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ARCHIVE H7N9 situation update

4 January 2017, 17:00 hours; Rome

The next update will be issued on 1 February 2017

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

Situation: Influenza A(H7N9) virus with pandemic potential.
Country: China; three human cases originated in China and were reported in Malaysia (1) and Canada (2).
Number of human cases: 825 confirmed; 321 deaths (since February 2013)
Provinces/municipalities: Beijing, Shanghai and Tianjin municipalities; Anhui; Fujian; Guangdong; Hubei and Liaoning provinces; Henan; Hunan; Jiangsu; Jiangxi; Shandong; Zhejiang; Guangxi; Guizhou; Jilin; Qinghai; Hubei; Taiwan Province of China; Hong Kong SAR; Macao SAR, Ningxia Hui and Xinjiang Uyghur Autonomous Regions; Sabah (Malaysia); British Columbia (Canada).
Animal/environmental findings: over 2,000 virological samples from the environment, chickens, pigeons, ducks and a tree sparrow tested positive; positives mainly from live bird markets, vendors and some commercial or breeding farms.
FAO actions: liaise with China and partners, monitor situation, monitor virus evolution, conduct market chain analysis, risk assessment, surveillance guidance and communication.

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. Precise location of 58 human cases in Fujian (28), Jiangsu (13), Zhejiang (13), Guangdong (1), Hunan (1), Hubei (1), Hebei (1) and Xinjiang (1) are currently not known. These cases are therefore not shown on the map. Imported cases in Canada (2) and Malaysia (1) are also not represented.

 

 

 Situation update

Animals

  • 28 December 2016, Zhejiang Province: environmental samples collected in a farmers market in Wenzhou City tested positive for H7N9 virus [reference].
  • 24 December 2016, Jiangsu Province: all types of live poultry trade is suspended in the urban areas of Suzhou from 26 December 2016. From 4 January 2017, the city-wide suspension of live poultry trading will also be implemented in Changshu City [reference].
  • 21 December 2016, Fujian Province: From 22 December 2016 all types of live poultry trade will be suspended in Siming District, Xiamen City [reference].
  • 16 December 2016: MoA published the results of the national animal H7N9 surveillance for the month of November. 117,238 serum and 24,936 virological samples were collected from 3,988 locations in 21 provinces. 24 serum samples from Liaoning (Chickens in 5 farms/ households in 2 cities) tested positive for H7 antibodies and no virological samples tested positive for H7N9 [reference].

Figure 1. Number of positive virological samples from birds or the environment, by province and origin as of 4 January 2017

Number of positive virological samples from birds or the environment, by province* and origin
Click to enlarge


Humans

  • Since the last update (30 November 2016), 20 new human cases have been reported in Jiangsu (5), Anhui (5), Fujian (2), Guangdong (2), Hunan (1), Jiangxi (1), Guizhou (1), Macao SAR (1), Hong Kong (1) and Shanghai (1).
  • For detailed information on human cases, please refer to WHO's Disease Outbreak News.

Figure 2. Number of officially reported human cases since February 2013 as of 4 January 2017

Number of officially reported human cases since February 2013
Click to enlarge

Figure 3. Incidence of officially reported human cases by month, based on onset date as of 4 January 2017

Incidence of officially reported human cases by week, based on onset date
Click to enlarge - Note: For cases with unknown onset dates from wave 1 (n=7), wave 2 (n=2), wave 3 (n=146), wave 4 (n= 27) and wave 5 (n=17) reporting dates were used instead.


Publications

  • In addition to the surveillance findings by MoA and MoH, 1,728 virologically positive samples have also been reported in 12 peer-reviewed articles (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12). A total of 71,920 samples have been collected in these studies since April 2013, of which 1,728 (2.4%) were positive for H7N9 (1,215 environmental samples, 501 chickens, 1 goose and 1 tree sparrow).
  • Characteristics of the three first waves of H7N9 circulation were compared and few differences were found between the epidemiologic and clinical characteristics: the median age of cases was statistically significantly older in the first wave (61 years vs. 56 years for waves 2 and 3, p<0.05) compared to the following two waves. Most reported cases were among men in all three waves. There was no statistically significant difference between case fatality proportions (33, 42 and 45%, respectively, p=0.08), time from illness onset to first seeking healthcare, lab confirmation or death between the three waves. A similar percentage of cases in all waves reported exposure to poultry or live poultry markets (87%, 88%, 90%, respectively). Twenty-one clusters were reported during these three waves (4, 11 and 6 clusters, respectively), of which, 14 (67% of clusters) were considered to be possible human-to-human transmission [reference].
  • Epidemiology and virology data from the most recent, fourth wave (September 2015-August 2016) were compared with those from the three earlier epidemics. Whereas age and sex distribution and exposure history in the fourth epidemic were similar to those in the first three epidemics, the fourth epidemic demonstrated a greater proportion of infected persons living in rural areas, a continued spread of the virus to new areas, and a longer epidemic period. The genetic markers of mammalian adaptation and antiviral resistance remained similar across each epidemic, and viruses from the fourth epidemic remained antigenically well matched to current candidate vaccine viruses [reference].
  • A total of 5,360 residual sera from patients of all ages admitted to a hospital in the city of Guangzhou in southern China in 2013 and 2014 were collected and screened for H7N9 antibodies. Two specimens tested positive. Based on this, authors estimated that 64,000 (95 % credibility interval: 7300 - 190,000) human infections with influenza A(H7N9) virus occurred in Guangzhou in early 2014, with an infection-fatality risk of 3.6 deaths (95 % credibility interval: 0.47, 15) per 10,000 infections. This study suggests that the number of influenza A(H7N9) virus infections in Guangzhou substantially exceeded the number of laboratory-confirmed cases there, albeit with considerable imprecision. These results also suggest that the lethality rate of the disease is likely to be overestimated. The study was limited by the small number of positive specimens identified, and larger serologic studies would be valuable [reference].

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