Else Beekman
The Junta de Andalucía has intensified its mosquito control efforts and has launched an emergency plan against the West Nile virus. These efforts were made after the virus was detected in mosquitoes in the province of Seville.
The Junta declared Castilblanco de los Arroyos, a municipality north of the city, as an alert zone on 2 August following the discovery of infected Culex mosquitoes near the Las Colinas housing development.
This marks the first detection of the virus in mosquitoes in Seville this summer. In response, the regional Ministry of Health has activated a reinforced emergency plan, prompted also by high mosquito densities in several municipalities in the Bajo Guadalquivir area, including Coria del Río, Palomares, Los Palacios y Villafranca, and La Puebla del Río. These areas were also heavily impacted by the virus in 2024.
Two-week target to cut adult mosquito levels
On Monday, health officials, municipal authorities, the Seville provincial government, the Doñana Biological Station (CSIC), and local rice farmers convened a technical coordination meeting. The goal: reduce adult mosquito density within two weeks.
“Although the current situation is better than last year, with no human cases recorded so far compared to 56 at this point in 2024, we decided to take early action,” said Manuel Fernández, Director General for Public Health and Pharmaceutical Regulation.
Adulticide treatments and weekly surveillance
The core of the plan involves adulticide treatments targeting mature mosquitoes. These will be carried out around urban perimeters and within towns. Specifically, in areas like parks and fountains where mosquitoes are likely to gather. Municipalities have been instructed to increase weekly surveillance and monitor known mosquito breeding grounds.
Municipalities in the affected region have been asked to maintain weekly monitoring until the end of August. Also, those with currently low mosquito density. The provincial government is furthermore exploring extending adulticide treatments up to 1.5 kilometres beyond urban limits. This way, it is aiming to coordinate with local councils and rice farmers who are conducting their own treatments.
Healthcare professionals in the region have been mobilised to closely monitor suspected cases, including mild ones, while public health inspectors will support local councils in implementing and managing control measures.
Alert status explained
Castilblanco de los Arroyos will remain under alert status for at least four weeks unless further virus activity is detected. If no new evidence emerges, it will then be classified as high risk by the regional government.
During the alert period, authorities will step up surveillance in three areas. These are entomological (mosquitoes), animal (especially birds and horses), and human. Awareness campaigns will be reinforced in local camps and care homes. Meanwhile, pharmacies and nursing professionals will help inform the public about necessary protective measures.
This comes in addition to the emergency response agreed during Monday’s coordination meeting.
105 Andalucian municipalities at high risk
According to the Ministry of Health, 105 municipalities across Andalucía are currently classified as high risk for the West Nile virus. Of these, 41 are in the province of Seville. The rest are spread across Almería (2), Cádiz (16), Córdoba (11), Granada (4), Huelva (15), Jaén (7), and Málaga (9).
A significant update to the West Nile virus surveillance and control programme this year is that every municipality in Andalucía is now included in a risk category. These categories are low, medium or high and reflect that no area is entirely risk-free. The simplified classification is designed to help both authorities and the public understand and implement appropriate prevention measures.
No confirmed human cases yet
So far, there have been no confirmed human infections. Laboratory testing has ruled out infection in 224 individuals. Furthermore, specialists did not report new cases in horses or birds this week.
However, the town of Zurgena in Almería remains under alert following the discovery of infected mosquitoes on 3 July, within 1.5 kilometres of its town centre.
Sources: El Periódico, Diario de Sevilla
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