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Trypanosoma evansi is a widely-distributed haemoflagellated parasite of veterinary importance that infects a variety of mammals including horses, mules, camels, buffalos, cattle and deer. It is the causal agent of a trypanosomiasis known as Surra which produces epidemics of great economic importance in Africa, Asia and South America. The main pathology includes an enlarged spleen with hypertrophy of lymphoid follicles, congested lungs, neuronal degeneration and meningoencephalitis, where migration of the parasites from the blood to the tissues is essential. Most cells, including pathogenic cells, use diverse strategies for tissue invasion, such as the expression of surface receptors to bind plasminogen or plasmin. In this work, we show that T. evansi is able to bind plasminogen and plasmin on its surface. The analysis of this binding revealed a high affinity dissociation constant (K d of 0.080 ± 0.009 μM) and 1 × 10 5 plasminogen binding sites per cell. Also a second population of receptors with a K d of 0.255 ± 0.070 μM and 3.2 × 10 4 plasminogen binding sites per cell was determined. Several proteins with molecular masses between ∼18 and ∼70 kDa are responsible for this binding. This parasite-plasminogen interaction may be important in the establishment of the infection in the vertebrate host, where the physiological concentration of available plasminogen is around 2 μM. [ABSTRACT FROM AUTHOR]

African Animal Trypanosomiasis (AAT) is endemic in at least 37 of the 54 countries in Africa. It is estimated to cause direct and indirect losses to the livestock production industry in excess of US$ 4.5 billion per annum. A century of intervention has yielded limited success, owing largely to the extraordinary complexity of the host-parasite interaction. Trypanotolerance, which refers to the inherent ability of some African livestock breeds, notably Djallonke sheep, N’Dama cattle and West African Dwarf goats, to withstand a trypanosomiasis challenge and still remain productive without any form of therapy, is an economically sustainable option for combatting this disease. Yet trypanotolerance has not been adequately exploited in the fight against AAT. In this review, we describe new insights into the genetic basis of trypanotolerance and discuss the potential of exploring this phenomenon as an integral part of the solution for AAT, particularly, in the context of African animal production systems. [ABSTRACT FROM AUTHOR]

Little is known about the genetic diversity and pathogenicity of trypanosomes in Australian bats. Recently a novel trypanosome species was identified in an adult female little red flying fox ( Pteropus scapulatus) with clinical and pathological evidence of trypanosomosis. The present study used morphology and molecular methods to demonstrate that this trypanosome is a distinct species and we propose the name Trypanosoma teixeirae sp. n. Morphological comparison showed that its circulating trypomastigotes were significantly different from those of Trypanosoma pteropi and Trypanosoma hipposideri , two species previously described from Australian bats. Genetic information was not available for T. pteropi and T. hipposideri but phylogenetic analyses at the 18S ribosomal RNA (rRNA) and glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) loci indicated that T. teixeirae sp. n. was genetically distinct and clustered with other bat-derived trypanosome species within the Trypanosoma cruzi clade. [ABSTRACT FROM AUTHOR]

Abstract: The present study aimed at comparing the trypanosome specific 18S-PCR-RFLP using samples stored either on Whatman filter papers (PCR-RFLP-fp) or in a commercial cell lysis and DNA protecting buffer (PCR-RFLP-pb) with the haematocrit centrifugation technique (HCT), a method widely used for the diagnosis of African Animal Trypanosomosis. Out of 411 head of cattle, 49 (11.92%) (CI=8.95–15.45) scored positive for the presence of trypanosomes by HCT whereas 75 (18.25%) (CI=14.63–22.33) and 124 (30.17%) (CI=25.77–34.86) scored positive using PCR-RFLP-fp and PCR-RFLP-pb, respectively. Out of the 49 positives by HCT, 14 (28.57%) (CI=16.58–43.26) and 28 (57.14%) (CI=42.21–71.18) were concordant by PCR-RFLP-fp and PCR-RFLP-pb, respectively. None of the PCR techniques detected parasites from the Trypanozoon group. Although HCT detected more cases of Trypanosoma vivax (33), species identification using PCR-RFLP-fp and PCR-RFLP-pb were significantly different (p <0.001) from the HCT technique. The use of DNA protective buffer is thus recommended as the output of the PCR-RFLP-pb is improved and the risk of contamination between samples is reduced. [Copyright &y& Elsevier]

