An abbatoir survey of the prevalence of caseous lymphadenitis in feral goats in Western Australia

Experimental Corynebacterium pseudotuberculosis infection in lambs: kinetics of bacterial dissemination and inflammation

Infection and pyogranulomas induced by Corynebacterium pseudotuberculosis were experimentally reproduced in lambs. In two separate experiments, bacterial multiplication and dissemination were studied in 30 male lambs inoculated subcutaneously into the right ear with 1.1 or 1.5 X 10(8) viable C. pseudotuberculosis strain 19R. Infected lambs were necropsied at various times until the 28th day following inoculation. After a transient hyperthermia and a strong local inflammatory reaction, an abscess developed in the right ear from postinoculation day (PID) 6; it enlarged until PID 14 and stabilized thereafter and was associated with adenopathy of lymph nodes draining the head. Three acute phase indicators of inflammation were followed in 14 out of 30 lambs; plasma levels of copper and haptoglobin increased rapidly following inoculation whereas zinc levels decreased. The peaks were reached from PID 1 to 5, and thereafter the values came back slowly to the baseline. Antibodies against C. pseudotuberculosis exotoxin increased from PID 5 and reached a plateau on PID 21. Bacterial dissemination, assessed by the number of infected organs per lamb, was maximal on PID 16 and then stabilized until the end of the experiment. Lungs were infected in seven out of 18 lambs necropsied on PID 28. These results demonstrate a significant relationship between the clinical score of superficial lymph nodes or inoculation site and the infection level of these organs, and an early localization of pyogranulomatous lesions in regional lymph nodes. The subsequent development of the disease was related to the enlargement of these lesions and, in some animals, to a bacterial dissemination from primary sites of infection in the right prescapular lymph node and in the lung.

Corynebacterium pseudotuberculosis infection in goats. IX. The effect of vaccination against natural infection

A vaccination trial was carried out in 10 infected herds. The trial included 247 female kids, the number of animals in each herd varying from 15 to 38. About half of the animals in each herd were vaccinated twice at 3 to 4 week intervals, the first vaccination being carried out before the age of 4 months. A combination of a crude filtrate of C. pseudotuberculosis toxoid with whole organisms, was used. Overall, the prevalence of animals with superficial swellings was higher in the unvaccinated than in the vaccinated group during the first 1-2 years following immunization. However, in some herds superficial swellings were as common in vaccinated as in unvaccinated animals. An antibody response following vaccination was demonstrated in the hemolysis inhibition test, but not in the bacterial agglutination test. Superficial swellings were more common in vaccinated animals which were negative than in animals which were positive in the hemolysis inhibition test at 1 1/2 months after vaccination. The vaccine used in the present study, was not sufficiently efficacious to be recommended as the only protective measure against caseous lymphadenitis in Norwegian goat herds.