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Aspetti entomologici delle malattie trasmesse da

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Sistemi di sorveglianza delle zanzare invasive
Bologna, 10 marzo 2014
Aspetti entomologici delle malattie trasmesse da
zanzare in Italia:
sorveglianza dei vettori indigeni e d’importazione
Roberto Romi
Dipartimento di Malattie Infettive, Parassitarie e Immunomediaete
Reparto Malattie Trasmesse da Vettori e Sanità Internazionale
Istituto Superiore di Sanità - Roma
Malattie trasmesse da vettori (VBD):
ruolo svolto dai Culicidi
1) Le zanzare non sono
semplici siringhe volanti
Molte infezioni sperimentali ottenute forzatamente in laboratorio
non hanno alcun riscontro in natura. Perché una specie venga
ritenuta vettore di un certo agente patogeno è necessario che
siano seguiti precisi criteri epidemiologici
Malattie trasmesse da vettori (VBD):
ruolo svolto dai Culicidi
2) Le malattie trasmesse da vettori
si affrontano combattendo il vettore
Esistono circolari Ministeriali,
piani di sorveglianza nazionali ed
Europei, linee guida locali e
internazionali sulle Mosquito
Borne Diseases (MBD) emergenti,
nella gran parte delle quali
manca ogni riferimento agli
interventi di controllo
Gli interventi di controllo
vanno condotti da personale
specializzato seguendo
protocolli specifici a
seconda del vettore,
che distinguano anche
tra routine ed emergenza.
Oltre che seguiti, gli
interventi devono essere
pianificati (pre)
e valutati (post)
Vectors of Mosquito Borne Diseases in Italy
65 species of Culicidae have been
reported in Italy. These are grouped
in 2 sub-families and 8 genera
• Subfami
ly Anoph
elinae
ae
ubfamily
Anophelin
1) Anopheles
(16 spp)
About 1/3 of the species was only
sporadically recorded or was no
longer reported after the 1950’s
1/3 are rare, un common or strictly
associated to peculiar biotopes
The remaining 1/3 are common
but less than 1/2 of them are very
annoiyng species or potential vectors
of human pathogens.
Up today, 4 species only play a
proved role as vectors of human
diseases in Italy
• Subfamily Culicinae
2) Aedes
3) Culex
4) Culiseta
5) Ochlerotatus
6) Ortopodomya
7) Uranotaenia
8) Coquillettidia
(7 spp)
(12 spp)
(6 spp)
(20 spp)
(1 sp)
(1 sp)
(2 spp)
Ae. albopictus
Cx. pipiens s.l.
An. Labranchiae, An. superpictus
EVENTS RELATED TO MOSQUITO-BORNE DISEASES IN ITALY
1997-2013
1996 Ae. atropalpus
eradicated
2011 Ae. koreicus
Veneto Region
1990 Ae. albopictus
widespread
2007. Outbreak of
Chikugunya fever
2008-2013.
West Nile Disease
1997. A single P.vivax
malaria case
transmitted by an
indigenous vector
Uno sguardo al Futuro
TODAY
WND become an endemic disease
Other ARBOv
in Italy Introduction of new WN viral
USUTU,
strain and rise of the number of
JEV
human cases
Unexpected new
RVF
Outbreaks of introduced
Tahyna
vectors reported
DENGUE and CHIK viruses among Indigenous
Sindbis
species
P. vivax malaria
Introduction and establishment
Increased number of
of invasive allochtonous mosquito
gametocyte carriers
species
Settembre 1990-Settembre 2014
25°
Tuttavia, almeno 2 cose le abbiamo
IMPARATE : I fattori che determinano
l’insediamento della specie e la sua
abbondanza stagionale sono sostanzialmente
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La pon
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L’e
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Aedes albopictus In Italy 2013:
Distribution of Ae.albopictus foci
by altitude (meters a.s.l.)
