The H1N1 virus, which is conscientious for causing swine flu, has returned a little over a year after it struck Kolkata last. While it had broken out at the height of summer in 2009, this time it has struck in monsoon. The worrying aspect this time is that the virus has originated locally, unlike the last instance, when it had been brought into the country by travellers from North America and south-east Asia.It is quite probable, experts pointed out, that the H1N1 has remained dormant in Kolkata and has mutated over the last 14 months. "We need to study the epidemiological history of the patients and check if they had come into contact with people travelling from abroad or other states. But it seems that the virus has not been brought from somewhere else, but has been brewing in our backyard. Influenza viruses like H1N1 have a propensity to mutate and linger. They return in waves and with varying degrees of intensity," said Tomonash Bhattacharya, a tropical medicine specialist.
It is too early, however, to predict if we are headed for a brutal outbreak this year, Bhattacharya added. "There is no model to the waves. Depending on factors like the weather, it could be severe in successive years," he said.
But the timing, said experts, is not unusual. Any influenza virus, including H1N1, is let loose by fluctuations in weather. The unreliable climatic conditions now prevailing in Kolkata are perfect for an outbreak, they felt. The fact that the temperature has been sliding up and down combined with irregular showers has helped the virus to spread. "Any influenza virus gets stimulated by temperature fluctuations and conflicting rainfall. Chances are that the virus had been floating around and has now got the right stimulus and turned potent. The virus won't vanish till the mercury starts dropping," said a virologist.
The initial symptoms of swine flu are similar to symptoms of regular flu. People with flu symptoms (see box) should seek medical attention, though mortality rate is not high for swine flu. "Many get cured without even knowing that they had the virus. But there is need to be cautious. The reason is that it is very infectious and a minor endemic could turn into a major outbreak in days," said Bhattacharya.
