Andalucía braces for another Nile virus battle after rains boost mosquito threat.
Concept image of specialist fumigators wearing protective suits disinfect stairs with spray chemicals to prevent the spreading of the West Nile Virus (WNV) in southern Spain, 2025.
Credit: Shutterstock, Prostock-studio
The intermittent rainy weather across Spain in recent weeks has brought with it a potentially deadly threat. The country’s water reserves might be brimming, but so are mosquito populations and West Nile virus counts, particularly in Andalucia. In response to the growing threat, Spanish health authorities have kicked off a contingency plan to prevent the spread of the virus to humans.
After weeks of heavy rainfall and rising temperatures, the South of Spain is on high alert for a potential comeback of the deadly West Nile Virus (WNV). And with over 100 municipalities now classed as high risk, public health officials aren’t taking any chances.
Despite efforts, last year’s outbreak claimed 11 lives, 10 of them in Sevilla province alone – making it ground zero once again. Now, with conditions ripe for mosquito breeding, authorities are pulling out all the stops to prevent history repeating itself.
Sevilla steps up – again
Sevilla’s not messing around this year. With 45 towns in the danger zone, the province has launched a €6 million blitz against the virus. The operation, dubbed the “Control y Seguimiento de Mosquitos Transmisores del Virus del Nilo Occidental,” kicked off last Friday, March 28, in La Puebla del Rio with a show of drones, fumigators and even rice field water samples taken in front of the press.
Javier Fernández, president of the Sevilla Provincial Council, proudly announced that they’ve brought this year’s prevention campaign forward by four months compared to 2024. “What worked last year, we’re doing even earlier this time,” he said.
The operation covers 15 municipalities near the Guadalquivir River, including Dos Hermanas, Utrera, and Coria del Rio. It targets both mosquito larvae and the bloodsucking adults, with aerial spraying planned once rice paddies flood – especially near towns.
It’s not just Seville… Cadiz, Huelva, Malaga, and Cordoba are also under pressure.
According to a March 2025 report by the Junta de Andalucia, Cadiz follows Seville with 16 towns at high risk, then Huelva (15), Malaga (9), and Cordoba (8). Across the region, more than 700 locations are under some level of surveillance or control.
In Cadiz, monitoring began as early as February. In Sevilla, traps and larval controls will kick in as soon as the skies dry up. Officials say the goal is clear: kill the bugs before they grow wings.
New West Nile Virus testing lab opens
To speed things up, Seville’s Virgen del Rocio Hospital is opening a second West Nile Virus testing lab – previously, all samples went to Granada’s Virgen de las Nieves. ‘This will save us precious time in public health decision-making,’ said Rocío Hernández, the region’s Health Minister.
A €1.2 million investment will also go toward increasing testing of mild cases and improving the predictive models. Any detection of infected mozzies within 1.5 km of towns will now trigger immediate alert status.
Huelva plays it cool – for now
Over in Huelva, the tone’s a little more relaxed. Officials there reckon things are ‘within the normal range’ despite the floods earlier this year. Francisco Cáceres, head of the local pest control team, said early treatment – starting in February – plus access to protected wetlands like Doñana, has given them a head start.
They’re even planning to hit the Marismas del Odiel this time – a nature reserve previously off-limits due to bird nesting. ‘We’re balancing environmental protection with tourism and public health,’ said Cáceres.
The province’s €3.3 million pest control operation will cover towns like Punta Umbria, Ayamonte, and Isla Cristina. A broader prevention plan is also set to go before local mayors for approval.
Almeria cranks up control after downpours
Meanwhile, Almeria isn’t waiting around. After heavy rains left puddles across the city, local authorities have begun larvicide treatments using biological products. Adult mosquitoes will be tackled next, using giant atomiser cannons.
Antonio Urdiales, the city’s councillor for environmental sustainability, said: ‘We’ve got a year-round mosquito control service in place, and now we’re intensifying it to minimise nuisance to residents.’
Even low-risk towns must take action now to prevent the spread
Thanks to Andalucia’s newly approved 2025 Vector Surveillance and Control Programme, even municipalities with “low risk” status must create local Mosquito Control Plans. The regional government has reminded town halls that mozzies aren’t just annoying – they’re a public health threat and must be tackled like any other pest.
Local health officers will guide and monitor these plans. If an outbreak occurs – in humans, birds, horses, or the insects themselves – the area will instantly move up to “high alert,” with mandatory new measures.
Don’t let the buzz kill your spring
West Nile Virus is spread through the bite of Culex mosquitoes – the kind that breed in stagnant water after rain. The virus can infect birds, horses, and humans, and in serious cases, cause swelling of the brain, meningitis, or even death.
If you’re in Andalucia this spring, be mosquito-smart: clear standing water, use repellent, and keep screens shut.
Authorities are doing their best. Now it’s up to all of us to stop the bite before it starts.
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