Distribution of Ae. albopictus
by number of infested Municipalities per Province
REGIONS
PROVINCES
MUNICIPALITIES
20/20
98/110
>3000/8092
SUSCEPTIBILITY OF Ae albopictus ITALIAN POPULATIONS TO
WNV AND CHIKV
Preliminary results of the experimental infection bioassays performed with a
membrane-feeder apparatus
Aedes albopictus is confirmed to be competent for WNV, although at lower
level than Cx. pipiens, and potentially could play a role in the trasmission in
urban environments.
10 Italian populations of the species have been infected with Chikungunia virus
Preliminary results show a qick rise of the viral titre, an early dissemination in legs
and wings and the presence of the virus in the saliva from day 3/6 followed by a quick eclypse of the vira
Culex pipiens and the West Nile Disease
Several species of Culex genus are considered to be involved in the WNV
transmission, but those belonging to the Cx. pipiens s.l. (complex) play the
:
major role as responsible of the human disease.
epizootic
cycle
enzootic
cycle
vector
reservoir
dead-end host
In Europe WNV circulation is confined in both rural and urban
ecosystems
In sylvatic cycle: wild and wetland birds / ornithophilic mosquito species
In urban cycle: domestic birds / mosquitoes feeding on both birds and
humans: as possible bridge-vectors species belonging to Cx. pipiens complex
5 years of
entomological
surveillance whitin the
WND National
surveillance program
2006-2011
32; 0%
65; 0%
Aedes albopictus
93; 1%
157; 1%
Anopheles claviger
231; 2%
1704; 12%
45; 0%
5434; 38%
6223; 45%
16005 adults
52; 0%
100; 1%
24; 0%
214; 1% 219; 1%
208; 1%
86; 1%
296; 3%
55; 0%
169; 1%
65; 0%
208; 1%
Anopheles maculipennis
Anopheles plumbeus
Coquillettidia richiardii
Culex pipiens
Culiseta annulata
Culiseta longiareolata
Ochlerotatus caspius
Ochlerotatus detritus
Ochlerotatus rusticus
Aedes albopictus
Anopheles maculipennis
Culex impudicus
Culex pipiens
Culex hortensis
Culiseta annulata
Culiseta longiareolata
13187; 91%
15 selected migratory bird
nesting areas
14081 larvae
Ochlerotatus caspius
Ochlerotatus detritus
Ochlerotatus sp.
Ochlerotatus zammitii
Culex pipiens s.l.
Two species , two biological forms or
……what……….?
Cx. pipiens pipiens
• Ornithophilic: feeds
predominatly on birds
• Anautogenous: its oviposition
requires a blood meal
• Eurygamous: mates in open
space
• Epigean habitat: occupies
aboveground sites
• Heterodynamic: undergoes
winter diapause
Cx. pipiens molestus
• Mammophilic: prefers to
feed on mammals, including
humans
• Autogenous: able to lay eggs
without a blood meal
• Stenogamous: mates in
confined spaces (< 0.1 m3)
• Hypogean habitat: lives in
underground sites
• Homodynamic: remains
active during winter
Cx.pipiens s.l. Italian
populations
Molecular studies
CQ11 assay that amplify a flanking region of CQ11
microsatellite (M
M=molestus form; P=pipiens pipiens
form M/P hybrids
Most of Cx. pipiens populations analyzed
with CQ11 include all three genotypes at
different frequencies. Pure Cx. pipiens
populations are rare. All three genotypes
coexist in simpatry in aboveground habitats,
are able to feed both on bird and human
(depending on availability), can mate also in
confined spaces, when reared in insectary.
Only the autogeny seems to be linked with the genetic
composition of the population, occurring in population
with M and/or M/P; intensity of autogeny is almost
directly proportional to M frequency.
Comparison between genetic and behavioral features
of Cx. pipiens s.l. strains
Molestus form (M)
Hybrid form (M/P)
M/P
Unexpected feature
Pipiens form (P
P)
Vector competence: susceptibility of Cx. pipiens s.l. to WNV
Experimental infection assays of Italian populations using a membrane feeding apparatus.
