Kolkata:  As north Bengal grapples with encephalitis and its deadlier variant Japanese encephalitis, residents of Kolkata have little to fear about the infection, according to a senior doctor at the Calcutta School of Tropical Medicine.

Virology department-in-charge at the facility Dr Nemai Bhattacharya told PTI, “Kolkata has little chances of being infected by the encephalitis virus. It is mostly a rural disease.”

Bhattacharya said the rate of its incidence in rural areas was higher because of the environmental factors there.

In case of Japanese Encephalitis (JE), mosquitoes of the Culex vishnui subgroup are the chief vectors which primarily use outdoor resting in vegetation, other shaded places and paddy fields for breeding, mostly in rural areas, according to Bhattacharya.

These vectors generally feed on cattle, though human and pig feeding are also recorded in some areas, he said.

“Commonly they breed in water with luxuriant vegetation mainly in paddy fields and the abundance is related to rice cultivation, shallow ditches and pools,” he explained.

In the cities Culex vishnui subgroup mosquitoes will hardly get places like these. The number of water bodies in cities are far less and even chances of migratory birds (which disperse ticks infected with the virus) visiting these places are quite bleak, he said.

“But encephalitis has a chance to make an impact on the outskirts of the city and places like Howrah and Hooghly where there are ample places for the vectors to survive,” the doctor said.

Putting the mortality rate of the disease at 30 per cent, Bhattacharya said that an early detection of the disease, zonal mapping and anti-mosquito measures would help doctors in treating the patient.

“The mortality rate of encephalitis is 30 per cent. The earlier the disease is detected, the better it is for the doctors to carry out a successful treatment,” he said.

Bhattacharya also emphasises that the disease can only be treated by supportive medication as there was no specific treatment method developed till date.

Vaccination is the only way to successfully counter encephalitis, both for children and adults, Bhattacharya says.

“Vaccination is very effective in encephalitis if it is applied during a person’s childhood, he becomes immune once he grows,” he said.

And even if a person gets well, he may develop neurological deformities and other complications, the virologist said.

Talking about the present encephalitis scenario in the state, the doctor said the rainy season had helped the virus to spread and make an impact.

He, however, stated that the effect would be minimised once the rainy season had gone away.

“The rainy season has actually helped the virus to spread this time. But I believe it would continue this month and would slowly die down from September,” Bhattacharya hoped.

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