Read more about this disease, some with Classification – Types – Signs and symptoms – Genetics – Pathophysiology – Diagnosis – Screening – Prevention – Treatment and management – Cures and much more, some including pictures and video when available.
Yellow fever (also called yellow jack, or sometimes black vomit or American Plague) is an acute viral disease.[1] It is an important cause of hemorrhagic illness in many African and South American countries despite existence of an effective vaccine. The yellow refers to the jaundice symptoms that affect some patients.[2]
Yellow fever has been a source of several devastating epidemics.[3] Yellow fever epidemics broke out in the 1700s in Italy, France, Spain, and England.[4] 300,000 people are believed to have died from yellow fever in Spain during the 19th century.[5] French soldiers were attacked by yellow fever during the 1802 Haitian Revolution; more than half of the army perished from the disease.[6] Outbreaks followed by thousands of deaths occurred periodically in other Western Hemisphere locations until research, which included human volunteers (some of whom died), led to an understanding of the method of transmission to humans (primarily[citation needed] by mosquitos) and development of a vaccine and other preventive efforts in the early 20th century.
Despite the breakthrough research of Cuban physician Carlos Finlay, American physician Walter Reed, and many others over 100 years ago, unvaccinated populations in many developing nations in Africa and Central/South America continue to be at risk.[7] As of 2001[update], the World Health Organization (WHO) estimates that yellow fever causes 200,000 illnesses and 30,000 deaths every year in unvaccinated populations.[8]
Yellow fever is caused by an arbovirus of the family Flaviviridae, a positive sense single-stranded RNA virus. Human infection begins after deposition of viral particles through the skin in infected arthropod saliva. The mosquitos involved are Aedes simpsaloni, A. africanus, and A. aegypti in Africa, the Haemagogus genus in South America,[8] and the Sabethes genus in France. Yellow fever is frequently severe but moderate cases may occur as the result of previous infection by another flavivirus. After infection the virus first replicates locally, followed by transportation to the rest of the body via the lymphatic system.[9] Following systemic lymphatic infection the virus proceeds to establish itself throughout organ systems, including the heart, kidneys, adrenal glands, and the parenchyma of the liver; high viral loads are also present in the blood.[1] Necrotic masses (Councilman bodies) appear in the cytoplasm of hepatocytes.[9],[10]
Yellow fever begins suddenly after an incubation period of three to five days in the human body. In mild cases only fever and headache may be present. The severe form of the disease commences with fever, chills, bleeding into the skin, rapid heartbeat, headache, back pains, and extreme prostration. Nausea, vomiting, and constipation are common. Jaundice usually appears on the second or third day. After the third day the symptoms recede, only to return with increased severity in the final stage, during which there is a marked tendency to hemorrhage internally; the characteristic “coffee ground” vomitus contains blood. The patient then lapses into delirium and coma, often followed by death. During epidemics the fatality rate was often as high as 85%. Although the disease still occurs, it is usually confined to sporadic outbreaks.
There is a difference between disease outbreaks in rural or forest areas and in towns. Disease outbreaks in towns and non-native people may be more serious because of higher densities of mosquito vectors and higher population densities.[11]
In 1937, Max Theiler, working at the Rockefeller Foundation, developed a safe and highly efficacious vaccine for yellow fever that gives a ten-year or more immunity from the virus.
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