Dengue is primarily a disease of the tropics. It is transmitted by a mosquito that prefers to feed on humans. Dengue Hemorrhagic Fever (DHF) is a more severe form of dengue. It can be fatal if unrecognized and not properly treated. DHF is caused by infection with the same viruses that cause dengue. With good medical management, mortality due to DHF can be less than 1%.
World-wide, there are an estimated 50 to 100 million cases of dengue fever (DF) and several hundred thousand cases of dengue hemorrhagic fever (DHF) per year. Cases in the U.S. are usually found in travelers who were bitten by mosquitos in countries where dengue is common.
The principal symptoms of dengue are high fever, severe headache, backache, joint pains, nausea and vomiting, eye pain, and rash. The rash may appear 3-4 days after the onset of fever. The illness may last up to 10 days, but complete recovery can take 2-4 weeks. Generally, younger children have a milder illness than older children and adults.
Dengue hemorrhagic fever (DHF) is characterized by a fever that lasts from 2 to 7 days, with general signs and symptoms that could occur with many other illnesses (e.g., nausea, vomiting, abdominal pain, and headache). This stage is followed by the tendency to bruise easily or other types of skin hemorrhages, bleeding nose or gums, and possibly internal bleeding. The smallest blood vessels (capillaries) become excessively permeable ("leaky"), allowing the fluid component to escape from the blood vessels. This may lead to failure of the circulatory system and shock, followed by death, if not treated. Average case fatality rate of DHF is about 5%.
The symptoms of dengue can be treated with bed rest, fluids, and medications to reduce fever, such as acetaminophen; aspirin should be avoided. Travelers should alert their doctor of any fever illnesses occurring within 3 weeks after leaving an area where dengue fever can be found. There is no vaccine for dengue fever.
As with dengue, there is no specific medication for DHF. It can, however, be effectively treated by fluid replacement therapy if an early clinical diagnosis is made. Hospitalization is frequently required in order to adequately manage DHF.
Dengue is transmitted to people by the bite of an Aedes mosquito that is infected with a dengue virus. The mosquito becomes infected with dengue virus when it bites a person who has dengue or DHF. After about a week the mosquito can then transmit the virus when it bites a healthy person.
Dengue cannot be spread directly from person to person.
For travelers to areas with dengue, the risk of being bitten by mosquitoes indoors is reduced by using air conditioning or windows and doors that are screened. Use a mosquito repellent containing 30% DEET on exposed skin and clothing. The risk of dengue infection for international travelers appears to be small, unless an epidemic is in progress.
Currently, there is no vaccine approved for Dengue, but there are multiple trials on-going to develop an effective vaccine.