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|Paradigm Shift Intervention Monitoring
Flu Pandemic Monitoring in Peoples Republic of China
December 31, 2004
>>Worries also have been stoked by the H5N1 bird flu virus, which decimated poultry stocks in Asia and spread to people. But there was no evidence it had acquired human-flu characteristics it would need to be passed easily among people.<<
Although the H5N1 avian fly virus in Vietnam and Thailand has not acquired human-flu characteristics it would need to be passed easily among people, these isolates have acquired, via recombination, polymorphisms commonly found in mammalian isolates. The acquisition of these polymorphisms has correlated with an expanded host range into tigers and domestic cats as well as humans. Limited human to human transmission is suspected in Vietnam and Thailand.
Similarly, 1933 human WSN/33 sequences in swine have acquired polymorphisms commonly found in recent swine and human isolates. This process has been dubbed swimanization. In addition to this type of recombination between closely related avian genomes, the swine isolates have undergone reassortment and recombination.
This reshuffling and creation of new genes is a concern, since lethal H5N1 isolates can grow to high titers in asymptomatic ducks and H3N2 swine isolates have recently jumped to turkeys in the United States.