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ARCHIVE LATEST H7N9 situation update

24 November 2017, 12:00 hours; Rome

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: 1,622 confirmed; 619 deaths (since February 2013).
New findings in birds / environment since last update (25 October 2017): 0

New human cases since last update (25 October 2017): 0

Map 1. Human cases and positive findings in birds or the environment

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. Precise location of 63 human cases in Anhui (2), Beijing (2), Guangdong (1), Guangxi (1), Hebei (3), Hunan (1), Hubei (2), Jiangsu (2), Jiangxi (6), Sichuan (2), Zhejiang (3) and unknown (38) Provinces are currently not known, these cases 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 54 poultry or environmental samples (42 chickens, 2 duck and 10 environmental samples); H7N9 virus isolates from 25 human cases were found to be HPAI virus.

 

Table. Number of locations testing positive for H7N9 HPAI virus (n=38) in birds and/or the environment, by province and sampling site as of 24 November 2017.

Province

LBM*

Farm

Backyard

Airport

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

Inner Mongolia

0

2

0

0

2

Shaanxi

0

1

0

0

1

Tianjin

0

1

0

0

1

Unknown

0

0

0

1

1

TOTAL

26

10

1

1

38

 

*LBM: live bird market

 

 

 Situation update

Animals

  • The Ministry of Agriculture, China has started autumn vaccination* using H5+H7 recombinant inactivated vaccine targeting all poultry in mainland, followed by post vaccination monitoring. A "two-dimensional code" traceability system is used for live poultry inter-provincial transport which is only allowed with animal quarantine certificate. Such certificate can be issued once H7N9 virology comes back negative (samples from one farm can be pooled), or if the flock immunization rate is >70% (with poultry H7 antibody titre ≥24) [reference].
    *Note: This is a mandatory vaccination campaign targeted at poultry breeders and commercial poultry farms, including broiler chickens, layers, pigeons, ducks, geese, quail, etc. The vaccine is financially supported by the central government; poultry producers do not pay for it. Currently, the China Central Government awarded 10 domestic manufactures to supply the vaccine. The H7N9 vaccination schedule, including frequency of vaccination as well as timing of first and/or second vaccination, adheres to the existing vaccination programs and accommodates the characteristics of local poultry farming system; e.g. the production cycle of yellow-wing broilers (the dominant broiler breed in southern China) is 120 days, so they are usually vaccinated twice within a 20-30 day interval.
  • 13 November, Guangdong: Guangdong province has used 174 million vaccines and vaccinated nearly 276 million poultry out of the target poultry population of about 282 million. The vaccination coverage is now above 97.87% [reference].
  • 7 November, Chongqing: Since fall 2017, a total of 62.44 million poultry were vaccinated using H5 + H7 bivalent inactivated vaccine. 414 serum samples from vaccinated chickens were collected from 14 large size farms as well as 19 free-range households in Yunyang, Bishan, Zhongxian, Wansheng and Changshou counties for post vaccination monitoring. H5 and H7 subtype of bird flu antibody compliance rates were 92.27% and 75.85%, respectively [reference].
  • 2 November, Guangdong: Foshan city set a province-wide rest schedule (no trade, cleaning, disinfection) for live bird markets (LBMs) from November 2017 to March 2018 [reference]:
    • November 2017 to January 2018: LBMs will close from the 15th to the 19th of each month, i.e. for 5 consecutive days;
    • LBMs will close from 8 to 12 February 2018 (i.e. for 5 consecutive days);
    • LBMs will close from 15 to 19 March 2018 (i.e. for 5 consecutive days).

Animal/environmental findings: Since 4 April 2013 around 2500 virological samples from the environment, chickens, pigeons, ducks and a tree sparrow 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 24 November 2017. Data include both high and low pathogenic H7N9 viruses.

Number of positive virological samples from birds or the environment, by province* and origin
Click to enlarge

Figure 2. Distributions of low* and highly pathogenic H7N9 virologically positive samples (nLPAI=210; nHPAI=38) collected from birds or the environment, by sampling location, between October 2016 and September 2017 (wave 5). Samples from the same location and time are grouped.

Number of positive virological samples from birds or the environment, by province* and origin
Click to enlarge - *may contain unconfirmed HPAI at the time of publishing

Figure 3. Distributions of low* and highly pathogenic H7N9 virologically positive samples (nLPAI=252; nHPAI=44) collected from birds or the environment, by sample origin between October 2016 and September 2017 (wave 5). Samples from the same origin, location and time are grouped.

Incidence of officially reported human cases by week, based on onset date
Click to enlarge - *may contain unconfirmed HPAI at the time of publishing

 

Humans

  • Since the last update (25 October 2017), no new humans cases have been reported.
  • For detailed information on human cases, please refer to WHO's Disease Outbreak News

Figure 4. Number of officially reported human cases since February 2013 as of 24 November 2017. Data include both high and low pathogenic H7N9 viruses

Incidence of officially reported human cases by week, based on onset date
Click to enlarge

Figure 5. Incidence of officially reported human cases by month, based on onset date as of 24 November 2017. Both high and low pathogenic H7N9 viruses are included.

Incidence of officially reported human cases by week, based on onset date
Click to enlarge - Note: For cases with unknown onset dates from wave 1 (n=7), wave 2 (n=2), wave 3 (n=146), wave 4 (n=27) and wave 5 (n=55), reporting dates were used instead.

