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Unlabelled: Human African trypanosomiasis is caused by two subspecies of Trypanosoma brucei. Trypanosoma brucei rhodesiense is found in East Africa and frequently causes acute disease, while Trypanosoma brucei gambiense is found in West Africa and is associated with chronic disease. Samples taken from a single focus of a Ugandan outbreak of T. b. rhodesiense in the 1980s were associated with either chronic or acute disease. We sequenced the whole genomes of two of these isolates, which showed that they are genetically distinct from each other. Analysis of single nucleotide polymorphism markers in a panel of 31 Ugandan isolates plus 32 controls revealed a mixture of East African and West African haplotypes, and some of these haplotypes were associated with the different virulence phenotypes. It has been shown recently that T. b. brucei and T. b. rhodesiense populations undergo genetic exchange in natural populations. Our analysis showed that these strains from the Ugandan epidemic were intermediate between the reference genome sequences of T. b. gambiense and T. b. brucei and contained haplotypes that were present in both subspecies. This suggests that the human-infective subspecies of T. brucei are not genetically isolated, and our data are consistent with genomic introgression between East African and West African T. b. brucei subspecies. This has implications for the control of the parasite, the spread of drug resistance, and understanding the variation in virulence and the emergence of human infectivity., Importance: We present a genetic study of the acute form of "sleeping sickness" caused by the protozoan parasite Trypanosoma brucei rhodesiense from a single outbreak in Uganda. This represents an advance in our understanding of the relationship between the T. b. rhodesiense and Trypanosoma brucei gambiense subspecies that have previously been considered geographically distinct. Our data suggest that introgression of West African-derived T. brucei haplotypes may be associated with differences in disease presentation in the East African disease. These findings are not only of scientific interest but also important for parasite control, as they suggest that the human-infective T. brucei subspecies are not genetically isolated.

Human African trypanosomiasis (HAT) due to Trypanosoma brucei gambiense or T. b. rhodesiense remains highly prevalent in several rural areas of sub-Saharan Africa and is lethal if left untreated. Therefore, accurate tools are absolutely required for field diagnosis. For T. b. gambiense HAT, highly sensitive tests are available for serological screening but the sensitivity of parasitological confirmatory tests remains insufficient and needs to be improved. Screening for T. b. rhodesiense infection still relies on clinical features in the absence of serological tests available for field use. Ongoing research is opening perspectives for a new generation of field diagnostics. Also essential for both forms of HAT is accurate determination of the disease stage because of the high toxicity of melarsoprol, the drug most widely used during the neurological stage of the illness. Recent studies have confirmed the high accuracy of raised immunoglobulin M levels in the cerebrospinal fluid for the staging of T. b. gambiense HAT, and a promising simple assay (LATEX/IgM) is being tested in the field. Apart from the urgent need for better tools for the field diagnosis of this neglected disease, improved access to diagnosis and treatment for the population at risk remains the greatest challenge for the coming years.

A series of novel aromatic derivatives based on the structure of methylglyoxal bis(guanylhydrazone) (MGBG) was examined for trypanocidal activities in human and veterinary trypanosomes of African origin. One agent, CGP 40215A, a bicyclic analog of MGBG which also resembles the diamidines diminazene (Berenil) and pentamidine, was curative of infections by 19 isolates of Trypanosoma brucei subspecies as well as a Trypanosoma congolense isolate. Several of these isolates were resistant to standard trypanocides. Curative doses were < or = 25 mg/kg of body weight/day for 3 days in these acute laboratory model infections. In addition, CGP 40215A also cured a model central nervous system infection in combination with the ornithine decarboxylase inhibitor DL-alpha-difluoromethylornithine (DFMO; Ornidyl, eflornithine). Curative combinations were 14 days of oral 2% DFMO (approximately 5 g/kg/day) plus 5, 10, or 25 mg/kg/day for 3 or 7 days given by intraperitoneal injection or with a miniosmotic pump. Combinations were most effective if CGP 40215A was given in the second half or at the end of the DFMO regimen. MGBG has modest activity as an inhibitor of trypanosome S-adenosylmethionine decarboxylase (50% inhibitory concentration [IC50]. 130 microM), while CGP 40215A was a more active inhibitor (IC50, 20 microM). Preincubation of trypanosomes with CGP 40215A for 1 h caused a reduction in spermidine content (36%) and an increase in putrescine content (20%), indicating that one possible mechanism of its action may be inhibition of polyamine biosynthesis.