Dengue fever (DF), a benign acute febrile syndrome, has been called the most vital mosquito-transmitted viral disease. It is caused by one of four closely related virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4), of the genus Flavivirus. Each serotype is antigenically distinct, so there is no cross-protection, and epidemics caused by multiple serotypes (hyperendemicity) can occur. The infectious disease is transmitted to humans by the bite of mosquitoes, most commonly Aedes aegypti. Dengue disease is sometimes called break-bone fever because it causes severe joint and muscle pain that feels like bones are breaking.
How is Dengue fever transmitted?
Dengue viruses are transmitted to humans (host) through the bites of the female striped Aedes aegypti mosquito (vector). This variety of mosquito breeds easily during the rainy seasons but can flourish in peridomestic fresh water, e.g. water that is stored in plastic bags, cans, flowerpots and old tires. The dengue virus is transmitted to its host during probing and blood feeding.
Dengue fever is caused by several related viruses (four different arboviruses). It is spread by the bite of mosquitoes, most commonly the mosquito Aedes aegypti, which found in tropic and subtropic regions. This includes parts of:
· Southeast Asia
· Indonesian archipelago into northeastern Australia
· Sub-Saharan Africa
Signs and Symptoms
Dengue fever usually starts suddenly with a high fever, rash, severe headache, pain behind the eyes, and muscle and joint pain. The severity of the joint pain has given dengue the name “breakbone fever.” Nausea, vomiting, and loss of appetite are common. A rash usually appears 3 to 4 days after the start of the fever. The illness can last up to 10 days, but complete recovery can take as long as a month. Older children and adults are usually sicker than young children.
More severe illness may occur in some people. These people may be experiencing dengue fever for the first time. However, in some cases a person may have already had dengue fever at one time, recovered, and then is reinfected with the virus. In these cases, the first infection teaches the immune system to recognize the presence of the arbovirus. When the immune cells encounter the virus during later infections, the immune system over-reacts. These types of illnesses, called dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS), involve more severe symptoms.
A fever occurs in nearly all dengue infections in children; the other most common symptoms are a red throat, a (usually mild) runny nose, cough, and mild gastrointestinal symptoms which of course may present similar to pharyngitis, influenza, and upper respiratory infections.
The dengue virus causes the blood vessels to swell and leak, creating small purple colored spots on the skin, called petechiae. The skin may appear bruised in areas where the bleeding is worse. Bleeding into the stomach causes severe abdominal pains and vomiting of a black, grainy substance that looks like coffee grounds. This severe bleeding, called hemorrhaging, occurs when the blood runs out of clotting factors.
Prevention of dengue fever is the key to staying healthy when traveling to high risk areas. Wear long-sleeved clothing and use insect repellent faithfully. Employ mosquito netting around sleep and lounging areas and avoid going out at night and just before dawn. Staying in air conditioned or screened in areas is optimal. Preventative measures goes a long way in preventing the contraction of dengue fever or any other tropical disease.
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