WNV mean viral titre
All Cx. pipiens s.l. populations
tested resulted susceptible to
WNV infection, showing
similar trends of viral growth
and viral titre.
IR = 100% of tested females
DR ranging from 47 to 100%
TR ranging from 29 to 44%.
Even if with different degree
of efficiency, all populations
resulted able to transmit WNV
The PTR of each population
was also calculated (range 20-34%)
POPULATION TR (PTR) = No
INFECTION RATE (IR) = No
with WNV positive abdomen/No
DISSEMINATION RATE (DR) = No
tested
WNV-positive winds+legs/IR
TRANSMISSION RATE (TR) = No with WNV/ positive saliva/IR
All three genotypes were found infected
With WNV, the frequencies depending on the different
Population tested. As a consequence, all three genotypes
could act as bridge-vectors, being infected and able to
bite on humans and birds !?
WNVWNV-positive saliva/No
tested
Some other indigenous mosquito species could play a
role of arbovirus secondary vector, particularly in
rural areas or in the outskirt of the
(sub) urban ones
Aedes vexans
Culex modestus
Other Culex spp.
Ochlerotatus caspius
Culiseta spp.
(urban areas too)
An. plumbeus
Specie indigene:
Specie alloctone invasive:
Aedes koreicus
Culiseta longiareolata
BL
TV
VI
Culiseta longiareolata è la terza
specie più comune in molte aree
cittadine dopo Ae. albopictus e Cx.
pipiens, con cui spesso condivide i
focolai larvali. La specie è prettamente
ornitofila ma non disdegna di pungere
occasionalmente anche l’uomo.
In laboratorio si infetta con WNV ma il
suo potenziale ruolo di vettore è tutto
da studiare.
Da IZS delle
Venezie
Aedes japonicus
BELGIO
E OLANDA
Aedes aegypti nel Bacino
del Mediterraneo
Ades aegypti
E’ un vettore più
più
competente di
Ae. albopictus per molti
Arbovirus
Presenta un maggiore
grado endofagia, endofilia
e antropofilia
L’uovo presenta maggiore
resistenza al disseccamento
ma non al freddo invernale
Sopporta meglio gli
ambienti Aridi, tuttavia
sembra richiedere maggiori
risorse trofiche per lo
sviluppo larvale
YELLOW FEVER and DENGUE outbreaks in the XIX century
YF 1804 Alicante, Livorno
YF 1821 Barcellona
YF 1857 Lisbona
YF 1878 Madrid YF was endemic (recurrent?) in ANDALUSIA up to
1880 (12,000 death during the century).
DEN 1927-1928 DENGUE and Haemorragic DENGUE in GREECE
(more than 20,000 cases and 2000 deaths)
Sorveglianza e monitoraggio
dei Culicidi potenziali vettori di arbovirus
LA SORVEGLIANZA ENTOMOLOGICA,
insieme a quella epidemiologica
Rappresenta i l primo mezzo di prevenzione
v ricerca attiva del vettore
v survey periodici nei sti a rischio
v sistemi e normative di quarantena
v valutazione globale (anche passiva)
v valutazioni di rischio
MONITORAGGIO (routine)
v In seguito a “reporting” passivo
v Dinamica e abbondanza stagionali delle
popolazioni del vettore
v Valutazioni degli interventi di controllo
Buona
conoscenza
dei “bionomics”
dei vettori e
metodi
differenziati
di sorveglianza
ENTOMOLOGICAL SURVEILLANCE STRATEGY
(for allocthonous invasive species)
VECTOR FREE (AT RISK) AREAS
Objectives: 1) to prevent the
infestait.tion; 2) early detection
of the species to eradicate it
The maximum effort should be
devoted to the monitoring
system (passive surveillance )
integrated by targteted surveys
in «at risk» areas (active
surveillance)
To begin data collection activities
required after any positive
response of the surveillance
system.
