The General Directorate of Public Health and Pharmaceutical Management of the Ministry of Health and Consumer Affairs of the Andalusian Government has declared alert areas in the neighborhoods of Retamar-El Toyo, with 11,000 inhabitants, and El Alquián, with 6,000 inhabitants, in the municipality of Almería after confirming the circulation of the West Nile virus (WNV) in mosquitoes captured in traps located in these areas. Likewise, it has raised the risk level from low to high for the entire municipality of Almería. This is the first declaration of an alert area and an elevation of risk level this season.
Health and Consumer Affairs sent samples of female mosquitoes collected on June 11 in El Retamar to the National Microbiology Center-Instituto Carlos III in Madrid to confirm the positive result for WNV that our laboratories had detected. The detection of these mosquitoes in a low-risk municipality confirms the working hypothesis of the Comprehensive Surveillance and Control Program for West Nile Fever Vectors for 2025 and reinforces the decisions made: no Andalusian municipality is exempt from the risk of WNV circulation and entomological surveillance precedes human surveillance.
The Ministry immediately conveyed the information and the decision made to the Almería City Council and has called a meeting for this Saturday attended by the Government Delegate of the Andalusian Government, Aránzazu Martín; the territorial delegate of Health and Consumer Affairs, Juan de la Cruz Belmonte; the Mayor of Almería, María del Mar Vázquez; the Councilor for Environmental and Energy Sustainability, Antonio Urdiales, and the company Athisa, responsible for pest control and environmental health in the municipality of Almería, which has been carrying out preventive treatments since April, to coordinate the joint action plan.
The meeting held at the Almería City Council was attended by the Government Delegate of the Junta, Aránzazu Martín; the territorial delegate of Health and Consumer Affairs, Juan de la Cruz Belmonte; the Mayor of Almería, María del Mar Vázquez; the Councilor for Environmental and Energy Sustainability, Antonio Urdiales, and the company Athisa, responsible for pest control and environmental health in the municipality of Almería.
The declaration of the alert area, for a minimum period of four weeks or until no new cases are reported or the circulation of the virus in the mosquito vectors of this disease, birds, or equines in this territory is detected for an equivalent period, involves intensifying the three surveillances (entomological, animal, and human) in the area, activating promotional actions in schools and residences in the area, and reinforcing communication actions to the public through community pharmacies and nursing to encourage the adoption of necessary protective measures against WNV.
On the other hand, the local administration must intensify the measures for controlling and treating mosquito vectors of the disease during the period the area is on alert.
Update of the Comprehensive Surveillance and Control Program for FNO Vectors
The Ministry of Health and Consumer Affairs approved the update of the Comprehensive Surveillance and Control Program for West Nile Fever Vectors for the 2025 season in February, in which more than 250 professionals participated including municipalities, provincial councils, scientific groups, public health inspectors, and companies, through meetings held between December and January.
This program establishes that all municipalities in Andalusia are included in some risk level, and therefore, all of them have a need for virus control because it was observed in the previous season that the species of mosquito vectors (Culex) are present throughout the Andalusian territory. These risk levels have been reduced to three (low, medium, and high) to facilitate understanding by all stakeholders, including the population, as well as the prevention and control measures associated with each level. In total, there are 103 municipalities at high risk, 313 at medium risk, and 369 at low risk.
The medium and high levels correspond to territories where the circulation of the West Nile virus has already been evidenced. The high level corresponds to evidence of WNV circulation near populations in any of the last three seasons. Thus, all municipalities should include mosquito control in their existing pest control programs (rodents, cockroaches, processionary caterpillar), conduct a diagnosis of potential larval sites within population centers or very close to them, and keep them under surveillance (in the case of low and medium risk) and, in municipalities at high risk, these measures should be extended to the entire municipal territory, with special attention to larval sites or adult refuge sites within a 1.5 km distance from populations.
In March, all municipalities were informed of their risk level, and the public health inspectors (over 400 deployed throughout Andalusia) contacted them to provide technical advice on the implementation of surveillance and control measures, which should cover the entire year with the aim of keeping mosquito populations as low as possible when the virus reaches its peak circulation period, from June to October.
Additionally, in the Specially Monitored Regions (La Janda in Cádiz and Bajo Guadalquivir in Seville), which have accounted for over 95% of confirmed cases since 2021, the Ministry of Health and Consumer Affairs has implemented a surveillance of mild cases of non-neuroinvasive FNO, in which other pathogens have been ruled out, through PCR. 80% of infections in humans are asymptomatic. Approximately 20% of infected individuals present with flu-like symptoms characterized by fever, headache, fatigue, myalgia, general malaise, nausea, vomiting, and sometimes maculopapular rash and adenopathy. Less than 1% of those infected develop severe illness with neurological involvement (meningitis, encephalitis, or flaccid paralysis).
Similarly, the program expands entomological surveillance, based on mosquito trapping and virus detection through PCR, both in terms of the number of traps and the covered territory and time. Thus, the number of traps has increased from 27 to 120, all Andalusian provinces are included, and the program started in May, a month earlier than in 2024 and two months earlier than in 2023.
The program also improves the predictive model for assessing the risk of WNV circulation, integrating the model designed by CSIC-Doñana, to which the Ministry’s own data has been added, including new variables such as land use, infected birds, or vector presence, among others.
It is worth mentioning the mobilization of all health promotion and prevention actors of the Ministry of Health and Consumer Affairs (Family and Community Nurses, 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, allowing for greater capacity and speed in diagnostic response.
Furthermore, coordination with other administrations is strengthened through winter season preparation working groups, and support for municipalities through increased visits by public health agents to affected municipalities since March. The communication plan to the population is also enhanced, encouraging active participation in vector surveillance and control.
The goal of this program update is to increase assistance to municipalities and provincial councils in preparing for vector control; to early identify the arrival of the virus; to mobilize other health actors and communicate and support the population better in case of an alert situation.
Recommendations to the population
The Ministry of Health and Consumer Affairs has launched a social media campaign, involving all pharmacies in Andalusia, coordinated by CACOF (Andalusian Council of Official Pharmacists), recommending the population to reinforce protective measures against this virus, especially among vulnerable individuals with compromised immunity.
Thus, the General Directorate of Public Health and Pharmaceutical Management emphasizes the need to use registered mosquito repellents (containing DEET (N,N-diethyl-m-toluamide), Icaridin, Citriodiol or PMD, IR 3535 (Ethyl butylacetylaminopropionate), and essential oils (geraniol, lavender…) at different concentrations and for topical use), cover most of the body with light-colored clothing and avoid strong odors (perfumes, scented soaps…) as they attract mosquitoes.
Health also reminds the population to strengthen domestic protective measures such as installing mosquito nets, using domestic insecticides/ambient repellents or turning off lights when not needed, as light attracts mosquitoes. Another key measure is to avoid creating stagnant water areas, where mosquitoes breed, so it is recommended to properly maintain pools, swimming pools, and wash basins and empty any water that may accumulate and go unnoticed in gardens, pots, toys, or buckets.
In the case of livestock farms, it is also advisable to regularly renew animal drinkers; avoid water from puddles in vehicle tracks or roads, water leaks from taps or broken pipes, leaking water troughs, or those with poor renewal.