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

Abstract

SUMMARYA 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.

Comparative study on the infection rates of different laboratory strains of Glossina species by Trypanosoma congolense

“…Another factor to consider is the differences amongst the trypanosome stocks in terms of their successful establishment in tsetse. The mature infection rates of some T.congolense stocks (Masake et al, 1987) are quite IOW in G.rn.centra1is which is an efficient vector of the Tanzanian and Nigerian T.congolense used in this study. Jordan (1965) reported that in Nigeria the source of food is the main factor involved in determining the level of trypanosome infection in Glossina.…”

Endemic type of animal trypanosomiasis is not associated with lower genotype variability of Trypanosoma congolense isolates circulating in livestock

“…As a possible strategy of trypanosomiasis control, local vaccine using a cocktail of trypanosome strains was previously suggested as a result of low serodemes circulating in an endemic area (Masake et al, 1987). However, in another study using trypanosomes circulating in a sylvatic cycle, the use of such local vaccine for the immunisation of livestock kept at the vicinity of the game areas was not found to be practical (Frame et al, 1990).…”

Parasite virulence and disease patterns in Plasmodium falciparum malaria.

“…The putative cytoadherence ligand Pf EMP1 and the associated agglutination phenotype have both been shown to undergo clonal antigenic variation (37,38 (39).…”