Parasite kinetics and cellular responses in goats infected and superinfected with Trypanosoma congolense transmitted by Glossina morsitans centralis.

Trypanosoma congolense infected tsetse were fed on the flanks of goats at sites drained by the prefemoral lymph node. The efferent lymphatic of this lymph node was surgically cannulated and the lymph was collected daily and examined for appearance of parasites, lymph flow and cells. Trypanosomes were detected in the lymph 4 days after infection, which was 2 days prior to the appearance of the local skin reaction or the presence of parasites in the blood. Once the animal became parasitaemic, trypanosomes were found to recirculate in the lymphatic system, appearing in the lymph of the contralateral lymph node 11 days after infection. In goats infected with T. congolense and superinfected 12 or 13 days later with a different tsetse-transmitted T. congolense serodeme, parasites belonging to the second serodeme were apparently delayed in their development in the skin and appeared up to 7 days later in the efferent lymph when compared to control animals. This delay in development might have implications for field situations where superinfections frequently occur; it might result in limiting the number of serodemes of T. congolense an animal can be infected with at any one time.