MAJOR ARTICLE
Bat Rabies in the United States and Canada
from 1950 through 2007: Human Cases
With and Without Bat Contact
Gaston De Serres,1 Frédéric Dallaire,2 Mathieu Côte,2 and Danuta M. Skowronski3
1
Institut national de santé publique du Québec and 2Université Laval, Quebec, and 3British Columbia Centre for Disease Control,
Vancouver, Canada
Background. Since the 1980s, rare cases of rabies in humans in Canada and the United States have been almost
exclusively caused by the bat-variant virus.
Methods. We reviewed indigenously acquired cases of bat-variant rabies in humans in Canada and the United
States from 1950 through 2007.
Results. Of 61 cases identified 5 occurred after organ transplantation and were excluded from further analysis.
A bite was reported by 22 (39%) of the case patients, 9 (16%) had a direct contact (i.e., were touched by a bat)
but no history of a bite, 6 (11%) found bats in their home (2 [4%] in the room where they slept) but reported
no direct contact, and 19 (34%) reported no history of bat exposure whatsoever. With the exception of California
(8 cases) and Texas (7 cases), no state or province had 13 cases. Of the case patients, 76% were men, and 40%
were 10–29 years of age. The median incubation period was 7 weeks (!10 weeks in 72% of cases). The incidence
of bat-variant rabies cases increased from 2.2 per billion person-years in 1950–1989 to 6.7 per billion person-years
in 1990–2007. Of 36 case patients with bat rabies described since 1990, 16 had no history of direct bat contact;
2 (13%) of the 16 would have qualifie for rabies postexposure prophylaxis on the basis of exposure criteria
expanded in 1995 to include bats that were in the same room as a sleeping person. The incidence of rabies for
this type of exposure was 0.6 cases per billion person-years.
Conclusion. The true preventable proportion of cases and the number needed to treat with rabies postexposure
prophylaxis to prevent 1 case would be useful information to inform the current guidelines.
Rabies is a dreaded disease. The rabies virus causes
encephalitis and death in humans and in most other
mammals. A distinct species-associated variant characterizes each of the major terrestrial animal hosts. Humans are not natural hosts but can become infected
through contact with other rabid animals. With a single
documented exception, human cases of rabies have
been uniformly fatal [1]. According to the best estimates worldwide, 155,000 deaths occur annually, most
of which are associated with dogs [2]. Prevention is
through a protocol of rabies postexposure prophylaxis
Received 12 October 2007; accepted 10 December 2007; electronically published
21 March 2008.
Reprints or correspondence: Dr. Gaston De Serres, Institut national de santé
publique du Québec, 2400 d’Estimauville, Quebec, PQ, Canada, G1E 7G9
([email protected]).
Clinical Infectious Diseases 2008; 46:1329–37
2008 by the Infectious Diseases Society of America. All rights reserved.
1058-4838/2008/4609-0001$15.00
DOI: 10.1086/586745
(RPEP) that consists of a single dose of immunoglobulin and 5 spaced doses of vaccine. RPEP is safe and
effective; failure rates, typically associated with a delay
or breach in protocol, have been estimated to range
from 1 in 80,000 in developed countries to 1 in 12,000
in developing countries [3]. The reported incubation
period varies from a few days to 119 years, but 75%
of patients become ill in the firs 90 days after exposure
[3, 4].
Three principal global areas of rabies have been define [4]. These areas are (1) countries with enzootic
canine rabies (all of Asia, Latin America, and Africa);
(2) countries in which canine rabies has been brought
under control and wildlife rabies predominates (Western Europe, Canada, and the United States); and (3)
rabies-free countries (mostly islands, including England, Australia, and Japan). In Canada and the United
States, rabies is enzootic in foxes, skunks, raccoons, and
bats; these animals are the only natural reservoirs in
Canada and the United States. The firs identificatio
Bat Rabies in the US and Canada • CID 2008:46 (1 May) • 1329
of rabid insectivorous bats in North America was in the early
1950s. Since then, the incidence of rabies in bat populations,
although known to vary according to the species, its social
preferences (colony forming vs. solitary), and migratory patterns, is not known to be on the rise [3, 4].
