an almost identical clinical
picture 2 days later. Both children followed an identical course with complete
recovery.
No laboratory tests were undertaken to confirm measles infection.
Campbell responded on behalf of the Joint Committee on Vaccination and
Immunization (JCVI), stating that ‘extensive testing and experience with measles vaccine
and MMR vaccine had not shown evidence of vaccine virus transmission to susceptible
contacts’ (3). This ‘evidence’ was neither provided nor cited. He concluded that
‘there is no risk of virus transmission following measles, mumps, or rubella vaccine’. This
conclusion was premature and the case is simply made. For example, following
maternal vaccination, rubella vaccine virus transmission from mother to infant
in infected breast milk has been established and is declared as a warning in the
MMR product insert. Horizontal transmission of mumps vaccine virus from a
vaccinated to a susceptible sibling, with molecular confirmation, has been
reported (4). The likely vertical transmission of measles vaccine through breast
feeding is described by Yazbak and Diodati (5).
A critical review of early measles vaccine transmission studies
The foregoing opinion, expressed so resolutely by Campbell of the JCVI, is the
public face worn on the question of transmissibility by vaccine policy makers.
The evidence upon which this perception relies merits scrutiny, given the
importance of this issue for public health. The original studies of measles
vaccine were relatively small, poorly controlled, of short follow up and
methodologically limited. The reporting itself is somewhat ambiguous and the
findings, as described, are inconsistent with some of the overly dogmatic
conclusions. This is exemplified by a series of papers from Katz (one of the
architects of measles vaccine experimentation and policy) and his colleagues,
5
including one based upon a 1960 study of 39 children (6). Despite the claim
that there was no evidence of horizontal transmission, the authors state ‘The
earliest exposure in an immunized child to a sibling contact was nine days after vaccination
and only three days after fever developed’….In this case the unvaccinated child in whom
measles developed had a known outside exposure and ran a typical moderately severe course of
measles, making it unlikely that this was acquired from the vaccinated child.’ No details of
either the ‘contact’ or the evolution of measles in the unvaccinated sibling are
provided, while measles had developed in a susceptible contact exposed to a
vaccinee 9-days after inoculation i.e. ‘who gave what to whom?’, is uncertain.
The author’s uncritical view and unsubstantiated exoneration of the vaccine, is
a feature that appears to pervade these early reports. Elsewhere, Smith et al
describe their observations on siblings of vaccinees receiving the Goffe
(Edmonston-derived) strain of the vaccine in the UK (7). Unvaccinated siblings
developed ‘an unusually high prevalence of upper respiratory symptoms seven to ten days
after [sibling] vaccination’. Despite the consistent pattern of these symptoms
occurring at a relatively discrete time point after sibling vaccination with live
measles virus, the authors suggested that the symptoms ‘might possibly be due to
intercurrent infection in the family and ‘not necessarily to the vaccination’. This statement
nonetheless, clearly acknowledges the possibility of horizontal transmission.
In summarizing the US studies, Katz and colleagues (8) reported that two other
investigating groups (6,9) ‘both commented upon the concomitant prevalence of cough and
coryza [typical features of measles] among unvaccinated controls’. The authors later
note that Lepow et al (9) and Haggerty et al (6) followed a total of 21
successfully vaccinated children who had ‘no evidence of disease when intimately
exposed in their homes a few weeks or months thereafter to siblings with natural measles’.
The possibility of a reverse causation – transmission from vaccinated to
6
susceptible sibling in the ‘few weeks or months’ following vaccination does not
appear to have been considered. As lead investigator in an experimental study
of measles vaccine in institutionalized children with mental deficiency (10) Katz
noted ‘absence of clinical signs of infection in susceptible contact controls and inability to
demonstrate inapparent infection of controls by alteration of serologic tests’. He concluded,
‘Accordingly, there seems to be little or no chance that attenuated measles virus would regain
virulence as a result of repeated passages from one human being to another’. Katz based
this conclusion on observations in a total of 2 susceptible ‘controls’.
None of the aforementioned findings provide direct evidence of horizontal
transmission. Nonetheless, a different complexion might be placed upon the
findings of these studies in a more objective search for evidence of possible
horizontal transmission.
Certainly, the lack of laboratory evidence for
transmission, limited by methodology and numbers, could not exclude its
occurrence. Since the availability of PCR, the potential for shedding of
measles vaccine virus in urine (11,12), nasopahrangeal aspirates, and nose
and throat swabs (11), for in excess of 3 weeks post-vaccination in some
instances (13), has become apparent.
Horizontal transmission of measles vaccine virus
As with rubella vaccine, the position on measles vaccine virus transmission has
shifted significantly. A review by Pütz et al draws attention to the implications
for the increasingly persuasive evidence of measles outbreaks originating in
vaccinated individuals, in limiting efforts towards global measles eradication
(14). These outbreaks consist of clade A virus infection (Figure 2a) occurring in
an atypical pattern. Clade A virus outbreaks, unlike those of wild-measles,
7
occur sporadically, are not geographically confined, and show virtually no
genetic diversity over time. In the laboratory, clade A viruses behave like the
vaccine virus and unlike most wild-type viruses in that they grow spontaneously
in Vero cells.
Unraveling the origins of clade A measles virus
Nucleotide sequence analysis of the different genes of measles virus has shown
that most variation occurs in the hemagluttinin (HA) and carboxy-(C) terminal
region of the nucleocapsid protein (NP). Sequence analysis of these two viral
genes from different viruses has provided a classification in which isolates are
separated into eight clades (A-H), each containing variations or genotypes (15).
This molecular epidemiology approach has enabled decoding of the genetic
signatures and hence, the origin of the respective clades. Clade A viruses, which
are virtually identical to the measles vaccine strain, bear vaccine strain signature
single nucleotide polymorphisms. In particular, the genetic consistency between
clade A isolates and derivatives of the progenitor Edmonston vaccine virus
occur in the HA (Figure 2b) and the C-terminal region NP genes. The history
of this discovery merits description in some detail if one is to appreciate the
significance of the findings.
8
Figure 2a. Phylogram of representatives of the 15 measles virus genome types
identified at present (5) along with 4 strains retrieved from sequence databases and
found not to fit into the 15 genome types of WHO (5)(Clade A highlighted). All
bootstrap values above 80% for major clusters are indicated (Adapted from 16).
9
Figure 2b. Phylogram of the 30 sequences of the HA-coding region retrieved from
the sequence databases showing the highest similarity to the HA sequence of the
Edmonston strain. All bootstrap values above 80% are indicated (Adapted from 16).
10
Some of the sentinel data emerged from a measles outbreak in Coventry in
mid-1993. Outlaw and Pringle described the characterization of 5 clinical
measles isolates, 2 of which came from children vaccinated with MMR, 2 cases
were unvaccinated and one case, a Chinese student, was of unknown
vaccination status (17). There was no obvious link or contact between the
cases. Their findings were summarized as follows: “Comparisons were made with the
Edmonston strain and the current MMR vaccine strain. It was found that a high degree of
homology existed between all strains examined, but that the majority of clinical samples
shared a premature termination signal – A to T substitution at nucleotide position 9019 that potentially shortened the haemagglutinnin (HA) protein by 35 amino acids”. None of
the changes found in the Coventry isolates matched any other isolate from the
UK or US. NP and Matrix (M) gene regions resembled vaccine strain virus
more than either of the two wild-type lineages circulating at that time in the
UK.
A 2002 Danish study reported on the characterization of 18 measles virus
strains isolated from a serum archive that antedated the institution of mass
vaccination in Denmark in 1987 (18). The considerable genetic diversity
exhibited by these wild isolates was ‘at odds’ with the prior assumption that one
genome type prevailed among globally circulating measles virus. Their data
indicated that, in contrast with the genetic diversity of wild-type isolates, the
similarity of vaccine strains could be attributed to their having derived from the
same primary (Edmonston) isolate compared with the relatively disparate
ancestry of wild-type viruses.
Specifically, vaccine strains and isolates of apparent vaccine ancestry all shared
four signature polymorphisms in the HA coding region, C72, T129, C826 and
11
Andy 9/6/10 7:33 AM
Deleted:
A1149, none of which were present in the contemporaneously circulating nonclade A strains. Elsewhere, a unique mutation introduced to the EdmonstonZagreb measles vaccine strain – A1451 – was also found in clinical isolates
including Leningrad-16, Changchun-47 and Changai-191 (19) and “in the Asian
type A field strains”, thus, as Christensen and colleagues suggest, “supporting the
hypothesis that Zagreb in the former Yugoslavia could have played a geopolitical role in
disseminating the Edmonston strain to Asia” (18). Continued, sporadic re-emergence
of ancient clade A genotypes is another possibility.
A further polymorphism - A351- documented exclusively in the Schwarz and
Edmonston-P9 vaccine strains, was identified in South African clade A field
isolates, where the Schwarz vaccine was used, but has not been recorded in any
clade A field isolate from Europe, Asia or the USA (21). Wairagkar et al
identified two clade A isolates in 11 measles virus-positive throat swabs
obtained from sporadic and outbreak cases in Pune, India during 1996-1998
(20). The NP-gene sequences of these isolates were identical to the
Edmonston-Zagreb strain used in India. One HA-gene sequence was identical
to the vaccine strain while the other differed by 4 nucleotides out of 1,854.
Neither case had any record of having been vaccinated. The authors concede
the possibility of these being either vaccine-associated measles or laboratory
contamination. Given the distinct HA-gene signatures, the latter explanation
seems unlikely. In the vaccine era, clade A measles virus has been detected
additionally, in acute cases of measles in South and North America, Japan,
Eastern Europe and Finland (22). During a 3-year investigation in Australia,
vaccine associated illness accounted for ten sporadic cases of clade A infection,
mainly but apparently not exclusively in symptomatic infants that were recently
12
vaccinated (13). Details of these other potentially important cases were not
provided by the authors.
Christenesn and colleagues concluded that “a small number of clinical manifestations
of measles virus worldwide from which strains similar to the vaccine strain were identified,
were vaccine related rather than being caused by members of a persistently circulating ancient
genome type” (18).
