Both forms are caused by the same virus, which is a member of the Flaviviridae family of viruses. Transmission Yellow fever is transmitted to humans by the bite of infected mosquitoes from a variety of species, principally the Aedes and Haemagogus species. These mosquitoes are day-time biters. From time to time in endemic areas, the number of yellow fever cases can increase dramatically to the epidemic level. For the most part, yellow fever transmission is restricted to rural and jungle areas.
Some infected individuals have no symptoms.
There is no specific treatment for yellow fever. Deaths from yellow fever have been reported among unvaccinated travellers. The single-dose 'live' vaccine for yellow fever is safe, effective and recommended for individuals 9 months of age and older. The vaccine becomes protective after 10 days, and provides immunity to a vaccinated individual for 10 years or more. For individuals who are pregnant, immuno-suppressed or allergic to eggs, the yellow fever vaccination may not be recommended.