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Poultry wet market likely source of virus of H7N9 human infection: research

English.news.cn   2013-04-26 22:54:56            

Photo taken on April 5, 2013 shows chickens are tied up to be dealt with at a market in Shanghai, east China.  (Xinhua File Photo)

HONG KONG, April 26 (Xinhua) -- Chinese scientists have made a breakthrough in understanding the human infections with avian influenza A

H7N9 virus by finding out that poultry wet market might be the source of the deadly virus, according to a research published online on Thursday by the leading international medical journal The Lancet.

The research was conducted by a collaborative research team from The University of Hong Kong and Zhejiang University. They analyze four infected patients in southeast China's Zhejiang Province, and discover for the first time that the patient's virus is genetically very closely related (>/=99.4%) to the chicken virus isolated from the epidemiologically linked poultry market.

The Lancet publishes the research entitled "Human infections with the emerging avian influenza A H7N9 virus from wet market poultry: clinical analysis and characterization of viral genome" in a timely manner, according to a statement from The University of Hong Kong.

The research analyses four epidemiologically unlinked Zhejiang patients suffering from severe acute community acquired pneumonia not responding to typical and atypical antimicrobial coverage who are found to have the H7N9 virus.

The team shows for the first time that the patient's virus is genetically very closely related (>/=99.4%) to the chicken virus isolated from the epidemiologically linked poultry market. Indeed about 20% of the chickens in the epidemiologically linked markets were infected with this virus. The researchers thereby believe that poultry wet market might be the source of virus of avian influenza A H7N9 human infection.

Moreover, the team conducts a characterization of viral genome. They find that the patient virus has a PB2 Asp701Asn mutation which is important for adaptation to mammalian host. There are also important mutations on the haemagglutinin, a virus surface protein, facilitating the virus attaching to mammalian host cell. These include the HA Gly186Val and Gln226Leu.

But no person-to-person transmission was found in 303 household or workplace contacts and 82 health-care workers with unprotected exposure to the four patients, according to the research.

Among these four patients, two of them died with respiratory failure, multiorgan dysfunction and markedly elevated serum cytokines and chemokines when compared with the survivors. Research found fatal but not the mild cases exhibit aberrant proinflammatory response of "cytokine storms," which resembles that observed in H5N1 or SARS patients. Another important finding is that virus testing appeared to be more sensitive with lower respiratory tract specimens such as sputum than throat swabs.

All in all, further studies on the virus evolution and disease pathogenesis will be performed to improve disease management and epidemic control, said the statement.

The research team is led by Professor Li Lanjuan of Zhejiang University and Professor Yuen Kwok-yung, the Co-director of the State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology of The University of Hong Kong Li Ka Shing Faculty of Medicine.

The deadly H7N9 virus has caused a total of 108 human infections on the Chinese mainland, including 23 cases that have ended in death, the National Health and Family Planning Commission said on Wednesday.

Related:

No H7N9 virus found in poultry farm samples: ministry

BEIJING, April 26 (Xinhua) -- No samples collected from poultry farms so far have tested positive for the H7N9 strain of avian influenza, China's agricultural authorities said on Friday.

As of Friday, of the 68,060 samples collected from poultry markets, habitats, farms and slaughterhouses across the country, 46 have tested positive for the virus, according to a statement by the Ministry of Agriculture (MOA).  Full story

Xinhua Insight: Challenges and hope loom in H7N9 fight

BEIJING, April 24 (Xinhua) -- Although infections in three people in a family have been confirmed, there are encouraging signs that the spread of the H7N9 avian influenza virus could be brought under control.

From April 13 to 23, H7N9 cases in China doubled to 108. As of Tuesday, 22 of the total cases have ended in death and 14 patients have been discharged from hospitals after treatment. Full story

No proof of H7N9 interpersonal transmission: China, WHO

BEIJING, April 24 (Xinhua) -- China and the World Health Organization (WHO) said on Wednesday that all the H7N9 infections identified so far are isolated cases and there is no evidence of any inter-human transmission.

Although several cases of family-clustered infections with H7N9 avian influenza have occurred in China, there is no definitive evidence indicating that the virus was transmitted from the same source or among different people, according to a China-WHO joint statement.  Full story

Editor: Zhu Ningzhu
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