Dengue and yellow fever

Both illnesses are caused by viruses carried by mosquitoes, and both can cause fever and feeling unwell. They are different diseases, however, with different prevention advice and clinical assessment. Having a yellow-fever vaccine does not make a person immune to dengue.

Travel plans, destination, vaccination history, mosquito exposure, and the timing of symptoms help a clinician decide what needs consideration. Do not rely on a vaccine record to explain new illness after travel.

Discuss destination-specific prevention with a qualified travel-health clinician before departure. Ask whether yellow-fever vaccination is recommended or required for the itinerary, and use repellent, protective clothing, screens, and mosquito-control measures because vaccination does not cover dengue.

Seek medical advice for fever or significant illness during travel or after returning from an area where mosquito-borne infections occur. Get urgent help for bleeding, severe abdominal pain, repeated vomiting, breathing difficulty, faintness, confusion, unusual drowsiness, or inability to drink.

Ask which vaccine is appropriate for your itinerary, when it should be given, what precautions still matter, and how to seek assessment if fever develops during or after travel.