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Title: Detection and early warning of WNV circulation in Central Macedonia, Greece using sentinel chickens and mosquitoes

item CHASKOPOULOU, ALEXANDRA - University Of Florida
item DOVAS, CHRYSOSTOMOS - Aristotle University Of Thessaloniki
item CHAINTOUTIS, SERAFEIM - Aristotle University Of Thessaloniki
item KASHEFI, JAVID - European Biological Control Laboratory (EBCL)
item KOEHLER, PHILIP - University Of Florida
item PAPANASTASSOUPOULOU, MARIA - Aristotle University Of Thessaloniki

Submitted to: Vector-Borne and Zoonotic Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2013
Publication Date: 8/16/2013
Citation: Chaskopoulou, A., Dovas, C.I., Chaintoutis, S.C., Kashefi, J., Koehler, P., Papanastassoupoulou, M. 2013. Detection and early warning of WNV circulation in Central Macedonia, Greece using sentinel chickens and mosquitoes. Vector-Borne and Zoonotic Diseases. doi:1089/vbz.2012.1176.

Interpretive Summary: As a result of the 2010 epidemic of West Nile Virus (WNV) in Greece, a mosquito vector and sentinel chicken surveillance program was initiated in 2011. Due to the presence of multiple strains of WNV of varying virulence within Europe it is important to adapt an arbovirus surveillance strategy that not only allows for early detection of the virus but which is also capable of identifying the strain. Our monitoring program successfully identified transmission of the virus and demonstrated that the WNV lineage 2 responsible for the Greek 2010 epidemic was actively circulating in 2011 and probably managed to overwinter. The system was valuable as an early warning indicator by detecting WNV one month prior to human cases. As a result, public health authorities were informed promptly and control measures were implemented. We showed that the rural agricultural region of Thessaloniki represents an important WNV transmission focus. This was the first effective arbovirus surveillance system for WNV lineage 2. Deployment of similar systems in Greece and other countries worldwide will provide early warning information in relation to WNV activity and guide vector control efforts at the right place and the right time to prevent or minimize the outcome of WNV epidemics.

Technical Abstract: Following West Nile Virus (WNV) epidemic in 2010 in Central Macedonia, Greece, which resulted in 197 human neuroinvasive disease cases, we determined the seasonal appearance and prevalence of the virus in 2011 by testing weekly for WNV genomic RNA in mosquitoes collected in carbon-dioxide baited traps, and for anti-WNV antibodies in sentinel chickens. We detected enzootic circulation in chickens one month prior to the onset of the first human cases in 2011. Culex pipiens and Cx. modestus were abundant throughout the sampling period and at all sites of increased transmission. Molecular identification and phylogenetic analysis of WNV isolates from two chickens and one Culex pipiens mosquito pool suggested that a) the virulent “Nea Santa-Greece-2010” WNV lineage 2 strain responsible for the 2010 epidemic was actively circulating in 2011, and b) all Greek isolates belong to a distinct recent evolutionary clade. In Europe, where numerous strains of different virulence coexist, sequencing information for WNV is important for phylogeography and identification of virulent strains for human health risk assessment.