A study of cattle-to-cattle transmission of Mycobacterium bovis infection.
Twenty steers, positive to the single intradermal comparative tuberculin test (SICTT), were selected from herds with a recent history of Mycobacterium bovis infection. Ten steers, negative to SICTT, were selected from herds with no history of M. bovis infection and served as in-contact animals. The animals were divided into 10 groups, each consisting of two SICTT-positive (reactor) animals and one in-contact animal. Each group was housed in an individual loose-box for a period of 1 year. Five of the groups were fed a restricted diet for part of the experiment. All cattle were slaughtered at the end of the study period and examined at post mortem. Transmission of infection to an in-contact animal occurred in four of the 10 groups. One of the four in-contact animals, which became infected, had a retropharyngeal lymph node tubercle and M. bovis was isolated from lymph nodes without visible lesions from the other three. Two of the infected in-contact animals without visible lesions did not show any detectable cell-mediated immune response. There was no evidence that dietary, restriction had any effect on transmission of disease.
Costello
E
E
Veterinary Research Laboratory, Dublin, Ireland.
Doherty
M L
ML
Monaghan
M L
ML
Quigley
F C
FC
O'Reilly
P F
PF
D000822:Animal Husbandry; D000818:Animals; D002417:Cattle; D004032:Diet; D006799:Housing, Animal; D008198:Lymph Nodes / Q000382:microbiology / Q000473:pathology; D008297:Male; D009163:Mycobacterium bovis / Q000472:pathogenicity*; D009752:Nutritional Status; D014380:Tuberculosis, Bovine / Q000635:transmission*