Maryland Department of Agriculture

We knew yellow fever epidemics best from the Americas when they occurred in seaports. American history has many epidemics including those in Philadelphia, Baltimore and New Orleans that ravaged the populace. It has been known for some time that yellow fever is endemic to parts of Africa, and occurs in two forms: urban and jungle. Curiously enough, it does not occur in Asia.

Yellow fever is a mosquito-borne disease caused by a virus. The vector is the mosquito, Aedes aegypti. Commonly known as the Yellow Fever Mosquito, it lives in much of the Southeastern United States and appears in Maryland each year. Its range extends throughout much of the world and it can overwinter where the mean low temperature is above 10ºC (50ºF). This mosquito is a domestic species, living in close association with humans. It thrives in containers or other man made articles that hold water.

Humans are the reservoir for the disease in urban epidemics while other primates, especially monkeys, maintain the disease cycle in jungle or forested areas. Monkey populations in Americas have been reduced or eliminated as have most of the sylvatic habitats needed to maintain them. In Africa, the needed elements for disease maintenance exist but its transmission has declined due vaccinination. Transmission still occurs in jungle areas in Africa and South America where the vaccine is not administered and mosquito control is lacking.

E-Mail Jeannine Dorothy, Maryland Department of Agriculture Mosquito Control