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Avian Influenza H7N9 epidemiological situation analysis and lines of defense
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Avian Influenza H7N9Situation Analysis and Prevention
Dr. Tong Ka Io
2013.04.18
Spatial distribution Shanghai municipality
Zhejiang province: Hangzhou, Huzhou, Jiaxing
Anhui province: Xuzhou, Haozhou
Jiangsu province: Nanjing, Suqian, Suzhou, Wuxi, Rugao, Zhenjiang, Yaozhou, Changshou, Jiangying, Yancheng, Kunshan
Henan province: Kaifeng, Zhoukou, Zhengzhou
Beijing municipality
Spatial distribution
Spatial distribution
Shanghai02.19~ 32 cases 11 deaths
Zhejiang03.07~ 27 cases 2 deaths
Anhui03.09~ 3 cases 1 death
Jiangsu03.19~ 21 cases 3 deaths
Henan04.06~ 3 cases 0 death
Beijing04.11~ 1 case 0 death
Interpersonal distributionOf the first 87 cases
ŸAge range = 2~87y, median = 63y, elder people more common, only 3 child cases with milder clinical presentations
M:F = 2.4:1
Occupational exposure to birds in at least 19 cases, retired people account for 44 cases, none HCW
It was said that most fatal cases were male smokers
Suspect clusters1) Shanghai Li’s family
55y son became ill on 11th Feb, with severe pneumonia, died on 28th Feb, no sample collected for H7N9 testing
87y father became ill on 19th Feb, with severe pneumonia, died on 4th Mar, H7N9 PCR positive
69y son became ill on 19th Feb, with milder clinical course, H7N9 PCR negative, retrospective serological test positive
Suspect clusters2) Jiangsu Zhang’s family
32y daughter became ill on 21st Mar, H7N9 PCR positive
Her father had been ill before, H7N9 tests negative
Suspect clusters3) Shanghai Gu’s
family
52y wife became ill on 27th Mar, died on 3rd Apr, H7N9 PCR positive
56y husband became ill on 1st Apr, H7N9 PCR positive
Hypothetical mixing of avian flu viruses from east Asia migratory birds and east China ducks and chickens.
Animal and environment testing Since 20th Mar, animal facilities around human
cases in Anhui, Jiangsu and Shanghai had been checked, with no animal illness found.
Until 3rd Apr, agricultural departments of Shanghai, Jiangsu, Zhejiang, and Anhui did not have specific testing agents for H7N9.
Animal and environment testing As of 16th Apr, provincial and national AI
reference laboratories had collected a total of 84444 samples, covering 473 live poultry markets, 32 slaughterhouses, 896 farms, 79 wild bird habitats, 36 pig slaughterhouses, and 137 environmental sampling spots. Tests for 47801 samples had been concluded, yielding only 39 positive results (0.05%), of which 38 were poultry and environment samples from live markets of Shanghai, Anhui, Zhejiang and Jiangsu, 1 was from wild pigeon from Nanjing, Jiangsu.
Positive testsDate Sampling sites Positive rate Positive samples
04.04 Shanghai Huhuai Market ?/? Shanghai Huhuai Market Pigeon
04.05 Shanghai live markets 19/738(2.6%)
Huhuai Market Chicken, environment
Jingchuan Market Chicken, environment
Fengzhuang Market Chicken, pigeon, environment
04.06 Zhejiang Hangzhou Bangsheng Market 5/12(41.7%) Zhejiang Hangzhou Bangsheng
Market Environment
04.10Farms and live markets in Jiangsu, Zhejiang and Anhui province
14/2099(0.7%)
Zhejiang Huzhou Zhebei Market Duck
Anhui Hefei Huishangcheng Market Duck
3 markets in Jiangsu Chicken
04.16 Suspect samples from Jiangsu and Zhejiang 5/12/?
Jiangsu Nanjing Wild pigeon
Zhejiang Huzhou Zhebei Market Chicken
Zhejiang Huzhou Daoxiang Market Chicken
Negative testsDate Location Sample quantity Tests
04.02 Shanghai natural preservation district and zoos
Migratory and wild birds 229 H7 gene
~04.09 Shanghai farms Animals 366 AI common PCR
04.01~04.11 Farms, parks, wild bird habitats and supermarkets in 16 districts of Beijing
Chickens, pigs, ducks, gooses, pigeons, crows, wild birds, animal products
5609 ?
04.14 Gucheng villange in Beijing Poultry 61+95
Virology+Serology
End of Mar ~04.17
35 pig farms and 11 pig slaughterhouses in Shanghai, Anhui, Zhejiang, and Jiangsu
Pigs 2050+2000
Virology+Serology
Source of H7N9 virus may be the migratory birds in Changjiang river mouth
Ducks along the bank of Changjiang rivermay be all infected
H7N9 continuously evolves, hard to predict riskThe virus is still searching for a more compatible combination
Risk assessment1. The reassortment of avian influenza viruses had
occurred, probably in East China
2. The reassorted virus massively go across the animal-human boundary to infect human
3. The virus is low pathogenic for birds and highly pathogenic for human
4. Up to the moment, there is no evidence that the virus further go across the boundary to sustained human-to-human transmission, though limited human-to-human transmission can not be excluded
Avian influenza dynamics
Phase 1Bird-to-bird transmission
Phase 2Bird-to-human transmission &
limited human-to-human transmission
Phase 3Widespread
human-to-human transmission
Avian disease surveillance, prevention and control
Minimizing human exposure Detection and isolation ofhuman cases
Ensuring care for patients Slowing down spread
H1~H16
H7N9
Risk assessment5. It is probably that the virus spreads beyond East
China to Central and North China by migratory birds, which infect local Poultry and the latter infect human
6. Comparing with H5N1, H7N9 infection in poultry seems more widespread and persistent, constituting a greater threat for human
7. At this moment, it is impossible to precisely predict if the virus will come to Macao, or how (birds or human?), but preparedness is necessary
Animal-animal line of defense Separate poultry with migratory birds and wild
birds
Separate water fowls and land fowls
Separate poultry from different regions
Separate infected poultry with other poultry
Significant measures taken in Macao
All local poultry farms eliminated
Raising poultry prohibited
Importation of live water fowls prohibited
Management in the source, surveillance, separation, and double quarantine for poultry provided from inland to Macao
Culling of all live poultry before the live markets close everyday
Animal-human line of defense Biosafety measures for poultry industry. In case of
animal epidemic, handling infected poultry under strict protection
General people avoiding contact with live poultry or presenting in places with live poultry, washing hands after contact with raw poultry meat or egg, eating poultry meat or eggs thoroughly cooked
According to situational, government adopting appropriate risk management measures in sites for poultry wholesale, sale, or watching
Human-human line of defense Raising people’s alert for prompt seeking medical advice if
severe acute respiratory illness develops
Raising HCW alert, strengthening surveillance system, building laboratory capacity, testing acute respiratory patients with travel, poultry or patient contact history, and patients with pneumonia of unknown cause, for early detection of cases
Strengthening infection control in medical facilities. Early isolation and treatment of detected cases
Tracing and health management of close contacts of cases