Cost-effectiveness of diagnostic strategies to identify Mycobacterium avium subspecies paratuberculosis super-shedder cows in a large dairy herd using antibody enzyme-linked immunosorbent assays, quantitative real-time polymerase chain reaction, and bacterial culture.
Diagnostic strategies to detect Mycobacterium avium subsp. paratuberculosis (MAP) super-shedder cows in dairy herds have been minimally studied. The objective of the current study was to compare the cost-effectiveness of strategies for identification of MAP super-shedders on a California dairy herd of 3,577 cows housed in free-stall pens. Eleven strategies that included serum or milk enzyme-linked immunosorbent assay (ELISA), quantitative real-time polymerase chain reaction (qPCR) or culture of environmental samples, pooled or individual cow fecal samples, or combinations thereof were compared. Nineteen super-shedders (0.5%) were identified by qPCR and confirmed by culture as cows shedding ≥ 10,000 colony forming units (CFU)/g feces (median of 30,000 CFU/g feces). A stratified random sample of the study herd based on qPCR results of fecal pools was the most sensitive (74%) strategy and had the highest cost ($5,398/super-shedder). The reference strategy with the lowest cost ($1,230/super-shedder) and sensitivity (47%) included qPCR testing of fecal samples from ELISA-positive lactating (milk) and nonlactating (serum) cows housed in pens with the highest MAP bioburden. The most cost-effective alternative to the reference was to perform qPCR testing of fecal samples from ELISA-positive cows (milk and serum for milking and dry cows, respectively) for a sensitivity of 68% and cost of $2,226/super-shedder. In conclusion, diagnostic strategies varied in their cost-effectiveness depending on the tests, specimen type, and labor costs. Initial qPCR testing of environmental samples from free-stall pens to target cows in pens with the highest MAP bioburden for further testing can improve the cost-effectiveness of strategies for super-shedder identification.
Veterinary Medicine Teaching and Research Center, University of California, Davis, 18830 Road 112, Tulare, CA 93724, USA. saly@ucdavis.edu
Sharif S
SS
Aly
Randall J
RJ
Anderson
Robert H
RH
Whitlock
Terry L
TL
Fyock
Susan C
SC
McAdams
Todd M
TM
Byrem
Jiming
J
Jiang
John M
JM
Adaska
Ian A
IA
Gardner
D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D057138:Bacterial Shedding / Q000502:physiology; D001431:Bacteriological Techniques / Q000191:economics / Q000379:methods / Q000662:veterinary*; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis* / Q000191:economics; D003362:Cost-Benefit Analysis; D004797:Enzyme-Linked Immunosorbent Assay / Q000191:economics / Q000379:methods / Q000662:veterinary*; D005243:Feces / Q000382:microbiology; D005260:Female; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification*; D010283:Paratuberculosis / Q000175:diagnosis* / Q000191:economics; D060888:Real-Time Polymerase Chain Reaction / Q000191:economics / Q000379:methods / Q000662:veterinary*
D000907:Antibodies, Bacterial