Yellow fever other feverish illnesses such as malaria. Other viral hemorrhagic fevers, such as Ebola virus, Lassa virus, Marburg virus, and Junin virus, must be excluded as the cause. Personal prevention of yellow fever includes vaccination and avoidance of mosquito bites in areas where yellow fever is endemic. Institutional measures for prevention of yellow fever include vaccination programmes and measures of controlling mosquitoes. Programmes for distribution of mosquito nets for use in homes are providing reductions in cases of both malaria and yellow fever. Use of EPA-registered insect repellent is recommended when outdoors. Exposure for even a short time is enough for
Yellow fever vaccine vaccine, ten years after a primary dose, is not necessary. Since yellow fever vaccination began in the 1930s, only 12 known cases of yellow fever post-vaccination have been identified, after 600 million doses have been dispensed. Evidence showed that among this small number of "vaccine failures", all cases developed the disease within five years of vaccination. This demonstrates that immunity does not decrease with time. The World Health Organization recommends the vaccine between the ages of 9 and 12 months in areas where the disease is common. Anyone over the age of 9 months who has not been previously immunized