Rota and Bellini at the Centers for Disease Control and Prevention (CDC),
have contributed considerably to the genetic epidemiology of measles virus. In
commenting upon the earlier findings they referred initially, to the Coventry
isolates as ‘wild circulating measles virus of Type A’ (22). In reference to the stability
of group 1 (clade A) measles virus – then presumed to be ‘wild-type’ - they stated
that ‘it is very unlikely that [they] represent laboratory contamination or re-isolation of
vaccine virus from recently vaccinated persons’. They were to reverse this opinion,
presumably in light of the Danish, Indian, and other data, later describing the
formerly ‘wild’ clade A isolates as probable ‘vaccine viruses or laboratory contaminants’
(23). The latter explanation is highly unlikely, given the idiosyncrasies of the
sequence data and the pattern of associated outbreaks (17,20).
Transmission of measles vaccine virus is likely to be a real if apparently
uncommon occurrence, as least if the frequency of this event is judged by the
presentation of typical clinical measles infection in susceptible contacts and the
rigor of molecular sleuthing and reporting. However, neo-pathogenesis – the
emergence of a new clinical disease or syndrome, arising as a consequence of
vaccination and horizontal transmission - would be likely to escape detection
for some time. Early efforts to examine transmissibility of measles vaccine virus
13
were limited in their scope and sensitivity, given the lack of adequately
permissive cell lines and molecular detection technology at the time. A critical
review of the data indicates the possibility of horizontal transmission even in
the limited early trials (6-10). Moreover, study design did not account for (i) the
potential for delayed transmission from prolonged virus shedding by
immunosuppressed individuals (a factor of increasing concern) and (ii) possible
change in the route of transmission following injection rather than respiratory
contagion. Both of these factors and the potential for fecal transmission, in
particular, are of specific interest to some of those involved in the investigation
of children with autistic regression and bowel disease with onset following
MMR vaccination, issues that will be considered below.
Horizontal transmission: evidence from non-human primates
Measles infects non-human primates, reproducing key aspects of the human
disease including fever, rash, systemic lymphoid infection, immunodeficiency,
and induction of specific protective cellular and humoral immune responses.
Chen and colleagues described sporadic measles-associated colitis in captive
Tamarins (Saguinus mystax) following a measles outbreak in their colony (24).
Similarly, experience involving measles vaccination of captive Rhesus macaques
at the UC Davis colony identified a sporadic diarrheal disease with failure to
thrive and apparent behavioral disturbances [unpublished data]. Surgical
pathology of ileal and colonic tissues revealed an enterocolitis consistent with
moderate-to-severe human inflammatory bowel disease (Figure 3). TaqMan
RT-PCR analysis of gut tissues for measles virus Fusion (F) gene sequences was
positive in these animals (unpublished observations).
14
In describing experimental measles exposure in this same colony, McChesney
later wrote ‘In collaboration with the CDC we have tested several novel measles vaccines in
Rhesus monkeys. We have detected persistent measles virus infection by reverse transcriptase
polymerase chain reaction (RT-PCR) in the tissues of monkeys exposed to pathogenic measles
virus from six months to one year earlier. Tissues that were PCR-positive [for measles
virus] included peripheral lymph node, spleen and gut.’ (McChesney M, personal
communication) The ability of measles vaccine strains to establish persistent
infection of the intestine associated with pathologic change, appears to have
been confirmed in these preliminary studies.
Figure 3. Chronic active colitis in a Rhesus macaque, as described above. A dense
mononuclear cell and polymorph infiltrate is accompanied by crypt abscess
formation and distortion of crypt architecture (Hematoxylin and eosin; original
magnification x40).
Subsequently one of the authors [JL] helped investigate a pattern of disease in
one type of monkey at the Brookfield Zoo, Maywood, Illinois. The monkeys
15
were New World primates, Callimico goeldii, some of whom had received measles
vaccine prophylaxis. Previously thriving, the population of C. goeldii in
American zoos has been in decline since the 1990s, with mortality exceeding
natality. A retrospective tabulation of mortalities among animals > 1 year old
showed renal involvement. Nevertheless, a pattern of presentation, with
chronic diarrhea, failure to thrive and apparent, if somewhat poorly
characterized behavioral disturbances, was evident. This is of interest, given
reports of the propensity of New World primates to intestinal complications
following measles, with depression, loss of appetite, and high mortality (24). In
this unplanned, diagnostic study at Brookfield Zoo, tissues from affected
animals were submitted to pathologic and virologic examination. A number of
viruses were isolated from various primate tissues including a cytomegalovirus,
a retrovirus, and SV40 from kidney cells (25) and a different syncytium-forming
virus - not a retrovirus - from other tissues (Figure 4; unpublished). Microscopy
of diseased intestinal tissues revealed sporadic giant cell syncytia consistent with
viral involvement. The syncytium forming virus appeared to be a
paramyxovirus by electron microscopy.
This author [JL] suspected Canine
distemper virus (CDV), as CDV had been causing outbreaks of distemper among
area wildlife and had been transmitted to some animals in the zoo (26,27). Like
measles virus, CDV is also a morbillivirus. Contrary to popular belief, CDV can
infect primates (28) as well as certain omnivores (29). However,
immunohistochemistry using an antibody specific for CDV was negative, but
weakly positive with a CDV antibody that also cross-reacts with some other
morbilliviruses (including measles virus). Using a universal RT-PCR protocol
for morbilliviruses followed by sequencing, the virus was identified, to the
author’s disappointment, as measles virus, not CDV. Additional RT-PCR work
and sequencing identified Moraten measles vaccine-strain specific genomic
16
sequences. Subsequent molecular tests confirmed the presence of the same
measles virus strain in the monkey tissues. It is important to note that the
laboratory had not worked with measles virus previously. What was somewhat
unexpected in these studies is the fact that non-vaccinated cage mates of
vaccinated, diseased Callimicos manifested the same tissue pathology and the
same virologic findings as their sick, vaccinated cage-mates. Irrespective of any
role for measles virus in the intestinal pathology, the data provide direct
evidence of horizontal transmission. The implications for enteric spread in the
contaminated environment of cage mates with diarrheal disease associated with
shedding of a vaccine-derived virus and possible pathogen, are self-evident.
Figure 4. Syncytial cytopathic effect of Moraten-strain measles virus grown from the
tissue of Callimico goeldii in Vero cells culture at X weeks. Original magnification x100
17
Horizontal transmission: evidence from the field
The question of whether measles vaccine has become transmissible among socalled “virgin-soil populations” arose in connection with a measles vaccination
experiment conducted by the geneticist James Neel, among the Yanomami
Indians of Venezuela. In 1968, despite an apparent prohibition by the
Venezuelan government, Neel employed the most reactive of the early measles
vaccines - the Edmonston B - on the Yanomami (30). The results were
unexpected. He recorded the highest temperatures for any measles vaccine
among any population (31) Then a measles epidemic, of unknown origin,
spread in Neel’s words, “as a wave away from the original point” where the
vaccinations had occurred. And, “Within two months of the first case, measles had
developed in no fewer than 15 villages” (31). Steinvorth-Goetz, a physician and
anthropologist, described measles morbidity and mortality among the
Yanomami (32): “Many Indians fled deep into the forests, but for most of the people living
near the Orinoco it was already too late. They carried the disease germs with them, infecting
others and dying by the score. They had absolutely no resistance. Only a very few even
developed the characteristic rash, which is a sign of the skin’s fight to throw off the disease.
Mucous membranes became horribly inflamed, with extreme toxic vomiting and diarrhea.
Many had hemorrhaging of the inner walls of the larynx. Many developed pneumonia and
died from it. All too often even relatively mild cases failed to respond to penicillin.”
Although Neel claimed that a Venezuelan doctor, Marcel Roche, had diagnosed
measles in an anonymous Brazilian boy on the same day the expedition arrived,
mission records (33) and Neel’s own correspondence with Roche contradicted
the claim (34). In fact, sound records of the expedition, made by the filmmaker
Timothy Asch, showed that measles caught the expedition by surprise. Asch’s
audio tapes of the expedition, discovered by one of the authors (PT) and
18
witnessed by editorial staff at Science, suggest that expedition members
themselves, bewildered by the way the disease seemed to be springing up
everywhere around them, wondered whether the vaccine might be a cause (35).
The film of Neel’s Atomic Energy Commission-sponsored genetics – entitled
Yanomama: A Multidisciplinary Study – showed the residents of a village,
Patanowa-teri, being vaccinated against measles in order to prevent an
outbreak. The humanitarian goal was achieved, according to Neel, the film’s
narrator. “This village is fortunate”, he said. “It was vaccinated in time” (36). This has
since been refuted by an investigation by the American Anthropological
Association: “Of course we know now that measles did reach Patanowa-teri, causing many
deaths” (37). An independent investigation by the Venezuelan Congress found
that Yanomami survivors blamed the vaccine for the epidemic (38).
Is it likely, or even tenable, that villagers who had lived without epidemic
measles exposure but with regular outside contact, should first experience a
natural measles epidemic at precisely the same time and apparently, in precisely
the same place as it was first exposed to a measles vaccine capable of being
shed; furthermore, with the same pattern of subsequent spread as the
vaccination procedures.
Further questions about the role of vaccinated individuals in spreading measles
have been raised by researchers in the arctic, where, historically, identification
of measles carriers has been highly accurate (39).
The Scoresbysund district of Greenland represents an ideal area for the study
of measles vaccination; it is an isolated and relatively closed community that
has very little contact with the outside world. A measles vaccination program
19
for its 500 inhabitants, mainly Polar Eskimos, was conducted in 1967. Pedersen
et al reported that 94 percent of this population, which had never been exposed
to natural measles, was vaccinated using the Schwarz live further-attenuated
vaccine (40). Children born after 1967 likewise received measles vaccination. In
a subsequent study, Pedersen et al noted that a temporary increase in measles
antibodies occurred in the majority of those who were examined 2-4 years after
vaccination (41). This was not accompanied by clinically observed measles.
Pedersen suggests that this was most likely due to an inapparent measles
infection in a population considered highly immune after vaccination (41).
Based upon these observations and in the absence of any identified source or
carrier, Pedersen and his colleagues made the controversial suggestion that
“…measles can spread from a majority of vaccinated, to a minority of unvaccinated people,
causing overt disease” (41).”
