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ARCHIVE H7N9 situation update

08 May 2019, 17:00 hours; Rome

The next update will be issued on 5 June 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; 615 deaths (since February 2013).
New findings in birds / environment since last update (03 April 2019): 0

New human cases since last update (03 April 2019): 1

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 08 May 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 April 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 08 May 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 08 May 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 08 May 2019. Samples from the same origin, location and time are grouped.

 

Humans

  • Since the last update (03 April 2019), one human case was reported in Alxa League, Inner Mongolia Autonomous Region.
  • For detailed information on human cases, please refer to WHO report.

Figure 4. Number of officially reported human cases since February 2013, as of 08 May 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 08 May 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.

 

For a phylogenetic tree on relationships of A(H7) Eurasian HA genes, including H7N9 isolates, please click here. Acknowledgements: WHO report ‘Antigenic and genetic characteristics of zoonotic influenza viruses and development of candidate vaccine viruses for pandemic preparedness’ – February 2019 [reference].

 

 Publications

  • Chan LLY, Hui KPY, Kuok DIT, Bui CHT, Ng KC, Mok CKP, Yang ZF, Guan W, Poon LLM, Zhong N, Peiris JSM, Nicholls JM, Chan MCW. Risk assessment of the tropism & pathogenesis of the highly pathogenic avian influenza A/H7N9 virus using ex vivo & in vitro cultures of human respiratory tract. J Infect Dis. 2019 Apr 18. pii: jiz165. doi: 10.1093/infdis/jiz165. [reference] In this study the authors compared the tropism, replication competence, and cytokine induction of HPAI-H7N9, LPAI-H7N9 and HPAI-H5N1 in ex vivo human respiratory tract explants and in vitro culture of human alveolar epithelial cells (AECs) and pulmonary microvascular endothelial cells (HMVEC-L). While replication competence of HPAI- and LPAI-H7N9 were comparable in ex vivo cultures of bronchus and lung, the study found that HPAI-H7N9 predominantly infected AECs, while limited infection was observed in bronchus. The reduced tropism of HPAI-H7N9 in bronchial epithelium may explain the lack of human-to-human transmission despite a number of mammalian adaptation markers.
  • Ning Bai, Juan Zhang , Li Li, Zhen Jin. Evaluating the effect of virus mutation on the transmission of avian influenza H7N9 virus in China based on dynamical model. Mathematical Biosciences and Engineering. 2019-04-03. [reference] This paper establishes a non-autonomous dynamical model for H7N9 virus transmission in Guangdong province using factors such as environmental. By fitting the model with the newly confirmed human cases in Guangdong province, the model was confirmed and applied to explain the dynamics of historical human cases. By carrying on parameter estimation, it is deduced that at least 5279376 human beings in Guangdong province had been infected with avian influenza H7N9 virus from March 2013 to September 2017, but most of them were not confirmed, since they had no obvious symptoms or had been cured as common influenza.
  • Lycett SJ, Duchatel F, Digard P. A brief history of bird flu. Philos Trans R Soc Lond B Biol Sci. 2019 Jun 24;374 (1775):20180257. doi: 10.1098/rstb.2018.0257. [reference]  In this paper the authors review the history of avian influenza viruses through the lens of their genetic makeup: from their relationship to human pandemic viruses, starting with the 1918 H1N1 strain, through to the highly pathogenic epidemics in birds and zoonoses up to 2018. The genesis of novel influenza A virus strains by reassortment and evolution in wild and domestic bird populations, as well as the role of wild bird migration in their long-range spread is described.
  • Yan Q, Tang S, Jin Z, Xiao Y. Identifying Risk Factors Of A(H7N9) Outbreak by  Wavelet Analysis and Generalized Estimating Equation. Int J Environ Res Public Health. 2019 Apr 12;16(8). pii: E1311. doi: 10.3390/ijerph16081311. [referenceThis study looked at  potential risk factors associated with disease transmission for A(H7N9) in China between 2013-2017.  Based on long-term observation data, the authors found that males predominated the majority of A(H7N9)-infected individuals and that most males were middle-aged or elderly. Further, wavelet analysis was used to detect the variation in time-frequency between A(H7N9) cases and meteorological factors. The main results revealed that the impact factors of A(H7N9) prevalence are many, and the number of LPMs has a significantly positive effect on reported A(H7N9) cases, while the effect of weekly average temperature is significantly negative. This confirms that the interaction of multiple factors could result in a serious A(H7N9) outbreak. Therefore, public health departments adopting the corresponding management measures based on both the number of LPMs and the forecast of meteorological conditions are crucial for mitigating A(H7N9) prevalence.

  • Shan X, Lai S, Liao H, Li Z, Lan Y, Yang W. The epidemic potential of avian influenza A (H7N9) virus in humans in mainland China: A two-stage risk analysis.  PLoS One. 2019 Apr 19;14(4):e0215857. doi: 10.1371/journal.pone.0215857. eCollection 2019. PubMed PMID: 31002703; [reference] This study provides a unified risk assessment of A (H7N9) to detect the two-stage heterogeneity of epidemic potential among different provinces in mainland China, allowing proactively evaluate health preparedness at subnational levels to improve surveillance, diagnostic capabilities, and health promotion.

 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