The West Nile virus season has begun in earnest in Spain, particularly in Andalusia, where several human cases have already been confirmed. So far, five people have been diagnosed with West Nile fever, all with mild symptoms and residing in municipalities in the province of Seville. The Andalusian Regional Government has declared fifteen towns and cities as alert areas, which entails increased entomological, animal, and human surveillance, as well as public awareness campaigns.
The virus, transmitted through the bite of Culex mosquitoes , has also been detected in wild birds for the first time this year. Outbreaks in animals have been located in Huelva and Lleida, demonstrating the circulation of the pathogen beyond the borders of Andalusia. Health authorities emphasize that prevention is key , as there is no vaccine for humans and the only way to avoid infection is to protect oneself from mosquito bites.
Confirmed cases and areas on alert
The first cases of the season were reported in mid-July: a man from the province of Alicante who required hospitalization, a woman from Seville who spends time in Palomares del RÃo, and a man from Villamanrique de la Condesa. All presented mild symptoms, except for the first, who needed hospitalization. Subsequently, two new cases were confirmed: a man from Coria del RÃo and two women from La Puebla del RÃo. In total, five people have tested positive , all of them in the province of Seville, and all with mild symptoms that did not require hospitalization.
The Andalusian Regional Government has declared alert areas in fifteen municipalities: Pulpà (AlmerÃa), Torredonjimeno (Jaén), Salobreña (Granada), and in Seville: Almensilla, Aznalcázar, Bollullos de la Mitación, Constantina, Coria del RÃo, Gelves, La Puebla del RÃo, Mairena del Aljarafe, Palomares del RÃo, and Villamanrique de la Condesa. Additionally, Fuengirola and the Las Lagunas area in Mijas, Málaga province, have been added to the alert. The alert will remain in effect for at least four weeks or until the virus is no longer detected in mosquitoes, birds, or equines.
Vector surveillance and control
To monitor the circulation of the virus, the Regional Ministry of the Presidency, Health, and Emergencies has a network of 120 of its own traps, in addition to those operated by provincial councils, the Doñana Biological Station (CSIC), and the University of Córdoba, totaling nearly 215 sampling points. Since the start of the season, more than 3.300 tests have been carried out in 213 traps, detecting positive results in several locations. The density of female mosquitoes that transmit the virus has increased progressively, with abundant levels in municipalities such as Los Palacios, La Puebla del RÃo, and Palomares del RÃo.
Local councils in the areas on alert must intensify mosquito control treatments not only in urban centers, but also within a 1,5-kilometer radius of breeding sites. In Mijas, for example, the frequency of fumigation has been reduced from every two weeks to weekly , and parks have been closed for extraordinary pest control measures. In Salobreña, the council has launched an emergency plan with increased fumigation and new traps.
Prevention measures for citizens
The main recommendation from authorities is to avoid mosquito bites. To do this, they advise using registered, topical repellents , wearing light-colored clothing that covers most of the body, and avoiding strong scents such as perfumes or scented soaps, which attract insects. At home, it is essential to install mosquito nets, use household insecticides, and turn off unnecessary lights, as light also attracts mosquitoes.
Another key measure is to eliminate any accumulation of stagnant water , where mosquitoes lay their larvae. It is recommended to keep swimming pools and ponds in good condition, empty flowerpots, buckets, and toys, and frequently change animal waterers on livestock farms. The Regional Government reminds everyone that early detection and vector control are the most effective tools for limiting the spread of the virus.
First outbreaks in wild birds
The Ministry of Agriculture has confirmed the first cases of West Nile virus in wild birds this year. Two outbreaks have been reported in the province of Huelva, in the municipalities of Almonte and Hinojos, both in Iberian imperial eagle chicks that died with neurological symptoms. These cases correspond to lineage 1 of the virus . Additionally, an outbreak has been detected in a goshawk chick in Lleida, in this case from lineage 2. Last year, 19 outbreaks were recorded in Spain, most of them in Andalusia.
The detection of these first cases in animals is possible thanks to the FNO National Surveillance Program, which collects samples from equines, birds, and mosquitoes. Horses account for 96,9% of cases in non-human mammals , and their early detection has great epidemiological value for activating action protocols. Currently, the virus has not been detected circulating in equines or wild birds in Andalusia, although 208 specimens have been analyzed.
In short, the West Nile virus situation in Spain this summer requires the utmost attention from authorities and the public. With five confirmed mild human cases, fifteen municipalities on alert, and the first outbreaks in birds, prevention remains the best tool. Avoiding mosquito bites and eliminating standing water are the most effective measures to reduce the risk of infection, while the surveillance network continues to monitor the virus's evolution throughout the country.
