Andalucía declares alert for West Nile Virus

Disease has been detected in mosquitoes and can be spread to humans

A Culex pipiens or common house mosquito

A health alert has been declared in several municipalities in Andalucía, after it was confirmed that West Nile Virus (WNV) is circulating in Culex mosquitoes captured there.

The first places to be put on alert by the regional health department were Pulpí (Almería), Chiclana (Cádiz), Baeza and La Carolina (Jaén), as well as Guillena and Gerena (Sevilla).

This has now been extended to include La Luisiana (Sevilla), Tarajal (Málaga), and the hamlet of Tahivilla (Tarifa, Cádiz).

Health authorities have ruled out any new human cases for now, having conducted 323 tests on residents in the affected areas, all of which returned negative results.

However, surveillance has also detected a horse infected with WNV on a farm over 1.5 kilometres from the town centre of Antequera (Málaga), which therefore remains at a high-risk level.

Health authorities explained that the decision was made after receiving laboratory results analysing mosquito species, their density, and the presence of the virus. Recent samples confirmed the presence of WNV in several batches of mosquitoes captured using surveillance traps.

The three active surveillance systems (entomological, animal, and human) will be intensified for a minimum of four weeks, or until viral circulation is no longer detected in mosquitoes, birds or equines.

Local councils and provincial authorities in Sevilla, Cádiz, and Málaga are taking action by strengthening control and treatment of vector mosquitoes, particularly in wet areas and locations close to residential zones; awareness campaigns in schools, care homes and health centres; and direct communication with the public to prevent bites and eliminate potential mosquito breeding grounds.

What is West Nile Virus?

According to the European Centre for Disease Prevention and Control (ECDC), WNV is usually spread to humans and other mammals from mosquitoes that have bitten infected birds, although about 80% of human infections have no symptoms.

About 20% of WNV infections in humans may cause West Nile fever (WNF), characterised by: headache, malaise, fever, myalgia, vomiting, rash, fatigue and/or eye pain.

Less than one per cent may cause West Nile neuroinvasive disease (WNND), which affects the nervous system and can have a mortality rate of up to 17%.

There is no specific treatment for the virus, only supportive care, but personal protective measures include: use of mosquito nets, sleeping in screened or air-conditioned rooms, wearing clothing that covers most of the body, and using mosquito repellent.

Since the beginning of 2025, and as of 8 October 2025, 13 countries in Europe have reported human cases of West Nile virus infection: Albania, Bulgaria, Croatia, France, Greece, Hungary, Italy, Kosovo, North Macedonia, Romania, Serbia, Spain and Turkey.

The confirmed human cases in Spain this year include one in Alicante province, one in Almería and 21 in Badajoz.

Europe is experiencing longer and more intense transmission seasons for mosquito-borne diseases, including WNV infection and chikungunya virus disease.

This shift is driven by climatic and environmental factors such as rising temperatures, longer summer seasons, milder winters and changes in rainfall patterns.

ECDC has warned that record breaking outbreaks of WNV infection and chikungunya virus disease point to a ‘new normal’ in Europe, prompting the need for a robust and coordinated response to protect public health across Europe.

Image: ECDC