West Nile virus infections may be going unnoticed in Portugal, health council warns

The Portuguese Council for Health and Environment (CPSA) warned on Monday 2 November that human West Nile virus infections are likely going undiagnosed in Portugal due to the widespread presence of vector mosquitoes and four animal outbreaks recorded this year. Although ECDC data shows 2,009 human cases across 20 European countries this year—including 149 in Spain, particularly in border regions—Portugal has reported no human cases, which the council attributes to underdiagnosis. The virus is transmitted mainly by Culex mosquitoes, which accounted for over 45% of adult mosquitoes captured by INSA in 2025.