Recurring outbreaks of dengue fever(DF)/DHF have been reported from various states/ UTs—Andhra Pradesh, Chandigarh, Delhi, Goa, Haryana, Gujarat, Karnataka, Kerala, Maharashtra,Rajasthan,UttarPradesh,Puducherry,Punjab,TamilNaduandWestBengal.
During 1996, one of the most severe outbreaks of DF/DHF occurred in Delhi, with 10 252 cases and 423 deaths being reported (country total being 16 517 cases and 545 deaths). In 2006,thecountrywitnessedanoutbreakofDF/DHFwith12317casesand184deaths.
The incidence of dengue is increasing in the last few years. During 2010, a total of 28 292 cases were reported, which increased to 50 222 in 2012 and 75 808 in 2013 – the highest since 1991. The case fatality ratio (CFR – deaths per 100 cases) has declined from 3.3% in 1996 to 0.4% in 2010 after the national guidelines on clinical management of DF/DHF/dengue shock syndrome (DSS) were developed and circulated in 2007. This further declined to 0.3%in 2013.
Every year, during the period July–November, an upsurge in the cases of dengue/DHF has been observed. The disease has a seasonal pattern; the cases peak after the monsoons and are not uniformly distributed throughout the year. However, the states in the southern and western parts of the country report perennial transmission