The complement fixation test and African trypanosomiasis: I. Experimental infection and re-infection in cattle before and after treatment.

The complement fixation test was applied to assess antibody responses in cattle infected with T. brucei, T. congolense, and T. vivax which had been treated and re-infected. After the first infection, the specificity of the results was low in T. congolense, fair in T. brucei, and high in T. vivax infected animals. After re-infection with the same trypanosoma species as used for previous infections, the specificity of CF results was high in all cases. After a foregoing T. vivax infection, specific titres of T. congolense and to a lesser degree of T. brucei infections were frequently masked by residual T. vivax titres. After treatment of trypanosoma-infected cattle the fasted drop of CF antibody titres occurred in T. congolense cases, followed by T. brucei infections. T. vivax titres persisted over prolonged periods.