A horse in Maó, Menorca, has tested positive for West Nile virus, marking the first confirmed case of the disease in the Balearic Islands. The animal, which was showing neurological symptoms, was diagnosed at Madrid’s Central Veterinary Laboratory in Algete.
Authorities say the case is being closely monitored as part of Spain’s wider West Nile surveillance programme, which tracks horses, wild birds, and mosquitoes to detect the virus early. West Nile virus is mainly spread through mosquito bites. Mosquitoes become carriers when they feed on infected birds and can then pass the virus to humans or animals. Horses and birds are considered important “sentinel” species, often showing signs of the virus before human cases emerge. Spain has previously experienced outbreaks. In 2020, 77 human cases were reported, mostly in Andalucía and Extremadura. More recently, 2024 saw 138 confirmed cases across the country, resulting in 15 deaths.
No other cases have been detected in the Balearic Islands or mainland Spain so far this season. Public health officials are advising residents and visitors to take precautionary steps against mosquito bites, particularly during the late summer months when the risk is highest.
Recommendations include using insect repellent, wearing long sleeves and trousers in mosquito-prone areas, and limiting outdoor activity at dusk and dawn.
According to the World Health Organization, around 80% of people infected with West Nile virus do not develop symptoms. Of those who do, most experience mild illness known as West Nile fever, which can include fever, headache, fatigue, body aches, nausea, or rash.
In rare cases, the infection can lead to severe neurological disease such as encephalitis or meningitis. Approximately 1 in 150 infected individuals develop these more serious complications.
People over 50 and those with weakened immune systems are considered at higher risk of severe illness. There is currently no vaccine or specific treatment for West Nile virus. Patients who require hospital care are typically treated with intravenous fluids, respiratory support, and monitoring to prevent secondary infections.
Authorities in Menorca stress that this is a single confirmed animal case and that measures are already in place to monitor and reduce the risk of further spread.