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Dengue fever (pronounced /’d??ge?/ (BrE), /’d??gi?/ (AmE)) and dengue hemorrhagic fever (DHF) are acute febrile diseases, found in the tropics and Africa, and caused by four closely related virus serotypes of the genus Flavivirus, family Flaviviridae.[1] It is also known as breakbone fever. The geographical spread is similar to malaria, including northern Australia, Singapore, Malaysia, Taiwan, Thailand, Vietnam, Indonesia, Philippines, Pakistan, India, Bangladesh, Puerto Rico, Brazil, Guyana, Venezuela, Trinidad and now Samoa[2]. Unlike malaria, dengue is just as prevalent in the urban districts of its range as in rural areas. Each serotype is sufficiently different that there is no cross-protection and epidemics caused by multiple serotypes (hyperendemicity) can occur. Dengue is transmitted to humans by the Aedes aegypti or more rarely the Aedes albopictus mosquito, which feed during the day.[3]
This is manifested by a sudden onset of severe headache, muscle and joint pains (myalgias and arthralgias—severe pain gives it the name break-bone fever or bonecrusher disease), fever, and rash.[4] The dengue rash is characteristically bright red petechiae and 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 in their home countries inadvertently, having not been properly diagnosed at the height of their illness. Patients with dengue can pass on the infection only through mosquitoes or blood products and only while they are still febrile.
The classic dengue fever lasts about six 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 the patient’s temperature is normal.
Cases of DHF also show higher fever, variable haemorrhagic phenomena, thrombocytopenia, and haemoconcentration. A small proportion of cases lead to dengue shock syndrome (DSS) which has a high mortality rate.
DHF combined with a cirrhotic liver has been suspected in rapid development of Hepatocellular Carcinoma. Given the DEN virus is related to the Hepatitis C virus this is an avenue for further research as HCC is the leading Cancer cause of death outside of Europe and North America. Normally HCC does not normally occur in a cirrhotic liver for 10+ years after the cessation of the poisioning agent. DHF patients can develop HCC within one year of cessation of abuse.
The diagnosis of dengue is usually made clinically. The classic picture is high fever with no localising source of infection, a petechial rash with thrombocytopenia and relative leukopenia – low platelet and white blood cell count. Care has to be taken as diagnosis of DHF can mask end stage liver disease and vice versa.
The WHO definition of dengue haemorrhagic fever has been in use since 1975; all four criteria must be fulfilled:[5]
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