Measles virus and neo-pathogenesis in human disease
From the foregoing human and non-human primate examples, transmission of
measles virus – specifically fecal-oral transmission - may be an important
alternative to classical respiratory portal, particularly in the context of measles
vaccination and a potential intestinal pathogen. It is of relevance, therefore, that
measles virus has been implicated in the cause of a number of chronic human
immunpathologies including inflammatory bowel disease (IBD) (42-49). While
the evidence is controversial (50-52), there is a body of data indicating that
atypical exposures to measles virus – younger age of infection (47,49) and
concurrent exposure to mumps virus (48,53,54) - are associated with an
increased risk of IBD. These findings are consistent with the knowledge that
early measles virus exposure is a major risk for acute and delayed adverse
20
outcomes, including persistent infection and chronic immunopathology, and
that ‘interference’ associated with concurrent viral exposures alters the antiviral
immune response (Reviewed by Wakefield and Montgomery, 54). Until
recently, however, persistent measles virus infection in intestinal tissues from
IBD patients had not been confirmed by RT-PCR based methods, a key factor
in any argument for persistence and the potential for enteric transmission.
In seeking to resolve the latter issue, one of the authors (AW) initiated a study
by Drs Ward and Seidman, working respectively at McGill University and St
Justine Children’s Hospital in Montreal, encouraging them to conduct RT-PCR
analysis of intestinal tissues taken from children with IBD and controls. The
rationale was that, if measles were associated with onset of IBD, it would more
likely be detected in children whose affected tissues were biopsied in closer
temporal proximity to their vaccine exposure, compared with adults presenting
20-30 years after measles or measles vaccination.
Ward subsequently presented the results of this study, describing the detection
of measles virus NP-gene sequences in 43% of IBD cases and 17% of nonIBD controls, (Ward BJ, MacFarlane S, Vinh D, Wild G, Seidman E.
Paramyxovirus transcripts in healthy and diseased bowel. N. Am Soc.
Microbiol. Reference not available). Of added interest was the identification of
an apparently novel paramyxovirus NP-gene sequence in one case. In addition
to presenting his findings to the American Society for Microbiology, Ward
communicated his findings to the Oak Brook meeting on autism and
vaccination, convened by the American Academy of Pediatrics (56) and was
apparently encouraged to publish them in full by the organizing committee. He
has declined to publish the data on the basis that, ‘the differences between cases and
21
controls did not achieve statistical significance’. Ward’s reasoning was also confirmed
on a separate occasion by his co-worker Dr Seidman (personal communication
to Professor John Walker-Smith, then at the Royal Free Hospital School of
Medicine).
The fact that the statistical difference in a relatively small sample achieved a p
value of 0.07 is relatively trivial in comparison with the potential biologic
significance of establishing, for the first time and in the face of prevailing
dogma, persistence of vaccine strain virus in diseased and control intestinal
tissues.
The data, while in the public domain, remain unpublished as a full scientific
paper. This notwithstanding, preliminary data from the analysis of pediatric
bowel tissues indicate the potential for persistent measles virus infection
following vaccination, consistent with McChesney’s findings in the Davis
macaques.
Neo-pathogenesis: autistic enterocolitis and MMR vaccine
Autism spectrum disorders (ASDs) are a complex set of developmental
disorders of childhood, characterized by pervasive impairments in social
interaction; deficits in verbal and non-verbal communication and stereotyped,
repetitive patterns of behavior and interests. Manifestations frequently begin
within the first three years of life. The prevalence of ASD diagnoses has
increased substantially over the last several decades in developed countries
(57,58). The etiologic origins of this epidemic are not known but must involve
a major environmental contribution.
22
Recognition of a viral etiology in autism is not new. Indirect clues come from the
observation of factors such as a season-of-birth effect in different countries (5963). This phenomenon appears to have disappeared from more recent birth
cohorts (64), a trend that may reflect an historical pattern of epidemic infectious
exposure that has changed in more recent years.
Atypical patterns of exposure to measles, mumps, and rubella viruses, in their
natural form, have been linked to childhood developmental disorders, including
autism (65,66) and disintegrative disorder (67). Measles-containing vaccines have
been causally linked to developmental regression (68).
Ring et al modeled the number of autism births with epidemics of measles, rubella,
poliomyelitis, viral meningitis and viral encephalitis. Children born during
epidemics of measles and viral meningitis were at significantly greater risk of
developing autism (66). While measles may have accounted for a relatively modest
number of cases in this historically rare condition, transition to a high risk pattern
of exposure may have changed this.
A possible association between MMR vaccination and autistic regression in
previously developmentally normal children has recently been reported (69,70).
The evidence for this link is controversial, reflecting the widely differing
conclusions of basic and clinical science versus epidemiology. The background to
this phenomenon merits description if one is to appreciate the possible
implications for neo-pathogenesis and horizontal transmission.
Age of exposure
As documented earlier, younger age of exposure to measles
virus is associated with an increased risk of adverse outcome, including persistent
23
infection and delayed disease. Is there evidence for such a risk in autism? A recent
epidemiologic study by Richler et al posed the question of whether there is an
autism phenotype characterized by regression associated with significant GI
symptoms (one or more symptoms lasting for more than 3 consecutive months)
following MMR vaccine in a previously developmentally normal or near-normal
child (71). Children meeting these criteria were compared with all other autistic
children in their study cohort. In this, the only epidemiologic study to at least
attempt to segregate this sentinel autism phenotype, age-of-exposure to MMR
vaccine was significantly lower (mean age 14.38 months) when compared with the
remaining autistic population (mean age 17.71 months; p<0.05). By limiting their
‘regression’ group to those children who had a skill at 24 months that was
subsequently lost, thus excluding all children who regressed between 12 and 24
months (the majority of the relevant population), the true extent of the age-ofMMR-exposure phenomenon will potentially have been masked. Strangely - and
at odds with their own reported findings - the authors concluded that, ‘there was no
evidence that onset of autistic symptoms or of regression was related to MMR vaccination’.
Three further aspects of age-of-exposure to MMR and autism have been reported:
DeStefano and colleagues performed a case-control study comparing age at first
MMR vaccination in children from the Atlanta metro area (72). By 36 months of
age, significantly more cases with autism (93%) had received MMR than controls
(91%)(Odds Ratio 1.49; 95% confidence interval [CI] 1.04-2.14). This association
was strongest in the 3 to 5-year age group with an Odds Ratio of 2.34. Due to
diagnostic delay, a significant proportion of this group had yet to be diagnosed
with autism, potentially underestimating this risk.
Moreover, in a subgroup
analysis looking at children with different disease characteristics, they found a
significant association between MMR vaccination by 36 months and autistic
24
children with no evidence of mental retardation (IQ>70; OR 2.54 [1.20-5.00]).
The odds ratios were increased to 3.55 in a subgroup analysis adjusted for birth
weight, multiple gestation, maternal age and maternal education, thus
strengthening the association between age-of-exposure to MMR and autism. It is
interesting that their ‘regressive group’ did not show this effect although the
interpretation of this finding is severely constrained by their retrospective
ascertainment of regression from medical records. First, regression did not form
part of the diagnostic algorithm for autism and second, the concept of regression
conflicted, until very recently, with the beliefs of most autism diagnosticians. IQ,
on the other hand, is an objective measure and a normal IQ appears to be an
increasingly common feature among recent cohorts of affected children (73). An
IQ within the normal range may well reflect a period of normal cerebral
development and in this instance, be a better marker of the late-onset phenotype
than retrospective record review. Having tested a hypothesis and found a
significant association between autism and age of first MMR exposure, the
authors, somewhat curiously, ascribe this effect to an ‘artifact of immunization
requirements for pre-school special education attendance in case children’. Such an
interpretation would only possibly be valid if the immunization mandate for
normal pre-school children were different from that of special education children;
it is not. Moreover, the special education group, with a likely excess of
contraindications to MMR vaccination such as seizures, should have a lesser
exposure to MMR. In addition, if there were no true association, lower exposure in
the special education group would be expected in light of higher levels of parental
concern and consequent rates of abstention in this group, a possibility that could
have been easily checked by comparing the proportions of exemption filings held
by law in all state schools. This notwithstanding, the data of DeStefano et al are
not consistent with the author’s post hoc rationalization.
25
Second, Edwardes and Baltzan (74) reanalyzed the California autism data of
Dales and colleagues (75) who had reported that there was "essentially no
correlation'' between rates of autism and measles-mumps-rubella (MMR) vaccine
uptake. Nonetheless their data showed that the age of immunization was
becoming younger between 1981 and 1993 (a factor of potential relevance to
DeStefano et al’s observations of a statistically more significant association
between autism and earlier MMR vaccination in more recent birth cohorts
(72)). Edwardes and Baltzan plotted the ratio of children immunized before age
17 months with those immunized between age 17 and 24 months. This ratio
increased 200% from 1981 to 1993. The data suggest that the rate of early
MMR immunization is correlated with the incidence of autism. Dales and
colleagues acknowledged in their response that, ‘these data do indicate a temporal
trend toward MMR vaccine receipt at younger ages’ but pointed out the
disproportionately low magnitude of rise in MMR vaccine coverage of young
children compared with the approximately 400% relative increase in the
incidence of autism (76). The latter argument, which appears to imply the
assumption of some simple mathematical relationship between age and risk,
may not be appropriate and is less important than the potential impact of a
shift, at the population level, towards a possible high-risk pattern of exposure,
that is, younger age. Such a risk, normally distributed by age, could account for
a substantial and apparently disproportionate increase in cases with
progressively earlier MMR exposure.
In addition, what these authors also failed to take into account is the potential
impact of booster MMR vaccination that, according to recent data on rechallenge with MMR (77), might lead to a substantial impact on the disease and
thus, the numbers of children meeting full syndrome autism (as a requirement
for registration in the California Developmental Disorders System, 73).
26
Third, Suissa pointed out that according to the Danish data of Madsen et al the
rates of autistic disorder by age at MMR vaccination, are 18.9, 14.8, 24.6, and
26.9 per 105 per year respectively for ages <15, 15-19, 20-24, 25-35, falling to
12.0 per 105 with age at vaccination >35 months, compared with the overall
rate of 11.0 for the reference group of no vaccination, over all ages (78,79).
Suissa considered it somewhat implausible for the age-adjusted rate ratio to fall
below 1 (as presented), unless the risk profile by age in the unvaccinated is
vastly different than in the vaccinated. Thus, rather than an apparent
association between exposure and outcome being a spurious result of
confounding, this would actually represent effect modification. The data
support the hypothesis of an association between exposure and outcome,
modified, rather than confounded by, age of exposure.
While an effect of age of exposure to MMR vaccine on autism risk is evident
from these studies, the nature of that risk is not known.