A program of rabies immunization for domestic dogs led to
a dramatic decline in human cases of canine rabies in Canada
and the United States in the 1950s. In its place, the bat-variant
virus has become the dominant cause of rabies in humans. The
advent of the detection of anti-nucleocapsid monoclonal antibody in the late 1970s and the more-recent nucleotide sequencing applied to virus strains recovered from humans has
facilitated distinction between bat-variant rabies and virus
strains originating in other terrestrial reservoirs; this has led to
increased links with bats that may have been previously unknown or unrecognized [3, 5]. Transmission of bat-variant rabies through other terrestrial animals to humans is theoretically
possible, but no such human cases have been documented [4].
A squirrel infected with bat-variant rabies was reported to have
bitten a person, but RPEP was administered, and human disease
did not follow [6].
Bats apply sophisticated echolocation to navigate, and
healthy bats are easily able and prefer to avoid collision or other
contact with humans. Bats are night creatures, and it is unusual
for them to fl in daylight. Those active during the day are
suspect, as are any found on the ground. The behavior demonstrated by rabid bats is not always dramatically altered [4].
Although some may become aggressive, others may simply become disoriented, lose their flyin ability, and appear clumsy.
Healthy juvenile bats acquiring new skills may also demonstrate
such erratic behavior. Relentless attachment, particularly to the
hands or heads of humans, is a clear sign of abnormality.
Bat teeth are very fine and bat bites may be undetectable as
pinpoint puncture marks ⭐1 mm in diameter. Most bat-inflicte scratch marks are !1 cm long. Such minor evidence of
contact may be difficul to recall or elicit from a person dying
from rabies. In the past 2 decades, most human case patients
with bat-variant rabies in the United States and Canada did
not report a history of a bat bite [5, 7, 8]. The recognition that
indigenous cases of rabies in humans in North America are
largely associated with bats and that even direct contact with
bats may not be perceived has led to the lowering of the threshold for RPEP administration. In 1995, the Centers for Disease
Control and Prevention (CDC) urged “consideration of postexposure prophylaxis for persons potentially exposed to bats
even where a history of physical contact cannot be elicited” [9,
p. 272]. This is reflecte in guidelines published by advisory
committees in the United States in 1999 and in Canada in
2002, which include scenarios in which a bat is found in the
same room as a sleeping person, an unattended child, a mentally
disabled person, or an intoxicated person [10, 11].
1330 • CID 2008:46 (1 May) • De Serres et al.
Individual case reports of bat-variant rabies have been published previously. This report summarizes all cases of bat-variant rabies identifie in humans in the United States and Canada from 1950 through 2007, including those with and those
without recognized bat contact.
METHODS
We reviewed all human cases of rabies from January 1950
through September 2007 in the United States and Canada as
described in the Morbidity and Mortality Weekly Report and
Canada Communicable Disease Report. The number of human
cases we found with bat-variant rabies corresponds with totals
published by the CDC and the Public Health Agency of Canada.
Only indigenously acquired cases were considered; cases acquired elsewhere but diagnosed and treated in the United States
or Canada were excluded.
The incidence rate per person-year was calculated by dividing
the number of cases by the sum of the populations of each
year from 1950 through 2007. Population data were obtained
from the US Census Bureau [12, 13] and Statistics Canada [14].
RESULTS
From January 1950 through September 2007, the total number
of human cases of rabies declined considerably, from a peak
of 20 cases in 1952 to never more than 6 cases per year since
the 1960s, which mostly reflect the control of canine-variant
rabies (figu e 1A). Even recently, however, year-to-year variation in the number of human cases of rabies is evident. There
were 23 cases for which the source of rabies was unknown,
including 21 (21%) of 102 cases from 1950 through 1959 and
2 (7%) of 29 cases from 1960 through 1979. Since 1980 and
the advent of anti-nucleocapsid monoclonal antibody detection
and nucleotide sequencing, distinct species-associated variants
were identifie in all reported human cases of rabies.
Since 1950, 61 human cases of bat-variant rabies were reported in the United States (55 cases) and Canada (6 cases).
A list of the characteristics and the bat-contact history of cases
is presented in table 1. Five cases occurred following the transmission of the virus to organ transplant recipients from 2 infected donors; 3 of the cases involved recipients in Texas [34].
These 5 cases have been excluded from further analysis.
