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ARCHIVE H7N9 situation update

04 December 2019, 17:00 hours; Rome

The next update will be issued on 05 February 2020

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 (06 November 2019): 0

New human cases since last update (06 November 2019): 0

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

Human cases and positive findings in birds or the environment
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. During period 7 (October 2018-September 2019), 8 positive samples were detected in the exact same location in Liaoning Province (see map). For 14 samples from Inner Mongolia Autonomous Region the precise geographic location is currently unknown; these findings are therefore not shown on the map.

 

Provinces/municipalities affected: 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 04 December 2019.

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

  • Since the last update (06 November 2019), no H7N9 outbreak or H7N9 positive animal or environment findings were reported.

 

Table 2. Post vaccination monitoring results in China during the period January to August 2019, by month.

Reporting period (2019)

#serum samples collected

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

#virological samples collected

#H7N9 positive virological samples

January

126 998

92.36

34 815

0

February

66 572

94.84

17 042

0

March

85 973

94.19

21 975

8

April

87 940

93.03

16 980

14

May

96 152

95.39

13 029

0

June

189 453

95.34

26 767

0

July 131 819 94.54 26 035 0
August 100 529 96.07 16 525 0

 

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.

Figure 1. Number of positive virological samples from birds or the environment, by province and origin as of 04 December 2019

Number of positive virological samples from birds or the environment, by province and origin. Data include both high and low pathogenic H7N9 viruses
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) collected from birds or the environment, by sampling location, between October 2016 and 04 December 2019. Samples from the same location and time are grouped.

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.

Figure 3. Distributions of low* and highly pathogenic H7N9 virologically positive samples (nLPAI=281; nHPAI=50) collected from birds or the environment, by sample origin between October 2016 and 04 December 2019. Samples from the same origin, location and time are grouped.

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.

 

Humans

  • Since the last update (06 November 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 04 December 2019

Phylogenetic relationships of A(H7) Eurasian HA genes, including Chinese-origin H7N9
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 2014 (beginning of period 3) to 04 December 2019

Phylogenetic relationships of A(H7) Eurasian HA genes, including Chinese-origin H7N9
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

  • Inui, K., Nguyen, T., Tseng, H.J., Tsai, C.M., Tsai, Y.L., Chung, S., [..], & Claes, F. A field‐deployable insulated isothermal RT‐PCR assay for identification of influenza A (H7N9) shows good performance in the laboratory. Influenza and other respiratory viruses, 13(6), 610–617. [reference]. This study aimed at determining analytical and diagnostic sensitivity and specificity of the portable insulated isothermal reverse transcriptase PCR (iiRT-PCR) for H7N9 virus detection. The H7 and N9 iiRT-PCR reagents yielded comparable levels of analytical sensitivity and specificity with real-time RT-PCR for the detection of H7N9 virus. Diagnostic sensitivity and specificity of H7 iiRT-PCR were 98% and 100%, respectively.
  • Yu, H., Zhang, K., Ye, X., Wang, W., Wu, W., Wang, X., […], & Jiao, P. Comparative Pathogenicity and Transmissibility of the H7N9 Highly Pathogenic Avian Influenza Virus and the H7N9 Low Pathogenic Avian Influenza Virus in Chickens. Viruses, 2019 November 10;11(11). pii: E1047. [reference]. Two H7N9 avian influenza virus (AIV) strains, one low pathogenic (LP) - A/chicken/Guangdong/A46/2013 - and one highly pathogenic (HP) - A/chicken/Guangdong/Q29/2017 -, were selected to compare the pathogenicity and transmissibility between H7N9 LP and HP AIV in chickens. Compared with early H7N9 LPAIVs, the pathogenicity and transmissibility of the emerging H7N9 HPAIV was stronger in chickens, indicating that H7N9 influenza virus may continue to threaten human and poultry health.
  • Xu, Y., Peng, R., Zhang, W., Qi, J., Song, H., Liu, S., […], & Gao, G.F. Avian-to-Human Receptor-Binding Adaptation of Avian H7N9 Influenza Virus Hemagglutinin. Cell Reports, 2019 November 19;29(8):2217-2228.e5. [reference]. This study consists in a molecular analysis of H7N9 avian influenza virus hemagglutinins. Mutagenesis and structural studies reveal that a G186V substitution is sufficient for H7N9 AIVs to acquire human receptor-binding capacity, and a Q226L substitution would favor binding to both avian and human receptors only when paired with specific hydrophobic residues.
  • Quan, C., Wang, Q., Zhang, J., Zhao, M., Dai, Q., Huang, T., […], & Gao, G. F. Avian Influenza A Viruses among Occupationally Exposed Populations, China, 2014-2016. Emerging infectious diseases, 25(12), 2215–2225. [reference]. A sero-epidemiological study in seven areas of China was conducted during December 2014–April 2016 to determine the seroprevalence and seroconversion of avian influenza virus (AIV) antibodies in poultry workers. A seroprevalence of AIV antibodies was observed for the subtypes H9N2, H7N9, H6N1, H5N1-SC29, H5N6, H5N1-SH199, and H6N6. In serum from participants with longitudinal samples, a seroconversion with more than 4-fold rise in titers was observed for H9N2, H7N9, H6N1, H5N1-SC29, H6N6, H5N6, and H5N1-SH199 subtypes.

 FAO actions

  • The Tripartite Zoonoses Guide is now available in all UN languages [link]
  • Report of the WHO Vaccine Composition Meeting – February 2019 [link]
  • FAO published a risk assessment update entitled, “Chinese-origin H7N9 avian influenza: spread in poultry and human exposure” [link]
  • A webinar entitled “Pros and cons of avian influenza 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