Human and entomological surveillance of West Nile fever, dengue and chikungunya in Veneto Region, Italy, 2010-2012.
BACKGROUND
Since 2010 Veneto region (North-Eastern Italy) planned a special integrated surveillance of summer fevers to promptly identify cases of West Nile Fever (WNF), dengue (DENV) and chikungunya (CHIKV). The objectives of this study were (i) To increase the detection rate of imported CHIKV and DENV cases in travellers from endemic areas and promptly identify potential autochthonous cases.(ii) To detect autochthonous cases of WNF, besides those of West Nile Neuroinvasive Disease (WNND) that were already included in a national surveillance.


METHODS
Human surveillance: a traveler who had returned within the previous 15 days from endemic countries, with fever >38°C, absence of leucocytosis (leukocyte count <10,000 μL), and absence of other obvious causes of fever, after ruling out malaria, was considered a possible case of CHIKV or DENV. A possible autochthonous case of WNF was defined as a patient with fever >38°C for <7 days, no recent travel history and absence of other obvious causes of fever. Entomologic surveillance: for West Nile (WNV) it was carried out from May through November placing CDC-CO2 traps in five provinces of Veneto Region, while for DENV and CHIKV it was also performed around residences of viremic cases.


RESULTS
Human surveillance: between 2010 and 2012, 234 patients with fever after travelling were screened, of which 27 (11,5%) were found infected (24 with DENV and 3 with CHIKV). No autochthonous case of DENV or CHIKV was detected. Autochthonous patients screened for WNF were 408, and 24 (5,9%) were confirmed cases. Entomologic surveillance: the WNV was found in 10, 2 and 11 pools of Culex pipiens from 2010 to 2012 respectively, in sites of Rovigo, Verona, Venezia and Treviso provinces). No infected Aedes albopictus with DENV or CHIKV was found.


CONCLUSIONS
Veneto is the only Italian region reporting WNV human cases every year since 2008. WNV is likely to cause sporadic cases and unforeseeable outbreaks for decades. Including WNF in surveillance provides additional information and possibly an early alert system. Timely detection of DENV and CHIKV should prompt vector control measures to prevent local outbreaks.
Centre for Tropical Diseases, Sacro Cuore-Don Calabria Hospital, Negrar, Verona, Italy. federico.gobbi@sacrocuore.it.
Federico
F
Gobbi
Gioia
G
Capelli
Andrea
A
Angheben
Mario
M
Giobbia
Mario
M
Conforto
Marzia
M
Franzetti
Anna Maria
AM
Cattelan
Enzo
E
Raise
Pierangelo
P
Rovere
Paolo
P
Mulatti
Fabrizio
F
Montarsi
Andrea
A
Drago
Luisa
L
Barzon
Giuseppina
G
Napoletano
Francesca
F
Zanella
Francesca
F
Pozza
Francesca
F
Russo
Paolo
P
Rosi
Giorgio
G
Palù
Zeno
Z
Bisoffi
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018354:Alphavirus Infections / Q000453:epidemiology* / Q000821:virology; D000818:Animals; D065632:Chikungunya Fever; D002646:Chikungunya virus / Q000235:genetics / Q000302:isolation & purification; D009033:Culicidae / Q000145:classification* / Q000821:virology; D003715:Dengue / Q000453:epidemiology* / Q000821:virology; D003716:Dengue Virus / Q000235:genetics / Q000302:isolation & purification; D062665:Epidemiological Monitoring; D005260:Female; D006734:Horse Diseases / Q000453:epidemiology; D006736:Horses; D006801:Humans; D007303:Insect Vectors / Q000821:virology*; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D014195:Travel; D014901:West Nile Fever / Q000453:epidemiology* / Q000662:veterinary / Q000821:virology; D014902:West Nile virus / Q000235:genetics / Q000302:isolation & purification; D055815:Young Adult