Yellow Fever
This article is general health information for the selected condition. It is not a diagnosis and does not replace clinical judgement. If you have questions or need treatment advice, please consult a qualified healthcare professional.
What is yellow fever?
Yellow fever is a viral haemorrhagic illness spread by mosquitoes in parts of Africa and South America. Most infections are mild, but around 15 percent of people enter a toxic phase with jaundice, bleeding and organ failure, which carries high mortality. A single dose of vaccine gives lifelong protection for most people.
Causes
- Yellow fever virus, a flavivirus
- Bite of infected Aedes or Haemagogus mosquitoes
- Urban cycle between humans and mosquitoes
- Sylvatic cycle involving forest primates
Symptoms
- Sudden fever, chills and headache
- Muscle pain, particularly in the back
- Nausea and vomiting
- Brief remission after three or four days
- Return of fever with jaundice in the toxic phase
- Bleeding from the mouth, nose or stomach
- Reduced urine output and organ failure
Risk factors
- Travel to or residence in endemic areas of Africa and South America
- Lack of vaccination
- Outdoor and forest exposure
- Living in areas with poor mosquito control
Diagnosis
- Serology for yellow fever specific IgM
- PCR testing in the early viraemic phase
- Liver function tests showing marked derangement
- Exclusion of malaria, dengue and viral hepatitis
- Immediate notification to public health authorities
Treatment
- Vaccination, which is highly effective and usually lifelong
- No specific antiviral treatment
- Supportive care with fluids and organ support
- Management of bleeding and liver failure in intensive care
- Avoiding aspirin and NSAIDs because of bleeding risk
- Mosquito bite prevention
Self care
- Seek medical care rather than managing at home
- Rest and maintain fluid intake
- Use paracetamol only, avoiding aspirin and anti inflammatories
- Prevent mosquito bites to avoid transmitting the virus onward
- Carry your vaccination certificate when travelling
When to see a doctor
Book an appointment if:
- Fever after travel to an endemic area
- Any illness within two weeks of returning from an affected region
- Before travel, to arrange vaccination in good time
- Uncertainty about your vaccination status
- Persistent fatigue after recovery
Some symptoms need emergency care rather than an appointment. See the warning signs listed above.
Prevention
- Vaccination, which gives lifelong protection for most people
- Obtain vaccination at least ten days before travel
- Use insect repellent and cover up during the day
- Sleep under screens or nets in endemic areas
- Check entry requirements for certificates
Outlook
Most infections are mild and resolve within a week with lasting immunity. Around 15 percent progress to a toxic phase with jaundice, bleeding and organ failure, and mortality in that group is high. There is no specific antiviral, so vaccination before travel is by far the most important intervention.
Common questions
Is vaccination required for travel?
Many countries require proof of vaccination on an International Certificate of Vaccination for entry from endemic areas. Check requirements well in advance, since the certificate becomes valid 10 days after vaccination.
Who should not have the vaccine?
It is a live vaccine, so it is generally avoided in infants under 6 months, people with significant immunosuppression, and those with severe egg allergy. Advice for pregnancy and older adults should be individualised.
Why is it called yellow fever?
The name comes from the jaundice that develops in the toxic phase, when liver damage causes yellowing of the skin and eyes. Most people with mild infection never develop this.
References
Important: Dard AI is not a medical device and does not diagnose, treat, or replace clinician judgement. This article is general information only. Always consult a qualified healthcare professional about diagnosis and treatment, and seek emergency care for severe or rapidly worsening symptoms.