title: Impact of virus strain characteristics on early detection of highly pathogenic avian influenza infection in commercial table-egg layer flocks and implications for outbreak control.
abstract: Early detection of highly pathogenic avian influenza (HPAI) infection in commercial poultry flocks is a critical component of outbreak control. Reducing the time to detect HPAI infection can reduce the risk of disease transmission to other flocks. The timeliness of different types of detection triggers could be dependent on clinical signs that are first observed in a flock, signs that might vary due to HPAI virus strain characteristics. We developed a stochastic disease transmission model to evaluate how transmission characteristics of various HPAI strains might effect the relative importance of increased mortality, drop in egg production, or daily real-time reverse transcriptase (RRT)-PCR testing, toward detecting HPAI infection in a commercial table-egg layer flock. On average, daily RRT-PCR testing resulted in the shortest time to detection (from 3.5 to 6.1 days) depending on the HPAI virus strain and was less variable over a range of transmission parameters compared with other triggers evaluated. Our results indicate that a trigger to detect a drop in egg production would be useful for HPAI virus strains with long infectious periods (6-8 days) and including an egg-drop detection trigger in emergency response plans would lead to earlier and consistent reporting in some cases. We discuss implications for outbreak control and risk of HPAI spread attributed to different HPAI strain characteristics where an increase in mortality or a drop in egg production or both would be among the first clinical signs observed in an infected flock.
authors: USDA Animal and Plant Health Inspection Service, Veterinary Services, Centers for Epidemiology and Animal Health, Center for Animal Health Information and Analysis, Natural Resource Research Center, Building B MS-2W4, 2150 Centre Avenue, Fort Collins, CO 80526, USA. todd.weaver@aphis.usda.gov
authors: J Todd
authors: JT
authors: Weaver
authors: Sasidhar
authors: S
authors: Malladi
authors: Timothy J
authors: TJ
authors: Goldsmith
authors: Will
authors: W
authors: Hueston
authors: Morgan
authors: M
authors: Hennessey
authors: Brendan
authors: B
authors: Lee
authors: Shauna
authors: S
authors: Voss
authors: Janel
authors: J
authors: Funk
authors: Christina
authors: C
authors: Der
authors: Kathe E
authors: KE
authors: Bjork
authors: Timothy L
authors: TL
authors: Clouse
authors: David A
authors: DA
authors: Halvorson
mesh_terms: D000818:Animals; D002645:Chickens; D004196:Disease Outbreaks / Q000517:prevention & control / Q000662:veterinary*; D004531:Eggs; D005260:Female; D009980:Influenza A virus / Q000145:classification*; D005585:Influenza in Birds / Q000175:diagnosis / Q000821:virology*; D008954:Models, Biological; D015233:Models, Statistical; D010058:Oviposition; D013269:Stochastic Processes