Addressing the Avian Influenza A(H7N9) Emergency15 July 2013
The United Nations Food and Agriculture Organization (FAO) has reported on the H7N9 situation in China earlier this year. The authors cover emergency risk assessment, risk management along the food chain, guidelines for emergency risk-based surveillance and lab protocols and algorithms.
On 31 March 2013, the Chinese authorities reported the identification of a new strain of avian influenza A(H7N9) virus in three people displaying flu-like symptoms in Shanghai City and Anhui Province. All of these people died. This marked the first time this particular strain had been identified in humans or poultry.
FAO’s Emergency Prevention System (EMPRES) – Animal Health, with the assistance of international experts, developed four guiding documents to help member countries meet the challenges triggered by the H7N9 events:
- Emergency risk assessment summarizes the latest knowledge on the potential introduction and spread of the virus.
- Risk management along the food chain examines short- term management measures and provides a long-term vision to prevent the spread of H7N9 and minimize its socio-economic impact.
- Guidelines for emergency risk-based surveillance details strategies to assist national authorities to rapidly detect an incursion of H7N9 in non-affected countries and areas and to investigate the presence of the virus along the poultry production and market chain.
- Laboratory protocols and algorithms describes select protocols for diagnosis and the revised and updated laboratory algorithms for the detection of H7N9.
Emergency Risk Assessment
FAO has consolidated the findings of the risk assessment into four areas.
- The highest likelihood of avian influenza spreading within affected areas is associated with pathways that involve live bird markets (LBMs), trade in live birds, illegal or illicit movements of live birds and fomites.
- The likelihood of the virus spreading from affected regions to poultry in other geographic areas through migratory wild bird movements is difficult to assess at this stage owing to gaps in knowledge, but is estimated to be moderate.
- The risk of the virus spreading through trade is highly dependent on the regulatory frameworks applied in low- risk countries.
- The likelihood of exposure of humans is considered high in affected areas because it can occur through aerosol or water particles; however, the likelihood of H7N9 spreading to other poultry flocks through meat or eggs for human consumption is very low.
The risk assessment also identifies the major data gaps, including the surveillance results, market chain analysis and economic impacts on poultry producers, markets and meat production.
Risk Management Along the Food Chain
FAO’s risk management guidance details the importance of focused control measures in LBMs and poultry farms, need to preserve wildlife while controlling trade, promotion of public awareness and long-term approach to addressing risk behaviour at the animal-human interface.
Control measures along the poultry value chain
In order to mitigate health risks and halt the spread of avian influenza infection, FAO proposes the consideration of the following control measures along the poultry value chain, including LBMs:
- closure of live bird markets
- strict controls on the sources and movements of poultry
- market rest days and bans on keeping poultry overnight in markets
- species segregation or bans on the sale of certain bird species
- barriers between people and live poultry and slaughter areas
- regular cleaning and disinfection of markets and disposal of by-products
- proper LBM infrastructure, including waste/drainage systems
- poultry transport and cage washing facilities
- hygienic slaughtering, de-feathering and processing
- regular market testing to detect the presence of viruses
- poultry batch processing
- education and awareness on food preparation and hygiene
- market restructuring and rehabilitation, and
- examination of alternatives to LBMs.
Farm level control activities
Control of H7N9 at farm level must take into consideration:
- the production of H7N9 vaccines for poultry
- guidelines for targeted humane culling with adequate compensation
- biosecurity measures, and
- movement and transport controls.
Should the virus become widespread, alternatives to mass culling need to be considered.
Trade in wild birds
Trade in wild birds needs to be strictly controlled, with regular testing of these birds in markets and new consignments. Conversely, even if the H7N9 virus is found in wild birds, no action should be taken to disturb these birds or their natural habitat.
It is essential to publicise known risks and preventive measures in order to:
- reduce unnecessary product avoidance
- impart biosecurity messages to poultry producers, and
- ensure transparent communication between national local authorities and the general public for long-term programming.
Socio-economic incentives and human behaviours
Greater attention needs to be directed towards understanding the social and economic incentives that drive human social behaviours. This information needs to be used to advise policy makers on necessary measures, since human behaviours affect zoonotic disease spill-over.
Guidelines for Emergency Risk-based Surveillance
The principal objective of FAO’s Guidelines for emergency risk-based surveillance is to assist the national authorities of infected countries to facilitate rapid detection of an incursion of H7N9 in domestic birds and other susceptible species in non-affected countries or areas and in controlling the spread of infection along poultry market chains. Specific objectives will vary according to the epidemiological status of infection in an area or country. Similarly, the risk-based surveillance strategy will depend on the infection status and risk of introduction of infection into the area or country concerned.
For countries at risk, FAO recommends:
- enhanced surveillance at high-risk entry points of live birds and poultry products
- risk-based surveillance along the market chain, and
- retrospective surveillance through screening of historical samples from domestic poultry and laboratory testing.
Those LBMs most likely to become contaminated or infected should be selected in order to increase the likelihood of virus detection. It is therefore crucial to understand the poultry market chain in order to target surveillance.
Additional monitoring and surveillance activities include:
- the live bird trade network
- surveillance of migratory bird populations with habitats close to poultry production sites
- surveillance of pigs and other non-avian species, and
- monitoring of production parameters on commercial poultry farms.
Laboratory Protocols and Algorithms
FAO’s guidance on laboratory protocols and algorithms details the validation data for the detection of H7N9 provided by participating laboratories and validated by the World Organisation for Animal Health (OIE)/FAO reference centres and the World Health Organization (WHO) collaborating centres. All the protocols developed are highly sensitive in detecting H7N9 viruses in the field. The OIE/FAO Network of Expertise on Animal Influenza (OFFLU) and FAO recommend that any of these protocols be used. Information on the FLI validated protocols for the detection of H7N9 is publicly available on the OFFLU web site (www.offlu.net).
In order to carry out diagnosis on animal samples for the presence of H7N9, FAO stresses the need for oropharyngeal sampling and the importance of serology. Furthermore, online guidance documents should be consulted for: i) the overview of primers and probes to test for H7 and N9 (for real-time reversetranscriptase polymerase chain reaction [RT-PCR] assays1 and conventional PCR assays2); and ii) validated RT-PCR protocols (for OFFLU protocols3 and WHO protocols [H7 and N9]4).
1. www.offlu.net/fileadmin/home/en/guidance/pdf/OFFLU_real-time_ diagnostics_of_H7N9_Dv07.pdf
2. www.offlu.net/fileadmin/home/en/guidance/pdf/OFFLU_conventional_ diagnostics_of_H7N9_Dv05.pdf
4. www.who.int/influenza/gisrs_laboratory/cnic_realtime_rt_pcr_protocol_a_ h7n9.pdf
The spread of H7N9 is most likely to occur through LBMs with low biosecurity levels. These increase the likelihood of direct contact with animals and allow virus circulation to amplify and be sustained. Lessons learned from the highly pathogenic avian influenza H5N1 should be applied.
The control measures detailed in three of the four documents (particularly in Risk management along the food chain) need to be implemented as prompt, short-term measures to limit human exposure and the spread of the virus in birds. Intervention approaches can be based on: i) joint animal and public health outbreak investigations; and ii) exploration of the direct contacts between infected humans and infected birds and exposure to contaminated environments.
A long-term vision is also necessary to bring together the people implementing the measures and the human populations targeted by such measures. Ensuring that the people who work and live with birds are not negatively affected by control and prevention measures assists in building public trust and ensuring the success of interventions.
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