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Title: Risk reduction modeling of high pathogenicity avian influenza virus titers in non-pasteurized liquid egg obtained from infected but undetected chicken flocks

item WEAVER, J. TODD - Animal And Plant Health Inspection Service (APHIS)
item MALLADI, SASSIDHAR - University Of Minnesota
item Spackman, Erica
item Swayne, David

Submitted to: Risk Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2015
Publication Date: 4/13/2015
Publication URL:
Citation: Weaver, J., Malladi, S., Spackman, E., Swayne, D.E. 2015. Risk reduction modeling of high pathogenicity avian influenza virus titers in non-pasteurized liquid egg obtained from infected but undetected chicken flocks. Risk Analysis. doi: 10.1111/risa.12374.

Interpretive Summary: The spread of important diseases like avian influenza can be modeled to determine the risks associated with certain activities. In this report, the risks associated with the movement of liquid egg products during an outbreak of avian influenza are modeled. Data from diagnostic tests, egg pasteurization and current surveillance programs are incorporated into the model to provide meaningful information that will inform response plans which aim to maintain business continuity in the even of a disease outbreak.

Technical Abstract: Control of highly pathogenic avian influenza (HPAI) has traditionally involved the establishment of disease containment zones, where poultry products are only permitted to move from within a containment area under permit. Non-pasteurized liquid egg (NPLE) is one such commodity for which movements may be permitted, considering inactivation of HPAI virus via pasteurization. Active surveillance testing at the flock level, using targeted matrix gene real-time reversed transcriptase-polymerase chain reaction testing (RRT-PCR) has been incorporated into HPAI emergency response plans as the primary on-farm diagnostic test procedure to support continuity of business in the United States table-egg industry. To inform decisions regarding the movement to pasteurization of NPLE produced from eggs originating from commercial table-egg production flocks located within a HPAI containment zone, average HPAI virus concentrations in NPLE produced from a HPAI virus infected, but undetected commercial table-egg layer flock were estimated for 3 HPAI virus strains using quantitative simulation models. Daily RRT-PCR active surveillance testing of table-egg layer flocks, substantially reduced estimated HPAI viral titers in NPLE to within inactivation levels in newly proposed international pasteurization design standards (5 log10 reduction) compared with estimated virus titers in NPLE from the first few flocks identified in the outbreak before implementation of official control measures. Dilution of HPAI virus from contaminated eggs in eggs from the same flock, and in a 40,000 lb. tanker-truck load of NPLE containing eggs from disease free flocks was considered. HPAI disease control measures evaluated in this quantitative study could be included in veterinary health certificates and product movement permits, and should be recognized by international trading partners during the product certification process required for commodity-based trade in egg-industry products.