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H7N9 situation update

08 September 2021, 17:00 hours; Rome

The next issue will be distributed on 06 October 2021. If interested in a previous issue please send an email to EMPRES-Animal Health specifying the intended use of the document.

Disclaimer

Information provided herein is current as of the date of issue. Information added or changed since the last H7N9 situation update appears in red. Human cases are depicted in the geographic location of their report. For some cases, exposure may have occurred in one geographic location but reported in another. For cases with unknown onset date, reporting date was used instead. FAO compiles information drawn from multiple national (Ministries of Agriculture or Livestock, Ministries of Health, Provincial Government websites; Centers for Disease Prevention and Control [CDC]) and international sources (World Health Organization [WHO], World Organisation for Animal Health [OIE]) as well as peer-reviewed scientific articles. FAO makes every effort to ensure, but does not guarantee, accuracy, completeness or authenticity of the information. The designation employed and the presentation of material on the map do not imply the expression of any opinion whatsoever on the part of FAO concerning the legal or constitutional status of any country, territory or sea area, or concerning the delimitation of frontiers.

 

 Overview

Hazard: Influenza A(H7N9) virus with pandemic potential.
Country: China; imported cases in Malaysia (1) and Canada (2).
Number of human cases: 1,568 confirmed; 616 deaths (since February 2013).
New findings in birds / environment since last update (07 July 2021):0
New human cases since last update (07 July 2021): 0

Map. Human cases and positive findings in birds or the environment in China

Human cases and positive findings in birds or the environment in China
Click to enlarge - Note: Human cases are depicted in the geographic location where they were reported; for some cases, exposure may have occurred in a different geographic location. Centroid geo-coordinates were used for H7N9 positive animal/environment samples where the precise geolocation is unknown.

 

Provinces/municipalities affected (since 2013): Beijing, Chongqing, Shanghai and Tianjin Municipalities; Anhui, Fujian, Gansu, Guangdong, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Qinghai, Shaanxi, Shanxi, Shandong, Sichuan, Taiwan, Yunnan and Zhejiang Provinces; Hong Kong SAR, Macao SAR; Guangxi, Inner Mongolia, Ningxia Hui, Tibet and Xinjiang Uyghur Autonomous Regions (China); Sabah (Malaysia); British Columbia (Canada).

Highly pathogenic virus findings: Since 10 January 2017, highly pathogenic avian influenza (HPAI) type H7N9 virus was detected in a total of 66 poultry or environmental samples (46 chickens, 8 peacocks, 2 duck and 10 environmental samples); H7N9 virus isolates from 32 human cases were found to be HPAI virus.

 

Table 1. Number of locations testing positive for H7N9 HPAI virus (n=44) in birds and/or the environment, by province and sampling site as of 08 September 2021.

Province

LBM*

Farm

Backyard

Others**

Total

Anhui

0

1

0

0

1

Fujian

1

0

0

0

1

Guangdong

22

0

0

0

22

Guangxi

0

1

0

0

1

Hebei

0

1

0

0

1

Heilongjiang

0

1

0

0

1

Henan

0

1

0

0

1

Hunan

3

1

1

0

5

Liaoning 0 1 0 1 2

Inner Mongolia

0

2

0

0

2

Ningxia Hui

0

2

0

0

2

Shaanxi

0

2

0

0

2

Shanxi

0

1

0

0

1

Tianjin

0

1

0

0

1

Unknown

0

0

0

1

1

TOTAL

26

15

1

2 44

*LBM: live bird market; **Others include one airport and one zoo.

 

 Situation update

Animals

Ministry of Agriculture and Rural Affairs (MARA), China published results of the national animal H7N9 surveillance and post-vaccination monitoring for the month of June 2021 (see Table 2). None of the samples collected tested positive for H7N9 virus during this period. The overall post-vaccination monitoring results* from targeted provinces (between 23 and 31 provinces depending on the month) were close to or above 90%** during the period January 2020 to June 2021. [reference].

* antibody titre ≥ 24 as required by the MARA regulation.
** proportion of poultry samples which achieved required immunity level, the MARA target being 70%.

