Yellow fever (YF) is a mosquito-borne viral disease of humans and other primates that is currently endemic (occurring regularly) in 44 tropical zone African and South American countries.
How yellow fever spread
YF is spread by several species of Haemagogus and Aedes mosquitoes. In forest areas and humid regions of Africa, people become infected by the bites of mosquitoes that have previously fed on infected nonhuman primates. During large epidemics in crowded urban areas, mosquitoes can spread the disease from person to person.
What are the symptoms and signs of yellow fever?
Infection with YF virus can cause no symptoms or signs in some cases. In other cases, signs usually appear three to six days after the infected mosquito bite and include fever, muscle pain, shivering, loss of appetite, nausea and vomiting, congestion of the conjunctivae and face and a relatively slow heart rate during fever. Approximately 15% of infections are associated with more severe symptoms, such as jaundice (yellowing of the conjunctivae and skin), bleeding and liver and kidney failure that can lead to death. Severe YF can be confused with malaria, leptospirosis, viral hepatitis, other types of haemorrhagic fevers and poisoning.
What are the complications of yellow fever?
About 20–50% of patients who develop liver and kidney failure die, usually seven to 10 days after the onset of the disease. Survivors may experience prolonged weakness
and fatigue, but the liver and kidneys usually heal completely.
What is the treatment for yellow fever?
There is no WHO recommendation for antiviral medication in YF treatment.
Supportive measures should be taken to alleviate symptoms. Severe cases usually require hospital care. Paracetamol is used in mild cases that can be managed at home. Aspirin and similar medications should be avoided since they may cause bleeding, particularly in the stomach and intestines.
How is yellow fever prevented?
YF is prevented by immunization, which is recommended to protect people living in endemic and epidemic disease areas and travellers visiting these areas, and to prevent international spread by infected travellers. Large-scale YF vaccination has been very effective in endemic areas, but major outbreaks have occurred where coverage has decreased after the discontinuation of immunization campaigns.
Measures to control mosquito populations in urban areas have also been part of prevention strategies.