Amid news of another H7N9 case reported from Guangdong Province (see CHP notified of additional human case of avian influenza A(H7N9) in Guangdong), Dr. Ian Mackay weighs in with a blog on the importance of closing live bird markets (LBMs) in China in order to reduce the spread of the virus.
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Guangdong province in southern China is suspending its poultry markets. All of them. From 15-Feb to 28-Feb. While the closures are only for 2-weeks, this will be very important for stopping human cases of avian influenza, particularity of the H7N9 subtype, during the bustling spring period in China.
Live poultry market closures also remove a traditional dish of fresh cooked chicken. One can be certain that no-one will die because of the substitution of frozen or factory prepared chicken for a fresh chicken, even if chefs don't succumb to the tantrums of last year and refuse to prepare dishes made from anything but fresh market-selected poultry. One can be equally certain that if the markets remain operating during the peak season for influenza virus circulation as they have been, that human infections, and deaths, due to H7N9 infections, will also continue
Last summer, in CDC: Risk Factors Involved With H7N9 Infection we looked at a case-control study conducted by an international group of scientists, including researchers from both the Chinese and the US CDC which concluded.
Exposures to poultry in markets were associated with A(H7N9) virus infection, even without poultry contact. China should consider permanently closing live poultry markets or aggressively pursuing control measures to prevent spread of this emerging pathogen.
In October of 2013 we saw another study (see The Lancet: Poultry Market Closure Effect On H7N9 Transmission) which found:
Closure of LPMs reduced the mean daily number of infections by 99% (95% credibility interval 93—100%) in Shanghai, by 99% (92—100%) in Hangzhou, by 97% (68—100%) in Huzhou, and by 97% (81—100%) in Nanjing. Because LPMs were the predominant source of exposure to avian influenza A H7N9 virus for confirmed cases in these cities, we estimated that the mean incubation period was 3·3 days (1·4—5·7).
Despite the evidence that it would greatly reduce the transmission of the virus, closing LMBs is a hard sell to the Chinese public. Purchasing live market birds is deeply ingrained in the culture, as it reassures the buyer that the bird is both fresh and healthy.
China, Indonesia, and other countries have attempted to close or strictly regulate live bird markets in the past – only to be met with tremendous public resistance (see 2009 blog China Announces Plan To Shut Down Live Poultry Markets In Many Cities).
That ambitious plan, announced more than 5 years ago to `shut live poultry markets in all large and medium-sized cities throughout China’, obviously never happened.
While the temporary closure of markets Guangdong will hopefully reduce the impact of this year’s H7N9 outbreak, as Ian points out temporary closures are only expected to provide temporary relief.