 

Animal/environmental findings: Since 4 April 2013 around 2500 virological samples from the environment, chickens, pigeons, ducks, turkeys, peacocks, a tree sparrow and a magpie robin tested positive; positives mainly from live bird markets, vendors and some commercial or breeding farms.

 

Table 2. National H7N9 surveillance and post-vaccination monitoring results from January 2020 to June 2021 published by MARA, China

Reporting period

#serum samples collected from birds

Average post-vaccination monitoring immunization rate (target 70%)

#virological samples collected from birds and the environment

#H7N9 positive virological samples

2020

January

72 845

96.24

17 536

0

February

107 409

94.27

34 501

0

March

127 074

95.05

42 190

0

April

104 650

95.34

24 017

0

May

180 261

95.59

21 961

3

June

221 577

95.77

31 183

0

July

166 193

92.32

43 404

0

August

110 926

96.08

17 053

0

September

106 163

95.67

16 410

0

October

78 070

95.15

11 647

14

November

168 938

95.87

32 425

0

December

302 599

94.21

84 929

0

2021

January

96 733

95.70

31 780

0

February

67 509

94.99

29 836

0

March

78 760

95.77

20 481

0

April

89 500

89.96

17 821

0

May

128 826

94.48

20 759

0

June

213 902

94.70

52 273

0

Source: Published by MARA, China. Note: sample sizes and collection sites can vary significantly from one administrative region to another. Detailed results can be consulted on the official website of the Ministry of Agriculture and Rural Affairs, China [reference].

Figure 1. Number of positive virological samples from birds or the environment, by province and origin as of 08 September 2021

Number of positive virological samples from birds or the environment, by province and origin
Click to enlarge - Data include both high and low pathogenic H7N9 viruses.

Figure 2. Distributions of low* and highly pathogenic H7N9 virologically positive samples (nLPAI=246; nHPAI=44).

Phylogenetic relationships of A(H7) Eurasian HA genes, including Chinese-origin H7N9
Click to enlarge - Note: * May contain unconfirmed HPAI at the time of publishing. Samples collected from birds or the environment, by sampling location, between October 2016 and September 2021. Samples from the same location and time are grouped. Some data on H7N9 positive virological samples collected during national H7N9 surveillance could not be included due to absence of information on the sampling location and the sample origin.

Figure 3. Distributions of low* and highly pathogenic H7N9 virologically positive samples (nLPAI=281; nHPAI=50).

Distributions of low* and highly pathogenic H7N9 virologically positive samples (nLPAI=281; nHPAI=50)
Click to enlarge - Note: * May contain unconfirmed HPAI at the time of publishing. Samples collected from birds or the environment, by sample origin between October 2016 and September 2021. Samples from the same origin, location and time are grouped. Some data on H7N9 positive virological samples collected during national H7N9 surveillance could not be included due to absence of information on the sampling location and the sample origin.

 

Humans

  • Since March 2019, no human cases were reported.
  • For detailed information on human cases, please refer to WHO report.

Figure 4. Number of officially reported human cases since February 2013, as of 08 September 2021

Number of officially reported human cases
Click to enlarge - Data include both high and low pathogenic H7N9 viruses.

Figure 5. Incidence of officially reported human cases by month, based on onset date from October 2015 (beginning of period 4) to 08 September 2021

Incidence of officially reported human cases by month, based on onset date
Click to enlarge - Note: For cases with unknown onset dates from period 2 (n=2), period 3 (n=146), period 4 (n=27) and period 5 (n=55), reporting dates were used instead. Both high and low pathogenic H7N9 viruses are included.

 

 Publications

 

He, D., Gu, J., Gu, M., Wu, H., Li, J., Zhan, T., […], & Liu, X. Genetic and antigenic diversity of H7N9 highly pathogenic avian influenza virus in China from 2017 to 2019. Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases, 93, 104993. Advance online publication. [reference]. To characterize the ongoing evolution of H7N9 avian influenza viruses (AIV), analyses of H7N9 glycoprotein genes obtained from 2013 to 2019 were conducted. Results showed that H7N9 highly pathogenic AIV experienced an increasing selection pressure since wave 5, and the national implementation of vaccination might intensify the role of natural selection during the evolution waves 6 and 7.

