Larissa: 11 West Nile virus cases confirmed

Eleven confirmed cases of West Nile virus have been recorded in the Larissa regional unit, seven of which presented with manifestations affecting the central nervous system, according to figures released on Monday 17 August 2026 by in.gr and Kosmos Larissas. The cases are spread across three municipalities: seven in the Municipality of Larissa, two in the Municipality of Tempi and two in the Municipality of Kileler, while five of the seven neuroinvasive forms concern the Municipality of Larissa. The data refer to the period up to 12 August 2026, according to the weekly record kept by the National Public Health Organisation. The virus is transmitted to humans exclusively through the bite of an infected mosquito and is not passed from person to person, with birds acting as its natural reservoir.

The proportion of severe cases is the striking element. In the overwhelming majority of West Nile virus infections no symptoms appear at all, and only a small percentage develop a febrile illness. Involvement of the central nervous system, in forms such as encephalitis and meningitis, as a rule concerns less than one per cent of those infected. The fact that seven of the eleven cases recorded in the regional unit are neuroinvasive does not mean the virus is becoming more aggressive, but that the severe cases which reach hospital are mainly the ones detected, while mild cases go undiagnosed.

At national level EODY has recorded 110 domestically acquired cases up to 12 August 2026, of which 81 involve the central nervous system, with 45 new cases within one week and spread across 39 municipalities and 14 regional units. Beyond Thessaly, intense circulation of the virus is recorded in Attica, Central Macedonia and the Peloponnese. The peak of the transmission season is placed between the second half of August and mid-September, since that is when the largest mosquito population and the greatest human exposure outdoors coincide.

The recommended measures remain the same and are mainly individual: use of insect repellents, screens, clothing that covers the skin around sunrise and sunset, and the elimination of standing water in yards and on balconies. Thessaly has extensive irrigated crops and wetlands, conditions that favour the reproduction of the vector. TodayGrid has recorded the recommendations of infectious disease specialists in the report «West Nile: infectious disease experts call for 12 measures». More on the Health page. There is no vaccine and no specific antiviral treatment for humans; management of severe cases is supportive and takes place in hospital. Municipalities run mosquito control programmes at the larval stage, planned from the spring and assessed through trapping.