The Andalusian Board has declared Huelva capital as an area on alert for the West Nile virus (WNV) after confirming its presence in mosquitoes captured in one of the surveillance traps installed in the municipal term. The measure will initially last four weeks and involves reinforcing controls over the insects and intensifying recommendations to avoid bites among the population.
The incorporation of the capital expands the map of areas under special surveillance in a province that has experienced an increase in the circulation of the virus in recent weeks. Huelva has accumulated six confirmed human cases in 2026, located in Almonte, Hinojos, Gibraleón, Niebla, San Bartolomé de la Torre, and Mazagón. Throughout Andalusia, as of this Friday, there were 63 human cases recorded, 56 of them in Seville, six in Huelva, and one in Málaga.
The alert in Huelva capital has, however, an important difference regarding those infections: the decision is not made due to the detection of a new human case in the city, but because mosquitoes with the virus were found in a surveillance trap. The Board's system considers a situation of alert when there are human cases or the circulation of WNV is confirmed to be sufficiently close to a populated area.
Huelva capital joins other areas on alert
Before the incorporation of the capital, the following areas were already under this situation in the province: Almonte, Hinojos, Niebla, San Bartolomé de la Torre, Gibraleón, and the nucleus of Mazagón, the latter shared by the municipal terms of Moguer and Palos de la Frontera.
The last municipality to join had been Gibraleón, after a human infection was confirmed. Just a few days earlier, positives had been reported in Mazagón and Almonte, while Hinojos, Niebla, and San Bartolomé de la Torre had already registered cases during the season.
The declaration of an alert area requires simultaneously intensifying human, animal, and entomological surveillance. The municipalities must also reinforce treatments and actions against the transmitting mosquitoes, while Health increases information to the population and monitoring of the virus circulation.
How to avoid mosquito bites
The main tool to reduce the risk of infection is to avoid bites, especially during the months of greater mosquito activity. The Board recommends using registered repellents, covering as much of the body as possible with light clothing, long sleeves, and long pants and limiting exposure at dawn and dusk, when these insects are most active.
Inside homes, it is advised to install screens on doors and windows, use insecticides or environmental repellents when necessary, and avoid keeping lights on unnecessarily. It is also advisable to refrain from using perfumes and soaps with strong scents that may attract mosquitoes.
Another fundamental measure is to eliminate any place where water can accumulate. Flower pots, buckets, toys, waterers, pools, or small containers can become breeding grounds for mosquitoes if they hold stagnant water for several days. The recommendation is to empty them or refresh the water frequently and properly maintain pools, water tanks, and laundry areas.
Most infections do not present symptoms
The West Nile virus is primarily transmitted to people through the bite of infected mosquitoes, which acquire the virus by feeding on carrier birds. It is not transmitted between people through everyday contact.
According to the World Health Organization, around 80% of infected people do not develop symptoms. Among those who do become ill, symptoms may include fever, headache, fatigue, muscle aches, nausea, vomiting, or skin rashes.
Severe forms are much less common. Approximately one in 150 infections can progress to a neuroinvasive disease, such as meningitis or encephalitis, with symptoms like high fever, neck stiffness, disorientation, tremors, seizures, or muscle weakness. The risk of complications increases especially among older individuals and immunocompromised patients.
Four weeks of enhanced surveillance
The declaration of Huelva capital as an alert area will be maintained initially for four weeks, although this period may be extended if new detections of the virus occur. During this time, mosquito captures and analyses will be intensified, as well as municipal actions aimed at reducing the vector population.
The situation does not imply that all mosquitoes in Huelva are infected nor that a bite automatically means contracting the disease. The alert indicates that the circulation of the virus has been confirmed and that, therefore, both public control measures and individual precautions must be increased.
With the incorporation of the capital, the surveillance map is once again expanded in Huelva in the middle of September, one of the periods in which there is still significant mosquito activity. The health recommendation remains simple: repellent, clothing that reduces the surface area of exposed skin, mosquito nets, and eliminating any accumulation of water around homes.