The spread of Corynebacterium pseudotuberculosis infection to unvaccinated and vaccinated sheep.

摘要

Three groups of 150 sheep, of which 50 in each group were artifically infected with C. pseudotuberculosis and 100 in each group were uninfected, were run separately for 40 months and shorn 5 times to promote the spread of caseous lymphadenitis (CLA). One lot of 50 infected sheep and 2 lots of 100 uninfected sheep were vaccinated against CLA. The rate of spread of CLA was recorded. Sheep vaccinated against CLA and naturally exposed to infection had a 74% lower infection rate than unvaccinated sheep.Sheep vaccinated against CLA and exposed to only vaccinated infected sheep had a 97% lower infection rate. Unvaccinated sheep had a 76% infection rate, with 77% of the transmission occurring at the 4th and 5th shearings, without any discharging CLA abscesses being observed. It is suggested that in Australian wool producing flocks, CLA spreads mainly from sheep with discharging lung abscesses to sheep with shearing cuts. Vaccinated sheep infected with CLA had 96% fewer lung lesions compared with unvaccinated infected sheep and were therefore less likely to spread this disease to other sheep.