Yellow fever is a virus carried by a species of mosquitoes common to the southern United States. The virus is thought to have originated in Africa and was likely carried to North America several hundred years ago on ships sailing from the African continent. Remarkably, Yellow fever in the US is rare-there hasn't been a reported case since 1905. But in parts of Africa and South America, there are frequent pandemic outbreaks, particularly during mosquito season.
Yellow fever is not contagious, but spreads by a disease-carrying mosquito biting an infected person and then biting another individual who is not already infected. When mosquitoes transmit Yellow fever between humans, it is referred to as urban Yellow fever. When a mosquito bites an infected monkey and then bites another monkey or a human, it is referred to as jungle Yellow fever. Jungle Yellow fever in humans is very rare and limited to individuals who live in rain forests.
The name Yellow fever comes from the skin-yellowing effects of one of its worst symptoms-liver disease. Symptoms can range from mild flu-like symptoms to hepatitis or hemorrhagic fever.
Because it is a virus, there is no known cure for Yellow fever. For those who are infected, pain relievers for treating symptoms of fever and aches are the only option. Severity of illness depends on the strength of an individual's immune system. Many people recover from the Yellow fever virus, but when there are severe symptoms, between 15 percent and 50 percent of affected persons may die.
An effective vaccine has been developed which can provide immunity for up to ten years. The Yellow fever vaccine is only effective as a preventive measure for individuals who are not already infected with the virus, and it usually recommended for those living in or traveling to areas where the disease is present.