 

Publications        

  • Shi J, Deng G, Kong H, Gu C, Ma S, Yin X, […], Chen H. H7N9 virulent mutants detected in chickens in China pose an increased threat to humans. Cell Res. 2017 Oct 24. doi: 10.1038/cr.2017.129. [reference]. The evolution of H7N9 viruses isolated from avian species between 2013 and 2017 in China was evaluated and 23 different genotypes found, 7 of which were detected only in ducks and were genetically distinct from the other 16 genotypes that evolved from the 2013 H7N9 viruses. Importantly, some H7N9 viruses obtained an insertion of four amino acids in their hemagglutinin (HA) cleavage site and were lethal in chickens, resulting in an intravenous pathogenicity index (IVPI) of 3 (i.e. most pathogenic). The virus also systemically replicated in chickens after intranasal inoculation, and all chickens died within 4 days. H7N9 viruses inoculated in mice or ferrets rapidly obtained mutations in their PB2 segment causing these viruses to become highly lethal. H7N9 viruses bearing the HA insertion and PB2 mutation have already been detected in humans in China.
    (Note: Another experiment using an H7N9 HPAI isolate from confiscated Muscovy duck meat from a flight passenger in Japan (A/duck/Japan/AQ-HE29-22/2017(H7N9), GenBank LC315927), showed that chickens inoculated intranasally died within 2 days whereas no ducks died with similar viral inoculations. For details, see here)
  • Lei Zhou, Enfu Chen, Changjun Bao, Nijuan Xiang, Jiabing Wu, Shengen Wu, […], Qun Li. Clusters of Human Infection and Human-to-Human Transmission of Avian Influenza A(H7N9) Virus, 2013–2017. Emerg Infect Dis. 2018 Feb 17;24(2). doi: 10.3201/eid2402.171565. [reference]. An analysis of 40 clusters of case-patients spanning the five epidemics (2013-2017) was conducted to detect changes in human-to-human transmission of influenza A(H7N9). Similarities in number and size of clusters and proportion of clusters with probable human-to-human transmission across all epidemics suggest no change in human-to-human transmission risk.
  • Qi W, Jia W, Liu D, Li J, Bi Y, Xie S, […], Liao M. Emergence and adaptation of a novel highly pathogenic H7N9 influenza virus in birds and humans from a 2013-human-infecting low pathogenic ancestor. J Virol. 2017 Oct 25. pii: JVI.00921-17. doi: 10.1128/JVI.00921-17. [reference]. A study revealed the presence of three different amino acid motifs at the cleavage sites of novel H7N9 HPAIV variants isolated from chickens and humans. Animal experiments showed that these variants are both highly pathogenic in chickens and lethal to mice.
  • Jidang Chen, Jipei Zhang, Wanjun Zhu, Yishan Zhang, Hualong Tan, Minfang Liu, […], Jianhong Chen. First genome report and analysis of chicken H7N9 infuenza viruses with poly-basic amino acids insertion in the hemagglutinin cleavage site. Sci Rep. 2017 Aug 30;7(1):9972. doi: 10.1038/s41598-017-10605-6. [reference]. Full-length sequences of two chicken source influenza A (H7N9) viruses found in a Guangdong live poultry market (City of Foshan) during wave 5 of human infections are available. These viruses carry insertion of poly-basic amino acids at the protease cleavage site of the HA protein. Phylogenetic analysis suggested that their genomes reassorted between the Yangtze River Delta and Pearl River Delta clades. Molecular clock analysis indicated that they emerged several months before the HP human strains.
  • Wang N, Sun M, Wang W, Ouyang G, Chen Z, Zhang Y, […], Jiao P. Avian Influenza (H7N9) Viruses Co-circulating among Chickens, Southern China. Emerg Infect Dis. 2017 Dec;23(12):2100-2102. doi: 10.3201/eid2312.170782. [reference]. Three avian influenza (H7N9) viruses were isolated from chicken samples collected in Guangdong Province in June 2016 and January 2017. Each virus had different insertion points in the cleavage site of the hemagglutinin protein (i.e. HPAI). These viruses were confirmed to be double or triple reassortant viruses.
  • Hu Z, Liu X, Jiao X, Liu X. Newcastle disease virus (NDV) recombinant expressing the hemagglutinin of H7N9 avian influenza virus protects chickens against NDV and highly pathogenic avian influenza A (H7N9) virus challenges. Vaccine. 2017 Dec 4;35(48 Pt B):6585-6590. doi: 10.1016/j.vaccine.2017.10.010. [reference]. Newcastle Disease Virus (NDV)-vectored H7 bivalent vaccine candidate provided a dual protection from virulent NDV and HPAI H7N9 virus challenges. The vaccine provided 80% protection against H7N9 HPAI challenge.
  • Dong-Hun Lee, Mia K. Torchetti, Mary Lea Killian, Yohannes Berhane, and David E. Swayne. Highly Pathogenic Avian Influenza A(H7N9) Virus, Tennessee, USA, March 2017. Emerg Infect Dis. 2017 Nov; 23(11): 1860–1863. doi:  10.3201/eid2311.171013. [reference]. Surveillance data and genetic analyses of all available sequences of the North America wild bird H7N9 lineage suggest that the virus in the Wyoming blue-winged teal represents a precursor to the poultry viruses in the south-eastern United States (Tennessee, March 2017) before mutation to high pathogenicity and inter-farm transmission. Note: these viruses are not related to H7N9 viruses circulating in China. 

FAO actions:

  • FAO published a risk assessment entitled, “Chinese-Origin H7N9 Highly Pathogenic Avian Influenza: Spread in poultry and human exposure” [reference]
  • 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