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|Paradigm Shift Intervention Monitoring
Probable Human Transmission in Thailand
September 28, 2004
I>>The "documentation of human-to-human transmission in this situation is better than it has been in previous cases," <<
The above is the key statement in the report below. It is unlikely that this is the first H5N1 human to human transmission. It is just the one with the strongest epidemiological data because the mother was in Bangkok, when the daughter became ill in northern Thailand. The key epidemiological fact in this case and the cluster in southern Vietnam in late July / early August was the fact that the relative/care-giver developed symptoms 1-2 weeks after the initial case.
The publicly available sequences of chicken isolates from southern Vietnam associated withe the Vietnamese cluster were virtually identical to the isolates from the beginning of this year.
In Vietnam and Thailand in particular, the isolates have polymorphisms not found in other H5N1 isolates. However, these polymorphisms are found in other mammalian isolates such as H1N2. Thus the virus has already recombined and is capable of transmitting human to human fatal infections under the appropriate conditions, such as close contact during the care of infected patients.