Increasing risk of urban yellow fever outbreaks.

Uncontrollable outbreaks of yellow fever in urban areas of Africa are more likely than ever and increased efforts are needed to contain the threat warns a new WHO report. Intense migration to cities has concentrated a largely unimmunised population into shanty towns where stagnant water provides breeding sites for the vector mosquito Aedes aegypti the report says. Between 1994–99 and 2000–04 the number of west African countries reporting yellow fever increased by 30% revealing “a worrying increase in the circulation of the virus in a non-immune human population”. About 62% of Africa’s population is still rural but urban growth in Africa is at 4% nearly twice the global average. “There are now 43 cities in Africa with more than 1 million people most of them with populations that have never been vaccinated against yellow fever” says Sylvie Briand (WHO). “The risk of a multipoint and uncontrollable epidemic is greater now than ever. The only way to prevent yellow fever is to vaccinate at least 80% of the population. However the vaccination coverage for yellow fever remains below 40% in most of the countries where yellow fever is endemic.” (excerpt)