Evidence of viral pathogenesis
In considering the potential role of
measles virus, an enterotropic virus capable of producing profound immune
disruption, in the etiology of a regressive autistic encephalopathy, it is evident that
affected children have a high frequency of GI symptoms (80,81). Investigation of
these symptoms has provided substantial reproducible evidence for GI and
immune system pathology (82-90). Such findings may have important implications
for mode of horizontal measles virus transmission.
Briefly, the mucosal lesion consists of a patchy, mild to moderate pan-enteric
inflammation with lymphoid nodular hyperplasia and is consistent with a viral
etiology. Within the mucosa there is an increased CD3+ and CD8+ T-cell density,
IgG and complement C1q co-localization at the epithelial basolateral membrane,
27
suggestive of autoimmunity. This is accompanied by marked pan-enteric immune
dysregualtion with excess CD3+TNF-α, CD3+INF-γ, and Th2 cytokines, and a
reduced counter-regulatory IL-10 (91,92). These changes are largely mirrored in
the spontaneous peripheral blood CD3+ lymphocyte cytokine profile of affected
children, and in the induced cytokine production by peripheral blood
mononuclear cells in response to lipopolysacharride, phytohemagluttinin and
dietary antigen exposure (93-95). These changes are frequently accompanied by
lymphopenia in both CD4+ and CD8+ populations (87). Consistent with allergic
predisposition, IgA is usually in the lower quartile of the normal range (87).
Differentiation status of circulating CD8+ lymphocytes indicates an overrepresentation of the chronically activated/exhausted CD38+CD28-CD27phenotype (96), consistent with a persistent viral infection (unpublished data).
It is likely that reported physiologic GI dysfunction in many affected children,
including impaired brush border enzyme activity (83), dysbiosis (97-99),
permeability changes (100,101), oxidative stress (102), and elevation of systemic
markers of inflammation (103), are a reflection of this underlying mucosal
immunopathology. Moreover, given the ability of inflammatory cytokines to
modulate neuronal survival (104) and differentiation (105), as well as dendrite
growth and complexity (106), a role for the mucosal immunopathology – possibly
as a primary event – in the pathogenesis of neurologic injury and autism is
plausible. This scenario is supported by both the experimental data of Welch et al
showing that a primary inflammatory bowel disease can lead to immediate-early
(Fos) gene activation in the brain in those areas involved in autism (107) and the
observation that systemic immune activation can modulate microglial activation
status (108). Immunohistochemical evidence of microglial activation in proximity
to neuronal loss, has recently been reported in post-mortem autistic brains (109).
28
The aggregated findings are consistent with a persistent viral pathogenesis, in
particular with a virus capable of producing substantial immune disruption.
Autistic enterocolitis exhibits a striking overlap with human immunodeficiency
virus (HIV) enteropathy, features of which include inflammation and LNH in
which the hyperplasic lymphoid follicles are a nidus of HIV infection.
Viral detection: In light of clinical histories and pathologic findings, and the
recognized enteric (110) and immunologic effects of measles virus (111), viral
RNA and protein were sought in the reactive ileal lymphoid follicles.
Analysis of ileal lymphoid tissues from affected children and developmentally
normal pediatric controls, was conducted with well characterized specific
antibodies against measles virus, including WHO reference monoclonal
antibodies, mumps, rubella, HSV I & II, HIV and adenovirus (112). A
characteristic pattern of staining for measles virus was observed in the tissues of
some affected children at a significantly higher rate than developmentally normal
pediatric controls. The staining pattern was consistent with the follicular dendritic
cell (FDC) matrix, as seen in HIV infection. Similar staining for other viruses was
not seen. Measles virus Fusion (F) gene genomic RNA was identified by TaqMan
RT-PCR in 75 (82%) of 91 children with ASD and 5 (7%) of 70 developmentally
normal controls, confirming an association between the presence of measles virus
and gut pathology in children with developmental disorder (113). In seeking to
determine strain specificity, O’Leary and colleagues developed an allelic
discrimination (AD) assay, based upon the data of Parks et al. (114), that exploits
an A to C base-change from Edmonston wild-type to Edmonston-derived strains
at position 7901 in the HA-gene resulting in a predicted serine to glycine
29
substitution at amino acid position 211 of the measles virus. In this way, all 50
HA-gene amplicons obtained from affected children were shown to be consistent
with the vaccine strain (115).
Several of the authors (SW & AK) have sought to replicate these findings in an
independent population of children with a similar constellation of GI and
developmental symptoms (116). All children had received MMR vaccine as their
only documented exposure to measles virus. Ileal biopsy tissue was assayed by
nested RT-PCR for the presence of measles virus RNA and PCR-positive
samples were sequenced. Analysis of initial 82 patients showed that 70 (85%)
were positive for the F-gene amplicon. Fourteen had been verified by DNA
sequencing which was pending for the remaining amplicons at the time of
publication. Preliminary results from this large cohort of pediatric autistic
patients with chronic GI symptoms confirm earlier findings of measles virus
RNA in the terminal ileum and support an association between measles virus
and autistic enterocolitis.
While presence of viral RNAs in diseased tissue is not proof of causation, its
absence is not proof of lack of causation. Samples are taken, often many years
after MMR exposure and autistic regression has occurred; neurologic injury
may be effected within a critical window of viral presence. In support of this, a
recent report has shown a statistically significant association between recovery
of cognitive skills and absence of measles virus RNA in ileal lymphoid biopsy
and therefore, possible viral clearance (117). Ref needs to go in
Viral serology
In a series of studies of similarly affected children from the
US, Singh et al. have identified quantitative and qualitative differences in the IgG
30
antibody response to measles virus (70,118,119) compared with developmentally
normal populations. Anti-measles virus IgG antibody levels are significantly higher
in the blood of affected children compared with developmentally normal children
of the same age, and sibling controls. This was not the case for IgG antibodies
against rubella virus and mumps virus. In addition, immunoblotting studies
identified a specific IgG antibody response in 80 per cent of affected children to a
74kD protein antigen from the measles virus HA-protein derived from the MMR
vaccine that was not detected in any controls.
In children examined in a UK pediatric clinic, serum IgG immunoreactivity for
measles virus was significantly elevated in autistic children referred with GI
symptoms, compared with children of a similar age; mumps, rubella and
cytomegalovirus IgG antibody titres were not similarly elevated (120).
The data confirm an association between measles virus and GI pathology in some
children with developmental disorder, particularly regressive autism. The presence
of the virus may reflect a bystander effect due to sequestration of measles virus in
foci of activated lymphoid tissue, although this is unlikely, due to its absence from
inflamed pediatric control tissues. In view of the presence of both measles virus
antigen and genomic RNA in reactive lymphoid tissues, it is also unlikely that the
observations indicate long term trapping of viral antigen by FDC, as part of a
normal immunological process. The interpretation of the findings in mucosal
biopsies is not mitigated by failure to identify measles virus in peripheral blood
mononuclear cells (121). Needs to go in.
31
The data indicate that the intestinal mucosa may be a source of persistent infection
and hence possible shedding of measles virus. Is there any evidence for the latter
occurring in the context of autistic enterocolitis?
Horizontal transmission: further evidence from autistic enterocolitis
Further evidence of horizontal transmission of measles vaccine virus has come
from several sources. We are aware of an increasing number of siblings of
children affected by autistic enterocolitis, onset of which followed MMR
vaccine exposure. For reasons of parental concern, these siblings did not
receive MMR or any other measles-containing vaccine; nor did the sibling have
any documented exposure to natural measles. These siblings are, however,
seropositive for measles, often at high titer and on repeated measurement.
Some suffer GI and/or behavioral symptoms while others are asymptomatic.
Given the wide geographic distribution of these cases and lack of any other
mode of exposure, it is likely that these children were infected horizontally
from their vaccinated autistic sibling.
Further evidence in support of this observation has come from a large
preliminary study by one of the authors [PA] who has conducted a large
serological analysis of IgG titers to vaccine exposures (measles, mumps, rubella,
diphtheria, tetanus, and pertussis) and natural viral exposures (cytomegalovirus,
and influenza A and B) (122). Importantly, study populations were segregated
into: children with an autistic spectrum disorder, their siblings, unrelated
general population controls, and developmentally normal children with atopic
disease. Consistent with the observations elsewhere of immunodeficiency in
the autistic population, total IgG, IgA, and IgM titers were significantly
decreased in ASD children compared with the other groups. In the study as
32
presented (following correction of the data presented initially in the abstract)
Antibody titers to all antigens except measles and rubella were significantly
lower in the ASD children compared with other groups, a finding that may
reflect the low total serum IgG in these children. Paradoxically, measles and
rubella IgG titers were significantly greater in the ASD children, despite low
total IgG, compared with the general population and atopic disease control
groups. The data provide independent support for the observations of Singh
and colleagues. Crucially, and in contrast with the general population pediatric
controls, measles virus IgG titers in unaffected siblings were very similar to the
ASD population.
There are several explanations for these findings, including a similar geneticallydetermined antibody response to the vaccine between affected children and
their siblings. Alternatively, the data are consistent with antibody boosting
following re-exposure of the siblings through episodic horizontal transmission
from affected siblings. The findings are consistent with the phenomenon of
antibody boosting following subclinical exposure, based upon similar
observations of Pederson et al in Greenland natives (38).
Molecular evidence of horizontal transmission in autistic enterocolitis
As part of a viral replication study of autistic enterocolitis, performed by two of
the authors (AK and SW) measles virus genomic RNA was identified in the
ileal lymphoid tissue of an MMR-vaccinated child with onset of autistic
regression following vaccination.
This child was found to have mucosal
pathology consistent with autistic enterocolitis.
Their younger sibling was
unvaccinated, had no documented exposure to natural measles, and yet
suffered from an ASD and GI symptoms. RT-PCR analysis of this child’s ileal
33
lymphoid tissue similarly revealed the presence of measles virus RNA. This
sentinel case provides clear evidence, not only of horizontal transmission of the
vaccine virus, but also indicates the possibility of the emergence of a gutadapted pathogenic variant.
Implications for neo-pathogenesis, epidemiologic predictions and
disease phenotype
Compared with the typical pattern of natural exposure, infants are now
exposed to measles virus by a different route, using a different strain, and at a
different mean age and intensity compared with their ancestors. The additional
implications of viral interference for increasing risk of persistent infection and
delayed disease in combination vaccines, is not known. Concern is raised at the
possibility that neopathogenesis – persistence of the virus in intestinal tissues
associated with an emergent chronic immunopathology – may be one result.
