Pooled-sample testing as a herd-screening tool for detection of bovine viral diarrhea virus persistently infected cattle.
The study was conducted to develop methodology for least-cost strategies for using polymerase chain reaction (PCR)/probe testing of pooled blood samples to identify animals in a herd persistently infected with bovine viral diarrhea virus (BVDV). Cost was estimated for 5 protocols using Monte Carlo simulations for herd prevalences of BVDV persistent infection (BVDV-PI) ranging from 0.5% to 3%, assuming a cost for a PCR/probe test of $20. The protocol associated with the least cost per cow involved an initial testing of pools followed by repooling and testing of positive pools. For a herd prevalence of 1%, the least cost per cow was $2.64 (95% prediction interval = $1.72, $3.68), where pool sizes for the initial and repooled testing were 20 and 5 blood samples per pool, respectively. Optimization of the least cost for pooled-sample testing depended on how well a presumed prevalence of BVDV-PI approximated the true prevalence of BVDV infection in the herd. As prevalence increased beyond 3%, the least cost increased, thereby diminishing the competitive benefit of pooled testing. The protocols presented for sample pooling have general application to screening or surveillance using a sensitive diagnostic test to detect very low prevalence diseases or pathogens in flocks or herds.
Muñoz-Zanzi
C A
CA
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis 95616, USA.
Johnson
W O
WO
Thurmond
M C
MC
Hietala
S K
SK
D000818:Animals; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D002417:Cattle; D003198:Computer Simulation; D017931:DNA Primers / Q000737:chemistry; D004279:DNA, Viral / Q000097:blood*; D001908:Diarrhea Viruses, Bovine Viral / Q000235:genetics / Q000302:isolation & purification*; D004197:Disease Reservoirs / Q000662:veterinary*; D009010:Monte Carlo Method; D016133:Polymerase Chain Reaction / Q000191:economics / Q000379:methods / Q000662:veterinary*; D015995:Prevalence
D017931:DNA Primers; D004279:DNA, Viral