In vitro activity of selected ruminant sera on <i>Trypanosoma congolense</i> Broden, 1894

Abstract

Trypanosomiasis is one of the most important problems to man and his livestock. The in vitro Trypanosoma congolense activity of sera from some ruminants viz: West African dwarf goat, Red Sokoto goat, Sahel goat, Yankassa sheep, Uda sheep, Balami sheep, N’Dama cattle, Sokoto Gudali cattle, Friesian cross/Bunaji cattle, White Fulani cattle was investigated. Blood samples from the donor ruminants were screened for trypanosomes using the thick film and haematocrit centrifugation technique (HCT). Trypanosoma congolense was suspended in RPMI supplemented with FCS. After the addition of each test serum, the motility of the parasite was used as index of viability. None of the sera from the selected small ruminants exhibited any anti-trypanosomal activity against T. congolense in vitro. Their survival times were all significantly higher (p<0.05) than the control (74.67Ç0.58 hrs), with negative Anti-trypanosomal Activity Index (ATI). The highest survival time which reflects the highest supportive activity was recorded with Yankassa sheep serum (171.33Ç2.31 hrs), a supportive activity significantly greater (P<0.05) than that of sera from other small ruminants. The survival time of the parasites in the West African Dwarf goat serum was the least (100.00Ç8.72 hrs), although significantly (p<0.05) higher than the control (74.67Ç0.58 hrs). All the sera from selected large ruminants recorded negative ATI, showing the lack of antiTrypanosoma congolense activity. Sokoto Gudali serum had the highest supportive activity, significantly higher (p<0.05) than that of other large ruminants (ATI of -1.38), with a mean survival time of 178.00Ç2.00 hrs. N’Dama cattle serum had the least supportive activity (ATI of -0.42 and survival time of 106.00Ç3.46 hrs). This study shows that all the sera from selected ruminants lack anti-Trypanosoma congolense activity, and are rather very supportive of the survival of T. congolense in vitro.

Keywords: Anti-Trypanosoma congolense activity; in vitro; survival time; ruminants; inhibition index; anti-trypanosomal activity index; supportive activity.