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HK: Top microbiologist calls for pig monitoring to avoid H1N1 mutations
Tuesday, October 13, 2009
Hong Kong's pig population should be monitored for human swine flu (H1N1), experts say, as the virus could possibly mutate again into a deadlier pandemic strain.
Hong Kong University chair professor of microbiology Malik Peiris broached the idea of pig surveillance because the animal is a natural mixing vessel for influenza viruses.
If the flu strain goes back to pigs and mixes with human or bird flu viruses, it could reassort to become more severe, he said.
The World Health Organization said the H1N1 virus is a reassorted mix of swine influenza A viruses from North American and Eurasian lineages (H1N1, H1N2 and H3N2).
The virus has gene segments originating from swine, human and avian influenza A viruses.
David Hui Sui-cheong, a specialist in respiratory medicine at Chinese University, agreed that monitoring the pig population for the novel H1N1 virus "will be a good surveillance measure."
He said: "If you transfer the infection back to the pig, it is a very efficient vehicle to produce a new virus."
Frederick Leung Chi-ching, of Hong Kong University's school of biological sciences, and his team said the predecessor of this year's pandemic "might have sporadically transmitted from swine to humans between 1999 and 2006."
He said it is possible the new flu was undetected because symptoms were "virtually indistinguishable with that of seasonal flu infections."
"The initial patients of H1N1 had no recent exposure to swine and the current surveillance data does not support the circulation of human H1N1 in North American pigs," he said.
He said it is possible the new strain had been transmitted to North America through "a human carrier" from Asia.
He said Asia and certain parts of the world could be "a missing link" in the evolution of the pandemic.
But Takeshi Kasai, the WHO regional adviser for communicable diseases surveillance and response for the Western Pacific, said the organization is aware of these reports but "there is so far no evidence showing that the virus" came from Asia.
Meanwhile, Centre for Health Protection controller Thomas Tsang Ho-fai said that pig workers, unlike poultry workers, will not be vaccinated against seasonal flu.
For pandemic H1N1 the predominant mode of transmission is human to human, Tsang said. "You have a much ... higher chance of getting swine flu from a person near you than from a pig," he said.
Tsang said poultry workers are being vaccinated for seasonal flu "to prevent co- infection with H5N1 by virtue of their profession."
He added: " Although we are not facing an H5 pandemic, it is important to continue with [vaccination] because every year, especially every winter, we do have isolated cases of H5N1 in birds and persons and so on."
Hong Kong's pig population should be monitored for human swine flu (H1N1), experts say, as the virus could possibly mutate again into a deadlier pandemic strain.
Hong Kong University chair professor of microbiology Malik Peiris broached the idea of pig surveillance because the animal is a natural mixing vessel for influenza viruses.
If the flu strain goes back to pigs and mixes with human or bird flu viruses, it could reassort to become more severe, he said.
The World Health Organization said the H1N1 virus is a reassorted mix of swine influenza A viruses from North American and Eurasian lineages (H1N1, H1N2 and H3N2).
The virus has gene segments originating from swine, human and avian influenza A viruses.
David Hui Sui-cheong, a specialist in respiratory medicine at Chinese University, agreed that monitoring the pig population for the novel H1N1 virus "will be a good surveillance measure."
He said: "If you transfer the infection back to the pig, it is a very efficient vehicle to produce a new virus."
Frederick Leung Chi-ching, of Hong Kong University's school of biological sciences, and his team said the predecessor of this year's pandemic "might have sporadically transmitted from swine to humans between 1999 and 2006."
He said it is possible the new flu was undetected because symptoms were "virtually indistinguishable with that of seasonal flu infections."
"The initial patients of H1N1 had no recent exposure to swine and the current surveillance data does not support the circulation of human H1N1 in North American pigs," he said.
He said it is possible the new strain had been transmitted to North America through "a human carrier" from Asia.
He said Asia and certain parts of the world could be "a missing link" in the evolution of the pandemic.
But Takeshi Kasai, the WHO regional adviser for communicable diseases surveillance and response for the Western Pacific, said the organization is aware of these reports but "there is so far no evidence showing that the virus" came from Asia.
Meanwhile, Centre for Health Protection controller Thomas Tsang Ho-fai said that pig workers, unlike poultry workers, will not be vaccinated against seasonal flu.
For pandemic H1N1 the predominant mode of transmission is human to human, Tsang said. "You have a much ... higher chance of getting swine flu from a person near you than from a pig," he said.
Tsang said poultry workers are being vaccinated for seasonal flu "to prevent co- infection with H5N1 by virtue of their profession."
He added: " Although we are not facing an H5 pandemic, it is important to continue with [vaccination] because every year, especially every winter, we do have isolated cases of H5N1 in birds and persons and so on."