 

Li, C., & Chen, H. H7N9 Influenza Virus in China. Cold Spring Harbor perspectives in medicine, 11(8), a038349. [reference]. This review summarizes the biological properties of the H7N9 viruses, specifically their genetic evolution, adaptation, pathogenesis, receptor binding, transmission, drug resistance, and antigenic variation, as well as the prevention and control measures.

 

Liu, W. J., Xiao, H., Dai, L., Liu, D., Chen, J., Qi, X., [...], & Liu, Y. Avian influenza A (H7N9) virus: from low pathogenic to highly pathogenic. Frontiers of medicine, 15(4), 507–527. [reference]. This review summarizes the characteristics of the H7N9 viruses identified while controlling the spread of the disease. Several aspects are brought up including molecular epidemiology, clinical features, virulence and pathogenesis, receptor binding, T-cell responses, monoclonal antibody development, vaccine development, and disease burden.

 

Tang, H., Shen, C., Zou, L., Cai, C., Wang, Y., Robertson, I. D., [...], & Bruce, M. A mixed methods study of stakeholders' practices and attitudes on avian influenza H7N9 vaccination for the yellow broiler industry in Guangxi, China. Transboundary and emerging diseases, 10.1111/tbed.14286. Advance online publication. [reference]. This study investigated H7N9 vaccination practices in the yellow broiler industry in Guangxi and stakeholders' attitudes on H7N9 vaccination, using a mixed methods design. The study found H7N9 vaccination was well adopted in the yellow broiler industry in Guangxi regardless of the source of the vaccines.

 

Wei, X., Wang, L., Jia, Q., Xiao, J., & Zhu, G. Assessing different interventions against Avian Influenza A (H7N9) infection by an epidemiological model. One health (Amsterdam, Netherlands), 13, 100312. [reference]. This paper aims at evaluating the effectiveness of different intervention measures (e.g. poultry screening, vaccination, cleaning and disinfection) against the infection of avian influenza A (H7N9) by using an epidemiological model.

 

 FAO actions

  • FAO published the third edition of the Good emergency management practice - The essentials: A guide to preparing for animal health emergencies, freely available at this link.
  • As part of the OIE/FAO Network of Expertise on Animal Influenzas, FAO attended the Zoonotic Influenza Sessions of the WHO Vaccine Composition Meeting held from 2 to 4 March 2021. The report is now available online. [link]
  • WHO developed an online training course entitled Strengthening collaboration between human and animal health sectors for improved health security, freely available. The course covers the Tripartite Zoonosis Guide and associated tools in Module 2. [link]
  • The Tripartite Joint Risk Assessment (JRA) Operational Tool to address zoonotic health threats at the animal-human-environment interface is now available online. [link]
  • As part of the OIE/FAO Network of Expertise on Animal Influenzas, FAO attended the Zoonotic Influenza Sessions of the WHO Vaccine Composition Meeting held from 29 September to 1 October 2020; Report – October 2020. [link]
  • A paper from FAO entitled “A literature review of the use of environmental sampling in the surveillance of avian influenza viruses” (Hood et al., 2020) was published in the Transboundary and Emerging Diseases journal. [link]
  • Report of the WHO Vaccine Composition Meeting – February 2020. [link]
  • The Tripartite Zoonoses Guide is now available in all UN languages. [link]
  • FAO published a risk assessment entitled, “Chinese-Origin H7N9 Avian Influenza: Spread in poultry and human exposure”. [reference]
  • A webinar entitled “Pros and cons on AI vaccination” was presented by Leslie Sims on 14 May 2018 with technical support from FAO HQ. A recording of the webinar is available. [link]
  • FAO guidance and risk assessments are available on a dedicated website. [link]
  • Liaise with China and partners, monitor situation, monitor virus evolution, conduct market chain analysis, risk assessment, surveillance guidance and communication.

FAO’s support to countries