The first case reported this year was on Sunday, when a pensioner in Palaio Faliro, southern Athens, was taken ill. A resident of nearby Argyroupoli was confirmed as being infected with the virus the next day. But KEELPNO confirmed three more cases, involving people aged 18, 40 and 65, by Thursday evening. They were in Elliniko and Palaio Faliro, in southern Athens, and Piraeus.
Residents of these areas are advised to use mosquito repellent on their skin, to spray their homes, use nets on windows and not to leave receptacles containing water outside their homes. West Nile virus, which can cause encephalitis, was first discovered in 1937 in Uganda.
An outbreak of the virus in Greece in 2011 killed nine people of the 101 infected, according to KEELPNO, which said the average age of those infected was 70.