Local skin reactions in cattle at the site of infection with Trypanosoma congolense by Glossina morsitans and G. tachinoides

An account is given of the occurrence and development of local skin reactions in cattle at the site of infection with Trypanosoma congolense transmitted by Glossina morsitans and G. tachinoides. Reactions developed in most infected cattle and were first seen at the sites of the fly bites 7–11 days after flies were fed on the animals, and 4–12 days before trypanosomes were seen in wet blood films. Trypanosomes were always present in fluid expressed from the reactions. The blood of one animal was not infective for rats until 3 days after the appearance of the reactions. The mean length of trypanosomes in stained thin films of reaction fluid was 2·4 μ greater than the mean length of trypanosomes in the blood. Many organisms in the reaction were normal blood forms, but trypanosomes indistinguishable from insect forms were also present.