Commentary
Rapid
H5N1
Spread In Northwestern Assam India
Recombinomics Commentary
19:48
December 8, 2008
An alert has been sounded in lower Assam districts, as bird-flu is spreading to Nalbari, Baska, Barpeta and Bongaigaon from Kamrup (rural) district, official sources said here today.
The State Director of Veterinary Department Dr. Aswini Kotoky told our Guwahati Correspondent this evening that unnatural death of poultry birds have been reported from some more areas of Bongaigaon and Chirang districts.
Unnatural death of poultry was reported from a small farm in Chirang district yesterday.
The above comments from recent media reports indicate H5N1 has spread well beyond the four districts where samples have been confirmed in Bhopal (see updated map). These new areas (Baksa, Bongaigaon, Chirang), with locally confirmed bird flu or unnatural poultry deaths, are northwest of the four confirmed districts, which are adjacent to and include the two Kamrup (rural and metro) districts. These areas are closer to the wildlife sanctuaries in Bhutan / Assam (Manas) and West Bengal (Buxa) suggesting these sanctuaries may be the source of the H5N1 in lower Assam districts, but detection was delayed because of a lower population and poultry density in upper Assam.
Although there is routine testing of wild birds in India, much of the testing is on fecal samples which have low levels of clade 2.2 H5N1, which is the strain in circulation in West Bengal and Bangladesh last season. Similarly, all initial H5N1 positive samples from Assam this season were from tissue samples and not serum. Serum also has low levels of H5N1 and usually produces false negatives.
Thus, the confirmed cases are largely limited to dead or dying poultry , and the delay in generating the lab results in Bhopal allows for additional H5N1 spread prior to culling. Thus, levels of H5N1 may be high in the wild bird and poultry populations, leading to rapid spread early in the season, when temperatures in the region are still high.
This rapid spread at this time of the season raises concerns of a dramatic spread in H5N1 to the south as the temperature begins to drop.
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