H5N1 Culler Cluster in West Bengal Raises Pandemic Concerns
Recombinomics Commentary 04:22
January 22, 2008
The men reported influenza-like symptoms including fever, cough, sore throat and muscle ache.
Some of them are also suspected to be suffering from respiratory illness like pneumonia. A special team from the National Institute of Virology (NIV), Pune, collected blood and throat samples of the patients on Sunday.
They are being tested by scientists at the National Institute of Cholera and Enteric Diseases (NICED), Kolkata, and Delhi's National Institute of Virology and National Institute of Communicable Diseases - the only three bio safety level (BSL)-III labs in India equipped to test human samples for avian influenza.
The next 24 hours will be a nervous wait for officials monitoring the outbreak as final reports are expected on Tuesday.
The above comments on five likely H5N1 infections in cullers in West Bengal, India are cause for concern. If confirmed, the cluster would have striking similarities to the recent clusters in Pakistan. The H5N1 in India is likely to be similar to the H5N1 in Pakistan. Although Pakistan has not released any H5N1 sequences, and the last sequences from India or Pakistan’s neighbor, Afghanistan, were from outbreaks two years ago, those sequences were clade 2.2.3 and it is likely that the recent sequences in both countries will be the Uva Lake strain, which evolved from clade 2.2.3.
In Pakistan the index case for the outbreak was a culler and all initial cases seemed to be linked to culling operations. Brothers of the index cullers also developed symptoms, and two died. The two fatal cases and two others developed pneumonia, a common complication of H5N1 infections.
In India, H5N1 symptoms in five cullers from the same region, who apparently developed symptoms at the same time, suggests the H5N1 is efficiently transmitted to humans. The rapid spread of H5N1 in West Bengal (see satellite map) puts a large number of people at risk, in the region, which is densely populated with humans and domestic poultry, which also has wetlands frequented by migratory birds. The large number of dead resident crows, pigeons, owls, and hawks also suggests that the H5N1 infections are widespread and have reached a critical mass.
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Culling plans, based on limited confirmations due to limited testing, have targeted 2,000,000 birds, but will likely grow larger as more suspect poultry samples are tested. The excessive poultry deaths suggest H5N1 has spread across the entire West Bengal region.
West Bengal testing has been lagging, and rapid tests have generated false negatives. India has yet to confirm a human case, in part because of minimal testing.
That should change tomorrow.
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