Greek health authorities recorded 110 domestically acquired West Nile virus infections by 12 August 2026, with nine deaths and 16 patients in intensive care, as the country faces its most significant summer outbreak in years. All fatalities occurred among patients over 65, with a median age of 82.
The National Public Health Organization of Greece, EODY, reported 45 new locally transmitted infections in the final week covered by its epidemiological surveillance report. Of the 110 total cases, 81 involved manifestations affecting the central nervous system — including encephalitis, meningitis, meningoencephalitis or acute flaccid paralysis — while 29 cases presented milder symptoms or no central nervous system involvement. At the time of reporting, 35 patients remained hospitalised: 19 in ordinary wards and 16 in intensive care units.
Attica Hit Hardest
East Attica has emerged as the outbreak's epicentre. The municipality of Spata-Artemida recorded 11 patients with central nervous system manifestations and two without, translating to 31.5 cases per 100,000 inhabitants. Markopoulo Mesogaias reported eight patients with central nervous system involvement and three without — a rate of 36.8 per 100,000 inhabitants, the highest concentration in the country.
Cases have been recorded in 39 municipalities across 14 regional units in four regions: Attica, Thessaly, Central Macedonia and the Peloponnese. In Attica alone, affected areas include East Attica, the North, West, Central and South Sectors of Athens, and Piraeus. Outside the capital region, infections have appeared in Karditsa, Larissa, Trikala, Imathia, Thessaloniki, Pella, Serres and Laconia.
The median age of patients with central nervous system manifestations is 73 years, though the age range spans from 19 to 91 years. Sixty-one patients have been discharged, and five cases didn't require hospitalisation.
Public Health Response Under Scrutiny
EODY's surveillance efforts began months before the summer spike. In March 2026, the Ministry of Health issued a circular on integrated mosquito management programmes, and in May 2026 an information letter went to all health facilities and medical associations. EODY has asked regions and municipalities for timely launch, proper organisation and effective implementation of mosquito-control programmes. For 2026, an enhanced entomological surveillance network with mosquito traps has been deployed across Greece.
Veterinary surveillance identified recent West Nile virus infections in horses at five sites in East Attica, Drama, Preveza and the Metropolitan Unit of Thessaloniki. EODY said every reported case is investigated within 24 hours, with daily communication between laboratories and support for suspected cases.
Based on epidemiological and geomorphological data, additional municipalities have been classified as high-risk areas even though no human cases had been recorded there by 12 August: Kifisia, Iraklio, Filothei-Psychiko and Metamorfosi in the North Sector of Athens, Kallithea and Nea Smyrni in the South Sector, Nea Filadelfeia-Nea Chalkidona and Dafni-Ymittos in the Central Sector, as well as Amfipoli in Serres, Heroic City of Naousa in Imathia and Delta in Thessaloniki.
The Undetected Majority
The 110 laboratory-confirmed cases don't reflect the total number of infections. EODY cited a 2010 seroepidemiological study showing that for every single case of West Nile virus infection with central nervous system involvement, around 140 people are infected who either develop mild symptoms or remain asymptomatic. That suggests thousands of Greeks may have been exposed this summer without knowing it.
Cases have been recorded in Greece during the periods from 2010 to 2014 and from 2017 to 2025, mainly in summer and autumn months. The almost annual occurrence since 2010 indicates West Nile virus has become established in Greece, as it has in other European countries. EODY said additional cases are considered likely in the coming weeks, both in areas where the virus is already circulating and potentially in new areas.
Why This Matters:
The West Nile outbreak reveals the limits of public health infrastructure when seasonal threats become endemic. Despite advance planning — a ministerial circular about 5 months ago, information letters about 3 months ago, enhanced surveillance — the virus has spread rapidly through Greece's most densely populated region. The concentration of severe cases in East Attica, with rates exceeding 36 per 100,000 in some municipalities, raises questions about the effectiveness of local mosquito-control programmes and whether municipalities have the resources and capacity to implement them properly. With EODY projecting more cases in coming weeks, the outbreak tests whether decentralised public health responses can contain vector-borne diseases that don't respect municipal boundaries. The demographic profile of fatalities — all over 65, median age 82 — also highlights the vulnerability of Greece's ageing population to infectious disease threats that were once rare but are now recurring annually.