Dengue is an infectious, flu-like disease caused by strains of the Flavivirus and transmitted to humans by the mosquito. It spreads in a pattern similar to that of malaria, except it is commonly found in urban areas in tropical environments. The disease is prevalent over several continents, but the disparities in dengue strains vary from country to country, making it difficult to contain. If a person is infected by one of the four dengue serotypes, he is immune for life to that particular strain. He can become infected with another strain during his lifetime, however, especially in an epidemic-prone region.
History
The first dengue epidemics were recorded in 1779 and 1780 in Asia, Africa and North America. The disease was generally thought to be non-fatal and affected visitors to the tropics. Its transmission was not associated to mosquitoes until the twentieth century, however. World War II brought about a dengue pandemic in Southeastern Asia that soon spread globally due to shifting populations. Southeastern Asia saw its first great outbreaks of dengue in the 1950s, and by 1975 dengue was a common cause of hospitalization and death.
Geography
The World Health Organization estimates that about two-fifths of the world's population is at risk for dengue. According to WHO's reports for dengue infection, the top countries affected since 1955 are, by number of cases:
Brazil - 3,718,531
Thailand - 1,725,000
Cuba - 927,186
Indonesia - 842,689
Colombia - 642,729
Mexico - 426,724
Philippines - 383,816
Honduras - 332,859
China, Malaysia, Vietnam, Myanmar, Puerto Rico, Nicaragua and Paraguay follow closely behind with several thousand cases reported to WHO.
In recent years, several countries have seen severe outbreaks, such as Venezuela, which reported 80,000 cases in 2007 alone. In the same year, more than 890,000 cases were reported across the Americas. The Center for Disease Control says that dengue is considered endemic in most tropical countries as of 2005, including southern regions of the United States.
Identification
Symptoms of dengue are typical of flu: joint and muscle pain (dengue is nicknamed the "break bone" fever for the bone pain it causes), high fevers and intense headaches. These symptoms will appear after a three to 14 day incubation period. Persons affected may also experience rash, nausea and vomiting. Travelers to tropical regions who have been exposed to mosquito bites during the daytime should be wary of these symptoms up to two weeks after traveling. Severe symptoms that require immediate medical attention include bleeding in the gums or mucous membranes, and vomiting blood.
Warning
Approximately one percent of dengue cases progress to dengue hemorrhagic fever (DHF), a dangerous and potentially deadly complication of the transmission. It is characterized by enlargement of the liver and can lead to circulatory failure. The fatality rate for patients who progress to DHF is estimated at 5 percent, although with proper clinical treatment the patient has better chances of recovery.
Prevention/Solution
Because mosquitoes breed in moist spots, dengue can be prevented by environmental clean-up. Common breeding grounds include water collected in old tires, plant pots, and other storage containers. WHO recommends that communities prone to high dengue transmission have a weekly "dry day." That is, a concerted effort to drain and empty all standing water both indoor and outdoor around the home.
For personal protection, WHO recommends mosquito repellent and mosquito nets, and using screens and flywire on doors.
No vaccine is available for dengue. Symptoms usually subside after the fever has passed. Acetaminophen is recommended to reduce fever and manage pain. Anticoagulants such as ibuprofen and aspirin should be avoided.
Considerations
Travelers should be aware of dengue reports in tropical areas and should take extreme care to avoid mosquito bites. In addition to mosquito repellent, it is recommended that travelers wear clothing that covers as much exposed skin as possible. Repellent containing a 50-percent DEET concentration is advised for young children, and parents with infants should cover their carriers with tight-fitting mosquito netting.
Tags: mosquito bites, mosquito repellent, Southeastern Asia