Once horizontal transmission has started there is no model – since there are no
data- that enables prediction of the impact upon measles infection or associated
rates of conditions such as autistic enterocolitis. The potential for shedding and
horizontal transmission of a gut-adapted pathogenic clade A measles virus
would make redundant, published epidemiologic efforts to examine risk and
associations based upon records of vaccine exposure (79,123) or temporal
trend analyses comparing autism rates with MMR uptake at the population
level (124-126). At the very least, serologic analysis of unvaccinated populations
would be necessary in an effort to assess exposure status. This, too, may be
imperfect if horizontal transmission occurs in infants protected by maternal
immunity in whom there is consequent failure of seroconversion.
34
Caution would also be necessary in phenotyping of, for example, subpopulations of autistic individuals. The recognition of developmental traits
such as ‘early-onset’ and ‘regressive autism’, is starting to influence perception
of how investigation of distinct autism subsets, with presumed differences in
etiology, might advance research into understanding cause. Such a perception
will be of limited merit if transmission from an affected child who regressed
after MMR vaccination, is subsequently able to shed pathogenic measles virus
to a younger close contact who then acquires the disease at an age that classifies
him as ‘early onset autism’.
Siblings are not controls
Given the potential for transmission to close personal contacts, siblings whether healthy or symptomatic - cannot be considered controls in studies that
examine aspects of disease pathogenesis and etiology that may be related to, for
example, measles virus exposure and its potential immunologic and other
consequences. Interpretation of hereditability studies will need to be modified,
taking into account the potential for transmission of a possible causative agent
from older siblings in particular, combined with the lower chance of disease
expression in female pairs of mixed-sex twin pairs. The latter issue would be
relevant to the interpretation of disease concordance in monozygotic versus
dizygotic twins.
Implications for surveillance, control, and eradication of measles virus
Measles control strategies are based upon the assumption that measles virus
transmission occurs in chains of transmission of clinically recognizable measles
cases (127). As such, surveillance is limited to the identification of persons
meeting the case definition of measles, that is, generalized maculopapular rash
35
lasting for 3 or more days, a fever of 38.3oC or higher, and cough, coryza or
conjunctivitis (128). However, the occurrence of measles virus infections in
persons without classical measles (including, therefore, the majority of
vaccinees) may play an important role in the transmission if measles. Serologic
evidence of acute measles has been documented among people who are
exposed to measles virus but do not develop classical symptoms (128-136).
This phenomenon has been observed most frequently in highly vaccinated
populations with rates of infection of 4%-42%.
Liveano et al referred to these cases as ‘inapparent’ measles infections, a
nomenclature that is adopted here, and raised the issue that such infections
could be epidemiologically important if infected persons are capable of
transmitting measles virus (127). However, they failed to recognize that
inapparent measles infection may include not only asymptomatic and minimally
symptomatic disease, but also neo-pathogenetic disease symptoms that fall
outside the case definition, such as the diarrhea associated with autistic
enterocolitis. The authors consider that respiratory contagion is a “presumed
requisite for transmitting the virus”. This makes little sense for vaccine virus
transmission, since subcutaneous injection bypasses the initial phase of viral
replication and shedding in the respiratory tract. Some of the authors have
documented urinary shedding of both wild-type and vaccine virus, and fecal
shedding does not appear to have been examined.
Liveano et al sought to establish whether persons with inapparent measles –
based upon serum IgM response on days 12-16 following known exposure to a
measles case – were capable of subsequent shedding of virus in urine and
nasopgarangeal swabs (127). Eight percent of 133 exposures with inapparent
36
measles exhibited a diagnostic IgM response. Duration of exposure of 3 hours
or more was the only significant risk factor for developing a positive serologic
response, where the positive rate rose to 24%. Virus was not recovered by
culture or RT-PCR in any of those with inapparent infection.
While these findings provide some reassurance that some persons with
inapparent infection do not subsequently shed virus during the limited
observation period, it is apparent that the great majority, if not all, of the
contacts were already immune to measles. As such, their secondary immune
response would have been a major impediment to viral replication and
shedding. The findings, therefore, bear little relevance to the potential for virus
shedding in non-immune contacts, such as unvaccinated infants, who develop
inapparent measles, whether asymptomatic or neo-pathogenic. In the case of
the latter, the data indicate that children with autistic enterocolitis are capable
of shedding measles vaccine virus. Those exposed, such as siblings, are
inevitably in contact for well in excess of the 3 hour ‘intensive exposure’ window
reported by Liveano et al, and therefore at considerable risk of infection.
Persistent infection and waning immunity
The possibility that measles outbreaks may occur from a point source such as
persistently infected individual in whom immunologic surveillance has failed,
either due to waning of vaccine-induced immunity over time, or intercurrent
immunodeficiency, for whatever reason, is a concern shared by Pütz et al (14).
This may become increasingly important in acquired immunodeficiency states
such as HIV, and the setting of organ, bone marrow, and stem cell
transplantation. The associated immunodeficiency in children with autism and
autistic
enterocolitis,
in
particular,
with
immunoglobulin
deficiency,
37
lymphopenia, impaired NK cell cytotoxicity (137 & Vojdani A et al;
unpublished data), and possible cytotoxic T-cell exhaustion, may provide a
reservoir of individuals capable of initiating such outbreaks.
Horizontal transmission of measles vaccine virus is a serious threat to efforts at
global measles eradication. Mathematical modeling has suggested that
eliminating measles would be impossible if measles virus can be transmitted in
the absence of classical measles disease (138). This was considered to be the
case even though the model of Mossong et al did not take account of a neopathogenetic source of transmissible virus. Pütz et al observe that, ‘in the final
stages of an eventual measles elimination program, the reintroduction of a circulating vaccine
strain which has (partially) lost attenuation could be a serious threat’ (14). While the
meaning of ‘an eventual measles eradication program’ is somewhat obscure, it is clear
that such an intention would be thwarted by the emergence of horizontally
transmitted vaccine virus.
Why this concern should be confined to the
eventual stages of such a program is not clear.
Conclusion
This review has taken the position that: outbreaks of likely vaccine-associated
measles virus occur; measles-containing vaccine exposure is associated, in some
children, with neo-pathogenesis – particularly enterocolitis that may be
associated with an autistic encephalopathy; and that horizontal transmission of
measles vaccine virus may operate in both the affector and effector paths of
this neo-pathogenetic process. Evidence for these processes is emerging in
both human and non-human primate settings. Confirmation of such horizontal
transmission and neo-pathogenesis would send epidemiologists back to the
drawing
board.
The
implications
of
horizontal
transmission
and
38
neopathogenesis for measles surveillance, control, and eradication are farreaching.
This above perception will be considered to be controversial. However, the
data indicate that reliance can no longer be placed on the position taken
obversely, by Katz and colleagues in their dismissal of indications of horizontal
transmission in early clinical trials. In the inevitable schism of bias there is a
lesson to be learned: in the crucial issue of vaccine safety, particularly as more
and more vaccines are queued-up for licensing and inclusion in mandatory
vaccine programs, responsibility for evaluation, interpretation and both short
and long term monitoring of vaccine safety issues should fall wholly under the
jurisdiction of an independent agency. This agency should be completely
devolved in terms of accountability, resourcing, and oversight, from those
agencies and interests responsible for soliciting, funding, endorsing, and
profiting from, vaccines. The new agency should permit no conflict of interest
internally. Only in this way will the concerns of the consumer and the long
term interests of public health start to be best-served.
Key words: autism, autistic enterocolitis, fecal transmission.
Acknowledgements: This work was funded by the Johnson Family
Foundation and The Ted Lindsay Foundation.
Disclosures: AJW, AK and PA have acted as paid experts in MMR-related
litigation. AW in a named inventor of two viral diagnostic patents.
39
References
1. Rota JS, WangZ-D, Ota PA, Bellini WJ. Comparison of sequences of the
H, F and N coding genes of measles virus vaccine strains. Virus Research
1994, 31:317-330
2. Millson DS. Brother-to-sister transmission of measles after measles,
mumps, and rubella immunization. Lancet. 1989, Feb 4th :271
3. Campbell AGM. Brother-to-sister transmission of measles after MMR
immunization. Lancet. 1989, Feb 25th:442
4. Swada H, Yano S, Oka Y, Togashi T. Transmission of Urabe mumps
vaccine between siblings. Lancet 1993, 342;371
5. Yazbak FE, Diodati CJM. Postpartum live virus vaccination: lessons
from veterinary medicine. Med Hypotheses. 2002, 59:280-282
6. Haggarty RJ, Meyer RJ, Lenihan E, K.atz SL. Studies on an attenuated
measles-virus vaccine. VII. Clinical, antigenic, and prophylactic effects
in home dwelling children. NEJM 1960, 263:178-180.
7. Smith W, Evans DG, Gaisford W, Stuart-Harris CH, Stevenson-Logan J,
McCarthy K, Miller CL, Moncrieff A, Sutherland I, Thomson D, Watson GI,
Wilson G, Perkins FT. Vaccination against measles: a study of clinical
reactions and serological responses of young children. BMJ. 1965, 1:817823.
40
8. Katz SL, Kempe HC, Black FL, Lepow ML, Krugman S, Haggerty PJ,
Enders JF. Studies on an attenuated measles-virus vaccine: VllL General
summary and evaluation of the results of vaccination. NEJM 1960,
263:180-184.
9. Lepow ML, Gray N, Robbins FC. Studies on an attenuated measles-virus
vaccine. V. Clinical, antigenic and prophylactic effects of vaccine in
institutionalised and home-dwelling children. NEJM 1960, 263: 170-173.
10. Katz SL, Enders JF, Holloway A. Studies on an attenuated measlesvirus vaccine. II. Clinical, virologic and immunological effects of vaccine
in institutionalized children. NEJM. 1960, 263:159-162.
11. Rota P.A, Khan, A.S, Durigon E, Yuranm T, Villamarzo Y.S, Bellini W.J,
1995. Detection of measles virus RNA in urine specimens from vaccine
recipients. J. Clin. Microbiol. 1995, 33: 2485-2488.
12. Jenkin GA, Chibo D, Kelly HA Lynch P, Catton MG. What is the
cause of a rash after measles-mumps-rubella vaccination? Med J of
Australia 1999, 171;194-195.
