What to Know About Yellow Fever

It occurs in parts of Africa and Central and South America. It does not spread through ordinary close contact; transmission happens when an infected mosquito passes the virus to a person. Vaccination and avoiding mosquito bites are the main preventive measures.

Early illness may bring sudden fever, headache, muscle or back pain, nausea, vomiting, poor appetite, and marked weakness. These features overlap with malaria, dengue, viral hepatitis, and other infections, so symptoms alone cannot confirm yellow fever. A clinician considers recent travel, mosquito exposure, vaccination history, and blood-test findings.

Some infections become severe after an apparent improvement. Fever can return alongside jaundice, abdominal pain, repeated vomiting, reduced urination, confusion, bleeding, or shock. Jaundice means the skin or whites of the eyes look yellow and can signal liver injury.

Seek medical advice promptly if fever develops during or after travel in an area where yellow fever occurs. Tell the clinician where and when you travelled, whether mosquitoes bit you, when symptoms began, and whether you received a yellow fever vaccine. Call before arriving when possible so the service can direct testing and assess other travel-related infections.

There is no routine antiviral medicine that clears yellow fever. Care focuses on fluids, fever management, observation, and support for complications affecting the liver, kidneys, circulation, or breathing. Avoid starting aspirin or anti-inflammatory painkillers without clinical advice because illnesses that resemble yellow fever may also cause bleeding.

Go to an emergency department or call an ambulance for yellow eyes or skin, blood in vomit or stool, bleeding from the nose or gums, severe abdominal pain, repeated vomiting, confusion, fainting, breathing difficulty, very little urine, or inability to keep fluids down. These signs can reflect liver, kidney, or circulatory complications and should not be monitored at home.

A brief improvement does not remove the need for reassessment if fever returns or new warning signs appear. Continue using repellent and protective clothing while unwell in a place with mosquitoes to reduce the chance of mosquitoes acquiring and passing on the virus.

Before travel, ask whether your destination has yellow fever risk or certificate requirements and whether the vaccine suits your age, pregnancy status, immune health, allergies, and medical history. If you are unwell, ask which tests are planned, how to maintain hydration, which pain or fever medicines are appropriate, and which changes mean you should return immediately.