Responses to diagnostic tests for bovine tuberculosis in dairy and non-dairy cattle naturally exposed to Mycobacterium bovis in Great Britain.
Field surveillance of British cattle using the single intradermal comparative cervical tuberculin (SICCT) test shows a higher incidence rate of bovine tuberculosis (bTB) in dairy compared to beef herds, but a lower probability of post-mortem examination confirmed (PMC) Mycobacterium bovis infection in dairy herds. A cross-sectional study was conducted to compare animal level differences in bTB detection between dairy and non-dairy cattle in Great Britain. During the period from 2002 to 2005, 200 (41% dairy) reactors in the SICCT test (standard interpretation) were randomly selected, and 200 in-contact cattle (43% dairy) were purposively selected from bTB-infected herds. Interferon (IFN)-γ responses in blood to bovine and avian purified protein derivative (PPD), and early secretory antigen target 6 kDa and culture filtrate protein 10 (ESAT-6/CFP10), were measured. The post-mortem examination included gross pathological examination, mycobacterial culture and histopathology. The proportions of cattle positive to ESAT6/CFP10 were 26% (95% confidence interval, CI, 15-39%) in dairy reactors and 62% (95% CI 51-72%) in non-dairy reactors (P <0.001). PMC risk was 34% (95% CI 24-45%) in dairy reactors and 69% (95% CI 60-78%) in non-dairy reactors (P <0.001). The odds ratio for PMC risk in dairy reactors compared to non-dairy reactors, after controlling for bTB prevalence, herd size and SICCT test response, was 0.27 (95% CI 0.14-0.53; P <0.001). In surveillance data, adjusted animal level PMC risks were lower for dairy reactors than for beef reactors aged >2 years (P <0.001).
Animal and Plant Health Agency, Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK.
S H
SH
Downs
Animal and Plant Health Agency, Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK.
J M
JM
Broughan
Animal and Plant Health Agency, Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK.
A V
AV
Goodchild
Animal and Plant Health Agency, Weybridge, Woodham Lane, New Haw, Addlestone, Surrey KT15 3NB, UK. Electronic address: paul.upton@apha.gsi.gov.uk.
P A
PA
Upton
CSIRO Australian Animal Laboratories, Geelong, Victoria 3220, Australia.
P A
PA
Durr
D000818:Animals; D001344:Autopsy; D002417:Cattle; D003430:Cross-Sectional Studies; D003612:Dairying; D003955:Diagnostic Tests, Routine / Q000662:veterinary; D005260:Female; D015994:Incidence; D007428:Intradermal Tests / Q000662:veterinary*; D008297:Male; D009163:Mycobacterium bovis / Q000276:immunology / Q000302:isolation & purification*; D012307:Risk Factors; D014374:Tuberculin Test / Q000662:veterinary*; D014380:Tuberculosis, Bovine / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D006113:United Kingdom / Q000453:epidemiology
Bovine tuberculosis; Dairy cattle; Diagnosis; Single intradermal comparative cervical tuberculin test