13. Chibo D, Riddell M, Catton M, Lyon M, Lum G, Birch C. Studies of
measles viruses circulating in Australia between 1999 and 2001
reveals a new genotype. Virus Research 2003, 91:213-221.
41
14. Pütz MM, Bouche FB, de Swart RL, Muller CP. Experimental vaccines
against measles in a world of changing epidemiology. Int J Paristol. 2003,
33:525-545.
15. WHO, 2001. Nomenclature for describing the genetic characteristics
of wild-type measles viruses. Weekly Epidemiological Record 2001,
76:241-247.
16. Rota PA., Rota JS., Bellini WJ. Molecular Epidemiology of Measles
Virus. Seminars in Virology. 1995, 6:379-386
17. Outlaw MC, Pringle CR. Sequence analysis within an outbreak of
measles virus in the Coventry area during spring/summer 1993. Virus
Research. 1995, 39:3-11.
18. Christensen LS, Scholler S, Schierup MH, Vestergaard BF, Mordhurst CH.
Sequence analysis of measles virus strains during the pre- and earlyvaccination era in Denmark reveals considerable diversity of ancient
strains. APMIS 2002, 110:113-122.
19. Mulders, M. N., and C. P. Muller. Molecular epidemiology in measles
control. In, The Molecular Epidemiology of Human Viruses, In Thomas
Leitner (ed.). Kluwer Academic Publishers. Boston MA. 2002 pp. 237-272.
20. Wairagkar N, Rota PA, Liffick S, Shaikh N, Padbidri VS, Bellini JB.
Characterization of measles sequences from Pune, India. J. Med Virol.
2002, 68:611-614.
42
21. Riddell MA, Rota JS, Rota PA. Review of the temporal and geographical
distribution of measles virus genotypes in the pre-vaccine and postvaccine eras. Virology Journal. 2005, 2:87-92
22. Bellini WJ, Rota PA. Genetic diversity of wild-type measles viruses:
implications for global measles elimination program. Emerging Infectious
Diseases. 1998, 4:1-15. http://www.cdc.gov/ncidod/eid/vol4no1/bellini.htm
23. Rota PA, Bellini WJ. Update on the global distribution of genotypes of
wild type measles virus. J. Infect. Dis. 2003, 187:S270-S276.
24. Chen P, Miller GF, Powell DA. Colitis is a female tamarin (Saguinus
mystax). Contemporary Topics: American Association of Laboratory Animal
Scientists. 2000, 39:47-49.
25. Zdziarski JM, Sarich NA, Witecki KE, Lednicky JA. Molecular Analysis
of SV-40-CAL, a New Slow Growing SV-40 Strain from the Kidney of a
Caged New World Monkey with Fatal Renal Disease. Virus Genes 2004,
29:183-190.
26. Lednicky JA, Meehan TP, Kinsel MJ, Dubach J, Hungerford LL, Sarich
NA, Witecki KE, Braid MD, Pedrak C, Houde CM.
Effective primary
isolation of wild-type Canine distemper virus in MDCK, MV1 Lu and
Vero cells without nucleotide sequence changes within the entire
haemagglutinin protein gene and in subgenomic sections of the fusion
and phospho protein genes. J Virol Methods. 2004, 118:147-157.
43
27. Lednicky JA, J. Dubach TP, Meehan MJ, Kinsel M, Bochetta LL,
Hungerford NA, Sarich KE, Witecki MD, Pedrak CB, Houde CM.
Genetically distant American Canine distemper virus lineages have
recently caused epizootics with somewhat different characteristics in
raccoons living around a large suburban zoo in the USA. Virol. J. 2004, 1,
2 (volume 1, article 2).
28. Yoshikawa Y, Ochikubo F, Matsubara Y, Tsuruoka H, Ishii M, Shirota K,
Nomura Y, Sugiyama M, Yamanouchi K. Natural infection with canine
distemper
virus
in
a
Japanese
monkey
(Macaca
fuscata).
Veterinary Microbiology. 1989, 20:193-205.
29. Appel MJ, Reggiardo C, Summers BA, Pearce-Kelling S, Mare CJ, Noon
TH, Reed RE, Shively JN, Orvell C: Canine distemper virus infection and
encephalitis in javelinas (collared peccaries). Archives of Virology 1991,
119:147-152.
30. Hernádez JR, Casey H. Investigación con una Vacuna Diluida Contra el
Sarampión Segundo Informe. Caracas. 1967
31. Neel JV, Centerwall WR, Chagnon NA, Casey HL. Notes on the Effect of
Measles and Measles Vaccine in a Virgin-Soil Population of South
America. AJE 1970, 91:422.
32. Steinworth-Goetz I, Amild U. Life and belief of the forest Waika in the
Upper Orinoco. Translated by Furst P. Caracas: Asociacióm Cultural
Humboldt, 1969: p.56
44
33. The Mavaca Nun’s Chronicle (1968: January 24) states that the doctors of
the Venezuelan Institute of Scientific Investigation, which included Marcel
Roche, the doctor in question, diagnosed pneumonia. in Tierney P., “The
Fierce Anthropologist,” The New Yorker, October 9, 2000.
34. “It is very difficult for me to give you a reasonable comparative clinical
impression of the young Brazilian I saw at Ocamo. There is no question that he
was very sick; he kept a temperature in the vicinity of 400C for more than a
week, he obviously had bronchopneumonia and he was prostrated. He was
approximately 14 years old.” Marcel Roche, letter to James Neel, April, 1968.
35. Mann C, Anthropological Warfare. Science 2001, 291:416-421.
36. Neel JV, Asch T, Chagnon N. Yanomama: A multidisciplinary study.
(43 min video documentary) Washington D.C. Department of Energy, 1971.
37. Hill J. ‘Tierney’s use of the Asch sound tapes as evidence’, in El Dorado
Task Force papers Vol II. Virginia: American Anthropological Association,
2002, p. 139.
38. “As a representative of the community I want to give my word so that you
know what has happened with the anthropologists---that is, the real truth.
….Our people did not know how to speak well and did not understand
anything that was happening and what they were doing with the people. They
believed they were doing good to the people, but, on the contrary, their actions
were evil. And as they explained that the vaccine was not to become ill, they
believed it. Afterwards, they started to get sick. First, one became ill and soon
45
all the others were infected. The people fled from Chagnon who brought the
disease. And the nurse who was supposed to stay in the community came and
went, but did not stay put. That’s how it started. Others became lost in the
mountains and nobody in their family knew about it until they were found
dead.” Alfredo Aherowe, Yanomami, elected representative of the United
Shabonos of the Upper Orinoco, testimony to the Comision Indigena del
Congreso de Venezuela, Caracas, Venezuela, November 8th, 2000.
39. Cliff A, Haggett P, Smallman-Raynor M. Measles: an historical
geography of a major human viral disease from global expansion to local
retreat, 1840-1990. Oxford and Cambridge, MA., Blackwell, 1993, pp. 72-76.
40. Pedersen IR, Mordhorst CH, Evald T, von Magnus H. Long-term
antibody response after measles vaccination in an isolated Artic society
in Greenland. Vaccine. 1986, 4:173.
41. Pedersen IR, Mordhorst CH, Glikman G, von Magnus H, Subclinical
measles infection in vaccinated seropositive individuals in Arctic
Greenland. Vaccine. 1989, 7:347-348.
42. Wakefield AJ, Pittilo RM, Sim R, Cosby SL, Stephenson JR, Dhillon AP,
Pounder RE. Evidence of persistent measles virus infection in Crohn's
disease. J. Med. Virol. 1993, 39:345-353.
43. Miyamoto H, Tanaka T, Kitamoto N, Fukada Y, Shimoyama T. Detection
of immunoreactive antigen with a monoclonal antibody to measles virus
46
in tissue from patients with Crohn's disease. J. Gastroenterol. 1995, 30:2833.
44. Ekbom A, Wakefield AJ, Zack M, Adami H-O. Perinatal measles
infection and subsequent Crohn's disease. Lancet 1994, 344:508-510.
45. Lewin J, Dhillon AP, Sim R., Pounder RE, Wakefield AJ. Persistent
measles virus infection of the intestine: confirmation by immunogold
electron microscopy. Gut 1995, 36:564-569.
46. Balzola F, Khan K, Pera, A, Bonino F, Pounder RE, Wakefield AJ.
Measles IgM immunoreactivity in patients inflammatory bowel disease.
Ital J. Gastroenterol. 1998, 30:378-382.
47. Ekbom A, Daszak PS, Kraaz W, Wakefield AJ. Crohn's disease following
measles
virus
exposure
in
utero:
risk
estimates
and
clinical
characteristics. Lancet 1996, 344:508-509.
48. Montgomery SM, Morris DL, Pounder RE, Wakefield AJ. Paramyxovirus
infections in childhood and subsequent inflammatory bowel disease.
Gastroenterol.1999, 116:796-803.
49. Pardi DS, Tremaine WJ, Sandborn WJ, Loftus EV, Poland GA, Harmsen
WS, Zinsmeister AR, Melton LJ. Early measles virus infection is associated
47
with an increased risk of inflammatory bowel disease. Am J Gastroenterol.
2000, 95:1389-1392
50. Haga Y, Funakoshi 0, Kuroe K, Kanzawa K, Nakajima H, Saito H, Y
Murata, A Munakata and Y Yoshida. Absence of measles virus genomic
sequences in intestinal tissues from Crohn's disease by nested
polymerase chain reaction. Gut. 1996, 38:211-215.
51. Chadwick N, Bruce IJ, Schepelmann S. Pounder RE, Wakefield AJ.
Measles virus RNA is not detected in inflammatory bowel disease using
hybrid capture and reverse transcription followed by the polymerase
chain reaction. J. Med. Virol. 1998, 55:305-311
52. Fisher NC, Yee L, Nightingale P, McEwan R, Gibson JA. Measles virus
serology in Crohn’s disease. Gut. 1997, 41:66-69
53. Montgomery SM, Björnsson S, Jóhannsson JH, Tjodleifsson B, Pounder
RE, Wakefield AJ. Concurrent measles and mumps epidemics in Iceland
are
a
risk
for
later
inflammatory
bowel
disease.
[abstract]
Gastroenterology 1998; 114 (S1)G4270
54. Wakefield AJ, Montgomery SM, Pounder RE. Crohn’s disease: the case
for measles virus. Ital J Gastroenterol. 1999, 31:247-254.
