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  Title : #Avian #Influenza #H7N9 in #China: Preventing the Next #SARS. Subject : Avian Influenza, H7N9 subtype (Asian Lineage), poultry e...

18 Jul 2017

#China, #Influenza Weekly #Report - Week 27 – July 18 2017 (CNIC, edited)


Title: #China, #Influenza Weekly #Report - Week 27 – July 18 2017.

Subject: Human Influenza Viruses, seasonal epidemics in the Chinese region.

Source: China National Influenza Centre, full page: (LINK).

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Chinese Influenza Weekly Report - Week 27 2017 – July 18 2017

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(All data are preliminary and may change as more reports are received)


Summary

  • During week 27, influenza activity increased in southern China, A(H3N2) is becoming the dominant strain gradually, but almost no influenza activity was detected in northern China.
  • Among influenza viruses antigenically characterized by CNIC since September, 2016, 1281(99.8%) influenza A(H1N1)pdm09 viruses were characterized as A/California/7/2009-like;
    • 1259(99.1%) influenza A(H1N1)pdm09 viruses were characterized as A/Michigan/45/2015-like;
    • 356(41.7%) influenza A(H3N2) viruses were characterized as A/Hong Kong/4801/2014 (H3N2)(EGG)-like,
    • 834(97.8%) influenza A(H3N2) viruses were characterized as A/Hong Kong/4801/2014 (H3N2)(CELL)-like;
    • 624(93.8%) influenza B/Victoria viruses were characterized as B/Brisbane/60/2008-like;
    • 190(90.9%) influenza B/Yamagata viruses were characterized as B/Phuket/3073/2013-like.
  • Among the influenza viruses tested by CNIC for antiviral resistance analysis since September, 2016, all influenza A(H1N1)pdm09 and all influenza A(H3N2) viruses were resistant to adamantine;
    • All influenza H3N2 and B viruses were sensitive to neuraminidase inhibitors.
    • All but 4 influenza A(H1N1)pdm09 viruses were sensitive to neuraminidase inhibitors.


Outbreak Surveillance

  • During week 27(Jul 3- Jul 9, 2017), there were six outbreaks reported nationwide, four of them were A(H3N2),one of them was untyped, one of them was A(unsubtyped).


Surveillance of outpatient or emergency visits for Influenza-like Illness (ILI)

  • During week 27, the percentage of outpatient or emergency visits for ILI (ILI %) at national sentinel hospitals in southern China was 4.2%, higher than the last week and the same time of 2014-2016(4.0%,3.5%,3.9%,3.3%).(Figure 1)
  • During week 27, ILI% at national sentinel hospitals in northern China was 2.5%, lower than the last week and the same week of 2014(both 2.6%), same as the same week of 2015(2.5%), higher than the same week of 2016(2.3%). (Figure 2)

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Figure 1. Percentage of Visits for ILI at Sentinel Hospitals in South China (2014-2018)

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Figure 2. Percentage of Visits for ILI at Sentinel Hospitals in North China (2014-2018)

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Virologic Surveillance

  • During week 27, influenza network laboratories tested 4141 specimens, of which 333(8.0%) were positive for influenza, influenza A and influenza B viruses were 298(89.5%) and 35 (10.5%), respectively (Table 1).
  • During week 27, the percentage of specimens that were tested positive for influenza in south China was 10.7 %, which was slightly higher than the previous week (10.3%) (Figure 3).
  • During week 27, the percentage of specimens that were tested positive for influenza in north China was 0.3%, which was lower than the previous week (0.7%). (Figure 4).


Table 1 Laboratory Detections of ILI Specimens (Week 27, 2017)

[Week 27: South China - North China – Total]

  • No. of specimens tested – 3091 – 1050 – 4141
    • No. of positive specimens (%) - 330(10.7%)  - 3(0.3%) - 333(8.0%)
      • Influenza A - 295(89.4%) - 3(100%) - 298(89.5%)
        • A(H3N2) - 225(76.3%) - 2(66.7%) - 227(76.2%)
        • A(H1N1)pdm09 - 69(23.4%) - 1(33.3%) - 70(23.5%)
        • A (subtype not determined) - 1(0.3%) - 0(0) - 1(0.3%)
      • Influenza B - 35(10.6%) - 0(0) - 35(10.5%)
        • B (lineage not determined) - 3(8.6%) - 0(0) - 3(8.6%)
        • Victoria - 22(62.9%) - 0(0) - 22(62.9%)
        • Yamagata - 10(28.6%) - 0(0) - 10(28.6%)

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Figure 3. Influenza Positive Tests Reported by Southern Network Laboratories (Week 14, 2016–Week 27, 2017)

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Note: Analysis in this part was based on the test results of network laboratories. If it were not consistent with the results of CNIC confirmation, the results of CNIC confirmation were used.

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Figure 4. Influenza Positive Tests Reported by Northern Network Laboratories (Week 14, 2016–Week 27, 2017)

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Note: Analysis in this part was based on the result of network laboratories. If it were not consistent with the results of CNIC confirmation, the results of CNIC confirmation were used.


Antigenic Characterization

  • Since September 1st, 2016, 1281(99.8%) of the 1283A(H1N1)pdm09 viruses tested were characterized as A/California/7/2009-like;
    • 1259(99.1%) of the 1270 A(H1N1)pdm09 viruses tested were characterized as A/Michigan/45/2015-like;
    • 356(41.7%) of the 853A(H3N2)influenza viruses tested were characterized as A/Hong Kong/4801/2014 (H3N2)(EGG)-like,
    • 834(97.8%) of the 853A(H3N2) influenza viruses tested were characterized as A/Hong Kong/4801/2014 (H3N2)(CELL)-like;
    • 557(97.0%) of the 574 influenza B/Victoria lineage viruses tested were characterized as B/Brisbane/60/2008-like;
    • 190(90.9%) of the 209 influenza B/Yamagata lineage viruses tested were characterized as B/Phuket/3073/2013-like.


Antiviral Resistance

  • Since September 1st, 2016, among the influenza viruses tested by CNIC for antiviral resistance, all influenza A(H1N1)pdm09 and all influenza A(H3N2) viruses were resistant to adamantine ;
    • All influenza A(H3N2) and B viruses were sensitive to neuraminidase inhibitors.
    • All but 4 influenza A(H1N1)pdm09 viruses were sensitive to neuraminidase inhibitors.


H7N9 case report

  • Since the notification of human infection with novel reassortant influenza A(H7N9) virus on 31 March 2013, in total 1553 laboratory-confirmed cases have been reported to WHO.
  • Among 750 cases reported in fifth wave (Since Oct 2016), 25 cases were infected with HPAI A(H7N9) virus, which have mutations in the hemagglutinin gene indicating a change to high pathogenicity in poultry.
  • These 25 cases are from Taiwan (the case had travel history to Guangdong), Guangxi, Guangdong and Hunan provinces, with illness onset date before April 2017.
  • No increased transmissibility or virulence to human case was detected in the HPAI A(H7N9) virus.

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|-- Download:China flu report 1727.pdf –|

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Keywords: China; Updates; Seasonal Influenza; Avian Influenza; H1N1pmd09; H3N2; Influenza B, H7N9.

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