Mumbai saw 448 swine flu cases from January to November 2019: BMC

The number of swine flu cases in the city surged to 448, between January and November 2019, leading to five deaths, compared to 25 cases recorded in all of 2018.

The number of swine flu cases in the city surged to 448, between January and November 2019, leading to five deaths, compared to 25 cases recorded in all of 2018.

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The 2019 data was released by the public health department of the Brihanmumbai Municipal Corporation (BMC). Doctors attributed this rise to unprecedented rain during the monsoon creating favourable conditions for swine flu.

Swine flu, caused by the H1N1 virus, is a strain of an influenza virus that generally originates in pigs, but spreads primarily from person to person. As a human flu virus, it is transmitted like other strains of flu.

“We saw more patients suffering from swine flu owing to the long monsoon. Depending on the weather, the virus changes its strain every year. The virus becomes stronger and infects more people during years with sudden changes in the weather and unexpected rainfall,” said Dr Vikrant Shah, infectious diseases specialist, Zen Multi Specialty Hospital, Chembur. “The vaccine also therefore changes every year depending on the strain of the virus.”

To prevent the spread of the infection, 30,000 people from the vulnerable category – diabetes, pregnant women, hypertensive and elderly patients – were vaccinated at public hospitals throughout the year.

BMC’s medical experts pointed at better surveillance and reporting to explain the increased numbers. “We increased surveillance procedures due to heavy rain last year. We appointed additional volunteers who undertook door-to-door inspections to identify patients,” said an officer from the public health department.

In 2019, between June and September, Mumbai witnessed one of its wettest monsoons in history and November again saw more rainfall, creating favourable conditions for the H1N1 virus. The virus developed a stronger strain which led to an increase in transmission.

Dr Om Srivastava, infectious diseases expert, said the swine flu virus develops cells proteins called antigens. The body’s immune system identifies these antigens and produces antibodies to fight the infection. “But often the influenza virus mutates during monsoon season which changes the antigens. As a result, antibodies fail to identify and fight it. Thus the virus becomes predominant and affects more number of people with low immunity,” he said. He further added that while more research is needed, those afflicted have been known to develop resistance to the virus. “When there is a swine flu epidemic, those infected display resistance to the viral strain for a year. So we witness lesser number of patients next year,” he said.

According to World Health Organization (WHO), to prevent swine flu, trivalent quadrivalent intramuscular vaccine should be given to people before the onset of monsoon. Prompt testing for swine flu and immediate medical attention, when suggestive symptoms are present, helps avoid complications.