55. Wakefield AJ, Montgomery SM. Measles, mumps, rubella vaccine:
through a glass, darkly. Adverse Drug Reactions & Toxicological Reviews
2000, 19:265-283
48
56. Halsey NA, Hyman SL. Measles-mumps-rubella vaccine and autistic
spectrum disorder. Pediatrics 2001, 107:1-23.
57. Baird G, Simonoff E, Pickles A, Chandler S, Loucas T, Meldrum D,
Charman T. Prevalence of disorders of the autism spectrum in a
population cohort of children in South Thames: the Special Needs and
Autism Project (SNAP) Lancet 2006, 368:210-215
58. Fombonne E, Zakarian R, Bennet A. Meng L, McLean-Heywood MA.
Pervasive developmental disorders in Montreal, Quebec, Canada:
prevalence and links with immunizations. Pediatrics 2006, 118:139-150
59. Barak Y, Ring A, Sulkes J, Gabbay U, Elizur A. Season of birth and
autistic disorder in Israel and the Middle East. Am J Psychiatry, 1995,
152:798-800.
60. Barrlik BD. Monthly variation in birth of autistic children in North
Carolina. J Am Med Women’s Assoc., 1981, 36:363-368.
61. Konstantareas M, Hauser P, Lennox C. Season of birth in infantile
autism. Child Psychiatr Hum Develop 1986, 17:53-65.
62. Gillberg C. Do children with autism have March birthdays? Acta
Psychiatr Scand, 1990, 82:153-156.
63. Tanoue Y, Oda S, Asano F, Kawashima K. Epidemiology of infantile
autism in southern Ibaraki, Japan: differences in prevalence in birth
cohorts. J Autism Dev Discord, 1988, 18:155-166.
49
64. Landau EC, Cicchetti DV, Klin A, Volkmar FR. Season of birth in
autism: a fiction revisited. J Autism Dev Disord. 1999, 29:385-93.
65. Deykin EY, MacMahon B. Viral exposure and autism. Am J Epidemiol
1979, 109:628-638.
66. Ring A, Barak Y, Ticher A. Evidence for an infectious etiology in
autism. Pathophysiol. 1997, 4:1485-1488.
67. Steiner CE, Guerreiro MM, Marques-De-Faria AP. Genetic and
neurological evaluation in a sample of individuals with pervasive
developmental disorders. Arq Neuropsiquiatr. 2003, 61:176-80.
68. Weibel RE, Caserta V, Benor DE. Acute encephalopathy followed by
permanent brain injury or death associated with further attenuated
measles vaccines: a review of claims submitted to the national vaccine
injury compensation program. Pediatrics. 1998, 101:383-387
69. Wakefield AJ, Murch SH, Anthony A, Linnell J, Casson DM, Malik M,
Berelowitz M, Dhillon AP, Thomson MA, Harvey P, Valentine A, Davies SE,
Walker-Smith JA. Ileal-lymphoid nodular hyperplasia, non-specific colitis,
and pervasive developmental disorder in children. Lancet. 1998, 351:637-641.
70. Singh VK, Lin SX, Yang VC. Serological association of measles virus
and human herpesvirus-6 with brain autoantibodies in autism. Clin
Immunol Immunopathol. 1998, 89:105-108.
71. Richler J, Luyster R, Risi S, Hsu Wan-Ling, Dawson G, Bernier R, Dunn M,
Hepburn S, Hyman SL,McMahon WM, Goudie-Nice J, Minshew N,Rogers S,
Sigman M, Spence MA, Goldberg WA, Tager-Flusberg H, Volkmar FR, Lord
50
C. Is there a ‘regressive phenotype’ of autistic spectrum disorder
associated with the measles-mumps-rubella vaccine? a CPEA study.
Autism Dev. Dis. 2006, 36:299-316.
72. DeStefano F, Bhasin TK, Thompson WW, Yeargin-Allsopp M, Boyle C.
Age at first measles-mumps-rubella vaccination in children with
autism and school-matched control subjects: a population-based study
in metropolitan Atlanta. Pediatrics 2004, 113:259–266.
73. Autistic Spectrum Disorders: changes in the California caseload. An
update: 1999 through 2002. California Department of Developmental
Services. A Report to the Legislature, Department of Developmental Services.
Sacramento, Calif.: www.dds.ca.gov. Accessed Oct. 24, 2006.
74. Edwardes M, Baltzan M. MMR Immunization and Autism. JAMA 2001,
285:2852-2853
75. Dales L, Hammer SJ, Smith NJ. Time trends in autism and MMR
immunization coverage in California. JAMA 2001, 285:1183-1185
76. Dales L, Hammer SJ, Smith N. Time trends in autism and MMR
immunization coverage in California. JAMA 2001, 285:2853-2854.
77. Wakefield AJ, Stott C, Limb K. Gastrointestinal comorbidity, autistic
regression and measles-containing vaccines: positive re-challenge and
dose-response effects. Medical Veritas. 2006, 3:796-802.
51
78. Stott CA, Blaxill M, Wakefield AJ. MMR and Autism in Perspective: the
Denmark Story. Journal of American Physicians and Surgeons. 2004, 9:89-91
79. Madsen MK, Hviid A, Vestergaard M, Schendel D, Wohlfarht J, Thorsen P, et
al. A population-based study of measles mumps rubella vaccination and
autism. NEJM 2002, 347:1478-1482.
80. Horvath K, Perman JA. Autistic disorder and gastrointestinal disease.
Current Opinion in Pediatrics. 2002, 14:583–587.
81. Valicenti-McDermott M, McVicar K, Rapin I, Wershil BK, Cohen H,
Shinnar S. Frequency of Gastrointestinal Symptoms in Children with
Autistic Spectrum Disorders and Association with Family History of
Autoimmune Disease. Developmental and Behavioral Pediatrics. 2006,
27:128-136
82. Wakefield AJ, Anthony A, Murch SH, Thomson M, Montgomery SM, Davies
S, O'Leary JJ, Phil D, Berelowitz M, Walker-Smith JA. Enterocolitis in
Children with Developmental Disorders. Am J Gastroenterol. 2000, 95:22852295.
83. Horvath K, Papadimitriou JC, Rabsztyn A, Drachenberg C, Tildon JT.
Gastrointestinal abnormalities in children with autistic disorder. J. Pediatr.
1999, 135:559-63.
84. Furlano RI, Anthony A, Day R., Brown A, McGarvey L, Thomson MA,
Davies SE, Berelowitz M, Forbes A, Wakefield AJ, Walker-Smith JA, Murch
SH. Colonic CD8 and
T-cell infiltration with epithelial damage in
children with autism. J Pediatr 2001, 138:366-72.
52
85. Torrente F, Ashwood P, Day R, Machado N, Furlano RI, Anthony A, Davies
SE, Wakefield AJ,
Thomson MA, Walker-Smith JA, Murch SH. Small
intestinal enteropathy with epithelial IgG and complement deposition in
children with regressive autism. Mol Psychiatry, 2002, 7:375-382
86. Torrente F, Anthony A, Herushkel RB, Thomson MA, Ashwood P, Murch
SH, Focal-enhanced gastritis in regressive autism with features distinct
from Crohn’s and helicobacter pylori gastritis. Am. J. Gastroenterol. 2004,
4:598-605.
87. Ashwood P, Anthony A, Pellicer AA, Torrente F, Walker-Smith JA,
Wakefield AJ, Ogg GS, King A, Lechner F, Spina CA, Little S, Havlir DV,
Richman DD, Gruener N, Pape G, Waters A, Easterbrook P, Salio M,
Cerundolo V, McMichael AJ, Rowland-Jones SL. Intestinal lymphocyte
populations in children with regressive autism: evidence for extensive
mucosal immunopathology. J Clin Immunol 2003, 23:504-517.
88. Balzola F, Daniela C, Repici A, Barbon V, Sapino A, Barbrea C, Calvo PL,
Forni M, Isabella M, Gandione M, Rigardetto R, Smedile A, Rizzetto M.
Autistic enterocolitis: confirmation of a new inflammatory bowel disease
in an Italian cohort of patients [abstract].
Gastroenterol.
2005,
128:Suppl.2;A-303
89. Balzola F, Barbon V, Repici A, Rizzetto M, Clauser D, Gandione M, Sapino
A, Panenteric IBD-Like Disease in a Patient with Regressive Autism
Shown for the First Time by the Wireless Capsule Enteroscopy: Another
Piece in the Jigsaw of this Gut-Brain Syndrome? Am. J. Gastroenterol.
2005, 100:979
53
90. González L, López K, Martínez M, Navarro D, Negron L, Flores L,
Rodriguez R, Martinez M, Sabra A. Endoscopic and Histological
Characteristics of the Digestive Mucosa in Autistic Children with
Gastrointestinal Symptoms. Archivos Venezolanos de Puericultura y
Pediatria. 2006, 69:19-25.
Deleted: ;
91. Ashwood P, Anthony A, Torrente F, Wakefield AJ. Spontaneous mucosal
lymphocyte cytokine profiles in children with autism and gastrointestinal
symptoms: Mucosal immune activation and reduced counter regulatory
interleukin-10. J. Clin. Immunol. 2004, 24:664-674.
92. Ashwood P, Wakefield AJ. Mucosal and peripheral blood lymphocyte
cytokine profiles in children with regressive autism and gastrointestinal
symptoms: Mucosal immune activation and reduced counter regulatory
interleukin-10. J. Neuroimmunol. 2006, 173:126-134.
93. Jyonouchi H, Sun S, Lee H, Proinflammatory and regulatory cytokine
production associated with innate and adaptive immune responses in
children with autism spectrum disorders and developmental regression. J.
Neuroimmunol. 2001, 120:170-179.
94. Jyonouchi H., Sun S, Itokazu N. Innate immunity associated with
inflammatory responses and cytokine production against common dietary
proteins in patients with autism spectrum disorder. Neuropsychobiol. 2002,
46:76-84.
95. Molloy CA,
Andy 11/7/06 9:19 AM
Morrow AL, Meinzen-Derr J, Schleifer K, Dienger K,
Manning-Courtney P, Altaye M, Wills-Karp M. Elevated cytokine levels in
54
children with autism spectrum disorder. J. Neuroimmunol. 2006, 172:198205
96. Appay P, Dunbar RP, Callan M, Klenerman P, Gillespe GMA, Papagano L.
Ogg GS, King A, Lechner F, Spina CA, Little S, Havlir DV, Richman DD,
Gruener N, Pape G, Waters A, Easterbrook P, Salio M, Cerundolo V,
McMichael AJ, Rowland-Jones SL.
