Scientists of National Institute of Virology(NIV), who spotted it, said the new virus is of an Asian genotype that caused severe epidemics in Singapore in 2005 and Sri Lanka in 2009. The virus type was also responsible for dengue outbreaks in Tamil Nadu in 2012 and Kerala in 2013. It was again detected in a sample from Vellore in 2015.
Experts are studying samples from Maharashtra, Delhi and some other states to find out whether the new Asian genotype is circulating in these regions as well. Four distinct dengue virus are there which are circulating in India: DENV-1, DENV-2, DENV-3 and DENV-4. The new virus is an Asian genotype of DENV-1 and was found in blood samples drawn from patients in southern India.
The new Asian genotype has not completely replaced the old American-African genotype of DENV-1. Scientists said both genotypes of DENV-1 are now co-circulating in Tamil Nadu and Kerala.