The 56 non–transplant-associated cases of bat-variant rabies
were distributed across both countries in 27 states and 5 provinces, with no clear geographic clustering (figu e 2). Each state
or province had ⭐3 cases, with the exception of California (8
cases) and Texas (7 cases). More than 75% of case patients were
male (42 patients), and 41% (23 patients) were adolescents or
young adults (age, 10–29 years). By decreasing order of frequency, bat-variant rabies was diagnosed in persons aged 20–
29 years (24%), 10–19 years (18%), 40–49 years (18%), ⭓60
Figure 1. A, Number of human cases of indigenously acquired rabies in Canada and the United States since 1950, including cases involving organ
transplantation, by type of source animal. N/A, not available. B, Number of human cases of indigenously acquired bat rabies in Canada and the United
States from 1950 through 2007, excluding organ transplant cases.
years (18%) , !10 years (11%), 50–59 years (7%), and 30–39
years (4%).
Of the 56 case patients, 31 (55%) had direct contact with a
bat: 22 reported being bitten, and 9 had direct contact (i.e.,
were touched by a bat) but reported no history of a bite (table
1 and figu e 1B). The remaining 24 case patients (43%) did
not have recognized direct contact with a bat: 6 found bats in
their home (2 while sleeping) and 19 reported no history of
bat exposure whatsoever. Of the 12 case patients with a history
of a bat in their bedroom (cases 4, 5, 6, 8, 16, 21, 26, 28, 31,
33, 34, and 35), 3 had no direct contact, 5 were bitten, and 4
were awakened by a bat having landed on them. Of the 56
cases not associated with organ transplantation, 36 (64%) occurred from 1990 through 2007. Of these 36 cases since 1990,
16 involved no history of direct contact with a bat; 2 (13%)
of the 16 case patients would have qualifie for RPEP on the
basis of exposure criteria expanded in 1995 to include bats that
were in the same room as a sleeping person.
Among the 6 cases involving pediatric patients !10 years of
age (cases 2, 4, 5, 11, 33, and 35), only 2 occurred since 1990
(cases 33 and 35). A bat was found in the room of the firs of
these 2 case patients (case 33), but family members had examined the child and found no evidence of a bite. After the
child’s death, the bat that had been buried was recovered and
Bat Rabies in the US and Canada • CID 2008:46 (1 May) • 1331
1332
73
2007 Alberta
22
1994 Alabama
1995 California
1995 California
1997 Texas
1997 New Jersey
2000 Georgia
2000 Wisconsin
2000 California
23
24
25
26
27
28
29
30
Direct contact with no obvious bite (n p 9)
49
69
26
32
71
74
27
24
15
20
66
13
47
10
41
29
22
2006 Indiana
1991 Arkansas
14
2004 Wisconsin
1990 Texas
13
22
21
1985 Alberta
12
5
20
1983 Michigan
11
62
55
2004 Arkansas
1977 Nova Scotia
10
19
1976 Maryland
9
26
2003 California
1973 Kentucky
8
15
64
2002 Tennessee
1971 New Jersey
7
18
1970 Saskatchewan
6
6
17
1970 Ohio
5
4
53
2000 Minnesota
1959 Wisconsin
4
16
1958 California
3
7
43
1994 West Virginia
1953 Florida
M
M
M
M
M
M
M
F
M
F
F
M
M
M
M
M
M
M
M
F
M
F
M
M
M
M
M
F
M
F
Bitten on the left forearm while observing a moribund bat [15–18]
47
Bitten on his right index finger by a bat [16, 33]
∼35
60–90
UK
UK
UK
∼61
UK
UK
UK
180–270
∼107
37
Found a bat and brought it home [16, 32]
∼50
Removed a bat from his house [16, 31]
Said he was removing bats from his house with bare hands 2 or 3 times a year; he asked coworkers
if it was possible to acquire rabies from an insect bite [16, 31]
Told coworkers that bats from the attic had landed on him while he was sleeping; investigation revealed the presence of a 200-bat colony in the attic [16, 31]
Captured 2 bats with a towel in his house; investigation of the house revealed that up to 200 bats had
lived in the attic during the summer [16, 40]
Awakened by a bat that landed on his shoulder [16, 40]
No known exposure; his son said that the patient sometimes captured bats [16, 27, 39]
76 bats were living in the building where the patient worked; a family member believed that a bat had
landed on and was brushed off the patient’s chest [16, 27, 39]
Frequently retrieved dead or dying bats from her workplace’s chimney [9, 16]
Bitten by a bat and killed it [38]
Bitten by a bat while sleeping; had a small mark on her right arm [16, 37]
Bitten by a bat without further information; the only case of rabies survival without vaccination [1, 36]
Bitten by a bat without further information; was the donor of kidneys, iliac artery, and liver in cases
58, 59, 60, and 61 [16, 34– 36]
A friend said that the patient had been awakened by a bat that landed on his right hand; he killed it
and was bitten in the process; investigation of the house revealed traces of bat activities [16, 31]
∼54
UK
