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ARCHIVE H7N9 situation update

07 August 2019, 17:00 hours; Rome

The next update will be issued on 04 September 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 (03 July 2019): 0

New human cases since last update (03 July 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=44) in birds and/or the environment, by province and sampling site as of 07 August 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 (03 July 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 07 August 2019

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 07 August 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. Samples collected from birds or the environment, by sample origin between October 2016 and 07 August 2019. Samples from the same origin, location and time are grouped.

 

Humans

  • Since the last update (03 July 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 07 August 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 07 August 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

  • Nakayama, M., Uchida, Y., Shibata, A., Kobayashi, Y., Mine, J., Takemae, N., […], & Saito T. A novel H7N3 reassortant originating from the zoonotic H7N9 highly pathogenic avian influenza viruses that has adapted to ducks. Transboundary Emerging Diseases, 2019 July 11 [reference]. This study describes the genetic characteristics of a novel H7N3 reassortant of the zoonotic H7N9 HPAIVs, A/duck/Japan/AQ-HE30-1/2018 (HE30-1), that was detected in a poultry meat product illegally brought by a passenger from China into Japan. The genome of this reassortant comprised at least three different sources, however six of the genes were directly derived from H7N9 avian influenza viruses (AIVs). Experimental infection revealed that HE30-1 was lethal in chickens but not in domestic or mallard ducks. HE30-1 was shed from and replicated in domestic and mallard ducks and chickens, whereas previous zoonotic H7N9 AIVs have not adapted well to ducks. HE30-1 showed similar antigenicity to some of those H7N9 AIVs.
  • Naguib MM, Verhagen JH, Mostafa A, Wille M, Li R, Graaf A, Järhult JD, Ellström P, Zohari S, Lundkvist Å, Olsen B. Global patterns of avian influenza A(H7): virus evolution and zoonotic threats. FEMS Microbiol Rev. 2019 Aug 5. pii: fuz019. doi: 10.1093/femsre/fuz019 [reference]. In this review, study authors bring together data on global patterns of H7 circulation, evolution, and emergence in humans. Specifically, they discuss data from the wild bird reservoir, expansion and epidemiology in poultry, the significant increase of their zoonotic potential since 2013, and genesis of highly pathogenic H7. In addition, they analyse available sequence data from an evolutionary perspective, demonstrating patterns of introductions into distinct geographic regions and reassortment dynamics.
  • Walsh DP, Ma TF, Ip HS, Zhu J. Artificial intelligence and avian influenza: using machine learning to enhance active surveillance for avian influenza viruses. Transbound Emerg Dis. 2019 Aug 3. doi: 10.1111/tbed.13318 [reference]. Active surveillance programs provide critical information about viral evolution forming the basis of risk assessments and counter measure development. Unfortunately they are often resource-intensive, and thus enhancing programs for increased efficiency is paramount. Machine learning, a branch of artificial intelligence applications, provides statistical learning procedures that can be used to gain novel insights into disease surveillance systems. In this study gradient boosted trees were used to estimate the probability of isolating avian influenza viruses (AIV) from wild bird samples collected during surveillance for AIVs from 2006-2011 in the United States. Authors examined several predictive features including age, sex, bird type, geographic location and matrix gene rrRT-PCR results. The final model had high predictive power, and only included geographic location and rRT-PCR results as important predictors. Lower rRT-PCR Ct-values are associated with increased likelihood of AIV isolation, and the model estimated 16% probability of isolating AIV from samples declared negative (i.e., ≥35 Ct-value) using the rRT-PCR screening test and standard protocols. This model can be used to prioritize previously collected samples for isolation and rapidly evaluate AIV surveillance designs to maximize the probability of viral isolation given limited resources and laboratory capacity. 
  • Jia W, Wen X, Xie S, Dai Y, Li Z, Wang X, Hu J, Jin X, Li X, Qi W, Pradhan K, Liao M. A Novel Antigenic Drift of Avian Influenza A(H7N9) Virus in Poultry, China, 2018. J Infect Dis. 2019 Jul 8. pii: jiz190. doi: 10.1093/infdis/jiz190 [reference]. Recent findings have showed that key mutations affecting antigenicity of influenza A(H7N9) virus may have appeared over the past 5 years. To further evaluate the changes of antigenicity of H7N9, authors studied the antigenicity and molecular characteristics of a new H7N9 virus isolated from poultry. They found a novel antigenic drift, the first antigenic change found after the implementation of China’s immunization policy in poultry.

 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