Changing trends of dengue disease: a brief report from a tertiary care hospital in New Delhi.

Dear Editor, this is in response to the paper “Correlation of disease spectrum among four Dengue serotypes: a five-year hospital based study from India”, published by Dr Rajni Kumaria in the Journal (vol.14, no. 2).1 This study was conducted in the virology laboratory of Maulana Azad Medical College, New Delhi, from January 2002 to November 2006 as a part of a project funded by the Indian Council of Medical Research (ICMR). The findings obtained from the same laboratory for the subsequent three years (2007 -2009) were relatively different from the earlier published one1 and are being reported here. We wish to highlight the changing trends in the presentation of dengue from the same Dengue Serosurveillance Laboratory during this period. In contrast to 2002-2006 findings where Den-2 was the commonest serotype reported, ongoing study observed Den-1 to be the most prevalent serotype during 2007-2009. Den-1 was isolated in 50% of RT-PCR positive cases (20/40), whereas Den-2, Den-3 and Den-4 were identified in 22.5 %( 9/40), 15 % (6/40) and 12.5% (5/40) of cases respectively, indicating the replacement of earlier circulating Den-2 and Den3 by Den-1. Maximum number of Den-1 cases were isolated in the year 2008 (findings published earlier).2 These findings provide an insight to the changing trend of dengue serotypes indicating that all four serotypes are continuously co-circulating, which makes this region prone to epidemic spreads. Although the abovementioned study1 and few other studies3 have reported Den-1 to be associated with a milder form of disease, our study demonstrates a rise in number of Den-1 affected severe cases during 20072009. Sixty percent of the Den-1 affected cases presented with severe DHF. MoreoChanging trends of dengue disease: a brief report from a tertiary care hospital in New Delhi