Although there is an effective vaccine for yellow fever, the disease is still responsible for the deaths of 30,000 people every year. Recent outbreaks in Africa have led to concerns from public health officials.
Yellow fever is characterised by fever, muscle pain, headache, nausea and vomiting. Most patients improve, and the symptoms will disappear but in a small number the disease becomes ‘toxic’. This affects the liver and kidneys causing jaundice, and bleeding can occur from the mouth, nose, eyes and stomach. There is high mortality once the disease has entered the toxic phase.
Yellow fever used to be known as ‘Yellow Jack’ among European sailors who visited the tropics; the “yellow” in the name refers to the jaundice that sufferers can experience. With the introduction of the invasive Aedes aegypti mosquito into the Americas in the 16th and 17th centuries, yellow fever epidemics occurred as far north as Philadelphia, Pennsylvania, and as far south as Buenos Aires, Argentina.
Yellow fever is now mainly found in tropical and subtropical areas in South America and Africa, with an estimated 200,000 cases each year causing 30,000 deaths. Once in a community it can spread rapidly.
There has been a recent resurgent of yellow fever in Angola, resulting in over 2,000 suspected cases and 293 deaths as of May 11th 2016, according to the WHO. Several cases have been imported into other countries.
There is no specific cure for yellow fever, but there is a vaccine. Monitoring and rapid vaccination is therefore critical in stopping the disease once an outbreak occurs. The vaccine provides immunity in 99% of people; however it is expensive and availability is not sufficient to protect other parts of the world if the disease should move there from Latin America. Revaccination is required every ten years to maintain immunity.