The Department of Health and Consumer Affairs activates entomological surveillance of mosquitoes carrying the West Nile virus (WNV) during the first week of May. Along with this, a social media campaign has been launched, involving all pharmacies in Andalusia, coordinated by CACOF (Andalusian Council of Official Pharmacists), recommending that the population enhance protective measures against this virus, especially among vulnerable individuals with compromised immunity.
Therefore, the General Directorate of Public Health and Pharmaceutical Regulation emphasizes the need to use registered and topical mosquito repellents, cover most of the body with light-colored clothing, avoid strong odors (perfumes, scented soaps…) as they attract mosquitoes, and avoid going out at dawn and dusk, which are peak mosquito activity times.
Health also reminds the importance of enhancing domestic measures: installing mosquito nets, using domestic insecticides/ambient repellents or turning off unnecessary lights as light attracts mosquitoes.
Another crucial measure is to prevent stagnant water areas, where mosquitoes breed, so it is recommended to properly maintain pools, swimming pools, and washbasins and empty any accumulated water that may go unnoticed in gardens, pots, toys, or buckets.
In the case of livestock farms, it is also advised to regularly renew animal drinkers, avoid water from puddles on vehicle tracks or roads, water leaks from taps or broken pipes, as well as leaks or poor renewal in drinking troughs.
Authorized and registered repellents
Using body repellents is a good option to protect exposed areas of the body from bites (neck, hands…), but they must be suitable for age and specific situation, so it is recommended to carefully read the label instructions; verify that the repellent is authorized and registered (the registration number should appear on the packaging information); follow the application instructions and test it on a small area of the skin beforehand to avoid allergic reactions. The product should be applied on the hand to spread it on the skin while avoiding contact with eyes, mucous membranes, wounds, and sensitive areas. Special caution should be taken when applying repellents for children under three years, pregnant and lactating women, and individuals with pre-existing health conditions.
In general, repellents may contain DEET (N,N-diethyl-m-toluamide), Icaridin, Citriodiol, or PMD, IR 3535 (Ethyl Butylacetylaminopropionate) and essential oils (geraniol, lavender…) at different concentrations. These ingredients have been shown to be effective and safe when used according to their instructions, although their effectiveness depends, among other factors, on the active ingredient and its concentration, ambient temperature, exposure to water, simultaneous use of sunscreens, and individual’s level of sweating.
The Department of Health and Consumer Affairs emphasizes that repellent protects from bites, but does not kill the insect, so despite its use, other recommendations should also be followed. It also urges to extreme these protective measures during festivals and pilgrimages that will take place in the coming days in high-risk municipalities.
Infection by WNV is a zoonosis transmitted by mosquitoes of the Culex genus. The virus is transmitted among birds through the bites of infected mosquitoes, this being its natural cycle. Humans and other mammals can become infected collaterally, without leading to new transmissions from them. According to published risk assessments, around 80% of WNV infections in humans are asymptomatic. West Nile Fever (WNF) is the most common clinical presentation. Elderly individuals and immunocompromised persons are at higher risk of developing West Nile neuroinvasive disease.
Increased traps and other measures
The Comprehensive Surveillance and Control Program of West Nile Fever Vectors for the 2025 season also expands entomological surveillance, based on mosquito trapping and virus detection through PCR, both in terms of the number of traps, the area covered, and the time. Thus, the number of traps is increased from 27 to 120, all Andalusian provinces are included (all Andalusian municipalities have a risk level: low, medium, or high) and it starts in May, one month earlier than in 2024 and two months earlier than in 2023.
It is also worth highlighting the mobilization of all health promotion and prevention actors from the Department of Health and Consumer Affairs (Family nurses, school and community references, RELAS – Local Health Action Network – and pharmacies) in high-risk municipalities and the establishment of a second reference laboratory in Andalusia, at the Virgen del Rocío University Hospital, in addition to the one at the Virgen de las Nieves University Hospital, which will allow for a greater capacity and speed in diagnostic response.
Furthermore, coordination with other administrations is strengthened through working groups for season preparation that started in winter and support to municipalities through more visits by public health agents to affected municipalities since March (more than 400 agents deployed throughout the territory). The communication plan to the population is also improved, so that they can be an active part of vector surveillance and control.
The goal of this program update is to increase assistance to municipalities and provincial governments in preparing for vector control, early identification of virus arrival, mobilizing other health actors, and communicating and better supporting the population in case of an alert situation.