Yellow fever population is vaccinated. Control of the yellow fever mosquito "A. aegypti" is of major importance, especially because the same mosquito can also transmit dengue fever and chikungunya disease. "A. aegypti" breeds preferentially in water, for example in installations by inhabitants of areas with precarious drinking water supply, or in domestic waste, especially tires, cans, and plastic bottles. These conditions are common in urban areas in developing countries. Two main strategies are employed to reduce mosquito populations. One approach is to kill the developing larvae. Measures are taken to reduce the water accumulations in which the larvae develop. Larvicides are used,
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