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Pathology => Human Diseases => Dengue Fever
Dengue Fever
Dengue Fever, seasonal viral infection characterized by fever, headache, extreme pain in the joints and muscles, and skin rash. A more serious but less common form of the disease, dengue hemorrhagic fever (DHF), may cause severe and fatal internal bleeding. Dengue fever and DHF are caused by any of four different viruses, and are transmitted from one person to another by the female mosquito of two species of the genus Aedes. Outbreaks of the disease usually occur in the summer when the mosquito population is at its peak. The infection cannot be transmitted directly from person to person and not all people who are bitten necessarily contract the disease. Dengue fever and DHF occur in many tropical and sub-tropical areas in Asia, Africa, Central and South America. Isolated cases in the United States are usually the result of tourists bringing the disease back with them from travelling abroad. However, rare cases of dengue fever transmission have been documented in Texas. One type of mosquito that transmits dengue fever is now found throughout the southeastern United States, and some public health officials warn that an outbreak of the disease could one day occur in the United States.
The incubation period (time between infection and onset of symptoms) of dengue fever is five to eight days. The fever typically runs its course in six to seven days, but convalescence is usually slow. Treatment for dengue fever is directed at reducing symptoms.
The incubation period of DHF is two to seven days. In the early stages the symptoms are very similar to those of dengue fever. The second stage symptoms include nausea, vomiting, and abdominal pain. The onset of hemorrhagic symptoms rapidly follows-bleeding nose and gums, bruising easily, and sometimes internal bleeding. The amount of blood circulating through the body is reduced, sometimes producing shock, characterized by pale, cold extremities; a rapid, weak pulse; and falling blood pressure. Treatment for these symptoms is a standard fluid rehydration therapy in order to maintain blood pressure. If circulatory failure is not reversed, death may follow. DHF is most common among children under the age of 15. Ten percent of childhood cases of DHF are fatal.
The most effective preventive measure is the use of mosquito repellent. As yet no successful vaccine for dengue fever has been developed. According to the World Health Organization (WHO), dengue fever and DHF are among the most rapidly increasing insect-borne illnesses today. Several factors are believed to contribute to the wide spread of dengue fever. Inadequate water and waste treatment facilities, along with insufficient pest control measures, promote the rapid increase of mosquito populations in certain areas. In addition, dwindling public health resources cannot keep up with the needs of growing urban populations that are susceptible to infection.
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