The Third Wave: H7N9 Endemic Reassortant Viruses and Patient Clusters

Abstract

$ These authors contributed equally to this work. AbstractSouthern China experienced few cases of H7N9 during the first wave of human infections in the spring of 2013. The second and now the third waves of H7N9 infections have been localized mostly in Southern China with the Guangdong province an epicenter for the generation of novel H7N9 reassortants. Clusters of human infections show human-to-human transmission to be a rare but well-documented event. A recent cluster of infections involving hospital health care workers stresses the importance of care givers utilizing personal protective equipment in treating H7N9 infected or suspected patients.

The role of live poultry movement and live bird market biosecurity in the epidemiology of influenza A (H7N9): A cross-sectional observational study in four eastern China provinces

“…The third wave began in late 2014, started from Jiangsu and Xinjiang provinces, then massive affected Zhejiang and Jiangsu provinces in eastern China, as well as Fujian and Guangdong provinces in southern China. 3,4 Exposure to H7N9 infected poultry at LBMs has been implicated as the main risk factor for human infection and chickens are considered to be the species with an important role in the transmission for H7N9 influenza. 5e9 During the first wave, 82% of the 131 reported human H7N9 cases had a history of exposure to live poultry, particularly chickens.…”

Mammalian Pathogenesis and Transmission of H7N9 Influenza Viruses from Three Waves, 2013-2015

“…Asymptomatic H7N9 virus-infected chickens appear to be central to the persistence and expansion of this outbreak (3); accordingly, poultry contact and visitation of live poultry markets has been linked with H7N9 virus infection (4,5), and the closure of live poultry markets has been associated with a decline of new human infections in 2013 and 2014 (6,7). Limited family clusters of H7N9 virus infection have been reported (8,9), but human-tohuman transmission has remained a rarely documented and unsustainable event (10), while human infections continue to occur following exposure to H7N9 viruses circulating in avian reservoirs (11).…”

“…To date, three completed epidemiologic waves of human cases with H7N9 viruses have taken place in Southeast Asia (9). The first wave of human infection (30 March to 30 September 2013) resulted in over 130 confirmed cases with a Ͼ30% fatality rate, with human infection detected in mainland China and Thailand.…”

“…The first wave of human infection (30 March to 30 September 2013) resulted in over 130 confirmed cases with a Ͼ30% fatality rate, with human infection detected in mainland China and Thailand. The second wave (1 October 2013 to 30 September 2014) yielded over 260 additional cases, with the majority of cases detected in Guangdong and Zhejiang provinces of China (9) and additional cases detected in Hong Kong, Thailand, and Malaysia. The third wave (1 October 2014 to 30 September 2015) resulted in over 220 reported cases in China, Hong Kong, and Canada.…”

T cell epitope engineering: an avian H7N9 influenza vaccine strategy for pandemic preparedness and response

“…10 Both human-to-human household and hospital clusters have been described. 11,12 Transmissibility of avian influenza to humans depends on a balance of activities of the viral surface glycoproteins HA and neuraminidase (NA). The vast majority of human H7N9 isolates bears the hallmark Q226L mutation in HA that confers human receptor binding (α-2,6-linked galactose) and reduces avian receptor binding (α-2,3-linked galactose).…”