Friends and relatives said that the patient shot a bat from his front porch and then examined its head,
opened its mouth, and touched its teeth [16, 27, 30]
A friend said a bat landed on the mouth of the patient, who killed it and disposed of it; other friends
recalled seeing bites on his thumb and scratches on his chest [16, 26, 27]
Bitten by a bat on the right index finger [16, 27, 29]
∼94
∼43
Scratched or bitten in the face by a bat [28]
Parents recalled a possible bat bite [16, 26, 27]
∼90
Bitten on his left hand while trying to remove a bat from his house [4]
Bitten on a finger by a bat [16, 17, 22, 25]
Bitten on an ear by a bat while asleep [16, 17, 22]
Bitten on the lower lip by a bat [16, 17, 22]
A bat flew into his face and bit him while asleep; he then held the bat in his hands [4, 17, 24]
Bitten on the left thumb by a bat while asleep; received RPEP before onset of disease and survived
[16, 17, 22, 23]
Bitten on an ear by a bat while asleep [16, 17]
Bitten on a finger by a moribund bat [16, 17, 21]
Bitten several times in the upper pectoral region by a bat [15, 19, 20]
∼170
25
22
59
20
22
57
16
Patient circumstances and/or bat-contact information [reference(s)]
UK
UK
UK
Incubation
period,
Age, years Sex
days
15
1951 Texas
2
Year
1
Direct contact by bite/scratch (n p 22)
US state
or Canadian
province
Characteristics of the 61 human cases of indigenously acquired bat rabies in the United States and Canada, 1950–2007.
Case type and number
Table 1.
1333
31
1995 Washington
1997 Montana
2000 Quebec
2002 California
2005 Mississippi
34
35
36
37
1956 Texas
1959 California
1962 Idaho
1978 Oregon
1979 Kentucky
1979 Oklahoma
1984 Pennsylvania
1991 Georgia
1993 New York
1993 Texas
1994 California
1994 Tennessee
1996 Kentucky
1996 Montana
1997 Washington
1998 Virginia
2002 Iowa
2003 British Columbia
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
2004 Texas
2004 Oklahoma
2004 Texas
59
60
61
RPEP, rabies postexposure prophylaxis; UK, unknown.
2004 Texas
58
NOTE.
1978 Idaho
57
Organ transplantation (n p 5)
1955 Texas
38
No history of contact (n p 19)
1995 Connecticut
33
2006 Texas
32
No direct contact, house exposure (n p 6)
55
52
18
50
37
52
20
29
64
49
42
42
44
82
11
27
12
24
45
39
11
54
41
UK
10
28
9
65
4
13
16
F
M
M
F
F
M
M
M
M
M
F
F
M
M
F
F
M
M
M
M
M
M
M
UK
M
M
M
M
F
F
M
30
20–30
20–30
20–30
20–30
UK
UK
UK
UK
UK
UK
UK
UK
UK
UK
UK
UK
UK
UK
UK
41
∼30
UK
UK
UK
UK
∼25
∼120
16
∼31
28–42
Recipient of a segment of iliac artery from case 19 [34]
Recipient of the liver from case 19 [16, 34]
Recipient of a kidney from case 19 [16, 34]
Recipient of a kidney from case 19 [16, 34]
Recipient of a corneal transplant from case 42 [16, 22]
No known exposure; the patient had told relatives that he had been around bats in abandoned cabins
in the previous year [56]
No known exposure [16, 55]
No known exposure; some co-inmates reported having seen bats outside [16, 54]
No known exposure [16, 44]
No known exposure; sometimes saw bats outside his workplace [16, 27, 53]
No known exposure [16, 27, 53]
No known exposure [9, 16]
No known exposure [16, 27, 52]
No known exposure; no bat found, but the attic could have been accessible from the outside; a cow
living on the patient’s farm died from an unknown disease 3 months earlier [16, 27, 51]
No known exposure [16, 27, 50]
No known exposure [16, 27, 49]
No known exposure [16, 27, 48]
Patient was a caver; he went into a cave for the last time 3 years earlier [16]
Unknown [16]
Unknown; was the donor of the corneal transplant in case 57 [22]
Unknown [16]
Went to Frio Cave in Texas; transmission thought to be by aerosol [16, 17]
Went to Frio Cave in Texas; transmission thought to be by aerosol [16, 17]
Went to Frio Cave in Texas; transmission thought to be by aerosol [16, 17]
People recalled frequently seeing bats around the patient’s house; dead bats were found twice inside
the house [16, 47]
Killed a bat in his house; denied any direct contact with it; investigation of the house revealed the
presence of a bat colony in the attic [16, 46]
2 bats were found in a cabin where the patient slept; he reported no bite but 3 days later showed his
mother an erythematous 2-cm lesion on his upper left arm [45]
A bat was found in his bedroom [16, 44]
A bat was found in her bedroom; family members had examined the chil but found no evidence of a
bite; the bat was tested for rabies after the patient’s death and was positive for rabies [16, 27, 43]
A bat was found in her house while she was sleeping in an upstairs bedroom [16, 27, 42]
Had direct contact with a bat that flew into his bedroom [16, 41]
Figure 2. Geographic distribution and number of human cases of bat rabies in Canada and the United States from 1950 through 2007, excluding
cases involving organ transplantation. Provinces and states with no cases are in white.
