Over 40% of global population prone to dengue
NEW DELHI: Dengue has become a major global menace.
According to the World Health Organization’s estimates released on Wednesday, over 2.5 billion people – over 40% of the world’s population – are now at risk from dengue. WHO estimates there may be 50-100 million dengue infections worldwide annually.
Before 1970, only nine countries had experienced severe dengue epidemics. The disease is endemic in more than 100 countries. Cases across the Americas, south-east Asia and western Pacific have exceeded 1.2 million cases in 2008 and over 2.2 million in 2010.
In 2010, 1.6 million cases of dengue were reported in the Americas alone, of which 49 000 were severe dengue. An estimated 500, 000 people with severe dengue require hospitalization each year, a large proportion of whom are children. About 2.5% of those affected die, says the WHO.
According to a Union health ministry note, dengue has been identified as one of the 17 neglected tropical diseases by the UN body. It has also been listed among the 40 emerging diseases of global importance.
According to the Planning Commission, the occurrence of dengue fever was reported during 1956 from Tamil Nadu’s Vellore district. Since then, out of 35 states/UTS, 31 have reported dengue cases during last two decades (1991-2010). Recurring outbreaks of dengue fever /dengue haemorrhagic fever have been reported from Andhra Pradesh, Delhi, Goa, Haryana, Gujarat, Karnataka, Kerala, Maharashtra, Rajasthan, Uttar Pradesh, Puducherry, Punjab, Tamil Nadu and West Bengal. In 2006, India witnessed an outbreak of DF/DHF, with 12,317 cases and 184 deaths reported from 18 states/ UTs (270 districts).
In 2010, 28,292 cases and 110 deaths were reported from 27 states/UTs (403 districts), which is highest in the country over the last two decades. The case fatality rate (deaths per 100 cases) due to dengue which was 1.5% in 2006 has declined to 0.4% in 2010 after the national guidelines on clinical management of DF/DHF/DSS were developed and circulated in 2007.
All the four virus serotypes DENV 1-4 have been isolated in India. Aedes aegypti is the most efficient vector of dengue in India. A Planning Commission note says, “The risk of dengue has shown an increase in the recent years due to rapid urbanization, life style changes and improper water storage practices in urban, peri-urban and rural areas, leading to proliferation of mosquito breeding sites. Due to the manmade environmental and lifestyle changes DF/DHF has now spread to rural areas as well. Dengue is an ecological disease and the transmission is related to rainfall and temperature. Every year during the period of July-Nov there is an upsurge in the cases of Dengue/DHF. However, in the peninsular states and western parts of the country the disease has become perennial.”
Based on the dengue transmission potential at macro and micro levels, WHO has categorized the countries in SEARO. Till 2009, India was in Category B, grouped with Bangladesh and Maldives, where cyclical epidemics are becoming more frequent, multiple virus serotypes circulating and expanding geographically within countries.
However, in 2010 WHO grouped India in Category A countries with Indonesia, Myanmar, Sri Lanka, Thailand and Timor-Leste where dengue is a major public health problem, leading cause of hospitalization and death among children, hyper-endemicity in urban centres, spreading to rural areas and multiple virus serotypes circulating.
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