[The risk of yellow fever in travellers]

Yellow fever is a tropical virus disease characterised by high fever, jaundice, heart and kidney failure, and haemorrhagic diathesis. The causative Flavivirus is endemic in parts of tropical Africa and South America and is transmitted among humans and primates by mosquitoes. The chance that an unvaccinated traveller to West Africa will die of yellow fever is estimated at 1:650 to 1:5000 visitors per month of stay, depending on whether an epidemic occurs. Vaccination with the attenuated yellow fever Asibi 17D virus results in limited virus replication in the body and long-term protection due to the formation of neutralising antibodies. Vaccination is contraindicated in immunocompromised persons. Serious disseminated disease and encephalitis due to infection with the vaccine virus strain are seen more often in the elderly. One should therefore refrain from vaccination in persons over 60 years of age when the risk of infection is negligible. In recent years, the number of yellow fever epidemics has risen substantially, particularly in West Africa and the Amazon region. Reintroduction of yellow fever vaccination in childhood vaccination programmes is necessary in endemic areas to turn the tide of increasing outbreaks of yellow fever.