West Nile Virus Alert in Andalusia: What You Need to Know

The Current Situation

About 20 municipalities in Andalusia are currently on alert due to the spread of the West Nile Virus this year. The virus is transmitted by mosquitoes, and certain areas are seeing much higher activity than others.

Where Is the Risk Highest?

The highest concentration of cases is in the province of Seville, specifically in towns around the Guadalquivir River valley. This stretch runs from Constantina in the north down to La Puebla del Río and Coria del Río in the south.

Other Provinces on Alert

While Seville is the main hotspot, health authorities have also identified alert points in:

• Jaén
• Granada
• Málaga

A Look at the Numbers

Since 2020, the virus has taken a serious toll in Andalusia:

Important Point

2024 was the worst year on record for West Nile fatalities in the region. However, after authorities strengthened preventive measures, the following year saw zero deaths and only five infections — proof that early action works.

What Authorities Are Doing

Aerial Spraying Operation Launched

This week, the Seville Provincial Council (Diputación de Sevilla) activated a scheduled phase of aerial biocide treatments targeting adult mosquitoes. The goal: control populations that can transmit the virus.

Key details about the operation:

1. It builds on earlier work — larvicide treatments were already applied in wetlands to stop mosquitoes before they matured.
2. Ultra-low volume (ULV) spraying — this method uses tiny amounts of product, works fast, and leaves minimal residue in the environment.
3. Precision targeting — flights are not random. They’re triggered by daily data from the entomological surveillance network (traps that monitor mosquito numbers and virus presence).
4. Focus zones — spraying concentrates on rice fields where:
   • Mosquito density is critically high, OR
   • The virus has been detected circulating.
5. Coverage area — the operation covers:
   • Isla Mayor
   • La Puebla del Río
   • Los Palacios y Villafranca
   • Utrera
   • Plus a 1.5 km safety buffer around each town to maximize protection for residents.

Why Now?

The operation coincides with the peak mosquito activity season. Enhanced monitoring has allowed authorities to:

• Detect virus circulation earlier
• Target interventions more precisely
• Help health services identify human cases faster

What YOU Can Do: Prevention at Home

Authorities emphasize that public cooperation is essential. Mosquitoes breed in standing water — even small amounts in private yards.

5 Steps to Mosquito-Proof Your Property

1. Empty or cover any containers that collect rainwater (buckets, flowerpot saucers, toys, tarps).
2. Maintain pools properly — unused or unchlorinated pools are perfect breeding grounds.
3. Clean gutters and drains so water doesn’t pool.
4. Change water in pet bowls and birdbaths every 2–3 days.
5. Report standing water in public spaces to your local town hall.

Personal Protection: How to Avoid Bites

Experts recommend these simple, effective habits — especially during dawn and dusk, when mosquitoes are most active:

Self-Protection Checklist

• Use insect repellent on exposed skin (follow label instructions).
• Wear light-colored, long-sleeved shirts and long pants — even in summer heat.
• Avoid strong perfumes, scented lotions, or soaps when outdoors — they attract mosquitoes.
• Install or repair window/door screens to keep mosquitoes out of your home.
• Use mosquito nets over beds or baby strollers if needed.

Science in Action: What Researchers Are Discovering

The Doñana Biological Station (Estación Biológica de Doñana) is studying two critical questions:

1. How is the virus spreading geographically? — Tracking its expansion across the region.
2. Are mosquitoes developing resistance to insecticides? — Genetic analysis to see if current treatments will remain effective.

Key Takeaway from Scientists

While research continues, prevention remains the single most effective tool against West Nile Virus. Community action + personal protection + targeted public health measures = the best defense.

Summary

• ~20 Andalusian towns are on alert for West Nile Virus, mainly in Seville’s Guadalquivir valley.
• 2024 was the deadliest year (11 deaths), but stronger measures in 2025 brought deaths to zero.
• Aerial spraying is underway in high-risk rice-growing areas, guided by real-time mosquito surveillance.
• You can help by removing standing water at home and protecting yourself from bites.
• Science is watching for virus spread and insecticide resistance — but prevention is still #1.

FAQ

1. What is West Nile Virus?

It’s a disease spread by infected mosquitoes. Most people (80%) have no symptoms. About 20% get fever, headache, body aches. Less than 1% develop serious neurological illness (encephalitis, meningitis), which can be fatal — especially in older adults or those with weakened immune systems.

2. Can I catch it from another person?

No. It does not spread person-to-person through casual contact. Only via mosquito bites (or rarely, blood transfusion/organ transplant).

3. Why are rice fields a focus for spraying?

Rice paddies are ideal mosquito nurseries — warm, shallow, stagnant water. High mosquito density there increases the risk of virus transmission to nearby towns.

4. Is the aerial spraying safe for people and pets?

Yes. The ultra-low volume (ULV) method uses very small doses of approved biocides, applied at night when fewer people are outdoors. It’s designed for rapid breakdown and low environmental impact. Still, it’s wise to stay indoors during spraying and keep windows closed.

5. What should I do if I think I have symptoms?

See a doctor — especially if you have high fever, severe headache, neck stiffness, confusion, or muscle weakness after a mosquito bite in an alert area. Early medical care improves outcomes.