tested positive for rabies. The second case patient had no known
bat bite but showed his mother a 2-cm erythematous lesion
on his upper arm 3 days after he slept in a cabin where 2 bats
had been found. The lesion was not identifie as a bat bite at
the time. The remaining 4 pediatric cases occurred before 1990,
and all 4 case patients had a history of bat bite.
Among the 25 persons with a discrete history of bat exposure,
under the assumption that the infection was caused by that
recognized exposure, the incubation period varied from 16 days
(cases 1 and 33) to 180–270 days (case 22). The onset of symptoms occurred before 10 weeks in 18 (72%) of the 25 case
patients (table 1 and figu e 3). The diagnosis of rabies was
considered for the firs time at autopsy in only 6 (11%) of the
cases (cases 11, 15, 18, 29, 34, and 38).
Excluding the 5 transplant-associated cases, the overall incidence rate of bat rabies in humans was 3.9 cases per billion
person-years, with similar rates in the United States and Canada
(3.9 and 4.4 cases per billion person-years, respectively). The
incidence of bat-variant rabies cases increased from 2.2 cases
per billion person-years in 1950–1989 to 6.7 cases per billion
person-years in 1990–2007 (table 2 and figu e 1B). It is likely
that a proportion of the 23 cases occurring from 1950 through
1979 with no known source of exposure and an uncharacterized
rabies virus were caused by the bat variant. Under the as1334 • CID 2008:46 (1 May) • De Serres et al.
sumption that all cases were caused by bat rabies, the overall
incidence would be 5.5 cases per billion person years, with 15.5
cases per billion person-years in 1950–1959, 0.5 cases per billion
person-years in 1960–1969, and 4.6 cases per billion personyears in 1970–1979 (table 2). From 1990 through 2007, there
were 2 case patients for whom the only known exposure was
the presence of a bat in the room where they slept. The incidence for this type of exposure was 0.6 cases per billion personyears. During the same period, there were 11 cases (2.0 cases
per billion person-years) with no recognized or reported history
of contact.
DISCUSSION
Rabies in humans in the United States and Canada remains
dreaded but rare. With the near elimination of human cases
caused by canine rabies, bats have become the animal source
of the greatest concern. This is in part because of frequent
opportunities for interaction through shared urban and rural
distribution and because controlling enzootic rabies in nondomesticated animals is more difficul than in domesticated
animals, as seen in the successful control of canine rabies
achieved through immunization of dogs.
Overall since 1950, we found an incidence rate of bat rabies
Figure 3. Incubation period of indigenously acquired human cases of bat rabies with a history of a bat bite (black), direct contact with no bite
(gray), or the presence of a bat in the house without direct contact (white), excluding cases involving organ transplantation.
in humans of 3.9 cases per billion person-years, with similar
rates in the United States and Canada. The introduction of
anti-nucleocapsid monoclonal antibody detection at the end of
the 1970s led to improved species attribution and the identificatio of the bat variant among persons with unrecognized
exposure. This and the increased concern about bat rabies generally make it difficul to comment on temporal trends. Rabies
in humans is dramatic in its clinical presentation and is accompanied by cardinal features. Nevertheless, the diagnosis
may be missed; in this series, 11% (6) of the cases of bat rabies
were diagnosed postmortem, and it is possible that additional
cases without an autopsy performed were missed. The extent
of this underestimation is impossible to determine but is likely
to be higher among those cases without recognized and sus-
pected exposure history. Although rabies is also enzootic among
bats in Europe, only 5 human cases of bat rabies have been
described there, 2 of which occurred in nonvaccinated professional bat handlers [57]. In Mexico, 2–3 human cases of bat
rabies were identifie per year since 2000, although the trend
as a proportion of all human cases of rabies has been increasing
in recent years [58]. For the rest of Latin America, data are
fragmentary, but some cases have been reported [59–62].
