Genetic diversity of trypanosomes pathogenic to livestock in tsetse flies from the Nech Sar National Park in Ethiopia: A concern for tsetse suppressed area in Southern Rift Valley?

In Ethiopia, home to the largest African herd of cattle, animal trypanosomiasis is a major constraint to the efforts made for food self-sufficiency. We searched for trypanosomes in tsetse flies caught in the Nech Sar National Park (NSNP), Southern Rifty Valley, Ethiopia, at the district of Arba Minch where intensive tsetse control is successfully improving cattle productivity. Despite narrow geographical and temporal scales of our survey, we found a remarkable diversity of trypanosomes using the sensitive and discriminative method of fluorescent fragment length barcoding. We also found a high density of Glossina pallidipes (47.8 flies/trap/day) showing relevant cytochrome oxidase I gene variability. The identification of blood meal sources through cytochrome b gene sequences revealed cattle and warthog as preferential ungulate hosts of tsetse flies in the study area. Our survey identified trypanosomes in 38% of the 287 flies examined (42% of proboscises and 32% of guts), and the following infection rates for each species: Trypanosoma vivax 23%, T. simiae 23%, T. congolense 22%, T. theileri 19.9%, T. (Trypanozoon) spp. 10.5%, T. godfreyi 9.4%, T. simiae Tsavo 6.3%, and mixed infections in proboscises (30%) and guts (61%). Phylogenetic analysis revealed T. vivax of the "West African-South American" genotype, T. congolense of Savannah (16.7%), Kilifi (3.5%) and Forest (2.1%) lineages, and new genotypes of T. simiae. To our knowledge, this is the first survey of trypanosomes in the NSNP, and the most comprehensive molecular characterisation of trypanosomes in tsetse flies of Ethiopia, including the comparison with samples from West and other East African countries. Our results support the diversification of T. vivax in East Africa, and the dispersion of the genotype herein identified in Ethiopia across West Africa and then in South America. Altogether, tsetse density and infection rate, repertoire of trypanosomes and feeding behavior indicate a high risk of transmission of trypanosomes pathogenic to ungulates by tsetse flies from the NSNP, a hotspot of tsetse infestation and trypanosome diversity. Our findings reinforce the need for constant surveillance, and the reliance on community efforts to prevent reinvasion of tsetse and animal trypanosomiasis in suppressed areas of Southern Rift Valley.

Remarkable richness of trypanosomes in tsetse flies (Glossina morsitans morsitans and Glossina pallidipes) from the Gorongosa National Park and Niassa National Reserve of Mozambique revealed by fluorescent fragment length barcoding (FFLB).

Trypanosomes of African wild ungulates transmitted by tsetse flies can cause human and livestock diseases. However, trypanosome diversity in wild tsetse flies remains greatly underestimated. We employed FFLB (fluorescent fragment length barcoding) for surveys of trypanosomes in tsetse flies (3086) from the Gorongosa National Park (GNP) and Niassa National Reserve (NNR) in Mozambique (MZ), identified as Glossina morsitans morsitans (GNP/NNR=77.6%/90.5%) and Glossina pallidipes (22.4%/9.5%). Trypanosomes were microscopically detected in 8.3% of tsetse guts. FFLB of gut samples revealed (GNP/NNR): Trypanosoma congolense of Savannah (27%/63%), Kilifi (16.7%/29.7%) and Forest (1.0%/0.3%) genetic groups; T. simiae Tsavo (36.5%/6.1%); T. simiae (22.2%/17.7%); T. godfreyi (18.2%/7.0%); subgenus Trypanozoon (20.2%/25.7%); T. vivax/T. vivax-like (1.5%/5.2%); T. suis/T. suis-like (9.4%/11.9%). Tsetse proboscises exhibited similar species composition, but most prevalent species were (GNP/NNR): T. simiae (21.9%/28%), T. b. brucei (19.2%/31.7%), and T. vivax/T. vivax-like (19.2%/28.6%). Flies harboring mixtures of trypanosomes were common (~ 64%), and combinations of more than four trypanosomes were especially abundant in the pristine NNR. The non-pathogenic T. theileri was found in 2.5% while FFLB profiles of unknown species were detected in 19% of flies examined. This is the first report on molecular diversity of tsetse flies and their trypanosomes in MZ; all trypanosomes pathogenic for ungulates were detected, but no human pathogens were detected. Overall, two species of tsetse flies harbor 12 species/genotypes of trypanosomes. This notable species richness was likely uncovered because flies were captured in wildlife reserves and surveyed using the method of FFLB able to identify, with high sensitivity and accuracy, known and novel trypanosomes. Our findings importantly improve the knowledge on trypanosome diversity in tsetse flies, revealed the greatest species richness so far reported in tsetse fly of any African country, and indicate the existence of a hidden trypanosome diversity to be discovered in African wildlife protected areas.

Diagnosis and genetic analysis of the worldwide distributed Rattus-borne Trypanosoma (Herpetosoma) lewisi and its allied species in blood and fleas of rodents.

