Cattle could be breeding grounds for future flu outbreaks, according to researchers who are tracking emerging strains in animals in the hope of averting further human pandemics.
The last flu pandemic swept the globe in 1968, killing nearly half a million people. Flu viruses originate in wild birds and are become lethal when they cross into poultry or pigs. Then the viruses pick up genes that enable them to infect humans.
Ian Brown and his colleagues at the Veterinary Laboratories Agency in the U.K. believe that cows, too, could be harboring new strains of flu, because they have detected influenza genes in cattle for the first time.
Dormant cattle viruses could emerge from cattle in more virulent forms to infect humans, agrees flu researcher Alan Hay of the National Institute for Medical Research in London. It is not known where the cattle virus originated or whether it can spread from cow to cow.
Each year, new human flu strains emerge due to mutations and annual flu vaccines are targeted against them. But varieties that jump to humans directly from animals are so different that our current vaccines would be useless against them. Such killer strains strike every 30-40 years. ?It?s now 34 years since the last pandemic; that?s why everyone is quite twitchy,? says Brown.
In 1997, six of 18 people infected were killed by a ?bird flu? that crossed into humans in the poultry markets of Hong Kong. Unable to spread from person to person, this flu died with its victims, but another killer flu is expected to come along eventually. ?It could spread across the globe before a vaccine could be prepared,? says Brown.
Most scientists predict the next flu pandemic will emerge in Southeast Asia, like the previous two, because wild birds, poultry, pigs and people mix in the same market-places. ?Live poultry markets are the breeding ground of these viruses,? says Robert Webster, director of the WHO Collaborating Center on the Ecology of Influenza Viruses in Lower Animals and Birds.
Meanwhile, avoid cows during the flu season.
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