Swine flu transmission surges, scientists rule out virus mutation

PUNE: Swine flu transmission is on the surge in the city with four persons testing positive for the contagion on Tuesday.
The number of people becoming critically ill with the infection has now gone up to five and all of them are on ventilator support at various hospitals across the city.

Scientists at Pune-based National Institute of Virology (NIV) have confirmed that it was the same Michigan strain of the swine flu virus doing the rounds in India since January 2017.

They, however, ruled out any mutation in the virus and attributed the spike in the transmission to the “seasonality”, “otherwise unpredictable nature” of influenza viruses, wide fluctuation in temperatures and the dwindling vaccine-induced immunity among people.

“The rise in the virus transmission in some parts of the county, including Pune, can be attributed to the seasonality and the unpredictable nature of influenza viruses, including swine flu. The virus is susceptible to oseltamivir and has not been mutated. People should exercise precautions and maintain a healthy lifestyle to ward off the infection,” NIV senior scientist Mandeep Chadha told TOI.

Chadha said, “There is a rise in the number of throat swab samples we are receiving for tests. On an average, we have been getting 10-15 throat swabs daily during the last seven days. Before that, the number was five a day.”

Since the 2009 swine flu pandemic, the California strain of swine flu virus was common in India. “Since January 2017, we have been witnessing only the Michigan strain. It is the same strain this year as well,” Chadha said.

Another influenza A virus is also co-circulating in the city. “Along with H1N1 (swine flu), the subtype H3N2 is co-circulating. It is also characterized by fever, cough, sore throat and weakness. The co-circulation of both H1N1 and H3N2 is one of the reasons why more cases of influenza-like ailments are seen these days,” Chadha said.

The NIV scientists are closely monitoring the H1N1 virus’s frequency of causing infection. “It is imperative to continue monitoring the genetic make-up of the H1N1 virus to understand its adaptability and evolutionary dynamics,” Chadha said.

Sharad Agarkhedkar, a senior paediatrician and former vice-president of Indian Medical Association (Maharashtra), said, “Long spells of cold wave and wide fluctuations in day and night temperatures are conducive for the growth of influenza viruses, including swine flu. About 20-40% of the population in some areas have been infected and they have some immunity.”

He added, “The vaccine-induced immunity also wanes over the years and does not give lifelong protection. In fact, it is advisable to get vaccinated against the virus every year.”

Public health expert Ramchandra Hankare said delay in seeking treatment has been the cause for most swine flu deaths. “Precious time is wasted in the first few days of the manifestation of the symptoms, when treatment is crucial. People those with co-morbid conditions such as hypertension and diabetes should opt for vaccination,” he said.