Yellow fever is a haemorrhagic fever of the tropics, caused by a flavivirus. Transmission is by
Aedes species of mosquitoes. It is a major problem in sub-Saharan Africa and south America con
Mild febrile illness lasting less than 1 week with headache, myalgia, conjunctival erythema and bradycardia. This is followed by fever resolution but in some cases fever recurs after a few hours to days. In more severe disease, fever recrudescence is associated with lower back pain, abdominal pain and somnolence, prominent nausea and vomiting, bradycardia and jaundice. Liver damage and DIC lead to bleeding with petechiae, mucosal haemorrhages and gastrointestinal bleeding. Shock, hepatic failure, renal failure, seizures and coma may ensue.
Clinical features in endemic area or recent travel
Virus isolation from blood in first 24 days
Leucopenia is characteristic.
IgM or fourfold rise in IgG antibody titre
Differentiation from malaria, typhoid, viral hepatitis, leptospirosis, haemorrhagic fevers, aflatoxin poisoning