During the latest LWNVIVAT webinar, Dr. Jordi Figuerola from the Estación Biológica de Doñana (CSIC) shared insights on the ecology and control of West Nile virus (WNV). He emphasized how monitoring mosquitoes has become a key tool for predicting outbreaks.

A Persistent Threat

West Nile virus, the world’s most widespread flavivirus, is now endemic across southern Europe. Spain’s first human cases appeared in 2004, with major outbreaks in 2020 and 2024.

Mosquito Clues and Environmental Factors

During the webinar, Dr. Figuerola explained that since 2020 his team has trapped and analyzed hundreds of thousands of mosquitoes across Andalusia’s wetlands. Their work identified Culex perexiguus, not the commonly suspected Culex pipiens, as the main vector. In some years, up to 12% of samples tested positive for WNV, often one to two months before human cases appeared, giving authorities time to act.

He also emphasized that environmental conditions shape virus activity: for example, warmer winters boost mosquito survival, and rice cultivation near Seville, covering 36,000 hectares, provides ideal breeding grounds.

Using all these data, researchers and Spain’s Ministry of Health developed risk maps to guide prevention efforts. When the virus is detected, rapid control measures, larvicides, adulticides, and public alerts are deployed.

Although West Nile virus is here to stay, Dr. Figuerola remains optimistic: “Its impact on humans will depend on how well we manage mosquitoes and prevent their proliferation.”