Dengue Fever

Dengue Fever exists throughout tropical and subtropical areas of Africa, Asia, the Americas, Australia and the South Pacific.  Dengue is transmitted to humans by the bite of infected Aedes aegypti, and less commonly, Ae.albopictus and Ae.scutellaris mosquitoes.  These mosquitoes generally feed on humans in mid-morning and mid-afternoon, several hours before sunset.  In contrast to some of the anopheline mosquitoes that transmit malaria, Aedes sp. are well adapted to urban environments where they breed in containers of clean water around the houses.  This makes the disease more common in urban settings than in rural settings.

MANIFESTATION
The incubation period is usually 5-8 days.  Dengue fever is characterized by acute onset of fever, chills, headache, eye pain and back ache.  A transient, generalized erythematous sometimes occurs in the first 24-48 hours.  This is followed by a wide spectrum of manifestations including body aches, fatigue, nausea, vomiting and respiratory symptoms.  On the third to fifth day the fever diminishes and a rash appears on the trunk and often spreads to the face and extremities.  There may also be petechiae and bloody nose.  In some individuals a severe form of the disease called dengue hemorrhagic fever (DHF) may develop.  This is characterized by petechiae, thrombocytopnia, and evidence of hemoconcentration.  This may progress to gross bleeding, shock, and death. 

DIAGNOSIS
The virus can be isolated from the blood samples during the acute illness.  Lab tests which are quite sensitive and specific can be done to diagnose dengue fever.  These lab tests are generally positive within 5 days of exposure. 

TREATMENT 
There is no specific treatment for dengue or dengue hemorrhagic fever.  Dengue fever is treated supportively with fluids, antipyretics (generally acetaminophen) and antiemetic.  DHF requires vigorous and well-monitored fluid replacement.  There are no prophylactic drugs for dengue.  Although vaccines currently are being developed, none are currently available.

RISKS & ADVICE
Travelers should avoid contact with the characteristic Aedes sp. mosquitoes.   The same measures as described for malaria should be used, but it should be remembered that Aedes sp. mosquitoes bite during the day rather than during the night.  Protective clothing and insect repellents are highly recommended.  These mosquitoes probably fly no more than 100 meters, and thus transmission of the disease is usually confined to a single household.  Long term visitors should eliminate any potential breeding sites, such as old tires, and treat containers with fresh, standing water with a larvicide.

In many parts of the world exposure to dengue fever is quite high, putting travelers to such areas at high risk.  Uncomplicated dengue fever is an extremely unpleasant illness, and individuals should take the necessary precautions to avoid this disease.

Make your appointment at the SHS Travel Clinic by calling (858) 534-8089.

Last Updated: 05/27/03