Dengue Fever
Dengue is an epidemic-prone disease that thrives in crowded urban slums or poor urban conurbations. It now ranks as the most important mosquito-borne viral disease in the world. In the past five decades, its incidence has increased 30-fold and is still rising.
Transmission is mainly through the bite of infected Aedes aegypti mosquitoes, but in some countries by Aedes albopictus as well. These mosquito species are well adapted to human habitation and will breed in any discarded container or storage water jars around the house or yard.
Dengue fever and Dengue Haemorrhagic fever (DHF) – a potentially lethal complication of dengue fever – is a mosquito-borne viral infection. It is found in over 100 countries throughout the world, putting some two billion people at risk.
The clinical features of dengue fever vary according to the patient’s age. It is a classic incapacitating disease with high fever, headache, pain behind the eyes, muscle and joint pains, and a rash. Its symptoms give rise to the name ‘break-bone fever.' The patient will be sick for at least two weeks and severely weakened for several more weeks. Dengue has a dramatic effect on a family’s income and a country’s economic situation.
DHF is characterised by haemorrhagic phenomena – often with enlargement of the liver – and can include bleeding from eyes, nose and ears followed by circulatory failure. In severe cases, the patient’s condition deteriorates suddenly after a few days of fever; the temperature drops, followed by signs of circulatory failure, and the patient may rapidly go into a critical state of shock and die within 12-24 hours. DHF patients face almost certain death unless sophisticated symptomatic hospital treatment is available.
At present, the only method of controlling dengue or DHF is to combat the vector mosquitoes by eliminating and treating their breeding sites with mosquito larvicides, and by controlling the adults using space sprays. Control is also implemented by using environmental management to reduce breeding sites through container clearance and improved water storage practices. These include covering water storage containers, and are methods encouraged through community programs. Vaccines are under development but there are no products likely to become available in the short term.