Tuesday, 11 February 2014

Illegal Beijing bird markets the source of exported H5N1 influenza virus

A backstreet illegal poultry market stall in Beijing was the likely source of the highly pathogenic avian influenza A(H5N1) virus infection that killed a Canadian visitor, infectious disease specialists have suggested.
In January a 28-year old woman developed H5N1 infection on her return to Alberta after visiting Beijing. She died after developing neurological complications. It was assumed that she had picked up the infection in Beijing but it was reported that she had not had close contact with poultry while in the city.
However, the woman probably picked up the virus from one of many illegal poultry market stalls that exist in Beijing, according to Dr Yang Peng of the Beijing Center for Disease Prevention and Control. In a letter to the Journal of Infection this week, Dr Yang says the Canadian case was only the second such case of H5N1 to be linked to the city. He describes a similar case in which a 19-year old woman developed H5N1 infection and died in 2009. Analysis showed that the H5N1 virus was avian in origin and belonged to clade 2.3.4. The woman had bought a live healthy duck from a street market and she had prepared it for cooking. Dr Yang said poultry breeding and live markets were prohibited in Beijing, but illegal markets had sprung up in the suburbs, and these sold poultry reared in nearby Hubei and Tianjin districts.The stall area where the women bought the duck tested positive for H5N1, according to Dr Yang. He therefore suggested that the recent Canadian case of H5N1 may have occurred after the visitor passed through a street market or stall.
The findings "indicate that illegal and uninspected selling and transportation of live poultry from regions outside of Beijing may have posed a high risk on human infection with avian influenza in the general population of Beijing currently. The enhanced inspection of illegal selling of live poultry, the strict regulation of transporting live poultry from regions outside of Beijing, as well as health education on changing dietetic culture is greatly warranted in Beijing, in order to reduce the risk of infection with avian influenza viruses in the general population of Beijing including visiting foreigners," the letter concluded.
And in another development this week, the full genomic analysis of the Beijing-derived H5N1 case has been published in the Emerging Infectious Diseases. The analysis "provides valuable insight into the presence of mutations that may reflect adaptive changes, altered virulence, and/or transmission phenotype," the researchers said.

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