With 3,000 cases, Tamil Nadu records 32-fold jump in H1N1 in 6 months

July 24, 2017 | Posted in: Uncategorized

With 3,000 cases, Tamil Nadu records 32-fold jump in H1N1 in 6 months


CHENNAI: The fogging machines may have turned to fight dengue, but the state hasn’t fully washed its hands of another virus. Since January, Tamil Nadu recorded close to 3,000 cases of H1N1influenza virus – the highest in the country.

This is a 32-fold jump from last year, when 122 people reported with the infection.

Across the country, till July 16, H1N1 affected 13,188 people and caused 632 deaths as against 1,786 infections and 265 deaths in the whole of last year.

According to data from the Integrated Disease Surveillance Programme, although Tamil Nadu topped in case detection, mortality was highest in Maharashtra, which saw around 300 deaths and 2,738 infections. This was followed by Gujarat, Kerala and Rajasthan.In Tamil Nadu,15 people died of flu-related complications.

Director of Public Health K Kulandaisamy said the influenza outbreak had been brought under control in the state. “Most of these cases were reported from February to April, during the cooler months. Now we see only around five to six flu cases a month,” he said, attributing the drop to sanitation campaigns and weather change. Coimbatore, Chennai and Tirunelveli accounted for the highest counted for the highest share of infections.

The H1N1 virus causes infection in the nose, throat, and lungs, and is spread when someone touches things with the contagion on it. The last time the state saw a spurt was in 2015, when close to 900 people tested positive for the virus, leading to 29 deaths.

Doctors say the burden of the disease might be even higher than the surveillance programme estimates since not all patients with symptoms of H1N1are tested.

In an effort to check a possible resurgence of the infection, public health officials are working on a mechanism to include influenza-like syndrome in their routine surveillance.”In our surveillance we usually look for only five symptoms that have the potential to be an epidemic-prone infection. This doesn’t include respiratory distress,” said Kulandaisamy . He said most doctors look specifically for H1N1 when they receive a patient with symptoms of flu. “They just rule out or confirm H1N1and don’t diagnose what other type of influenza the person has,” he said. This season, doctors treating patients with H1N1 had observed a change in symptoms: some patients who showed typical signs of H1N1 did not test positive when the laboratory investigations were done, while those who had no telling symptoms tested positive.

Experts say the numbers could have catapulted this year across the country because of two factors: antigenic drift and the spread of a different strain (sub-type of virus) of H1N1 virus. Antigenic drift are small changes in the genes of influenza viruses that happen continually over time as the virus replicates.

“These small genetic changes usually produce viruses that are closely related to one another. An immune system exposed to a similar virus usually recognises it and responds,” explained infectious disease specialist Dr Dilip Mathai. However, these small genetic changes can accumulate over time and result in viruses that are antigenically different.When this happens, the body’s immune system may not recognise those viruses. “Every viral infection happens in a cyclic pattern. We see a chikungunya outbreak once in 40 years, measles, once in five years. H1N1 is relatively new. We are still learning,” he said.

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