H7N9 Emerges Across China

Feb 23, 2017 | Ellen Do and Emily Cohn | Outbreak News


Europe is not the only continent in the middle of a bird flu epidemic. While other Asian countries such as South Korea and Japan have been struggling to deal with controlling the spread of other strains of influenza in their domestic poultry, China has experienced a sharp uptick in human cases of avian influenza H7N9 since late 2016. In November 2016, China reported a total of six cases, but by December of that same year it had already escalated to 106 cases, and between January 1st and February 5th there were 235 reported cases [1].


While China has been experiencing regular avian influenza epidemics since spring 2013, this year’s epidemic has a wider geographical range and a higher number of cases, which may be partially fueled by an early flu season or increased virus detection in poultry [2]. There is no evidence of human-to-human transmission, but China’s numerous live poultry markets present a ripe scenario for animal-to-human transmission, thus fueling the spread of the disease.


Avian influenza is a viral disease that occurs naturally in wild aquatic birds, but is sometimes transferred to domestic poultry [3]. Avian influenza has multiple viral strains and normally do not infect humans, but there are occasional outbreaks of avian influenza, perhaps the most notable ones being the annual outbreaks in China and the current outbreak in Europe.


Avian influenza infection in humans appears to act similarly to a seasonal flu, which spreads more often during cold weather versus warm temperatures [3]. It is also spread primarily through contact with infected birds or contaminated environments. For example, contact with contaminated bird droppings, saliva, or mucous may be one way of contracting the virus; it is also possible to be infected through airborne particles generated when a bird flaps its wings. Initial symptoms include high fevers and coughing, but many cases become more serious and may progress to severe pneumonia or acute respiratory distress syndrome (ARDS) [3].


Authorities have reportedly begun closing live poultry markets across the country to attempt to control the spread of the H7N9 virus, especially since there is currently no vaccine and the best recommended means of prevention is avoiding exposure [4]. Markets in Guangzhou, Sichuan province, Changsha, and more have already been closed. It is unclear if the epidemic has already peaked, but since the virus typically flares up during the winter flu season, there is hope that as time passes the case counts and spread of H7N9 will abate.




[1] http://outbreaknewstoday.com/china-reports-dozens-additional-h7n9-bird-flu-cases-90104/

[2] http://www.cidrap.umn.edu/news-perspective/2017/02/china-now-its-worst-h7n9-avian-flu-season-record

[3] https://www.cdc.gov/flu/avianflu/

[4] http://www.npr.org/sections/thetwo-way/2017/02/13/515039777/to-stem-spread-of-avian-flu-in-china-some-provinces-shutter-poultry-markets

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