Technical Report      [Total: 453 ]

MAPPING INFLUENZA A (H5N1) VIRUS TRANSMISSION PATHWAYS AND CRITICAL CONTROL POINTS IN EGYPT

Abdel Hakam Ali, 2013

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This report summarizes the results of a study undertaken in 2010 and 2011 to as- sess and map Influenza A (H5N1) virus transmission pathways in the poultry sec- tor and critical control points along the poultry value chains in Egypt. In order to focus specifically on the factors that either increase the risk of spread of H5N1 HPAI disease or are critical in disease risk management, a risk pathways diagram is sketched to describe the pathways (transmission routes, carriers and mechanisms) for transmitting virus from an infected node throughout the poultry value chain to disease-free premises. To assess the risk, the probability of virus movement into and from each point along the risk pathway and the impact of disease transmission from an infected node? to the next node along the value chain were assessed separately. Estimates of probability and impact were based on revision of quantitative epidemi- ological data and descriptive information from various sources, such as FAO study reports, General Organization for Veterinary Services (GOVS) reports and scien- tific literature. To fully understand all factors that contribute to the risk of virus transmission and to gather real-time information on control measures, activities, and priorities and information about historical outbreaks of HPAI, meetings were held with different key stakeholders which included GOVS, veterinary director- ates, district veterinary services, Central Laboratory for Evaluation of Veterinary Biologics (CLEVB), National Laboratory for Veterinary Quality Control on Poul- try Production (NLQP), poultry association and private veterinary practitioners, and visits made to sector 2 and 3 commercial farms, ? small-scale household (HH) poultry farms, slaughterhouses, live bird markets (LBMs) and poultry shops, mod- ern and traditional hatcheries, feed mills, veterinary pharmacies, poultry Borsa? and litter collection and composting points in eight high-risk governorates. The catego- ries of risk involved were divided into very high, high, medium, low and very low. Factors and actions involved in increase or decrease of risk were included. Analysis of the results revealed that for commercial farms, risk associated with the movement of people is considered highly significant due to weak farm gate control and decontamination activities. The very high risk (with low uncertainty) category includes vaccinators from outside the farm, day and part-time farm workers, and visiting veterinary practitioners. The high risk category includes drivers of feed delivery, and egg and litter collection vehicles, while the vehicles themselves represent medium risk with high uncertainty. The medium risk category includes medical representatives and drug suppliers. Equipment shared among farms, such as egg cartons, vaccine atomizers and bird crates represent high risk with medium uncertainty in the case of multi-age farms. Shared bird crates and gas cylinders represent medium risk with medium uncertainty for one-age farms. The overall risk related to rodents, insects, dogs is very low , cats medium, but very high for wild birds. Feed and water inputs represent low risk. In the small-scale household production, the risk associated with introduc- ing newly purchased adult waterfowl and Baladi chicken without quarantine, the movement of non-resident commercial farm workers and wild birds with access to the feed and water of poultry flocks is very high. The overall risk associated with purchased young birds and exotic chicken is low and medium, respectively. Litter collection points (litter is processed and used as fertilizer or fish feed in aquacultures) and feed mills represent very low risk nodes along the poultry value chain, and the former can be considered as an end point for the virus. However, both could act as disease pathways to and from different commercial farms because of the high frequency of movement of vehicle and drivers, and the poor application of cleaning and disinfection (C&D) measures by either commercial farms or stake- holders working at litter collection points or feed mills. Slaughterhouses do not facilitate virus replication or shedding because they ap- ply the “live-in, dead-out” policy and could eliminate the virus from the poultry value chain; as a result, they represent very low risk for the poultry value chain. The risk they could impose is contamination of the environment due to lack of drainage treatment system or absence of C&D for vehicles or crates. Most sector 2 and 3 producers buy feed on credit until batch selling, and due to fear of loss they may not notify any cases of infection, to illegally sell infected birds and to hide and improperly dispose of dead birds. Some specialized traders actu- ally profit from the disease by purchasing birds known to be infected at very low prices and reselling them via door-to-door peddlers or to the slaughterhouse, which in turn sells frozen birds to fast food outlets. Unsuspecting buyers, such as village women, and/or some fast food retailers with no or little risk awareness can facilitate this type of cheap trade and thus disease spread. The absence of signs of overt clinical disease in some duck breeds has led some to argue that ducks are the ‘‘Trojan horses’’ of H5N1 in their surreptitious spread of the virus (Kim et al. 2009). In Egypt, many Trojan horses for H5N1 virus are in place: weak application of farm-gate biosecurity measures, unregulated wide use of variable vaccination protocols and programmes by commercial farms, co- circulation with H9N2, lack of awareness of small-scale household producers on the importance of quarantine of newly purchased birds and keeping birds in a confined environment, unregulated live bird trading, and weak movement control together facilitate ‘‘silent spreading’’ of H5N1 HPAI viruses, continuing the circulation and endemicity of the disease. As long as birds are reared under management systems with poor biosecurity, including free movement without inspection or traceability, and an inefficient vaccination strategy, the spread and circulation of H5N1 HPAI will continue. Thus, critical control points for prevention of AI virus transmission along the poultry value chain include the quarantine of newly-purchased birds and keeping birds in a confined environment by small-scale household producers, strict farm-gate biosecurity by commercial producers, strict application of the “live in, slaughtered out” policy by LBMs, restructuring of LBMs in such a way as to permit sound decontamination and directional flow from dirty to clean zones, and efficient movement control by regulatory authorities. Due to the high density of commercial poultry farms and small-scale household production in most governorates, there is a need for a national poultry production standards and guidelines to regulate and support good management. The system should enhance the application of biosecurity measures by the poultry production and trade sector and by the actors involved in the poultry value chain, with clear critical limits that must be met. Programmes based on a range of clear, scientifically justified principles suitable for the Egyptian situation and applicable to any level of poultry production, and auditable measures intended to prevent disease-causing agents from entering and/or leaving premises. The formation or strengthening of grassroots producers’ associations could be instrumental in improving the dialogue with the authorities on the development of incentives for the improvement of biosecurity and in facilitating monitoring, coordination, communication, transparency and agreement among poultry producers, even among competitors in the same region, and make the poultry sector work for all.


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