Characterization ofTrypanosoma congolenseserodemes in stocks isolated from cattle introduced onto a ranch in Kilifi, Kenya

Abstract

SUMMARY: A herd of 20 cattle was introduced on a ranch in Kilifi, Coast Province of Kenya, where they were in contact withGlossina austenifor 6 months. In total, 65 trypanosome isolates were made from these animals. Examination of the isolates revealed that 61 wereTrypanosoma congolenseand 4 wereT. theileri. Out of the 61T. congolenseisolates, 55 were successfully passaged and cloned in mice to provide trypanosome populations for further analyses. The stocks and their clones were inoculated into goats on which teneralG. morsitans centraliswere later fed in order to provide metacyclics for use in serodeme analysis. Identification of serodemes was carried out by indirect immunofluorescence and neutralization using antimetacyclic hyperimmune sera prepared in mice against metacyclics of cloned trypanosome populations. So far 4 serodemes have been identified in 8 stocks and 7 clones. Each of the 9 stocks contained a mixture of at least 2 of the 4 serodemes identified. Furthermore, stocks isolated sequentially from individual animals contained the same serodemes despite repeated treatment with a curative dose (6 mg/kg body weight) of Berenil between isolations. From the latter finding, it can be inferred that the 4 serodemes were present on the ranch throughout the study period.