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2 Diagnosis 3 Treatment 4 Epidemiology 5 Prevention 6 Recent Outbreak |
Signs and symptoms
The disease is manifested by a sudden onset of fever, with severe headache, joint and muscular pains (myalgias and arthralgias, severe pain gives it the name break-bone fever) and rashes; the dengue rash is characteristically bright red, petechial and usually appears first on the lower limbs - 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.
The classical dengue fever lasts about six to seven days with a smaller peak of fever at the trailing end of the fever (the so-called "biphasic pattern"). Clinically, the platelet count will drop until the patient is afebrile.
Cases of DHF also shows higher fever, haemorrhagic phenomena, thrombocytopenia and haemoconcentration. A small proportion of cases leads to dengue shock syndrome (DDS) which has a high mortality rate.
Serology and PCR (polymerase chain reaction) studies are available to confirm the diagnosis of dengue if clinically indicated.
Significant outbreaks of dengue fever tend to occur every five or six years. There tend to remain large numbers of susceptible people in the population despite previous outbreaks because there are four different strains of the dengue virus and because of new susceptible individuals entering the target population, either through childbirth or immigration.
In Singapore, there are about 4-5000 reported cases of dengue fever or dengue hemorrhagic fever every year. In the year 2003, there were 6 deaths from dengue shock syndrome. It is believed that the reported cases of dengue are an underrepresentation of all the cases of dengue as it would ignore subclinical cases and cases where the patient did not present for medical treatment. The mortality rate for dengue is therefore probably less than 1 in 1000.
There is no commercially ready vaccine for the dengue flavivirus.
Primary prevention of dengue mainly resides in eliminating or reducing the mosquito vector for dengue. Initiatives to eradicate pools of standing water (such as in flowerpots) have proven useful in controlling mosquito borne diseases.
Recent Dengue outbreaks (February 2004) in Indonesia have claimed almost 200 lives. This number may still grow.
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Diagnosis
The diagnosis of dengue is usually made clinically. The classical picture is of fever with no localising source of infection, a petechial rash with thrombocytopenia and relative leukopenia.Treatment
The mainstay of treatment is supportive therapy. The patient is encouraged to keep up oral intake, especially of oral fluids. If the patient is unable to maintain oral intake, supplementation with intravenous fluids may be necessary to prevent dehydration and significant hemoconcentration. A platelet transfusion is indicated if the platelet level drops significantly.Epidemiology
The first epidemics occurred almost simulataneously, in Asia, Africa, and North America in the 1780s, the disease was identified and named in 1779. Initially it was rather benign. A global pandemic began in Southeast Asia in the 1950s, by 1975 DHF had become a leading cause of death among children in many countries in that region. Epidemic dengue has become more common since the 1980s, by the late 1990s dengue was the most important mosquito-borne viral disease affecting humans after malaria, there are around 40 million cases of dengue fever and several hundred thousand cases of dengue hemorrhagic fever each year. In February 2002 there was a serious outbreak in Rio De Janeiro, affecting around one million people but only killing sixteen.Prevention
Recent Outbreak