Virulence of two strains of Cowdria ruminantium in mice and their use to predict drug activity against heartwater.

A study was made of the infectivity of two mouse-adapted strains of Cowdria ruminantium in mice. The Kwanyanga strain was most virulent in Balb/C mice which died nine days after infection with homogenate of liver from infected mice. CD-1 mice were least susceptible of six strains tested. The du Plessis strain of C. ruminantium was equally virulent in all six mouse strains. The du Plessis strain in CD-1 mice was used as the basis of a drug screen to detect activity against heartwater (C. ruminantium infection) and was highly predictive when active compounds were tested in sheep infected with the Ball 3 strain of C. ruminantium.