dengue
Published 4 November 2026, 18:37
dengue (dengue fever) — a viral disease carried by mosquitoes of the genus Aedes
It is transmitted only through the bite of an infected mosquito and does not spread from person to person. According to the DGS, symptoms appear 3–7 days after the bite, and no later than 14 days: fever, severe headache, muscle and joint pain, vomiting, red spots on the skin; in rare cases it causes bleeding. Between 40% and 80% of infections cause no symptoms at all.
Where you come across it. Returning from the tropics with a fever, news about mosquitoes, a trip to Madeira.
There are four serotypes of the virus, and immunity only develops to the one you have had, so a second infection can be more severe. Dengue cases are diagnosed in Portugal every year, but those on the mainland are imported; local transmission has occurred in Madeira, in 2012–2013 and once in January 2025.
Official website: sns24.gov.pt/tema/doencas/doencas-infecciosas/dengue