Prevalence of Trypanosoma and Plasmodium Species’ Parasites in Small Rodents of Kakamega Forest in Western Kenya

Abstract

Objective: To determine the prevalence, intensity and morphometric parameters of haemoparasites of small rodents inhabiting Kakamega forest of Western Kenya.

Methods: Praomys jacksoni (n=59), Mastomys sp (n=27), Mus sp (n=7), Mylomys dybowski (n=6), and Tachyoryctes sp (n=44), randomly captured were surveyed for haemoparasites by microscopy. Observed parasites were described and thirteen morphometric parameter measurements of each group compared among the rodent species. Prevalence was determined by parasite detection and intensity was estimated by the numbers observed against 10,000 erythrocytes.

Results: Trypanosoma and Plasmodium species were found in P. jacksoni and Mastomys rats. Trypanosoma prevalence was 20.34% and 40.74% whereas that of Plasmodium was 6.78% and 3.70% in P. jacksoni and Mastomys, respectively. The mean Trypanosoma sp. and Plasmodium sp. intensity was 0.063% and 0.067% in
P. jacksoni, and 0.47% and 0.01% in Mastomys, respectively. Pleomorphic trypomastigotes were the main blood stage parasite forms in the two rodent species. Morphometric data showed that trypanosomes from the two rodent species differed significantly (P<0.05) in the means of their Nuclear (0.87- P. jacksoni vs 1.05- Mastomys sp) and Kinetoplast (1.36-P. jacksoni vs 1.52-Mastomys sp) indices. Ring-stage Plasmodium trophozoites (chromatin length =0.5-1.0µm, ring diameter =1.5-2.5µm with a rim of blue cloured cytoplasm (0.5µm thick) were observed in both the rodent species. Most trophozoites had single chromatin dots.

Conclusion: This study reports the occurrence of natural Trypanosome and Plasmodium parasites’ infection in small wild rodent species in a Kenyan forest with Trypanosomes being the most prevalent. The data suggest that there are two Trypanosome species and one Plasmodium species parasitizing the small rodents in the forest. More studies are however required to characterize and fully identify these parasites that from our point of view may be useful in the laboratory studies of malaria and trypanosomiasis infections using animal models in East Africa.

Keywords: Trypanosoma sp., Plasmodium sp., Praomys jacksoni, Mastomys sp., prevalence, intensity