Yellow fever seems to play a role in single, sudden breakouts of the disease. Three epidemiologically different infectious cycles occur, in which the virus is transmitted from mosquitoes to humans or other primates. In the "urban cycle", only the yellow fever mosquito "A. aegypti" is involved. It is well adapted to urban areas, and can also transmit other diseases, including Zika fever, dengue fever, and chikungunya. The urban cycle is responsible for the major outbreaks of yellow fever that occur in Africa. Except for an outbreak in Bolivia in 1999, this urban cycle no longer exists in South America. Besides the urban
1793 Philadelphia yellow fever epidemic authorized. After an extensive debate in the newspapers, the State Assembly denied the petition. The recurrences of yellow fever kept discussions about causes, treatment and prevention going until the end of decade. Other major ports also had epidemics, beginning with Baltimore in 1794, New York in 1795 and 1798, and Wilmington in 1798, making yellow fever a national crisis. New York doctors finally admitted that they had had an outbreak of yellow fever in 1791 that killed more than 100 people. All the cities that suffered epidemics continued to grow rapidly. The widespread recognition that the epidemics were based along