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Like many vector-borne diseases, yellow fever is a hemorrhagic virus that is transmitted by the Aedes species of biting mosquitoes and can also be passed on to mosquito offspring by infected eggs. An effective vaccine has been available for more than half a century; however, the number of people infected in Africa, the Caribbean and the Americas has once again become a major public health concern. The World Health Organization estimates that there are more than 200,000 cases of yellow fever each year, with more than 25,000 of these cases ending in death. Further, it is widely believed that, worldwide, only a small percentage of yellow fever cases are identified.
Yellow fever is typically a mild infection with symptoms similar to those of influenza. According to the World Health Organization, yellow fever is difficult to recognize. While symptoms occur in two distinct phases, not all of those who become infected reach the second phase, and some experience no symptoms at all. The first phase is typically accompanied by symptoms such as fever, muscle pain, nausea and vomiting, among others. Fortunately, the health of most patients improves after several days.
Unfortunately, 15 percent of those infected enter a second, “toxic” phase. In this phase, fever resurfaces and patients become rapidly jaundiced (hence the name yellow fever). As symptoms worsen, yellow fever can lead to the deterioration of the liver, kidneys and heart. It is estimated the yellow fever mortality rate is between 5 and 10 percent and that half of the toxic-phase patients die within two weeks.
Yellow fever vaccination has proven to be an extremely effective prevention tool. A second, equally important prevention tool is controlling the mosquitoes that carry and spread the virus. By using insecticides such as ABATE® larvicide to eliminate potential breeding sites and through spraying to kill adult mosquitoes where the vaccine is not widely available, communities are afforded valuable time for immunity to develop after an emergency vaccination effort. Further, the World Health Organization has stated that ABATE is an effective yellow fever preventative when used in drinking water according to label instructions. ABATE is the only formulation approved by the World Health Organization for use in drinking water.
The last two decades have seen a rise in yellow fever epidemics across a growing number of countries. These occurrences are due to increased mosquito numbers and habitats. Africa and the Americas are particularly susceptible. Additional information for the control of yellow fever can be found at the World Health Organization Web site.
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