Preliminary Epidemiology of Human Infections with Highly Pathogenic Avian Influenza A(H7N9) Virus, China, 2017

Abstract

We compared the characteristics of cases of highly pathogenic avian influenza (HPAI) and low pathogenic avian influenza (LPAI) A(H7N9) virus infections in China. HPAI A(H7N9) case-patients were more likely to have had exposure to sick and dead poultry in rural areas and were hospitalized earlier than were LPAI A(H7N9) case-patients.

Comparison of the three waves of avian influenza A(H7N9) virus circulation since live poultry markets were permanently closed in the main urban areas in Zhejiang Province, July 2014‐June 2017

“…Compared to urban residents, rural residents usually have higher likelihood of exposure to sick or dead poultry, which were attributed to the popular country lifestyle of raising backyard poultry in China 5, 20, 21, 22. The human cases of infection with highly pathogenic avian influenza (HPAI) A(H7N9) virus have been found in Guangxi, Guangdong, and Hunan Provinces during the fifth wave 23, 24, 25. So far, there were no human cases of infection with HPAI A(H7N9) virus confirmed in Zhejiang province.…”

“…So far, there were no human cases of infection with HPAI A(H7N9) virus confirmed in Zhejiang province. However, a preliminary epidemiological study of HPAI suggested that HPAI A(H7N9) case‐patients were more likely to have had exposure to sick and dead poultry in rural areas 23. As rural cases consistently contribute more than half of the new incidents in Zhejiang province, it is essential to raise public awareness of avoiding contacting the sick or dead poultry.…”

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

“…4 Along with an earlier onset of reported cases, there was also a sudden increase in human H7N9 cases reported. 3,5,6 Of the total number of human H7N9 infections identified since 2013, 52% of cases have occurred during the latest outbreak. 7 As of March 2018, a total of 1,567 cases of laboratory confirmed H7N9 infections were detected with at least 615 deaths reported.…”

“…14 Of note, before the fifth outbreak, human infections were caused by a low pathogenic avian influenza, which caused little or no disease in infected poultry. 6 However, in February of 2017 the National Health and Family Planning Commission of China reported genetic sequences from virus isolates from two patients located in Guangdong Province that had insertions at the HA gene cleavage site which is suggestive of a highly pathogenic avian influenza. 6,7 Additionally, mutations in the viral polymerase that may augment replication and pathogenicity in humans have been observed, however human cases of highly pathogenic H7N9 virus infection do not exhibit increased transmission and virulence.…”

“…6 However, in February of 2017 the National Health and Family Planning Commission of China reported genetic sequences from virus isolates from two patients located in Guangdong Province that had insertions at the HA gene cleavage site which is suggestive of a highly pathogenic avian influenza. 6,7 Additionally, mutations in the viral polymerase that may augment replication and pathogenicity in humans have been observed, however human cases of highly pathogenic H7N9 virus infection do not exhibit increased transmission and virulence. 15 Combined with already existing adaptations in H7N9 for increased viral replication in the mammalian lower respiratory tract 16 , the potential for further adaptations that increase human-to-human transmissibility raises concern for an H7N9 influenza virus pandemic, despite lower incidence in recent months than in previous years.…”