Scientists at the National Institute of Virology (NIV) in Pune have found a genetic variant of the existing dengue virus in Tamil Nadu. According to the World Health Organization, the dengue virus (DEN) comprises four distinct serotypes (DEN-1, DEN-2, DEN-3 and DEN-4). Distinct genotypes (genetic structures) have been identified within each serotype.

During this study, the scientists found that the Asian genotype of the serotype 1 had entered India from Singapore. The Asian genotype was responsible for epidemics in Singapore during 2005 and in Sri Lanka during 2009.

Scientists at the NIV, which is the apex body for virology research in the country under the Indian Council of Medical Research, spotted the new virus while carrying out a routine study that analyses samples of dengue virus to identify the virus strain circulating in different parts of the country. 

This identification of the Asian variant requires further study to understand its role in the recurrent dengue outbreaks in the country, so it is too early to say the Asian genotype has replaced the African-American genotype.