Mumbai, August 13: The northern hemisphere is bracing for a fresh and potentially deadlier outbreak of swine flu during winter. A large number of people who died after testing positive to swine flu, actually died of pneumonia, an illness exacerbated by cold temperatures.
The swine flu pandemicThe virus survives for a far longer time in cold places. For instance, in Mumbai, the virus will survive for just three hours, but in Michigan in the US, it will survive for six.
The dry spell in the city this monsoon is a positive thing as far as curtailing the spread of the virus is concerned. The scorching heat of October may further help in killing the virus.
Unfortunately India’s size and the large population make it highly vulnerable. It is impossible to stop human-to-human transfer of the virus. What is more, the virus has behaved differently in Pune, Mumbai, Nashik, Hyderabad and Delhi. Among those who tested positive for swine flu, 96% reported fever and chills, while 62% reported loss of appetite, vomitting, nausea and diarrhoea.
Like all influenza viruses, H1N1 changes constantly. Pigs can be infected by bird and human influenza viruses, as well as swine influenza viruses. When the infection comes from different species, the viruses can reassort (swap genes) and new viruses may emerge. This exactly has happened in the emergence of H1N1 in 2009. It is a variant of the H1N1 that caused the flu pandemic in 1918, which spread to nearly every part of the world, infecting one-third of its total population — approximately 1.6 billion at that time.
The H1N1 virus that has surfaced in 2009 is unique. It is a genetic mixture of viruses from pigs, birds and humans. Since it is a new virus, our immune systems do not know how to fight it. Past experience too is not a good guide as one cannot predict the course of the virus.
Vaccines for influenza viruses, which change in antigenicity every year, are brought out annually. Several pharmaceutical and research companies, including at least three in India, are in the process of researching for a vaccine to fight H1N1. However, this will take at least four more months. Unfortunately, we do not know if this H1N1 virus will mutate and form a different strain by then. In that case, the vaccine will not be effective. The bugs, as they say, are smarter than the drugs.
Epidemiologists are currently in the process of following trends for a month, watching out for weekly progressions, before coming up with a theory about the virus’ behaviour. Until then, one can only wait and watch.
(As told by the Dr SM Sapatnekar, who is an epidemiologist. He is a former director of Haffkine’s Institute and director of Clinical Research Education and Management Academy)
–Agencies