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ARCHIVE H7N9 situation update

25 July 2018, 17:00 hours; Rome

The next update will be issued on 05 September 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 (27 June 2018): 1

New human cases since last update (27 June 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 25 July 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

  • 29 June 2018: The Ministry of Agriculture (MoA), China published the results of the national animal H7N9 surveillance and post-vaccination monitoring for the month of May 2018. The overall post-vaccination monitoring result* from 29 provinces was 92.14%**. Out of the 40,294 virology samples collected from 25 provinces, one chicken sample tested positive for H7N9 in Anhui Province from a live bird market in Chuzhou City [reference].
    *antibody titre ≥ 24 as required by the MoA regulation.
    **proportion of poultry samples which achieved required immunity level.

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 25 July 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 25 July 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 25 July 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 (27 June 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 25 July 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 25 July 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  

  • Ma, Y., Zhang, Z. B., Cao, L., Lu, J. Y., Li, K. B., Su, W. Z., […], & Wang, M. A case of human infection with highly pathogenic avian influenza A (H7N9) virus through poultry processing without protection measure. Zhonghua Liu Xing Bing Xue Za Zhi, 2018;39(6):799-804. doi: 10.3760/cma.j.issn.0254-6450.2018.06.020. [reference]. This study investigates the infection pattern and etiological characteristics of a case of human infection with highly pathogenic avian influenza A (H7N9). The case had no live poultry contact history, but had a history of pulled chicken processing without taking protection measure in an unventilated kitchen before the onset.
  • Wang, X.-X., Cheng, W., Yu, Z., Liu, S.-L., Mao, H.-Y., & Chen, E.-F. Risk factors for avian influenza virus in backyard poultry flocks and environments in Zhejiang Province, China: a cross-sectional study. Infectious Diseases of Poverty, 7, 65. doi:10.1186/s40249-018-0445-0. [reference]. Two surveillance systems and a field survey were used to collect data and samples between May 2015 and May 2017 in Zhejiang Province. Eastern and southern cities exhibited a higher prevalence of avian influenza viruses (AIV). Contamination of AIV subtypes was most severe in January. Subtype H5 was the least prevalent, while subtypes H7 and H9 had similar positivity rates. The type of live birds was a risk factor and the sanitary condition of the setting was a protective factor against influenza A contamination.
  • Iwatsuki-Horimoto, K., Shi, J., Wang, X., Sakai-Tagawa, Y., Ito, M., Murakami, K., […], & Kawaoka, Y. Development of an Influenza Rapid Diagnostic Kit Specific for the H7 Subtype. Frontiers in Microbiology, 2018;9, 1346. doi:10.3389/fmicb.2018.01346. [reference]. The study shares the characteristics of rapid diagnostic kit specific for the H7 subtype that is accessible and easy to use. Although the detection limit of this H7 kit is one-tenth lower than that of a commercially available rapid influenza A and B diagnostic kit of similar design, this kit is highly specific, detecting only H7-subtype influenza viruses, including the recent highly pathogenic H7N9 viruses from humans, and does not show any non-specific reactions with other HA subtypes.
  • Ning, T., Nie, J., Huang, W., Li, C., Li, X., Liu, Q., Zhao, H., & Wang, Y. Antigenic Drift of Influenza A(H7N9) Virus Hemagglutinin. The Journal of Infectious Diseases, jiy408, doi:10.1093/infdis/jiy408. [reference]. The study analyses how antigenic drift in HA proteins of influenza (A)H7N9 virus occurs. The frequencies of 9 mutations incrementally increased over the past 5 years, with mutations identified at multiple sites. The most dominant variant (A143V/R148K) in the most recent season constituted 74.11% of all mutations and demonstrated a 10-fold reduction in its reactivity to influenza A/Anhui/1/2013(H7N9) virus antisera.
  • Wang, X., Wu, P., Pei, Y., Tsang, T. K., Gu, D., Wang, W., [...], & Yu, H. Assessment of human-to-human transmissibility of avian influenza A(H7N9) virus across five waves by analyzing clusters of case-patients in mainland China, 2013-2017. Clinical Infectious Diseases, 2018 . doi: 10.1093/cid/ciy541. [reference]. Data on human cases and clusters of A(H7N9) virus infection were collected and epidemiological characteristics and clinical severity of sporadic and cluster cases were compared. The small cluster size and low reproductive number observed suggest that human-to-human transmissibility of A(H7N9) virus has not changed over time and remains limited to date.
  • He, L., Liu, D., Hu, J., Sun, W., Gao, R., Shi, L., […], & Liu, X. A comprehensive comparison of the fifth‐wave highly pathogenic and low‐pathogenic H7N9 avian influenza viruses reveals potential threat posed by both types of viruses in mammals. Transboundary Emerging Diseases, 2018. doi: 10.1111/tbed.12954. [reference]. Biological characteristics of the highly pathogenic (HP) and low‐pathogenic (LP) H7N9 avian influenza viruses collected during the fifth wave were investigated. HP and LP viruses differed a little in the well‐established receptor binding sites. HP viruses displayed a higher thermostability than LP viruses, and the HP viruses were moderately pathogenic in mice, as opposed to the LP viruses, which were nonpathogenic. The LP viruses replicated more efficiently in the mouse lung and can spread to the extrarespiratory organs.

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