STUDIES OF EXPERIMENTAL-INFECTION AND CROSS-IMMUNITY BETWEEN STOCKS OF COWDRIA-RUMINANTIUM IN SOKOTO RED GOATS

The course of experimental infection and cross-immunity tests between stocks of Cowdria ruminantium were investigated using eight infected and four uninfected control Sokoto red goats. All eight infected goats reacted to the primary infection. The incubation period varied between 8 and 23 days. During the febrile reaction, the highest rectal temperature recorded was 40 degrees C and the lowest was 39.7 degrees C, compared with a range of 38.6 +/- 0.15 to 38.1 +/- 0.19 in control goats. Following the primary infection, each of the animals was treated with long-acting Tetracycline (Terramycin, Pfizer) at a dose of 20 mg kg(-1) body weight to control the resulting temperature reaction. They were reinfected with the homologous stock 3 weeks after treatment to demonstrate whether they had become immune. The homologous challenge did not give any temperature reaction during 3 weeks of monitoring. They were then challenged with the heterologous C. ruminantium stock. This did not result in a febrile reaction during 3 weeks of monitoring. The observed cross-protection indicates antigenic similarity between the two stocks.