A dangerous strain of avian influenza, H7N9, causing severe illness and deaths in China may be inhabiting a small fraction of its potential range and could be at risk of spreading, according to a study.
Other areas with conditions favourable to the influenza include India, Bangladesh, Vietnam, Indonesia and the Philippines, says a study in the journal Nature Communications.
Researchers from the Université Libre de Bruxelles (ULB), the International Livestock Research Institute (ILRI), Oxford University, and the Chinese Center of Disease Control and Prevention analysed new data showing the distribution and density of live poultry markets in China and of poultry production overall in the country.
They found that the emergence and spread of the disease up until now is mainly linked to areas that have a high concentration of markets catering to a consumer preference for live birds and does not appear related to China’s growing number of intensive commercial poultry operations.
H7N9t has infected 429 people so far and killed at least 100.
The scientists have pinpointed areas elsewhere in Asia with similar conditions, places with a high density of live bird markets, which could allow H7N9 to significantly expand its range.
Places at risk include urban areas in China where the disease has not yet occurred, along with large swaths of the Bengal regions of Bangladesh and India, the Mekong and Red River deltas in Vietnam, and isolated parts of Indonesia and the Philippines.
“We’re not saying these are areas where we expect to see infections emerge, but the concentration of bird markets makes them very suitable for infection should the virus be introduced there, and that knowledge could help guide efforts to limit transmission,” said Marius Gilbert, an expert in the epidemiology of livestock diseases at Université Libre de Bruxelles and the paper’s lead author.
The study notes there is evidence that certain factors within live poultry markets, such as the amount of time the birds are there, the rigor of sanitation measures, and “rest days,” that can influence the spread of the disease, suggesting potential options for reducing risks of further transmission of H7N9.
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