Infectivity to cattle of metacyclic forms of Trypanosoma (Nannomonas) congolense propagated in vitro. I. Development of localized skin reactions following intradermal inoculation

Skin reactions similar to those induced by tsetse infected with Trypanosoma congolense were elicited in cattle at sites of intradermal inoculation of in vitro propagated parasites which morphologically resembled metacyclic trypanosomes. The time to detection of the reaction, the time to maximal size and the maximal size attained were dependent on the number of parasites inoculated, although it was possible to induce a skin reaction with as few as 20 trypanosomes. All cattle became infected with the initial detection of the skin reaction preceding parasitaemia by 3 to 7 days.