VECTOR POSITIVE AREAS
Objectives: 1) risk assessment; 2) to address
prevenction and vector control activities
Knowledge of the factors that could influence
the vector competence of the invasive species
determining its vectorial capacity (the real degree of
efficiency of the vector):
•Current status of the infestation (routine monitoring may
be reduced to a few number of very informative collection stations)
•Seasonal dynamic and abundance of the local
population (s) - strictly related to Climatic data (in particular
the abundance and the distribution of the rainfall during the year)
•Rate (%) of infection of the vector population
(quantitative analysis of field-collected mosquito pools).
•Bionomics and behavior of the potential vector
(lenght of the larval development and gonotrophic cycles, Host
preference, expected life duration)
•Environmental and socio-economical factors (human
activities, housing, density of inhabitants, availability of breeding and
resting sites)
Urban areas, where
Culex pipiens and Aedes albopictus often share the same breeding sites
Routine monitoring (passive) is carried out according to the bionomics of the 2
speecies by
ovitraps and/or BG sentinel for Aedes albopictus
CDC light traps, with or without CO2 and/or BG sentinel for Culex pipiens
Active surveillance commonly includes larval sampling
Esempio dell’impatto che le diverse componenti delle attività
di controllo possono avere sulle 2 specie, in relazione alla loro
biologia e comportamento
ATTIVITA’
ATTIVITA’
Culex pipiens
Focolai naturali, artificiali,
epigei e ipogei, anche di
vaste dimensioni e/o con
carica organica elevata.
Ciclo di sviluppo più lungo
Attività trofica crepuscolarenotturna. Punge sia indoor che
outdoor (endo e esofagia)
Riposa al chiuso (endofila).
Slow feeder
.
Antilarvali
++++
++
+
++
+
++
IGR
+
+
Biologici
++
Source
reduction
++++
Adulticidi
Space spraiyng
+++
++
Tratt. del verde
--
++++
Tratt. murale
++
-Zanzariere
+++
+
Repellenti uso topico
+++
++
Aedes albopictus
Focolai solamente
artificiali. Raccolte
d’acqua medio-piccole
con carica organica
modesta
Ciclo di sviluppo rapido
Attività trofica
prevalentemente diurna
che si esplica con maggiore
intensità outdoor. Riposa
all’aperto nella vegetazione
bassa (esofila). Fast feeder
Malaria high receptivity ” at risk ” areas and distribution of the
main vectors in Italy and location of 2 suspected cases of autochtonous malaria
(2009-2011)
A recent 5-years study (carried out
within the EU EDEN project) established
a
globally very low malariogenic potential
for Italy, despite the high receptivity of
some areas.
GR
Regions with “at risk” areas
LT
CS
cases
No risk areas
Relatively major risk
sporadic P. vivax
may occur
Moderate risk
Anopheles labranchiae
Very Low
Possible North/eastern expansion of An.
Labranchiae (Inner hilly areas)
Location of the
autochtonous cases
Other members of the An. maculipennis
complex mainly zoophylic
1
An. superpictus
Proved
suspected
Mappe di rischio e modelli matematici predittivi
sono utili strumenti di prevenzione, ma vanno
sempre validati con l’esperienza di campo
Chikungunia coutries or areas at risk. WHO. 2006
Dengue countries or areas at risk. WHO. 2010
Tanto
per
dimostrare
quanto sia difficile creare
modelli
matematici
e
realizzare
mappe
di
rischio affidabili (spesso
basate
solo
su
dati
climatici),
nella
tarda
estate dell’Anno seguente
si è verificato l’outbreak di
febbre da Chik virus in
provincia di Ravenna e
nel 2010-11 i casi di
dengue
autoctoni
in
Francia e Croazia.
GRAZIE DELL’ ATTENZIONE
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