Molecular Characterization Of Trypanosoma Brucei Brucei And Trypanosoma Brucei Rhodesiense Isolates And Responses Of Glossina Pallidipes To Trypanosoma Brucei Brucei Challenge

ABSTRACT

African trypanosomiases are a group of related diseases that affect humans (Human African Trypanosomiasis - HAT) and their livestock (Animal African Trypanosomiasis), with devastating medical and economic consequences for Africa. The diseases are caused by trypanosome parasites cyclically transmitted by tsetse flies. Recent reports indicate that HAT is on the decline in sub Sahara Africa. However, the disease still remains a major health problem in some parts of Africa such as South Sudan, Democratic Republic of Congo and Uganda. Reports also indicate repeated irregular T. b. rhodesiense out breaks in traditionally endemic areas in south-east Uganda, with continued spread to previously unaffected areas in central Uganda. Although the disease has been reported to spread to new areas in Uganda, observations in the field indicate that the infection rates in tsetse flies are very low. Competence of the flies to transmit the parasite is determined by host midgut responses that either leads to clearance (selfcure) or establishment of the parasite infections. Investigations were conducted to determine evolutionary dynamics behind the origin of new foci and the impact of host species on parasite genetic diversity in Uganda. Trypanosoma brucei isolates {N = 269, n= 58(for Samples isolated from cattle)} were collected from different areas in Uganda and western Kenya and genotyped at 17 genetic marker loci (microsatellite). Analysis was carried out using Bayesian clustering and Discriminant Analysis of Principal Componens. Presence of serum resistance associated (SRA) gene in the isolates was determined using PCR. Results showed that the genotyped trypansosome isolates partitioned into three distinct genetic clusters. Clusters 1 and 3 included isolates from central and southern Uganda, whereas cluster 2 was composed of mainly isolates from western Kenya. FST values between sampling sites ranged from 0 to 0.67 while between the three genetic structures it ranged from0.24 to 0.46 with most values being statistically significant P