INFECTIOUS AGENT Dengue is caused by infection with any 1 of 4 related positive-strand RNA viruses of the genus Flavivirus, dengue viruses (DENV) 1, 2, 3, or 4. TRANSMISSION Transmission occurs through the bite of an infected Aedes mosquito, primarily Aedes aegypti and Ae. albopictus. Humans are the main host and the primary source of virus for female mosquitoes, which become infective after an extrinsic incubation period of 8–12 days and can then transmit DENV for the rest of their approximately 1-month lifespan. Because of the approximately 7-day viremia in humans, bloodborne transmission is possible through exposure to infected blood, organs, or other tissues (such as bone marrow). In addition, perinatal DENV transmission occurs, and the highest risk appears to be among infants whose mothers are acutely ill around the time of delivery. It is not known if DENV is transmitted through breast milk. EPIDEMIOLOGY Dengue is endemic throughout the tropics and subtropics and is a leading cause of febrile illness among travelers returning from the Caribbean, South America, and South and Southeast Asia, according to an analysis of data collected by the GeoSentinel Surveillance Network. Dengue occurs in >100 countries worldwide (Maps 3-01, 3-02, and 3-03), including Puerto Rico, the US Virgin Islands, and US-affiliated Pacific Islands. Sporadic outbreaks with local transmission have occurred in Florida, Hawaii, and along the Texas-Mexico border. Although the geographic distribution of dengue is similar to that of malaria, dengue is more of a risk in urban and residential areas than is malaria.
Posted on: Thu, 18 Sep 2014 01:23:02 +0000
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