An acute arbovirus (see ARBOVIRUSES) infection transmitted from animals to humans by various species of forest mosquito and from human to human by Aëdes aegypti. It is ENDEMIC in much of tropical Africa and Central and South America. Every year it causes about 30,000 deaths in Africa. In the urban cycle, humans constitute the reservoir of infection, and in the jungle/sylvan variety, mammals – especially subhuman primates – are involved in transmission. Historically, yellow fever was enormously important, causing devastating epidemics (see EPIDEMIC); it also carried a high mortality rate in travellers and explorers. Differentiation from other infections associated with JAUNDICE was often impossible.
Following an incubation period of 3 to 6 days, an initial illness is characterised by muscle aching, headache, loss of appetite and nausea. Most recover but about 1 in 7 develop a second phase with high fever, JAUNDICE, bleeding and kidney damage.
This is primarily based on virological techniques; serological tests are also of value.
Management consists of dealing with liver failure. The affected individual should be kept in an isolation unit, away from mosquitoes which could transmit the disease to a healthy individual. A vaccine has been available for around 70 years, which is given subcutaneously and provides lifelong protection in about 90% of those to whom it is given. The main reason why many persons in Africa remain unprotected is lack of availability of vaccine.