Experimental toxoplasmosis in buffalo calves

Eight buffalo calves were inoculated with infectious oocysts of a virulent strain of Toxoplasma gondii, five with 1 × 10⁵, and the other three with 5 × 10⁵ oocysts each while two more were kept as non-inoculated controls. Infected animals developed pyrexia, anorexia, conjunctivitis and dyspnoea. The clinical symptoms, haematological changes and serological response were of a low order. The appearance of haemagglutinating antibodies at significant levels (? 1:64) was first observed at 21 days after inoculation (DAI), peaked at 42 DAI and rapidly declined after 63 DAI. The inoculated calves were killed (or died) at intervals from 11 DAI to 110 DAI. The organism could be recovered from several times of a calf that died 11 DAI, but was rapidly removed subsequently. Only the lymph nodes were infective till 32 DAI. Parasitism of the retina was demonstrated in one calf. The significance of these findings is discussed.