INTRODUCTION RESULTS 2012 2013 West Nile Virus (WNV) is a mosquito-borne arbovirus of the Flaviviridae family. (I) WNV infection cases Transmission to humans occurs predominantly following a bite from an infected mosquito, Since the summer-autumn 2011, 132 laboratory-diagnosed cases of WNV infection were principally of the genus Culex, which acquires virus after feeding on avian amplifying hosts. identified and reported to the HCDCP from patients presented with symptoms and signs Peak transmission occurs during mosquitoes’ active period, usually between mid-summer compatible with WNV infection. and early autumn. 33 individuals (25%): WNF cases fever followed by headache, myalgias, arthralgias, Most people infected with WNV remain asymptomatic and only 20% of infected fine maculopapular or morbilliform rash on the chest, back, and upper extremities, and individuals develop West Nile fever (WNF), a mild and self-limited flu-like illness of fever, gastrointestinal symptoms, including anorexia, nausea, vomiting. headache and body aches, occasionally with skin rash and swollen lymph glands. Less 99 individuals (75%): WNV neuroinvasive disease (WNND) cases - meningitis, than 1% of WNV infections progress to clinical disease associated with severe neurological encephalitis and meningoencephalitis acute onset of fever with stiff neck, altered mental manifestations including aseptic meningitis, encephalitis and acute flaccid paralysis. status, seizures, limb weakness, CSF pleocytosis, abnormal neuroimaging. Since its first isolation in the West Nile district of Uganda in 1937, a geographic Year expansion and westward spread of WNV has occurred during the last 20 years. Except for WNND the USA, where the virus, after its first identification in 1999, extended its distribution and 2011 2012 2013 2014 became endemic within the following 10 years, several sporadic cases and a few WNV number of cases 25 45 25 4 outbreaks have been reported in Europe and the Mediterranean basin. median age (range) (years) 67 (25-86) 67 (19-25) 79 (17-95) 81 (76-85) In 2010, the first outbreak of WNV infection in Greece was recorded, the largest in male-to-female ratio 2.6:1 2.5:1 1.3:1 1:1 Europe since 1996. Overall, 262 probable and confirmed cases of WNV infection were 2012 2013 deaths 7 5 1 2 notified, mainly in Central Macedonia region, northern Greece. WNV outbreaks continued 2012 2013 to occur in different areas of the country. (II) Risk factors and underlying chronic diseases in WNND cases PURPOSE Most common risk factors: hypertension and diabetes mellitus Underlying chronic diseases: coronary artery disease, acute myeloid leukemia, After the first WNV human outbreak in Greece in summer 2010, the virus reemerged in lymphocytic lymphoma, kidney transplantation, thyroid cancer (thymoma), colon cancer, July 2011 and a WNV infection outbreak was ongoing in regions of Greece that had chronic obstructive pulmonary disease, cerebrovascular disease already been affected in 2010, but also in Southern Greece that had never reported human All WNND cases were hospitalized - 15 deaths occurred, all in elderly patients with cases before. The following years (2012-2014), WNV continued to circulate in the already underlying diseases affected areas and dispersed to new unaffected ones. The aim of this study is to present the main findings of WNV occurrence in southern Greece from 2011 to 2014. (III) Geographic distribution of reported WNND cases The detection of WNV IgG Abs in patients from previously unaffected regions indicated the In 2011, most cases were identified in the Eastern Attica prefecture, especially in the previous circulation of WNV in these areas. METHODS Marathon municipality where the Schinia wetland favored the reproduction of mosquito Clinical specimens: Serum, whole blood and/ or CSF specimens were collected from vectors. Maroussi patients originating from Southern Greece and considered “suspected” for WNV infection Agios 2011 Dimitrios during transmission periods (June to October). Patients were presented with febrile illness Athens Olympic Ilioupoli Stadium Vrilissia and/ or neurological manifestations ranging from headache to aseptic meningitis and/ or Palaio Faliro encephalitis. Serum and CSF specimens were tested for CNS Filothei Chalandri Chalandri stream signs the presence of IgG and IgM antibodies Viremia IgM Ab against WNV (WNV IgG DxSelect and IgM IgG Ab capture DxSelect ELISA kits, Focus Viral Diagnostics Inc., Cypress, CA, USA), RNA whereas whole blood and CSF samples were used for detection of WNV RNA (Real- time RT-PCR - LightMix® kit West Nile Virus, Podoniftis stream Vrilissia stream Pikrodafni stream Filothei - Chalkidona - Nea Ionia TIBMolBiol, Germany). Infection Onset of Disease 2-4 > 1 year fever 3-7 days months Schinia-Marathon In 2014, the timely use of larvicides directly to mosquito-breeding sites in late spring and National Park early summer reduced the number of emerging mosquitoes and contributed to the dramatic Case definition: Confirmed and probable WNV cases were defined taking into account reduction of WNV cases. a slightly modified 2008 European Union case definition that had also been used in the 2014 2014 2010 WNV infection outbreak in Greece. A confirmed case was defined as a patient Schinia wetland Schinia wetland meeting any of the clinical criteria (e.g. encephalitis, meningitis, fever ≥38.5oC without During summer of 2012 and 2013, WNND cases occurred in municipalities of southern specific diagnosis) and at least one of the following laboratory criteria: (i) detection of WNV and northern Attica respectively, in areas near surface water bodies of Attica. RNA in whole blood and/ or CSF, (ii) presence of WNV IgM antibodies in CSF with or Kifissos and Ilissos rivers (Kifissos river source: between Parnitha and Penteli mountains, without WNV IgG antibodies, (iii) detection of increasing levels of WNV IgM and IgG it flows southwest through Athens reaching the Saronic Gulf) antibodies in consecutive serum specimens. A case was considered probable if the patient Pikrodafni, Chalandri, Vrilissia, Podoniftis, Maroussi streams met the above clinical criteria and WNV IgM antibodies, with or without IgG antibodies, Sporadic cases: southwestern Greece (Achaia: Aegio, Ilia: Andravida, Aetoloakarnania: were detected in patient’s serum specimen. Confirmed and probable cases were notified to Agrinio, Mesologgi, and Ionian Islands: Lefkada, Meganisi). the Hellenic Centre for Disease Control and Prevention (HCDCP). Neo Faliro Moschato Geographic Information System (GIS): The available epidemiological data were stored CONCLUSIONS and processed in specially designed databases in GIS environment and their geographical The reoccurrence of human WNV infection cases in four consecutive years and the distribution in relation to WNV cases by municipality is presented. spread of WNV in newly affected areas suggests that WNV has been established in Greece and its transmission may continue to occur in the future. Epidemiological Kifissos River surveillance, integrated mosquito management programs and public education on personal estuary Ilissos River estuary Build Kifissos River channel Kifissos River protection are crucial to prevent the WNV transmission and control the disease..