New dengue virus caused outbreaks in southern India, say scientists

Scientists at the National Institute of Virology in Pune have found a genetic variant of the dengue virus which, they fear, was also responsible for outbreaks in Tamil Nadu in 2012 and Kerala in 2013.

Experts are studying samples to find out whether the Asian genotype of DENV-1 was present in these regions.

Scientists at the NIV, who spotted it and had been tracking it, said the new virus of an Asian genotype (genetic structure) was a concern as it was associated with severe and extensive epidemics in Singapore in 2005 and Sri Lanka in 2009.

The findings were published in a research paper, 'Emergence of the Asian genotype of DENV-1 in South India', in the peer-reviewed journal "Virology" this month.

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.

The Asian genotype of DENV-1 was found in virus isolates drawn from blood samples of dengue-infected patients in southern India.

The finding does not mean the Asian genotype has become more prevalent than the American-African genotype of DENV-1 that has been in circulation in India since the 1940s. Scientists said both types of DENV-1 were still cocirculating in TN and Kerala.

Experts are studying samples from Maharashtra, Delhi and some other states to find out whether the Asian genotype of DENV-1 was present in these regions.

"The Asian genotype was responsible for epidemics in Singapore during 2005 and in Sri Lanka during 2009. This genotype was not found earlier in India. It is a new entrant to India," The Times of India quoted senior scientist and director of NIV Devendra Mourya as saying.

However, it cannot still be deciphered that the Asian genotype of the virus is the cause of the outbreak of dengue in the southern states as scientists at NIV have not tested all the samples.

While samples of dengue positive patients from Tamil Nadu and Kerala were found to be infected with the Asian genotype, the samples from Maharashtra and Delhi did not find the presence of the new variant.

Though the identification of the Asian variant requires further study to understand its role in the recurrent dengue outbreaks in the country, the study proves how movement of DENV (dengue virus) can affect dengue outbreaks.