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H5N1 Migration and Meningitis in India
Recombinomics Commentary
May 21, 2005
>> According to the statistics, 11 deaths (out of 33 so far) have been reported this week alone. And there have been 54 new cases. "We were hopeful that the figure would come down but in the last few days, the number of new cases is again increasing,'' said Dr J.N. Banvalikar, Director, Hospital Administration, MCD.
Officials are now being careful and want to watch the trend before they comment any further. <<
The coincidence between the migration of ducks from the plains of India and outbreak of fatal meningitis cases in India raise obvious questions, but it remains unclear if anyone is working on answers.
China just confirmed that the wild birds that died in Qinghai in early May were infected with H5N1. These birds spend the winter on the plains of India and then return to the Qinghai Lake Nature Reserve to nest in May and June. Thus, the migration of the birds from India began right about the time of the meningitis outbreak in India. Bacterial meningitis and meningococcemia are secondary infections of influenza.
H5N1 has been in India in the past because local poultry workers have H5N1 antibodies, which were detected in samples collected in 2002.
There have been no reports on H5N1 in current samples from poultry workers or the meningitis patients in India. There was a similar outbreak last fall in the Philippines, which coincided with migratory birds flying from the northeast Asia. The meningitis / meningococcemia cases continue, but with a lower case fatality rate.
A lower case fatality rate has also been observed in bird flu patients in northern Vietnam, and the genetic changes in isolates in northern Vietnam are similar to isolates in Thailand, where there have been no reported H5N1 cases in humans.
In northern Vietnam clusters of H5N1 cases are larger and longer, and most patients have recovered. Some patients have been asymptomatic while a family of five recovered after 1-2 weeks in the hospital. These milder cases could easily be mistaken for flu caused by H3N2, and testing of most of these patients has been lacking.
A broad retrospective analysis of serum samples from flu and meningitis cases would be useful. In the past, PCR tests have yield a high percentage of false negatives, and antibody tests may give a clearer picture of just how far and wide H5N1 has spread in human populations in Asia.
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