Awareness of changing trends in epidemiology of dengue fever is essential for epidemiological surveillance.

Dengue has become endemic in India with outbreaks occurring almost every year. The seroprevalence and serotypic data of the last 7 years in samples obtained from suspected dengue patients from a tertiary care hospital were analyzed. Out of 7846 serum samples received in the virology laboratory from suspected dengue cases during 2002 to 2008, 2366 (30.15%) were serologically confirmed. Serotyping was done using mRT-PCR. All the four serotypes were detected in 2003, while data in 2004, 2005 and 2006 revealed the the predominance of Den-3. In the year 2007 predominance of Den-2 was observed, whereas in 2008 Den-1 was the most common serotype isolated. Overall, Den-2 and Den-3 were the most predominant serotypes during 2003-2007 but Den-1 replaced these strains in the year 2008. Since the emergence of a new predominant strain can lead to the occurrence of an outbreak, presence of Den-1 in the year 2008 would pose an alarming situation before us. Well-targeted population-based epidemiological studies are urgently required to control dengue menace.