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Dengue fever is an acute febrile viral disease
characterized by sudden onset, fever of 3-5 days, intense headache, myalgia, anthralgic retro-orbital pain, anorexia, GI
disturbances and rash. Dengue viruses are flaviviruses and include four serotypes 1, 2,
3 and 4 (Dengue – 1, -2, -3 and - 4). These viruses are also responsible for
Dengue Haemorrhagic Fever (DHF). The viruses are transmitted to man by the
bite of infective mosquitoes, mainly Aedesaegypti. The incubation period is 4-7
days (range 3-14 days). This disease is now endemic in most tropical
countries. DHF caused by the same viruses, is characterized by increased
vascular permeability, hypovolaemia and abnormal blood clotting mechanisms.
Dengue fever (DF) with its severe manifestations such as
Dengue Haemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS) has emerged
as a major public health problem of international concern. The geographical
distribution has greatly expanded over the last 30 years, because of
increased potential for breeding of Aedesaegypti, the vector species. This has
been prompted by demographic explosion, rapid growth of urban centres with a strain on public
services, such as potable water. This has been augmented by rainwater
harvesting in diverse types of containers resulting in multiple storage
practices.
As
per current estimates, availability of at least 100 countries are endemic for
DHF and about 40% of the world population (2.5 billion people) are at risk in
tropics and sub-tropics. As per estimates, over 50 million infections with about
400,000 cases of DHF are reported annually which is a leading cause of
childhood mortality in several Asian countries.
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