Commentary
Wild
Bird Deaths in Assam and Nagaland Raise H5N1 Concerns
Recombinomics Commentary
15:38
December 22, 2008
The above comments describe likely H5N1 in wild birds in the Karbi Anglang district of Assam as well as Nagaland in eastern India (see updated map). Although media reports suggest the H5N1 was not recently confirmed in Assam samples sent to Bhopal for testing, H5N1 confirmations in any host other than domestic poultry in India is rare.
Testing is minimal, and media reports cite shipment of serum samples and cloacal swabs to Bhopal for testing. However, both approaches are unlikely to produce H5N1 confirmations. Qinghai (clade 2,2) is characterized by sudden death, so hosts die too quickly to produce detectable antibodies and serum samples are negative. Similarly, use of the rapid test for viral RNA in the cloacal swabs is also unlikely to be positive because levels in cloacal swabs are low, and the rapid test lacks sensitivity. Experimental testing of lab infected wild birds yields detectable H5N1 in nasopharyngeal swabs, but undetectable H5N1 in cloacal swabs.
Many of the migratory birds in India come from nature reserves north of India, such as Qinghai Lake, the largest lake in China, or Uvs Lake, the largest lake in Mongolia. H5N1 has been detected at one or both location every year since 2005, yet India has never reported H5N1 in migratory birds.
Similarly, the widespread outbreaks last season were associated with the death of resident birds, including crows in West Bengal and Bangladesh. Although Bangladesh confirmed H5N1 in dead or dying crows at multiple locations, India did not. This season however, India has confirmed H5N1 in dead crows in Guwahati, the largest city in Assam, but has not confirmed H5N1 in hundreds of dead crows geographically linked to the confirmed outbreak in Malda.
Thus, although India’s ability to confirm H5N1 in resident or migratory wild birds remains suspect, the dead wild birds in the jungles described above, strongly suggest that once again H5N1 has migrated into India and Bangladesh this season, and more outbreaks are expected.
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