Dengue Fever

Definition
Dengue fever (pronounced UK: /ˈdɛŋɡeɪ/, US: /ˈdɛŋɡiː/) and dengue hemorrhagic fever (DHF) are acute febrile diseases which occur in the tropics, can be life-threatening, and are caused by four closely related virus serotypes of the genus Flavivirus, family Flaviviridae. It is also known as breakbone fever. It occurs widely in the tropics, including northern Argentina, northern Australia, Indonesia. Each serotype is sufficiently different that there is no cross-protection and epidemics caused by multiple serotypes (hyperendemicity) can occur (Wikipedia, 2010).
Dengue is transmitted to humans by the Aedes aegypti or more rarely the Aedes albopictus mosquito, both of which feed exclusively during daylight hours. The WHO says some 2.5 billion people, two fifths of the world's population, are now at risk from dengue and estimates that there may be 50 million cases of dengue infection worldwide every year. The disease is now endemic in more than 100 countries (Wikipedia, 2010).
2.2 Signs and symptoms
The disease manifests as fever of sudden onset associated with headache, muscle and joint pains (myalgias and arthralgias—severe pain that gives it the nickname break-bone fever or bonecrusher disease), and rash. The classic dengue rash is a generalised macular-papular rash with islands of sparing. A hemorrhagic rash of characteristically bright red pinpoint spots, known as petechiae can occur later during the illness and is associated with thrombocytopenia. It usually appears first on the lower limbs and the chest; in some patients, it spreads to cover most of the body. There may also be gastritis with some combination of associated abdominal pain, nausea, vomiting, or diarrhea. Some cases develop much milder symptoms which can be misdiagnosed as influenza or other viral infection when no rash is present. Thus travelers from tropical areas may pass on dengue inadvertently, having not been properly diagnosed at the height of their illness. Patients with dengue can pass on the infection only via Aedes mosquitoes or much more unusually, blood products and only while they are still febrile. The classic dengue fever lasts about two to seven days, with a smaller peak of fever at the trailing end of the disease (the so-called "biphasic pattern"). Clinically, the platelet count will drop until after the patient's temperature is normal. Cases of DHF also show higher fever, variable hemorrhagic phenomena, thrombocytopenia, and hemoconcentration. A small proportion of cases lead to dengue shock syndrome (DSS) which has a high mortality rate (Moore, 2010).

2.3 Cause
Four different dengue viruses are known to cause dengue hemorrhagic fever. Dengue hemorrhagic fever occurs when a person catches a different type dengue virus after being infected by another one sometime before. Prior immunity to a different dengue virus type plays an important role in this severe disease (Anonym, 2008).
More than 100 million cases of dengue fever occur every year. A small number of these develop into dengue hemorrhagic fever. Most infections hemoragic dengue fever catches people indonesia, because low immunity system until risk factors for dengue hemorrhagic fever include having antibodies to dengue virus from prior infection and being younger than 12, female, or male indonesia (Anonym, 2008).
2.4 Problem
The diagnosis of dengue is usually made clinically. The classic picture is high fever with no localising source of infection, a rash with thrombocytopenia and relative leukopenia - low platelet and white blood cell count. Dengue infection can affect many organs and thus may present unusually as liver dysfunction, renal impairment, meningo-encephalitis or gastroenteritis.
1. Fever, headaches, eye pain, severe dizziness and loss of appetite.
2. Hemorrhagic tendency (positive tourniquet test, spontaneous bruising, bleeding from mucosa, gingiva, injection sites, etc.; vomiting blood, or bloody diarrhea)
3. Thrombocytopenia (<100,000 platelets per mm³ or estimated as less than 3 platelets per high power field)
4. Evidence of plasma leakage (hematocrit more than 20% higher than expected, or drop in hematocrit of 20% or more from baseline following IV fluid, pleural effusion, ascites, hypoproteinemia)
5. Encephalitic occurrences.
Dengue shock syndrome is defined as dengue hemorrhagic fever plus:
• Weak rapid pulse,
• Narrow pulse pressure (less than 20 mm Hg)
• Cold, clammy skin and restlessness (Wikipedia, 2010).
Dependable, immediate diagnosis of dengue can be performed in rural areas by the use of Rapid Diagnostic Test kits, which also differentiate between primary and secondary dengue infections. Serology and polymerase chain reaction (PCR) studies are available to confirm the diagnosis of dengue if clinically indicated. Dengue can be a life threating fever (Wikipedia, 2010).