A total of 237 people have been confirmed dead in an outbreak of Yellow Fever in Brazil which began in July 2017. A further 468 people have been infected by the disease, including ten foreign nationals visiting Brazil (three from Argentina, three from Chile and one each from France, the Netherlands, Romania and Switzerland). The majority of the infections, and fatalities, have been reported from densely populated urban areas of Minas Gerais, São Paulo, Rio de Janeiro, and Espírito Santo states in southern Brazil, where the disease is not usually present and vaccination is not widespread. It is thought that the disease has spread to this area, along with the Aedes Mosquitoes that carry it, due to unusually hot and wet weather in the region, which favours the spread of the disease. In addition to the Human cases, 4161 cases of the disease have been reported in non-Human Primates, although only 554 of these have been confirmed by laboratory tests. Yellow Fever is thought to present a particular threat to the (often endangered) Monkey populations of Espírito Santo and Minas Gerais states, which are not familiar with the disease and which appear to be particularly vulnerable to it.
A Howler Monkey, Alouatta sp., killed by Yellow Fever in Brazil. Sergio Mendes/Projeto Muriqui.
Yellow Fever is a Mosquito-born Flavivirus (the group of RNA Viruses that also includes the West Nile, Zika and Hepatitis C Viruses), that originated in tropical Africa and appears to have been carried to South America and the Caribbean during the transAtlantic slave trade. Outbreaks of the disease have also been recorded in parts of tropical Asia and the Pacific in recent years, and many countries in tropical regions require visitors to carry a certificate proving they have been vaccinated against the Virus.
The Virus causes a mild fever, accompanied loss of apatite, nausea and muscle pains, which passes within about 15 days. However, in about 15 % of cases a more severe infection attacks the liver and kidneys, which can lead to their failure, and therefore the death of the patient.
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