People living in a dengue-endemic area can have more than one dengue infection during their lifetime, up to four times. There are four types of Dengue a person can become infected with: DEN-1, DEN-2, DEN-3, and DEN-4. Infection with one of these strains provides immunity to that serotype for life. The four different dengue serotypes are maintained in a cycle that involves humans and the Aedes mosquito.
Once a mosquito is infected it carries the virus for the rest of it's life. Humans serve as an amplifying host, though some monkeys may also serve as a source of the virus. Female mosquitoes can also transmit the virus to their offspring via ovaries, passing it down to the next generation. The Aedes Aegypti mosquito is also known to bite during the day.
Usually, a person will develop dengue fever as a result of initial exposure to one serotype. Upon recovery, a patient develops immunity to this particular serotype. After getting infected with a different serotype, the patient has a greater risk of developing dengue hemorrhagic fever (DHF), a more serious and potentially fatal disease.
Older children and adults are usually sicker than younger people. Dengue fever starts out suddenly after 4-6 days following infection, with a high fever, rash, severe headache, pain behind the eyes, and muscle and joint pain. The name "break bone fever" has been given to Dengue because of the severity of bone pain. A rash commonly appears 3 to 4 days after the start of the fever. Most dengue infections result in relatively mild illness, but some cases progress to dengue hemorrhagic fever.
Dengue is caused by a virus, so there is no specific medicine or antibiotic to treat it. The treatment is usually concerned with relief of the symptoms. Rest and plenty of fluid intake is important. Aspirin and nonsteroidal anti-inflammatory drugs should be avoided. Acetaminophen (Tylenol) and codeine may be taken for severe headache and for the joint and muscle pain. To determine a patient's condition, the following tests are recommended:- haematocrit
- blood gas and serum electrolytes studies
- liver function tests
- platelet count
Dengue hemorrhagic fever means the blood vessels start to leak and cause bleeding from the nose, mouth, and gums. Bruising can also be a sign of bleeding vessels. A person with hemorrhaging can go into shock without prompt treatment, since the blood vessels can collapse. DHF is fatal in about 5% of cases, mostly among children and young adults.
Dengue epidemics caused by multiple serotypes (hyperendemicity) are frequent. The geographic distribution of dengue viruses and their mosquito vectors has expanded, and DHF has emerged in the Pacific region and the Americas. Dengue is a rising infectious disease, threatening southern United States and reaching epidemic levels in central America. Public health systems to detect and control epidemics are declining worldwide. Dengue has been often misdiagnosed as influenza, however with recent advances in ELISA testing there has been better determination of the infecting serotype and gauging the potential severity of a dengue outbreak. Historically, the methods used to diagnose dengue were laborious and require specialized laboratory facilities. In addition, the level of circulating virus wanes as the antibody level rises, and these procedures are most successful only when done within about 5 days of onset of illness.
The Dengue ELISA test method for the detection of antibodies is currently the most useful procedure for providing a serological diagnosis of dengue infection.The Dengue ELISA method is generally replacing other techniques for diagnosis because of its sensitivity, potential for automation and ability to accommodate large numbers of samples.
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