Control and surveillance of H7N9 Avian Influenza in China Jiming Chen, PhD China Animal Health & Epidemiology Center Dec. 18-21, 2013, Tokyo
Haunted around the gate of China for years Japan:each year in 2008 2012, with H7N1, H7N6, H7N7 subtypes South Korea:each year in 2008 2011, with H7N3, H7N7, H7N8, H7N9 subtypes Thailand:each year in 2009 2011, with H7N1, H7N4, H7N6 subtypes Mongolia:each year in 2008 2012, with H7N7, H7N9 subtypes Vietnam:H7N1 in 2012
H7 AIVs appeared very infrequently in China
Attack suddenly and very seriously
Timeline of H7N9 events NEJM
143 cases, 46 deaths
Human infection source: birds in LBMs
A few human-human transmission( Jiangsu ) BMJ. 2013 Aug 6;347:f4752. doi: 10.1136/bmj.f4752. Probable person to person transmission of novel avian influenza A (H7N9) virus in Eastern China, 2013: epidemiological investigation. The infection of the daughter probably resulted from contact with her father (the index patient) during unprotected exposure, suggesting that in this cluster the virus was able to transmit from person to person. The transmissibility was limited and non-sustainable.
Most cases were old people Males: covering 71% cases and 70% deaths
Not due to exposure difference PLoS Curr. 2013 May 15;5 Estimating Human Cases of Avian Influenza A(H7N9) from Poultry Exposure.
H7N9 mainly attacks weak people The elderly are weaker than the young The male elderly are weaker than the female elderly with 5 years shorter in life span
Different from H1N1-2009 and H5N1cases infection with seasonal H1N1 viruses induced crossimmunity against the novel H1N1 and H5N1 viruses
The origin of H7N9 virus Eurosurveillance
Ian M. Mackay--VDU
Multiple mutations occurred as compared with their other viruses Eurosurveillance
Continue to mutate rapidly in birds and humans NEJM
Biological features of H7N9 virus H7N9 viruses from humans: Replicate in the upper and lower respiratory tract, heart, liver of mammals Transmit among ferrets via respiratory droplets at a low level Highly pathogenic to mice Pigs could secrete the virus for 6 days at a low level after infection H7N9 viruses from birds: not pathogenic to birds, ducks and mice
Receptor-binding of H7N9 viruses Bind to avian-like receptors (strongly) Also bind to human-like receptors (weakly)
A few bind only human-like receptors
Emergent response in China
1. Confirmation of poultry infection March 31: MoA received the notification of NHFPC March 31: MoA immediately organized Emergency epidemiological investigation and sampling works in animal population April 4: National AI Reference Lab confirmed H7N9 AI infection in poultries of a wholesale market in Shanghai. April 4: MoA released a public notification to uplift the response to H7N9 avian influenza as category Ⅰ Animal Diseases to prevent and control, which is at the highest level.
2. Resolutely culling of infected flocks Animal H7N9 Emergency Response Guideline. Movement control for suspicious flocks; Culling infected groups Clean, disinfect and close the market Totally, more than 571 000 birds have been culled
3. Investigation suggested that LBMs play a significant role in human infection
4. Strengthen the management of LBMs All LBMs should fulfill animal health requirements Whole-sale market is not allowed to be located in city proper Retailer should clean and disinfect their workplace everyday Each live bird sold to consumers must be slaughtered at LBMs Each wholesale and retail market should be closed for 3-4 days per month LBMs should be closed if needed, to minimize the risk for human or animal infection
5. Close LBMs temporarily Epidemiological curve of human cases in Shanghai and Zhejiang
7. Investigation suggested live bird transportation is important in H7N9 spread
8. Strict management of transportation and movement of live birds For provinces with human or avian infections, the intraand inter-province movement of commercial live birds were temporally prohibited Young fowls, only detected as H7N9 negative, were allowed to be transported through certain roads
9. Emergent surveillance in April and May
Sample type Sample number Positive number Positive rate Serological 839807 35 0.004% Virological 290079 53 0.018%
Species Distribution of positives in host Virological positive numbers Serological positive numbers Chicken 33 25 Duck 4 0 Goose 0 0 Pigeon 3 0 Wild birds 1 0 Pig 0 0 Environment 12 -
Distribution of positives in sites Site Virological Positive No. Serological Positive No. LBM 52 25 Wild bird (pigeon) 1 - Farm 0 10 Total 53 35
Distribution of positives in regions
Surveillance the period from July- October Month Swab sample detected Positives July 47070 0 August 9955 0 September 48513 15 October 5873 0
Distribution of the 15 positives All from chickens 10 from Langfang in Hebei province 4 from Dongguan in Guangdong province 1 from Zengcheng in Guangdong province
Conclusion of surveillance H7N9 virus has been detected only from chickens, ducks and pigeons No infected pigs or other animals have been found to be H7N9 positives Almost all of the identified H7N9 positives were from markets No birds from poultry farms have been found to be H7N9 positives H7N9 is of a very low prevalence in poultry in China
Three possibilities in the future
Three possibilities in the future If God bless us: disappear naturally If not: circulates permanently in birds for years and infect humans from time to time Spark catastrophe: evolve into HPAI viruses in poultry ; or a spark human pandemic
Why avian influenza frequently makes trouble in China?
Multiple reasons 1. China has, while many countries have not, built up the capacity in early detection and early warning for the control of EIDs 2. China is much bigger than a common country
3. Changes of the society and ecology of China China has been developing rapidly for >30 years People become richer and consume more poultry products Continuous increase of poultry production Domestic fowls 4.5 folds as against 1980
Huge poultry production with high density 7% fresh water, 8% arable land, 12% grasslands of the world Raising 30% chickens and 80% waterfowls in the world Poultry density: >3 folds as high as the average value of the world
>90% domestic fowls raised in the eastern China
4. >90% poultry farms are small with limited biosecurity
5. Prevalent transportation and marketing of live birds: esp. in Southern China
6. Wild birds bloom greatly due to ecological improvement and wild animal protection
The answer of the question AIVs can transmit easily in China Huge poultry production High poultry density Limited Biosecurity Live bird transportation and marketing Wild birds blooming Rapid viral evolution
Three classical measures are not enough for AI Surveillance can only find a small portion of the infected animals in an endemic status, though helpful for situation and risk assessment Culling can delete only a small portion of the infected animals in an endemic status Mass vaccination is of little value for elimination of all the infectious diseases caused by rapidevolving viruses, though sometimes it is of value to control them
Ecosystem health are paramount for One Health Why developed countries are of little burden of many kinds of infectious diseases, like rabies and avian influenza? Answer: More healthy ecosystem
The future of avian influenza control in China In the near future: very tough Ten years later: optimistic due to rapid transition of the ecosystem
1. Many small poultry farms have been declining annually by 8% since 2008
2. Large poultry farms have been increasing annually by 24.17% % since 2003 >50,000 birds/layer farms >100,000 birds/broilers
3. LBMs have been updated in hygiene, shrunk or closed
4. More poultry products are sold in supermarket
5. My advice: replace traditional LBMs with electronic LBMs ASAP Electronic LBMs using internet
Electronic LBMs Consumers can see the live birds they buy through internet/video Consumers can get the live birds they buy within hours (slaughtered) Minimize human/birds direct contact Of less cost than traditional LBMs Electronic marketing increases in China annually by 108% for > 6 years.
Acknowledgement Veterinary Bureau, MoA Local veterinary systems Multiple colleagues in CAHEC OIE-RRAP