Dengue Fever

Dengue fever is a flu-like viral disease common throughout the tropical and sub-tropical regions around the world, mainly in urban and peri-urban areas. Today, it afflicts an estimated 50 million to 100 million in the tropics (Epstein, 2000). The virus has four antigenically related serotypes, which are named DEN-1, DEN-2, DEN-3, and DEN-4. Each dengue serotype is a variation of the flavivrus genus. Dengue is spread by the aedes aegypti, a domestic, day-biting mosquito that prefers to bite humans. Currently, there is no vaccine available to prevent dengue.
Each type of the dengue virus is re-emerging worldwide, especially in the Western Hemisphere. Research has shown that several factors are contributing to the resurgence of dengue fever such as uncontrolled urbanization, increased international travel, substandard socio-economical conditions, and finally global warming. Global warming has shown to be a major contributor to the spread of dengue fever.
On a molecular level, dengue fever is classified as a flavivirus and appears as a spherical particle, about 40 to 50 nanometers in diameter (www.malarde.pf...). There is a lipid envelope enclosing a nucleocapsid core (www.malarde.pf/...). The dengue virus

On a more regional perspective, scientists have shown that dengue has broadened it’s range in the Americas over the past ten years (Rider, 1999). This means that dengue fever is steadily advancing toward the United States. A recent article in The World Disease Weekly, states that the CDC reported twenty two diagnosed dengue cases in travelers from New York, twelve from Massachusetts, and eight from Maryland (Henderson, 2000). The U.S. Centers for Disease Control and Prevention (CDC), affirms that the number of cases of dengue fever in the Americas has more than doubled to 741,794 in 1998 from 364,945 in 1997 (http://www.cdc.gov...). The article When a Pest Turns Menace, states that according to the CDC, the main carrier of dengue, the aedes aegypti mosquito, is present in 11 states, from Arizona to North Carolina (Morris, 2000). The increased presence of the infected mosquito would explain the increased transmittance of the virus in the United States.

Also increasing the aedes aegypti-breeding habitat is extensive urbanization in tropical regions. This rapid growth of cities has lead to overcrowding, urban decay, and substandard sanitation (http://www.astdhpphe.org...). All are factors that allow for more mosquitoes to live closer to more people. Additionally, over-populated cities equal more trash like old tires, non-biodegradable plastic containers, and junked cars. Each old piece of trash is a haven for standing water after heavy rains, which in turn attract more breeding mosquitoes.

If combinations of these preventative measures are not instituted soon enough, dengue fever will continue to expand, especially with increased global warming. Without a vaccine to eliminate this emerging infectious disease, dengue fever has the potential to become a major threat to human health that must be prevented at all costs.

Floods and droughts are two extreme weather events also triggered by global warming. These two weather events often act as catalysts for outbreaks of infectious diseases, namely dengue fever. Droughts, heavy rains, and floods create optimum breeding grounds for mosquitoes carrying the virus. Heavy rains after periods of drought

Most dengue infections are mild cases. However, if a person is re-infected with a different serotype of the dengue virus, there is an increased risk of a more serious disease resulting in dengue hemorrhagic fever (DHF). DHF causes the blood vessels to leak and causes bleeding from the nose, mouth, gums, and intestinal tract. In moderate cases of DHF all signs and symptoms subside after the fever drops. In severe cases the patient’s condition may suddenly worsen. The patient’s temperature may drop abruptly without warning. A rapid drop in blood pressure and signs of circulatory failure commonly follow this decline in body temperature. The blood vessels will soon start to collapse and the patient will enter into a state of shock, which can be fatal. The patient can die within a few hours or can quickly