Abstract: Equine trypanosomosis (ET) is a protozoan disease affecting equines in many parts of the world. We examined 509 samples collected from geographically distinct regions in eastern, central and western Sudan to estimate the endemicity of ET using the generic ITS1-PCR diagnostic methods. Results revealed that horses and donkeys were infected by Trypanosoma brucei subgroup, Trypanosoma vivax, Trypanosoma simiae and Trypanosoma congolense. The prevalence of Trypanosoma spp. was higher in horses (12.7%, n =393) than in donkeys (3.4%, n =116). The highest prevalence was observed in South Darfur State (19.3%, n =202), followed by Kassala State (15.1%, n =86), Gadaref State (3.7%, n =82), and Khartoum State (2.6%, n =76). No trypanosomes were detected in the 63 samples collected from North Kurdofan State. We report for the first time the presence of T. simiae and T. congolense in horses in the Sudan. This study should alert veterinary services, authorized bodies to take action toward ET by undertaking countrywide epidemiological studies of the disease and adopting control strategies. [Copyright &y& Elsevier]

Abstract: Trypanosoma evansi is responsible for the most largely distributed animal trypanosomosis, affecting a wide range of wild and domestic animals. Its surveillance requires the implementation of standardized and reliable diagnostic tools. Although the development of polymerase chain reaction (PCR) tools has greatly improved our diagnostic capacity, factors affecting their sensitivity need to be acknowledged and accounted for in the interpretation of results. The targeted gene and the primer design have already been shown to greatly affect the sensitivity of a PCR, and the best-performing sets of primers have been previously identified. However, the sensitivity of the PCR is also largely influenced by the DNA extraction or sample preparation method. In this paper, we selected 6 DNA extraction or blood sample preparation methods representative of what would be used in a budget-constrained setting: phenol–chloroform, Chelex®, Flexigen (Qiagen®) kit, Genekam® kit and two original protocols using sodium hydroxide. We studied the effects of the preparation method on the detection limit of the subsequent PCR. Our results show that the extraction method strongly affects the PCR sensitivity. The classical phenol–chloroform extraction method allowed for the PCR with the lowest detection limit. Some combinations of extraction method and primer set had detection limits that were not compatible with their use as a reliable diagnostic test, and would severely reduce the performance of a surveillance program. Therefore, we encourage laboratories to carefully select their sample preparation and PCR protocols, depending on the aimed sensitivity, cost, safety, time requirement and objectives. [Copyright &y& Elsevier]

Abstract: The role played by domestic animals in the transmission of gambiense Human African Trypanosomosis remains uncertain. Northwest Uganda is endemic for Trypanosoma brucei gambiense. Of the 3267 blood samples from domestic animals in four counties examined by hematocrit centrifugation technique (HCT), 210 (6.4%) were positive for trypanosomes. The prevalence of animal trypanosomosis was estimated at 13.8% in Terego County, 4.2% in East Moyo County, 3.1% in Koboko County, and zero in West Moyo County. The trypanosome infection rates varied from 0.2% in goats, 3.5% in dogs, 5.0% in sheep, 7.5% in cattle, to 15.5% in pigs. DNA was extracted from the blood samples by Chelex method, Sigma and Qiagen DNA extraction Kits. A total of 417(12.8%) DNA samples tested positive by polymerase chain reaction (PCR) using T. brucei species specific primers (TBR) indicating that the DNA was of Trypanozoon trypanosomes while 2850 (87.2%) samples were TBR–PCR negative. The T. brucei infection rates based on TBR–PCR were highest in pigs with 21.7%, followed by cattle (14.5%), dogs (12.4%), sheep (10.8%), and lowest in goats with 3.2%, which indicated that pigs were most bitten by infected tsetse than other domestic animals. TBR–PCR detected 6.3% more infected domestic animals that had been missed, and confirmed the 6.4% cases detected by HCT in the field. Statistical analysis done using one-way ANOVA Kruskal–Wallis test (Prism version 5.0) showed no significant difference in trypanosome infections among domestic animals using both HCT and TBR–PCR techniques in the different counties (Confidence Interval of 95%, p-values >0.05). All the 417 trypanosome DNA samples were negative by PCR using two sets of primers specific for the T. b. gambiense specific glycoprotein gene and serum resistance associated gene of T. b. rhodesiense, indicating that they were probably not from the two human infective trypanosomes. Polymerase chain reaction using primers based on ribosomal internal transcribed spacer-1 region (ITS–PCR) resolved the 417 DNA of trypanosome samples into 323 (77.5%) as single trypanosome infections due to T. brucei and 39 (9.4%) mixed infections but missed detecting 55 (13.1%) samples, possibly because of the low sensitivity of ITS–PCR as compared to TBR–PCR. The 31 mixed infections were due to T. brucei (T.b) and T. vivax (T.v); while 8 mixed infections were of T. congolense (T.c) and T. brucei but no mixed trypanosome infections with T. congolense, T. brucei, and T. vivax were detected. Statistical analysis done using one way ANOVA Kruskal–Wallis test (Prism version 5.0) to compare single and mixed trypanosome infections showed no significant difference in trypanosome infections due to single (T.v, T.b, T.c) and mixed (T.v + T.b; T.v + T.c; T.b + T.c; T.v + T.b + T.c) trypanosome species among domestic animals in the different counties using ITS–PCR technique (Confidence Interval of 95%, p-values >0.05). It was concluded that domestic animals in northwest Uganda were probably not reservoirs of T. b. gambiense and there was no infection, as yet, with T. b. rhodesiense parasites. [Copyright &y& Elsevier]

