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.