On a global scale, experts are especially concerned about the seemingly unstoppable outbreak of bird flu in cattle in the United States, where 244 herds in 14 states have been infected – plus at least 14 people. Though these cases have so far been mild, scientists are racing to determine whether there has been human-to-human transmission.
In that outbreak, too, felines have been badly hit – the US Department of Agriculture has detected 43 cases in domestic cats so far this year, with many of them infected after drinking H5 contaminated cows milk.
“So definitely felines seem to be more susceptible to H5N1 than some other mammals,” said Prof Ian Barr, deputy director of the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne.
Dr Charin Modchang, an specialist in disease modelling and epidemiology at Mahidol University in Bangkok, added that he was surprised to see tigers, leopards and panthers infected given the reports of H5 in domestic cats.
“But, from the evolutionary perspective, if the virus can infect and adapt to new mammalian hosts, this should be a concern, as infections in mammals can lead to adaptations that make the virus better suited for mammalian hosts, which are closer to humans than birds,” he said.
“As far as I know, most mammalian H5N1 cases are usually ‘dead-end’ infections with little onward transmission. So the important question is, is this also the case for these tiger infections? How did the tigers get infected, and were there any tiger-to-tiger transmission of the virus? I think we need to find out.”
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