Abstract: Trypanosoma vivax is major cause of animal trypanosomiasis and responsible for enormous economic burden in Africa and South America animal industry. T. vivax infections mostly run low parasitaemia with no apparent clinical symptoms, making diagnosis a challenge. This work reports the design and evaluation of a loop-mediated isothermal amplification (LAMP) test for detecting T. vivax DNA based on the nuclear satellite repeat sequence. The assay is rapid with results obtained within 35min. The analytical sensitivity is ∼1trypanosome/ml while that of the classical PCR tests ranged from 10 to 103 trypanosomes/ml. The T. vivax LAMP test reported here is simple, robust and has future potential in diagnosis of animal trypanosomiasis in the field. [Copyright &y& Elsevier]

Abstract: Blood samples were collected from 46 domestic ruminants comprising of 23 trypanosomiasis infected and 23 uninfected control groups to study some biochemical and haematological effects of trypanosomiasis under natural condition. The effect of trypanosome infection in ruminant animals showed that infected animals had significantly lower (P <0.05) packed cell volume, erythrocyte count and higher (P <0.01) mean cell volumes than uninfected animals. Leucocytosis, reticulocytosis and thrombocytopenia were also observed. The infection also produced a decrease in albumin (P <0.001), significant increase in total protein and bilirubin levels. These changes were not seen in the animals that were not infected. The outcome of the work shows that herds are severely affected by the disease, and therefore supports the prospect of routine check as an epidemiologic tool in trypanosomiasis based on its abnormal effects in blood. [Copyright &y& Elsevier]

Abstract: The aim of the present study was to develop a PCR-ELISA assay for the detection and differentiation of the main African pathogen trypanosomal species present in peripheral blood of cattle. The proposed methodology allows to specifically differentiate Trypanosoma congolense, Trypanosoma vivax and the subgenus Trypanozoon, by means of a sensitive universal PCR amplifying trypanosome DNA followed by an ELISA-based hybridization with three highly specific probes. The semi-nested PCR had a sensitivity of 15fg, 15fg, and 0.15fg of DNA from T. vivax, T. congolense, and Trypanosoma brucei brucei, respectively that is sufficient to detect parasites in blood during the chronic phase of the disease. Biotinylated second round asymmetric PCR amplification products were used in an ELISA set up using three species-specific probes for the diagnosis of T. congolense (type Riverine, Kilifi or Savannah), T. vivax and T. brucei brucei. A factor O.D. of 0.082 was determined on blood samples from bovines (n =18) from a non-endemic area in Africa. In a pilot study of blood samples of naturally and experimentally Trypanosoma infected cattle previously characterized by PCR-RFLP (n =42), a high rate of concordance (93.3%) was found between PCR-RFLP and PCR-ELISA. There is a good ratio between positive and negative O.D. values (3.00 vs. 0.1) and the technique can also be used to distinguish mixed infections. [Copyright &y& Elsevier]

Abstract: An experimental infection of red fronted gazelles (Gazella rufifrons) with Trypanosoma brucei strain MKAR/84/NITR/6 was carried out. Two waves of parasitaemia which corresponded with a significant decline (p <0.05) in packed cell volume (PCV) was encountered in the infected untreated controls and those treated at day 8 post-infection with a sub-optimal dosage of diminazene aceturate (Berenil®) at 3.5mg/kg body weight. At postmortem, hepatomegally, splenomegally, lymphadenopathy, nephritis, myocardial degeneration with pulmonary oedema was observed in the two groups. Similarly, histopathological studies of some organs revealed interstitial haemorrhages, severe degenerative changes with cellular infiltrations. On the other hand, those treated by day 8 post-infection with melarsamine hydrochloride (Cymelarsan®) at 0.3mg/kg, 0.6mg/kg or diminazene aceturate (Berenil®) at 7.0mg/kg body weight had apparently normal organs at the end of the experiment. These results suggest that, T. brucei can cause severe pathological changes in untreated red fronted gazelles (Gazella rufifrons). However, treatments at the onset of parasitaemia, by day 8 post-infection with melarsamine hydrochloride (Cymelarsan®) at 0.3 and 0.6mg/kg or diminazene aceturate (Berenil®) at 7.0mg/kg body weight ameliorated the deleterious effects of the infection in the gazelles. [Copyright &y& Elsevier]

