Untitled Document

Dengue and dengue hemorrhagic fever (DHF) are caused by one of four closely related, but antigenically distinct, virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4), of the genus Flavivirus. Infection with one of these serotypes does not provide cross-protective immunity, so persons living in a dengue-endemic area can have four dengue infections during their lifetimes. Dengue is primarily a disease of the tropics, and the viruses that cause it are maintained in a cycle that involves humans and Aedes aegypti, a domestic, day-biting mosquito that prefers to feed on humans. Infection with dengue viruses produces a spectrum of clinical illness ranging from a nonspecific viral syndrome to severe and fatal hemorrhagic disease. Important risk factors for DHF include the strain and serotype of the infecting virus, as well as the age, immune status, and genetic predisposition of the patient.

Symptoms

Dengue fever is characterized by the rapid development of a fever that may last from 5 to 7 days, with intense headache, joint and muscle pain, and a rash. The rash develops on the feet or legs, usually 3 to 4 days after the beginning of the fever. The hemorrhagic form of dengue fever is more severe and associated with loss of appetite, vomiting, high fever, headache, and abdominal pain. Shock and circulatory failure may occur. Untreated hemorrhagic dengue results in death in up to 50 percent of cases.

Transmission

Dengue is spread by the bite of infected Aedes mosquitoes.

Diagnosis

Dengue fever is diagnosed by a positive antibody test.

Treatment

There is no specific treatment available. Intravenous fluids and oxygen therapy are often used for patients who experience shock during their illness. No dengue vaccine is available. Recently, however, attenuated candidate vaccine viruses have been developed in Thailand. These vaccines are safe and immunogenic when given in various formulations, including a quadrivalent vaccine for all four dengue virus serotypes. Efficacy trials in human volunteers have yet to be initiated. Research is also being conducted to develop second-generation recombinant vaccine viruses; the Thailand attenuated viruses are used as a template. Therefore, an effective dengue vaccine for public use will not be available for 5 to 10 years.

Prevention

Control measures are limited to advising travelers to affected areas to minimize exposure to mosquitoes. Use of protective clothing, mosquito netting, and repellents are helpful in preventing mosquito bites.