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ARCHIVE H7N9 situation update

05 September 2018, 17:00 hours; Rome

The next update will be issued on 03 October 2018

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: 1,625 confirmed; 623 deaths (since February 2013).
New findings in birds / environment since last update (25 July 2018): 0

New human cases since last update (25 July 2018): 0

Map. 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. Regarding the fifth wave (October 2016-September 2017), precise location of 20 human cases in Guangdong (1), Guangxi (1), Hebei (3), Hunan (1), Hubei (1), Jiangsu (1), Jiangxi (5), Zhejiang (2) and unknown (5) 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 58 poultry or environmental samples (46 chickens, 2 duck and 10 environmental samples); H7N9 virus isolates from 32 human cases were found to be HPAI virus.

 

Table. Number of locations testing positive for H7N9 HPAI virus (n=43) in birds and/or the environment, by province and sampling site as of 05 September 2018.

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

Liaoning 0 1 0 0 1

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

1

43

*LBM: live bird market

 

 Situation update

Animals

No new official information were reported by the Ministry of Agriculture and Rural Affairs, China since the last update of 25 July 2018.

 

Animal/environmental findings: Since 4 April 2013 around 2500 virological samples from the environment, chickens, pigeons, ducks, turkeys, 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 05 September 2018. 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=246; nHPAI=43) collected from birds or the environment, by sampling location, between October 2016 and 05 September 2018. 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=280; nHPAI=49) collected from birds or the environment, by sample origin between October 2016 and 05 September 2018. 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 July 2018), no human cases were reported.
  • For detailed informationon human cases, please refer to WHO report.

Figure 4. Number of officially reported human cases since February 2013 as of 05 September 2018. 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 from October 2013 (Beginning of wave 2) to 05 September 2018. 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 2 (n=2), wave 3 (n=146), wave 4 (n=27) and wave 5 (n=55), reporting dates were used instead.


For a phylogenetic tree of H7N9 viruses isolated please click here. Acknowledgements:WHO report ‘Antigenic and genetic characteristics of zoonotic influenza viruses and development of candidate vaccine viruses for pandemic preparedness’ – September 2017 [reference].

 

 Publications

  • Shibata, A., Okamatsu, M., Sumiyoshi, R., Matsuno, K., Wang, Z.J., Kida, H., Osaka, H. & Sakoda Y. Repeated detection of H7N9 avian influenza viruses in raw poultry meat illegally brought to Japan by international flight passengers. Virology, 2018 August 20;524:10-17. [reference]. H7N9 highly and low pathogenic avian influenza viruses (HPAIV and LPAIV, respectively) were isolated from duck meat products that were brought illegally into Japan by flight passengers in their hand luggage. These H7N9 virus isolates were phylogenetically closely related to those prevailing in China.
  • Li, R., Zhang, T., Bai, Y., Li, H., Wang, Y., Bi, Y., Chang, J. & Xu, B. Live Poultry Trading Drives China's H7N9 Viral Evolution and Geographical Network Propagation. Frontier Public Health, 2018 July 27;6:210. [reference]. A phylogenic analysis examined the inter-subtype interactions between H7N9 viruses and the closest H9N2 lineages in China during 2010-2014. Viral propagation was geographically-structured and followed the live poultry trading network in China, with distinct north-to-east paths of spread and circular transmission between eastern and southern regions. Higher substitution rate was observed among isolates sampled from live poultry markets. Live poultry trading may have driven the network-structured expansion of the novel H7N9 viruses.
  • Lu, J., Raghwani, R., Pryce, R., Bowden, T.A., Thézé, J., Huang, S., […] & Ke, C. Molecular evolution, diversity, and adaptation of influenza A(H7N9) viruses in China. Emerging Infectious Diseases, 2018 Oct. [reference]. This study investigated the evolution and adaptation of H7N9 viruses in Guangdong Province during 2015–2017. Three antigenic clusters were identified for 16 strains of different virus lineages. Highly pathogenic strains likely emerged from viruses circulating in eastern Guangdong Province during March 2016 and are associated with a high rate of adaptive molecular evolution.
  • Xiang, D., Pu, Z., Luo, T., Guo, F., Li, X., Shen, X., […] & Shen, Y. Evolutionary dynamics of avian influenza A H7N9 virus across five waves in mainland China, 2013-2017. The Journal of Infection, 2018 September;77(3):205-211. [reference]. In this study, they evaluated all available genomes for H7N9 and H9N2 influenza A viruses. The assessment depicts from the first to the fifth wave the genomic evolution and divergence of H7N9 viruses.
  • Ning, T., Nie, J., Huang, W., Li, C., Li, X., Liu, Q., Zhao, H., & Wang Y. Antigenic Drift of H7N9 Viral Hemagglutinin. The Journal of Infectious Diseases, 2018 July 5. [reference] In this study, 902 H7N9 HA sequences from public database were retrieved and analyzed. Antigenic characteristics of 53 mutants with single amino acid substitutions in HA were analyzed. The most dominant variant (A143V/R148K) in the most recent season constitutes 74.11% of all mutations and demonstrated a 10-fold reduction in its reactivity to A/Anhui antisera. Importantly, compared to DNA construct without the corresponding HA mutation, DNA vaccine encoding A143V/R148K mutant induced a 5-fold increase in the neutralizing activity against this circulating virus.
  • Petrie, J. G. and Lauring, A. S.,  Influenza A (H7N9) virus evolution: Which genetic mutations are antigenically important? The Journal of Infectious Diseases, 2018 July 5. [reference]. This article depicts the work of Ning et al. about the evolution of H7N9 viruses which may complicate strain selection for vaccines, and the assessment of the antigenic effects of specific influenza A(H7N9) virus mutations.
  • Bertran, K., Lee, D.H., Criado, M.F., Smith, D., Swayne, D.E., & Pantin-Jackwood, M.J. Pathobiology of Tennessee 2017 H7N9 low and high pathogenicity avian influenza viruses in commercial broiler breeders and specific pathogen free layer chickens. Veterinary Research, 2018 August 29;49(1):82. The pathogenesis of the H7N9 LPAI virus was investigated in commercial broiler breeders. Infectivity, transmissibility, and pathogenesis of the H7N9 HPAI and LPAI viruses were also studied in 4-week-old specific pathogen free (SPF) leghorn chickens. No transmission to contact-exposed birds was observed for the LPAI isolate. In both bird types, virus shedding was almost exclusively from the oropharyngeal route. The BID50 for the HPAI isolate in SPF layer chickens was more than 2 logs lower than the LPAI isolate. Also, the HPAI virus was shed by both the oropharyngeal and cloacal routes and transmitted to contacts.

 FAO actions

  • 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 published a risk assessment update entitled, “Chinese-origin H7N9 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