West Nile virus cases surge in Greece

Greek health authorities are raising concerns over a sharp increase in West Nile virus infections this summer, with 45 new locally acquired cases reported in just one week. Attica has emerged as the main hotspot of transmission.

According to the latest weekly surveillance report from Greece’s National Public Health Organization (EODY), covering data through 12 August 2026, 110 locally acquired West Nile virus infections have been recorded across the country.

Of these, 81 patients developed neurological complications involving the central nervous system, including encephalitis, meningitis, meningoencephalitis and acute flaccid paralysis. The remaining 29 patients experienced milder symptoms or showed no neurological involvement.

The rapid rise in infections is particularly concerning. Forty-five new locally acquired cases were identified or reported over the past week alone, representing a substantial proportion of all cases recorded during the current transmission season.

Nine deaths and 16 patients in intensive care

The severity of the outbreak is reflected in the number of serious cases. By 12 August, nine people had died following West Nile virus infections involving the central nervous system.

All nine fatalities occurred among people over 65. Their median age was 82, with ages ranging from 66 to 91.

At the same time, 35 patients remained in hospital: 19 in regular wards and 16 in intensive care units. Another 61 patients had been discharged, while five did not require hospitalisation.

Older age appears to be an important factor in severe disease. The median age of patients with neurological complications was 73, although cases ranged from 19 to 91 years.

The actual number of infections may be much higher

The 110 confirmed cases are unlikely to represent the full extent of the outbreak.

EODY notes that, according to a 2010 seroepidemiological study, every case of West Nile virus infection affecting the central nervous system may correspond to around 140 additional infections in people who either develop mild symptoms or remain asymptomatic.

This means that officially reported cases of severe disease capture only a fraction of the virus's circulation in the population.

Attica remains the main hotspot

Attica is at the centre of this year's West Nile virus activity.

By 12 August, infections had been identified in 39 municipalities across 14 regional units and four regions: Attica, Thessaly, Central Macedonia and the Peloponnese.

Within Attica, cases have been reported in East Attica and across the northern, western, central and southern sectors of Athens, as well as in Piraeus.

Outside Attica, infections have been detected in Karditsa, Larissa, Trikala, Imathia, Thessaloniki, Pella, Serres and Laconia.

EODY says virus circulation is particularly intense in Attica, with a notable increase in cases in several municipalities and regional units.

Additional municipalities classified as high risk

Health authorities are also monitoring municipalities where no human cases have yet been detected.

Based on epidemiological and geographical assessments, several areas have been classified as high-risk zones, including Kifisia, Iraklio, Filothei-Psychiko and Metamorfosi in northern Athens; Kallithea and Nea Smyrni in southern Athens; Nea Filadelfeia-Nea Chalkidona and Dafni-Ymittos in central Athens; as well as Amfipoli in Serres, Naousa in Imathia and Delta in the Thessaloniki metropolitan area.

The classification is based on factors including proximity to affected areas, geographical characteristics and both current and historical epidemiological data.

Virus also detected in horses

Veterinary surveillance suggests that West Nile virus is circulating in additional areas.

By 12 August, recent infections had been detected in horses at five locations in East Attica, Drama, Preveza and the Thessaloniki metropolitan area.

The presence of infected horses is considered an indicator of active virus circulation in those areas.