What should you know about countries at risk for yellow fever?

Risk is not uniform across a whole country. It can depend on the region, season, rural or urban setting, altitude, and activities such as forest travel. The infection is spread by mosquitoes, not by ordinary contact with another traveller. Early illness may involve fever, headache, muscle aches, nausea, or weakness. Some infections become severe and can affect the liver or other organs, so travel preparation matters even when the itinerary seems short.

Some destinations may ask travellers for proof of vaccination because they want to reduce the chance of imported infection. Requirements can depend on the countries visited, transit stops, and onward travel.

Review every stop and transit point with a clinician before departure. Ask whether [Yellow Fever Vaccination](/treatments/preventive-care-and-vaccination/yellow-fever-vaccination/) is advised or required for your route, and carry any relevant vaccination documentation. Use repellent, long sleeves, trousers, and screened or air-conditioned rooms to reduce mosquito bites. Do not wait until the day of travel: medical history, age, pregnancy, immune conditions, and previous vaccine reactions can change the discussion.

After travel to an at-risk area, seek medical advice promptly for fever, severe headache, vomiting, jaundice, unusual bleeding, confusion, or marked weakness. Tell the clinician where you travelled and when symptoms began. Emergency care is appropriate for confusion, collapse, breathing difficulty, seizures, or rapidly worsening illness.

Ask which parts of your itinerary carry risk, whether vaccination fits your health history, what documentation you need, and how to protect yourself from mosquitoes throughout the trip.