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ARCHIVE H7N9 situation update

03 July 2019, 17:00 hours; Rome

The next update will be issued on 07 August 2019

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 (05 June 2019): 0

New human cases since last update (05 June 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. Regarding the fifth period (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 03 July 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 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

2 44

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

 

 Situation update

Animals

Since the last update (05 June 2019), no H7N9 outbreak or H7N9 positive animal or environment findings were reported.

 

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 03 July2019

Number of positive virological samples from birds or the environment, by province and origin as of 03 April 2019. 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)

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 03 July 2019. Samples from the same location and time are grouped.

Figure 3. Distributions of low* and highly pathogenic H7N9 virologically positive samples (nLPAI=280; nHPAI=50)

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. collected from birds or the environment, by sample origin between October 2016 and 03 July 2019. Samples from the same origin, location and time are grouped.

 

Humans

  • Since the last update (05 June 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 03 July 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 03 July 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

  • Gong, S., Qi, F., Li, F., Lv, Q., Wang, G., Wang, S., […], & Qin, C. Human-Derived A/Guangdong/Th005/2017 (H7N9) Exhibits Extremely High Replication in the Lungs of Ferrets and Is Highly Pathogenic in Chickens. Viruses, 2019 May 29;11(6). pii: E494. [reference]. The pathogenicity and transmissibility of the human-derived A/Guangdong/Th005/2017 H7N9 virus (Th005), especially its distribution and replication in tissues, were studied in ferrets. They also aimed to assess the level of Th005 pathogenicity in chickens. The results showed that the pathogenicity of Th005 was significantly increased in ferrets and chickens, especially compared with the A/Anhui/1/2013 strain. The replication of Th005 in the lung tissues of ferrets was 100-fold higher than that of the Anhui strain. Th005 pathogenicity reached an intravenous pathogenicity index score of 3 in avian models. Continuously high titres of viruses could be detected in the cloacal cavity of chickens infected with Th005.
  • Yang, L., Xie, J., Zhang, Y., Zhu, W., Li, X., Wei, H., […], & Wang, D. Emergence of waterfowl-originated gene cassettes in HPAI H7N9 viruses caused severe human infection in Fujian, China. Influenza Other Respiratory Viruses, 2019 June 11. [reference]. This publication investigates an H7N9 HPAI virus isolated from a human case and six environmental isolates, including five H7N9 HPAI and one H7N6 HPAI virus, all detected in Fujian Province, China during the 2016-2017 epidemic wave of influenza A(H7N9). Phylogenetic results showed the human and environmental viruses are highly genetically diverse and containing significantly different gene constellations from that of other H7N9 HPAI previously reported. The internal genes were derived from H7N9/H9N2, H5N6, and the Eurasian wild-bird gene pool, indicating that waterfowl-originating genotypes have emerged in H7N9/N6 HPAI viruses and caused human infection.
  • Liang, L., Jiang, L., Li, J., Zhao, Q., Wang, J., He, X., & Li, C. Low Polymerase Activity Attributed to PA Drives the Acquisition of the PB2 E627K Mutation of H7N9 Avian Influenza Virus in Mammals. mBio10(3), e01162-19. [reference]. In this study, they generate a series of reassortant or mutant H7N9 avian influenza viruses to challenge mice with the obtained viruses. Results show that, during H7N9 AIV replication in mice, the low polymerase activity attributed to the viral PA protein is the intrinsic driving force behind the emergence of PB2 E627K, a substitution thought to be critical for mammalian adaptation and pathogenesis of AIV.
  • Wang, G.L., Gray, G.C., Chen, J., & Ma, M. Will China’s H7N9 Control Strategy Continue to Be Effective? Open Forum Infectious Diseases, Volume 6, Issue 6, June 2019. [reference]. This publication describes the control strategy of China since the emergence of H7N9 virus in 2013 such as market closures and the recent H5 and H7 mass vaccination of birds conducted on mainland China since September 2017. The publication also highlights the new challenges China is facing in terms of H7Nx viruses reassortants, especially those found in unimmunized ducks.

 FAO actions

  • 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