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Subject: Change in H5N1 cases during 2007/08 [Print This Page]

Author: ajohn    Time: 14/04/2008 17:05     Subject: Change in H5N1 cases during 2007/08

During the winters of 2005/06 and 2006/07, there were a large number of cases of H5N1 avian influenza in Hong Kong.  Most of these were in the urban area, especially Kowloon, indicating that the disease was readily able to spread between birds in that area.  Many individuals were of regularly-traded species which are uncommon in the urban area, or of scavenging species.

In 2007/08, there have been considerably fewer cases. These have not been clustered around particular localities, suggesting a considerable reduction in the ability of the disease to spread by secondary infection of other birds.

As far as I can see, the most significant difference between the years is that there was a concerted effort by the government to properly clean the bird market last summer after a cagebird there tested positive for the disease:

As discussed so many times before, these results suggest to me that in the past the bird market has been the major source for bird flu spreading among 'wild' birds in Hong Kong. Sporadic cases among genuinely wild birds (as in 2007/08 ) may result in the deaths of individual birds but these do not seem to spread the disease to other individuals, or bring the disease into the urban area where it could be transmitted to humans.

Surely this should indicate to the government that the real danger of H5N1 in Hong Kong does not arise from wild birds, but in fact results from the arrival of an infected cagebird in the bird market, followed by rapid spread to other individuals in the cramped conditions, and a realistic risk of subsequent transmission to a market worker or tourist.

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