Among reported case patients, young-adult and adolescent
males seem to predominate. They may practice activities that
increase their exposure risk or may be less inclined to seek
medical attention or prophylaxis should a contact, even a bite,
occur. For this group in particular, it would be beneficia to
emphasize through public messages the importance of main-
Table 2. Incidence rate and number of human cases of bat rabies in the United States and Canada, excluding cases involving
organ transplantation, by decade and type of contact.
Cases per billion person-years (no. of cases)
Bat-variant rabies
Direct contact
Period
No direct contact
No history
of exposure
Total
Unknown source and
rabies variant
Total
0 (0)
0 (0)
1.7 (3)
0.5 (1)
3.9 (7)
0.5 (1)
11.6 (21)
0 (0)
15.5 (28)
0.5 (1)
0 (0)
0 (0)
0 (0)
0 (0)
1.3 (3)
0.4 (1)
3.8 (9)
1.1 (3)
0.8 (2)
0 (0)
4.6 (11)
1.1 (3)
1.7 (5)
1.6 (4)
0.6 (9)
1.0 (3)
1.2 (3)
0.4 (6)
3.1 (9)
0.8 (2)
1.3 (19)
6.9 (20)
6.4 (16)
3.9 (56)
0 (0)
0 (0)
1.6 (23)
6.9 (20)
6.4 (16)
5.5 (79)
Population
With bite
No bite
1950–1959
1960–1969
1,802,584,987
2,119,911,320
2.2 (4)
0 (0)
0 (0)
0 (0)
1970–1979
1980–1989
2,379,524,923
2,627,534,011
2.5 (6)
0.8 (2)
1990–1999
2000–2007
Total
2,904,437,968
2,507,594,847
14,341,588,056
1.0 (3)
2.8 (7)
1.5 (22)
House
exposure
Bat Rabies in the US and Canada • CID 2008:46 (1 May) • 1335
taining a safe distance from bats, avoiding the handling of bats,
and minimizing opportunities for contact with bats. Primary
preventive measures include education and the barring of bats
from human dwellings by sealing openings as small as 2 cm
and by placing screens on windows. Professional bat-control
advice may be necessary where human dwellings are already
inhabited with bats. Although effective, secondary prevention
through immediate wound washing and RPEP requires that
exposure has been both recognized and brought to the attention
of public health personnel. Given the frequently cryptic nature
of bat contact, this is clearly not always possible.
Among the 56 human case patients with bat rabies described
in this series, nearly half had no history of direct contact, and
one-third had no known or reported bat exposure at all. The
recollection of bite incidents can affect the analysis, and these
cases were likely caused by an unrecognized bite and salivary
contamination, as opposed to aerosol exposure. Since 1999,
RPEP recommendations have been broadened in the hopes of
preventing additional cases among persons with unrecognized
bat contact, including “persons who were in the same room as
the bat and who might be unaware that a bite or direct contact
had occurred (e.g., a sleeping person awakens to fin a bat in
the room or an adult witnesses a bat in the room with a previously unattended child, mentally disabled person, or intoxicated person)” [10, p. 8]. Only 2 (13%) of the 16 case patients
since 1990 who reported no direct contact had possible exposure while sleeping and, thus, would have qualifie for RPEP
had this been recognized as sufficien exposure. Although the
remainder may also have had qualifying contact that was not
elicited before illness or death, other types of exposure outside
the eligibility criteria for RPEP may have been responsible. The
true preventable proportion of cases and the number needed
to treat with RPEP to prevent 1 case would be useful information to inform the current guidelines. In that context, evaluation of the frequency of different types of bat contact and
the potentially at-risk but undeclared exposures in a representative sample of the population may be worthwhile.
Acknowledgments
Financial support. Ministère de la santé et des services sociaux du
Québec.
Potential conflict of interest. All authors: no conflicts
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