Yellow fever

Yellow fever is a viral infection, transmitted by mosquitoes. In the jungle environment, Haemogogus mosquitoes are the cause of infection, whereas in an urban environment, Anopheles aegypti mosquitoes are the culprit.

It is endemic in Central Africa, Central America and the northern half of South America.

Whilst not always serious, it can be fatal. In its more benign form it can resemble dengue fever.

Common symptoms and physical signs usually present 2-6 days after exposure, and include:

  • loss of appetite
  • fever
  • headache
  • vomiting
  • backache
  • reddening of tongue and eyes
  • flushed face

In mild cases the only symptoms may be headache and fever, or a dengue-like illness with chills, fever and severe muscle pain. In the most severe cases, when death may occur, it develops into a haemorrhagic illness, when the body’s clotting mechanisms fail and you get bleeding into the inner organs. Jaundice (yellow skin) is a sign that the illness is more severe.

Treatment consists of supportive measures only, there are no drugs to treat the virus. Immunisation is therefore vital and all the more important as it is virtually 100% effective. Immunity lasts for at least 10 years.

Some countries make immunisation mandatory for entry.

Yellow fever vaccine should not be given to anyone whose immune system is suppressed by disease or by drugs and to those who have had an anaphylactic reaction to egg or severe reactions to antibiotics Neomycin or Polymyxin. Children under 9 months old should be vaccinated only if the risk of yellow fever is unavoidable as they have an increased risk of a significant reaction to the vaccine. Pregnant women should also be vaccinated only if the risk of yellow fever cannot be avoided as there is an increased risk of adverse reaction.

See the nurse for more information on immunisation.

Further information

This article published on
08 September 2005

Next review date 9/1/2013



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