Yellow fever Because of this sylvatic cycle, yellow fever cannot be eradicated except by eradicating the mosquitoes that serve as vectors. In Africa, a third infectious cycle known as "savannah cycle" or intermediate cycle, occurs between the jungle and urban cycles. Different mosquitoes of the genus "Aedes" are involved. In recent years, this has been the most common form of transmission of yellow fever in Africa. Concern exists about yellow fever spreading to southeast Asia, where its vector "A. aegypti" already occurs. After transmission from a mosquito, the viruses replicate in the lymph nodes and infect dendritic cells in particular. From there,
Yellow fever cycle has yet been established, scientists believe this could happen again at any point. An outbreak in Paraguay in 2008 was thought to be urban in nature, but this ultimately proved not to be the case. In Africa, virus eradication programs have mostly relied upon vaccination. These programs have largely been unsuccessful because they were unable to break the sylvatic cycle involving wild primates. With few countries establishing regular vaccination programs, measures to fight yellow fever have been neglected, making the future spread of the virus more likely. In the hamster model of yellow fever, early administration of the antiviral