Abstract: The aim of this study was to assess the existence of possible cross-protection between Trypanosoma congolense strains of low and extreme virulence circulating in the same trypanosomiasis focus. Groups of six mice were infected using one of three strains of low virulence and challenged with one of three strains of extreme virulence. A group of six mice was used as control for each strain of low and extreme virulence. The results showed that mice infected with one of the strains of extreme virulence developed high parasitaemia and a significant drop of the PCV compared to mice infected with a strain of low virulence and challenged with one of the strains of extreme virulence. With an exception of one strain of extreme virulence (strain F), the survival time of mice infected with the strains of extreme virulence was shorter compared to mice infected with strains of low virulence and subsequently challenged with a strain of extreme virulence. These results suggest that in an area where trypanosomes of various virulence profiles circulate, livestock infected with T. congolense strains of low virulence can be protected against the adverse effects of extremely virulent T. congolense strains. [Copyright &y& Elsevier]

Abstract: An outbreak of trypanosomosis was observed for the first time in metropolitan France in October 2006, when five camels were proved to be infected by Trypanosoma evansi using parasitological methods. The parasite was isolated and used to produce a soluble antigen for antibody–enzyme linked immunosorbent assay (ELISA) in a protocol derived from a method previously developed for sheep and humans but using protein A conjugate. The animals were treated on three instances, alternatively with melarsomine hydrochloride and quinapyramine and followed up on a monthly basis for 2 years with various diagnostic techniques including parasitological, serological and DNA-based methods. Initially, five animals were detected as being positive using ELISA with 83.3% concordance to parasitological tests. Immediately after the first treatment, parasites and DNA disappeared in all animals; antibody levels decreased regularly until ELISA became negative 3–4 months later. Ten months after the first treatment, parasites and antibodies were detected again in one of the camels previously found to be infected. A retrospective study indicated that the weight of this animal had been underestimated; consequently, it had received underdosages of both trypanocides. However, since hypotheses of re-infection or relapse could not be fully substantiated, it is not known whether the ELISA results for this animal were true- or false-negative over a 7-month period. The study confirmed the value of this ELISA using protein A conjugate to detect antibodies directed against T. evansi in camels and the need to use several diagnostic techniques to optimize detection of infected animals. A warning is raised on surra, a potentially emerging disease in Europe. [Copyright &y& Elsevier]

Abstract: Trypanosomiasis caused by Trypanosoma evansi (“Surra”) is mainly a wasting disease affecting equids, camels and cattle as well as other domestic and wild animal species. In horses, infection may cause severe neurological abnormalities; however, the clinical progression, pathogenesis and molecular ante-mortem detection of this form of the disease have not been described in detail. A mare with progressive ataxia, head tilt, nystagmus and cranial nerve deficits submitted to treatment was diagnosed with central nervous system trypanosomiasis following the detection of a Trypanosoma tryposmastigote in cerebrospinal fluid cytology. Histopathology following necropsy showed that the brain, spinal cord and kidneys were the main affected tissues with disseminated multifocal non-suppurative meningoencephalitis of the central nervous system and membranoproliferative glomerulonephritis. Serology for T. evansi was positive and PCR indicated the presence of parasite DNA in the cerebellum, brain stem, spinal cord and bone marrow but not in other organs and confirmed the identity of causative agent as T. evansi. This is the first report of ante-mortem detection of T. evansi in the cerebrospinal fluid of a horse and the first description of post-mortem PCR identification of the parasite DNA in the nervous system. [Copyright &y& Elsevier]

Abstract: There are several T. vivax specific primers developed for PCR diagnosis. Most of these primers were validated under different DNA extraction methods and study designs leading to heterogeneity of results. The objective of the present study was to validate PCR as a diagnostic test for T. vivax trypanosomosis by means of determining the test sensitivity of different published specific primers with different sample preparations. Four different DNA extraction methods were used to test the sensitivity of PCR with four different primer sets. DNA was extracted directly from whole blood samples, blood dried on filter papers or blood dried on FTA cards. The results showed that the sensitivity of PCR with each primer set was highly dependant of the sample preparation and DNA extraction method. The highest sensitivities for all the primers tested were determined using DNA extracted from whole blood samples, while the lowest sensitivities were obtained when DNA was extracted from filter paper preparations. To conclude, the obtained results are discussed and a protocol for diagnosis and surveillance for T. vivax trypanosomosis is recommended. [Copyright &y& Elsevier]