Memory CD8+ T cells vary in
differentiation phenotype in different persistent virus infections.
Nature Medicine. 2002, 8:379-385
97. Sandler RH, Finegold SM, Bolte ER, Buchanan CP, Maxwell AP, Vaisansen
M-L, Nelson MN, Wexler HM. Short-term benefit from oral vancomycin
treatment of regressive-onset autism. J. Child Neurol. 2000, 15:429-435.
98. Parracho HM, Bingham MO, Gibson GR, McCartney AL. Differences
between the gut microflora of children with autistic spectrum disorders
and that of healthy children. J. Med Microbiol. 2005, 54:987-991.
99. Finegold SM, Molitoris D, Song Y, Liu C, Vaisanen ML, Bolte E, McTeague
M, Sandler R, Wexler H, Marlowe EM, Collins MD, Lawson PA, Summanen P,
Baysallar M, Tomzynski TJ, Read E, Johnson E, Rolfe R, Nasir P, Shah H,
Haake DA, Manning P, Kaul A. Gastrointestinal microflora studies in lateonset autism. Clin Infect Dis, 2002, 35:S6-S16.
100. D’Eufemia P, Celli M, Finocchiaro R, Pacifico L, Viozzi L, Zaccaginini M,
Cardi E, Giardini O. Abnormal intestinal permeability in children with
autism. Acta Paediatr 1996, 85:1076–1079.
55
101. Horvath K., Zielke H, Collins J, Rabsztyn A, Perman JA. Secretin
improves
intestinal
permeability
in
autistic
children.
J
Pediatr
Gastroenterol Nutr. 2000, 31:S30–S31.
102. James SJ, Cutler P, Jernigan S, Janak L, Gaylor DW, Neubrander JA.
Metabolic biomarkers of increased oxidative stress and methylation
capacity in children with autism. Am J Clin Nutr. 2004, 80:1611-1617.
103. Singh VK. Elevation of Serum C-Reactive Protein and S100 Proteins
for Systemic Inflammation in Autistic Children. J. Special Ed Rehab, 2005,
3:117-125
104. Marz CE, Jarskog LF, Lauder JM, Lieberman JA, Gilmore JH. Cytokine
effects on cirtical neuron MAP-2 immunoreactivity : implications for
schizophrenia. Biol. Psychiat. 2001, 50:743-749.
105. Ling ZD, Potter ED, Lipton JW, Carvey PM. Differentiation of
mesencephalic progenitor cells into dopaminergic neurons by cytokines.
Exp. Neurol. 1998, 149:411-423.
106. Gilmore JH, Jasrkog LF, Vadlamundi S, Lauder JM. Prenatal infection
and risk for schizophrenia: IL-1 beta, IL-6 and TNF alpha inhibit
cortical neuron dendrite development. Neuropsychpharmacol. 2004,
29:1221-1229.
107. Welch MG, Welch-Horan TB, Anwar M, Anwar N, Ludwig RJ, Ruggiero
DA. Brain effects of chronic inflammatory bowel disease in areas
abnormal in autism and treatment by single neuropeptides secretin and
oxytocin. J. Molec Neurosci. 2005, 25:259-273.
56
108. Ke ZJ, Bowen WM, Gibson GE. Peripheral inflammatory mechanisms
modulate microglial activation in response to mild impairment of
oxidative metabolism. Neurochem Int. 2006; 49:548-56
109. Vargas DL, Nascimbene C, Krishnan C, Zimmerman AW, Pardo CA.
Neuroglial Activation and Neuroinflammation in the Brain of Patients
with Autism. Ann Neurol 2005, 57:67-81
110. Norrby E, Oxman MN. Measles Virus, in Virology, Edited by Fields BN
& Knipe D. New York, Raven Press. Vol 37. pp. 1013-1044
111. Griffin D. Immune responses during measles virus infection. Current
Topics in Microbiol Immunol. 1995, 191:117-134.
112. Wakefield AJ. Enterocolitis, autism and measles virus. Molec. Psychiat.
2002, 7:S44-46
113. Uhlmann V, Martin CM, Sheils O, Pilkington L, Silva I.., Killalea A, Murch
SH, Wakefield AJ, O’Leary JJ. Potential viral pathogenic mechanism for new
variant inflammatory bowel disease. Molec Pathol 2002, 55:84-90.
114. Parks CL, Lerch RA, Walpits P, Wang H-P, Sidhu MS, Udem SA.
Comparison of predicted amino acid sequences of measles virus in
Edmonston vaccine lineage. J Virol. 2001, 75:910-920.
115. Sheils O, Smyth P, Martin C, O’Leary JJ. Development of an allelic
discrimination type assay to differentiate between the strain origins of
measles virus detected in intestinal tissue of children with ileocolonic
57
lymphonodular hyperplasia and concomitant developmental disorder
[abstract]. J. Pathol. 2002, 198 (suppl):5A.
116. Walker SJ, Hepner K, Segal J, Krigsman A. Persistent ileal measles virus
in a large cohort of regressive autistic children with ileocolitis and
lymphnodular hyperplasia: re-visitation of an earlier study [abstract].
International
Meeting
for
Autism
Research
(IMFAR)
2006,
http://www.cevs.ucdavis.edu/Cofred/Public/Aca/WebSec.cfm?confid=238&
webid=1245.
117. Stott, CM; Limb, K and Wakefield AJ (2005) Polyvalent Measles
Containing Vaccine (pMCV) and Developmental Regression: Data from
a UK litigation cohort. [Abstract] International Meeting for Autism
Research (IMFAR). 2005. www.imfar.org
118. Singh VK, Lin SX, Newell E, Nelson C. Abnormal measles-mumpsrubella antibodies and CNS autoimmunity in children with autism. J
Biomed Sci. 2002, 9:359-64.
119. Singh VK, Jensen RL. Elevated levels of measles antibodies in children
with autism. Pediatric Neurol. 2003, 28:292-294.
120. Wakefield AJ, Anthony A, Schepelmann S, Kawashima H, Sim R, Khan K,
Murch SH, Dhillon AP, Montgomery SM, Thomson MA, Thomas J, WalkerSmith JA. Persistent measles virus infection and immunodeficiency in
children with autism, ileo-colonic lymphonodular hyperplasia and nonspecific colitis [abstract]. Gastroenterol 1998, 174:A430
58
Andy 11/1/06 2:42 PM
Deleted:
121. D'Souza Y, Fombonne E, Ward BJ. No evidence of persisting measles
virus in peripheral blood mononuclear cells from children with autism
spectrum disorder. Pediatrics. 2006;118:1664-75.
122. Van de Water J, Ashwood P, Hansen R, Goodlin-Jones B, Lam K, Gershwin
ME. [abstract]. Reduced IG response to common vaccine antigens for
patients with autism spectrum disorder. International Meeting for Autism
Research. 2004, S4.5.6
123. Smeeth L, Cook C, Fombonne E, Heavey L, Rodrigues L, Smith P, Hall
A. MMR vaccination and pervasive developmental disorders: a casecontrol study. Lancet 2004, 364:963-969
124. Kaye JA, Mar Melero-Montes M, Hershel Jick. Mumps, measles and
rubella vaccine and the incidence of autism recorded by general
practitioners: a time trend analysis. BMJ 2001, 322:460-463.
125. Taylor B, Miller E, Lingam R, Andrews N, Simmons A, Stowe J. Measles,
mumps, and rubella vaccination and bowel problems or developmental
regression in children with autism: population study. BMJ, 2002, 324:393-6.
126. Chen W, Landau S, Sham P, Fombonne E. No evidence for links
between autism, MMR and measles virus. Psychological Medicine. 2004,
34:543–553
127. Lieveano FA., Papania MJ, Hefland RF, Harpaz R, Walls L, Katz RS,
Williams I, Villamarzo YS, Rota PA, Bellini WJ. Lack of evidence of measles
virus shedding in people with inapparent measles virus infection. J Infect
Dis. 2004, 189:S165-S170.
59
Andy 11/1/06 2:42 PM
Deleted:
128. Edmoston MB, Addiss DG, McPherson JT, Berg JL, Circo SR, Davis JP.
Mild measles and secondary vaccine failure during a sustained outbreak
in a highly vaccinated population. JAMA 1990, 263:2467 2471.
129. Huiss S, Damien B, Schneider F, Muller CP. Characteristics of
asymptomatic secondary immune responses to measles virus in late
convalescent donors. Clin Exp Immunol 1997, 109:416 20.
130. Muller CP, Huiss S, Schneider F. Secondary immune responses in
parents of children with recent measles. Lancet 1996, 348:1379 80.
131. Ozanne G, D'Halewyn MA. Secondary immune response in a
vaccinated population during a large measles epidemic. J Clin Microbiol
1992, 30:1778 82
132. Helfand RF, Kim DK, Gary HE, Edwards GL, Bisson GP, Papania MJ,
Heath JL, Schaff DL, Bellini WJ, Redd SC, Anderson LJ. Non-classic measles
infections in an immune population exposed to measles during a college
bus trip. J Med Virol. 1998, 56:337 341.
133. Vardas E, Kreis S. Isolation of measles virus from a naturallyimmune, asymptomatically re-infected individual. J Clin Virol 1999,
13:173 9.
134. Chen RT, Markowitz LE, Albretch P, Stewart JA, Mofenson LM, Preblud
SR, Orenstein WA. Measles antibody: reevaluation of protective titers. J
Infect Dis 1990, 162:1036 1042.
60
135. Whittle HC, Aaby P, Samb B, Jensen H, Bennett J, Simondon F. Effect of
subclinical infection on maintaining immunity against measles in
vaccinated children in West Africa. Lancet 1999, 353:98 102.
136. Reyes MA, De Borrero MF, Roa J, Bergonzoli G, Saravia NG. Measles
vaccine failure after documented seroconversion. Pediatr Infect Dis J 1987,
6:848 51.
137. Warren RP, Foster A, Margaretten NC. Reduced natural killer cell
activity in autism. J Am Acad Child Adolesc Psychiatry. 1987, 26:333-335.
138. Mossong J, Nokes DJ, Edmunds WJ, Cox MJ, Ratman S, Muller CP.
Modeling the impact of subclinical measles transmission in vaccinated
populations with waning immunity. Am J Epidemiol. 1999, 150:1238-1249
61