Trypanosoma (Herpetosoma) lewisi is a cosmopolitan parasite of rodents strongly linked to the human dispersal of Rattus spp. from Asia to the rest of the world. This species is highly phylogenetically related to trypanosomes from other rodents (T. lewisi-like), and sporadically infects other mammals. T. lewisi may opportunistically infect humans, and has been considered an emergent rat-borne zoonosis associated to poverty. We developed the THeCATL-PCR based on Cathepsin L (CATL) sequences to specifically detect T. (Herpetosoma) spp., and assess their genetic diversity. This method exhibited high sensitivity using blood samples, and is the first molecular method employed to search for T. lewisi in its flea vectors. THeCATL-PCR surveys using simple DNA preparation from blood preserved in ethanol or filter paper detected T. lewisi in Rattus spp. from human dwellings in South America (Brazil and Venezuela), East Africa (Mozambique), and Southeast Asia (Thailand, Cambodia and Lao PDR). In addition, native rodents captured in anthropogenic and nearby human settlements in natural habitats harbored T. (Herpetosoma) spp. PCR-amplified CATL gene fragments (253bp) distinguish T. lewisi and T. lewisi-like from other trypanosomes, and allow for assessment of genetic diversity and relationships among T. (Herpetosoma) spp. Our molecular surveys corroborated worldwide high prevalence of T. lewisi, incriminating Mastomys natalensis as an important carrier of this species in Africa, and supported its spillover from invader Rattus spp. to native rodents in Brazil and Mozambique. THeCATL-PCR provided new insights on the accurate diagnosis and genetic repertoire of T. (Herpetosoma) spp. in rodent and non-rodent hosts, revealing a novel species of this subgenus in an African gerbil. Phylogenetic analysis based on CATL sequences from T. (Herpetosoma) spp. and other trypanosomes (amplified using pan-trypanosome primers) uncovered rodents harboring, beyond mammal trypanosomes of different subgenera, some species that clustered in the lizard-snake clade of trypanosomes.

New insights from Gorongosa National Park and Niassa National Reserve of Mozambique increasing the genetic diversity of Trypanosoma vivax and Trypanosoma vivax-like in tsetse flies, wild ungulates and livestock from East Africa.

BACKGROUND: Trypanosoma (Duttonella) vivax is a major pathogen of livestock in Africa and South America (SA), and genetic studies limited to small sampling suggest greater diversity in East Africa (EA) compared to both West Africa (WA) and SA. METHODS: Multidimensional scaling and phylogenetic analyses of 112 sequences of the glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) gene and 263 sequences of the internal transcribed spacer of rDNA (ITS rDNA) were performed to compare trypanosomes from tsetse flies from Gorongosa National Park and Niassa National Reserve of Mozambique (MZ), wild ungulates and livestock from EA, and livestock isolates from WA and SA. RESULTS: Multidimensional scaling (MDS) supported Tvv (T. vivax) and TvL (T. vivax-like) evolutionary lineages: 1) Tvv comprises two main groups, TvvA/B (all SA and WA isolates plus some isolates from EA) and TvvC/D (exclusively from EA). The network revealed five ITS-genotypes within Tvv: Tvv1 (WA/EA isolates), Tvv2 (SA) and Tvv3-5 (EA). EA genotypes of Tvv ranged from highly related to largely different from WA/SA genotypes. 2) TvL comprises two gGAPDH-groups formed exclusively by EA sequences, TvLA (Tanzania/Kenya) and TvLB-D (MZ). This lineage contains more than 11 ITS-genotypes, seven forming the lineage TvL-Gorongosa that diverged from T. vivax Y486 enough to be identified as another species of the subgenus Duttonella. While gGAPDH sequences were fundamental for classification at the subgenus, major evolutionary lineages and species levels, ITS rDNA sequences permitted identification of known and novel genotypes. CONCLUSIONS: Our results corroborate a remarkable diversity of Duttonella trypanosomes in EA, especially in wildlife conservation areas, compared to the moderate diversity in WA. Surveys in wilderness areas in WA may reveal greater diversity. Biogeographical and phylogenetic data point to EA as the place of origin, diversification and spread of Duttonella trypanosomes across Africa, providing relevant insights towards the understanding of T. vivax evolutionary history.

Normal insulin sensitivity in lean offspring of obese parents.

OBJECTIVE: Offspring of diabetic or hypertensive patients are insulin resistant at a prediabetic/prehypertensive stage. We tested the hypothesis that insulin action may be impaired in the offspring of obese nondiabetic parents. RESEARCH METHODS AND PROCEDURES: Twenty-one lean offspring of nonobese subjects [(OL) 22 +/- 3 years of age] were matched to 23 lean offspring of obese subjects (OOb) by gender distribution, age, BMI, and waist circumference. Anthropometry, oral glucose tolerance, in vivo insulin sensitivity [by a euglycemic insulin clamp (6 pmol/min per kilogram(FFM); where FFM represents fat-free mass)], and thermogenesis (by indirect calorimetry) were measured in each subject. The study subjects were from a population of 267 nuclear families (one offspring and both his/her parents) in which there was statistically significant (chi2 = 30.2, p = 0.001) concordance of BMI between parents and offspring. RESULTS: In comparing OOb with OL, no statistically significant difference or trend toward a difference was detected in fasting plasma glucose and insulin concentrations, glucose and insulin responses to oral glucose, insulin sensitivity [metabolism value = 45 +/- 12 (OOb) vs. 47 +/- 17 micro mol/min per kilogram(FFM) (OL)], insulin-induced inhibition of protein and lipid oxidation, stimulation of glucose oxidation and nonoxidative glucose disposal, respiratory quotient, resting energy expenditure, and glucose-induced thermogenesis. DISCUSSION: The metabolic similarity between lean offspring of obese parents and those of nonobese parents suggests that insulin resistance and its correlates are not co-inherited with the predisposition to develop obesity.