Elimination of the gametocytes of Theileria annulata of cattle by primaquin phosphate.

Calves were experimentally infected with Theileria annulata and five drugs were administered in an attempt to exterminate the gametocytes of the parasite. The results of the experiment proved that primaquin phosphate is an effective parasiticide. The gametocytes from 30 calves treated with primaquin phosphate were exterminated completely. A further eight calves were treated with sulfamethoxypyrazine, trimethoprim, naganin and acaprin, but these drugs were not found to be effective in eliminating the gametocytes. The phase, size and colour of the gametocytes in these calves were the same as those of the four untreated control calves.