Avian Flu Scan for May 15, 2014

H7N9 case in China
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Evolution in H7N9 viruses

H7N9 sickens man after pigeon contact

China reported another H7N9 influenza case today, in a 66-year-old man from Jiangsu province, according to a provincial health department notice translated and posted by FluTrackers, an infectious disease news message board.

The man got sick after he slaughtered a pigeon he bought at a live market. He is listed in critical condition at a hospital in Wuxi.

The new case brings the overall outbreak total to 440, according to a list of officially confirmed cases kept by FluTrackers. So far 304 cases have occurred during the second wave of infections, which started last October, versus 136 in the first.
May 15 FluTrackers thread
FluTrackers human H7N9 case count

 

Study finds signs of ongoing H7N9 changes

A genetic analysis of avian influenza strains in China's Guangdong province—including its first human case—during the first wave of H7N9 activity suggests that the virus picked up internal genes from H9N2 viruses in local poultry, creating a new reassortant and showing that H7N9 can change quickly.

The study by Chinese researchers was reported yesterday in the Journal of Virology. Guangdong felt little impact during the first wave, and disease activity there was unusual, because the virus was detected in poultry and markets months before the first human illness was found.

The group's analysis is based on viruses identified during live poultry market surveillance from Apr 15 through May 31, 2013, and human surveillance for pneumonia of unknown causes that started on Apr 16, 2013.

Only two H7N9 positives were detected in the poultry markets, both in environmental samples from the same market in Meizhou. The study also included an H7N9 sample from a chicken detected on May 5 by animal health officials in Dongguan and a strain detected Aug 9 in the province's first human case, a 51-year-old woman who slaughtered poultry in a Huizhou poultry market.

Analysis of the viruses' internal genes revealed that the environmental and chicken strains were similar to those found in other provinces, but those from the human case a few months later were different. The internal genes from the human sample clustered with H9N2 viruses found in Guangdong between April and May of 2013.

The team concluded that genetic differences in H7N9 viruses collected in Guangdong at different times hint at continuing reassortment with local H9N2 viruses, which could be fueling rapid evolution of H7N9.

The findings are similar to those in another study of H7N9 viruses in Guangdong by another team, which published its analysis in the Feb 13 issue of Eurosurveillance. It focused on H7N9 sequences from viruses submitted by 11 Chinese provinces, plus some from Hong Kong, in 2013.

The team found increased diversity and reassortment with local H9N2 strains, such as ones found in a Guangdong/Hong Kong transmission cluster, which they said might be one factor triggering reemergence of infections in the second wave.
May 14 J Virol abstract
Feb 13 CIDRAP News story

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