Moving-average trigger for early detection of rapidly increasing mortality in caged table-egg layers.
Rapidly increasing and unexplained mortality in commercial poultry flocks may signal the presence of a highly transmissible and reportable disease. Activation of an infectious-disease surveillance system occurs when a key production parameter, i.e., mortality, changes. Various triggers have been proposed to alert producers when mortality exceeds normal limits for a given production system to enable early detection of such diseases. In this article we demonstrate that a simple moving-average trigger is useful for detecting any disease syndrome in caged table-egg layer flocks that manifests itself as sudden, rapidly increasing mortality. We superimposed HPAI disease mortality output data derived from a disease transmission model and from a naturally occurring HPAI outbreak onto normal mortality data from 12 healthy commercial egg-layer flocks, and compared the performance of 7-day moving-average triggers to previously proposed triggers. The moving-average trigger is more efficient, resulting in fewer false-positive alerts and an earlier time to disease detection. It can be easily calculated by using a computer spreadsheet providing only 7 days of mortality data and can be practically and inexpensively implemented by large commercial poultry integrators. A moving-average trigger can be an active component of a production-based surveillance system.
Center for Animal Health and Food Safety, University of Minnesota, 1354 Eckles Avenue, St. Paul, MN 55108, USA. malla042@umn.edu
Sasidhar
S
Malladi
J Todd
JT
Weaver
Timothy L
TL
Clouse
Kathe E
KE
Bjork
Darrell W
DW
Trampel
D000818:Animals; D002645:Chickens; D004196:Disease Outbreaks / Q000662:veterinary; D005260:Female; D006799:Housing, Animal; D005585:Influenza in Birds / Q000401:mortality*; D008954:Models, Biological; D010058:Oviposition; D011159:Population Surveillance; D013997:Time Factors