West Nile Virus

General Information

West Nile Virus infection, period 2024

West Nile virus (WNV) infection cases are recorded -on an annual basis- in many countries worldwide, including many european countries. In 2010-2014 and 2017-2023, cases of West Nile virus infection were recorded in various areas of Greece also, while virus circulation has been recorded in the past in all regions (sporadic cases, or clusters in the mainland). This suggests that the WNV has been established in our country, as well as in other european and neighboring countries. Therefore, the recurrence of WNV infection cases in our country and in other european and neighboring countries is considered likely and expected in each transmission period, during the mosquito circulation season.

Due to its complex epidemiology, WNV’s circulation and geographical distribution during each period cannot be safely predicted. Consequently, personal protective measures against mosquito bites are encouraged, during the mosquito circulation season, throughout the country (and strictly in particular in areas with recent recording of human or animal cases).

In brief, WNV infection cases diagnosed and recorded in our country during the last years (2010-2023) are demonstrated in the following Table.

WNV infection cases Year
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023
Total number of cases 262 100 161 86 15 0 0 48 3172 227 145 59 286 162
Cases with CNS manifestations1 197 75 109 51 14 0 0 28 243 140 116 38 184 119
Cases without CNS manifestations 65 25 52 35 1 0 0 20 74 87 29 21 102 43
Number of deaths 35 9 18 11 6 0 0 5 513 35 23 8 33 23

Table. Number of reported cases of WNV infection with and without central nervous system manifestations (CNS), and number of deaths among cases with WNV infection, Greece, 2010 – 2023

1 Encephalitis and/or meningitis and/or acute flaccid paralysis.

2 One case infected in 2018 but diagnosed in 2019 is also included.

3 One death of a hospitalized patient (infected in 2018) which occurred in 2019 is also included.


WNV is mainly transmitted through the bite of infected “common house” mosquitoes. The mosquitoes are infected from infectious birds (specific species of mainly wild birds), while infected humans cannot further transmit the virus to other mosquitoes.

The majority of infected humans remain asymptomatic or present mild symptoms of a viral syndrome and less than 1% present severe disease with central nervous systems manifestations (mainly encephalitis or meningitis). Older people (over 50 years of age), immunocompromised people and people with chronic underlying diseases are at higher risk for developing severe illness.

The epidemiological surveillance of the disease, the systematic and early implementation of mosquito control programs and personal protective measures against mosquito bites are considered globally the most appropriate measures for the prevention and control of the disease.

In this context, the vigilance of the health professionals and the continuing vigilance of the local and national authorities are considered crucial.

The Hellenic National Public Health Organization (N.P.H.O.), during each transmission period, conducts enhanced epidemiological surveillance of the WNV infection in humans, promptly investigates the cases, and collaborates closely and exchange information with other national, regional and local authorities, aiming to the timely implementation of targeted preventive and response measures.

On the N.P.H.O. website you can find information about WNV, as well as surveillance reports (weekly during the transmission season, and annual), which include updated information regarding the recording of human WNV cases and their geographical distribution (at Municipality level), as well as the public health prevention measures implemented by N.P.H.O.

Epidemiological Surveillance