Abstract:
Monitor lizards were sampled along the shores of Lake Victoria to detect natural
infections of potentially human-infective trypanosomes. In an area with endemic rhodesian
sleeping sickness, one of 19 lizards was infected (Busia, Kenya). Six of ten lizards also
showed indirect evidence of infection with Trypanosoma brucei (antibody ELISA). In an area
with no recent history of human disease (Rusinga Island), no parasites were found and no
antibodies to T. brucei were detected. The isolate was identified as T. brucei through
xenodiagnosis (completion of the life cycle in the salivary glands of tsetse), and through
molecular techniques (positive reactions with a peR primer and a microsatellite DNA probe
characteristic of the subgenus Trypanozoon). Experimental infections of monitor lizards were
also attempted with a variety of parasites and tsetse species. It was possible to infect monitor
lizards with T. brucei but not with forest or savannah genotypes of Trypanosoma congolense.
Parasites reached low levels of parasitaemia for a short period without generating any
pathology; they also remained infective to tsetse and laboratory rats. The implications of
these findings are discussed in relation to the endemicity of sleeping sickness.
