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Updated: Mar 19, 2019 00:13 IST

A six-year-old boy from Kerala, who died on Monday after contracting the West Nile Virus (WNV), could be the first casualty of the disease reported from the country, say experts in the Union ministry of health and family welfare.

The ministry said it will be tracking each case that tests positive for WNV disease to document the disease outcome.

“This could be the first death that we know of. There may have been deaths earlier but we don’t seem to have any documented evidence whether any of those [people] tested positive for the disease or not,” said an expert from the ministry, asking not to be identified.

Three cases of the WNV disease have been reported from the country so far this year, all from Kerala, and all in the past three months. The boy was one of them.

Six laboratories of the Indian Council of Medical Research (ICMR) have been routinely testing samples for WNV across the country.

There have been sporadic outbreaks in different parts of the country, including the north-east.

The six labs are in Lucknow, Thiruvananthapuram, Chennai, Patna, Dibrugarh and Agartala.

Read more| What is West Nile Virus and how does it spread? Read here

“ICMR’s viral research diagnostic labs have been testing samples and maintaining record of cases since 2016. Deaths, however, are usually not recorded at the laboratory level but in the hospitals where patients get treated,” said Dr RR Gangakhedkar, head, epidemiology and communicable diseases division, ICMR.

Since 2016, 124 cases of the disease have been reported from across the country, but no deaths.

Experts in virology say there is usually no single reason that leads to death in cases of WNV disease.

“There are many factors responsible, including some underlying medical condition that may aggravate the virulence of the virus, certain mutations that change the behaviour or exaggerated immune response of a person. There always is a balance of viral factors and the host factors, where host is the patient, which decides the disease outcome,” said Dr Ekta Gupta, senior virologist, Institute of Liver and Biliary Sciences.

“The cause needs to be investigated further,” she added.

According to previous research, WNV is not a new disease to India.

In India, the existence of antibodies (protein produced by the human body to fight bacteria and viruses) against WNV in humans was recorded for the first time in 1952, according to a 2006 research paper titled “West Nile Virus isolates from India: evidence for a distinct genetic lineage”.

The research was conducted by experts at the National Institute of Virology in Pune, and published in the Journal of General Virology.

Since WNV is a vector-borne disease, the health ministry has been monitoring the situation closely. A team of experts from health ministry’s National Centre for Disease Control has been assisting state authorities in managing the disease.