Characterization of Trypanosoma evansi type B

Equine Trypanosomiasis: Molecular Detection, Hematological, and Oxidative Stress Profiling

Surra caused by Trypanosoma evansi (T. evansi) is widely distributed and has significant impact on equine sector and international trades. However, there are no available data about the genetic characterization of this parasite in horses in Egypt. So, the goal of this study was to study the molecular characterization of T. evansi in horses and determine the changes in hematological parameters and oxidative stress associated with T. evansi infection. A total of 12 horses were examined using PCR targeting RoTat 1.2 VSG gene, and we evaluated the changes in hematological and oxidative stress between infected and healthy animals. The results revealed a notable reduction in red blood cell (RBC), hematocrit (HCT), and hemoglobin (Hb) levels in the infected horses, as compared to the control healthy group. In contrast, the infected group showed a substantial increase in mean corpuscular hemoglobin concentration (MCHC), mean corpuscular hemoglobin (MCH), and mean corpuscular volume (MCV). In addition, the infected group exhibited monocytopenia, eosinopenia, and notable lymphocytopenia. Regarding oxidative stress profile, the infected horses showed decreased levels of glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and antioxidant capacity (TAC) compared to the control group. Moreover, the PCR assay targeting RoTat 1.2 VSG gene revealed positive specific band (205 bp) in all examined samples for T. evansi and the phylogenetic analysis demonstrated that strain of this study is closely related to T. evansi isolate in horses from India (MT501210) while showed difference from sequences of other species. The results emphasize the changes in blood composition and the body's response to oxidative stress caused by T. evansi infection in horses.

Molecular identification of new Trypanosoma evansi type non-A/B isolates from buffaloes and cattle in Indonesia

Trypanosoma evansi is reportedly divided into two genotypes: types A and B. The type B is uncommon and reportedly limited to Africa: Kenya Sudan, and Ethiopia. In contrast, type A has been widely reported in Africa, South America, and Asia. However, Trypanosoma evansi type non-A/B has never been reported. Therefore, this study aims to determine the species and genotype of the Trypanozoon subgenus using a robust identification algorithm. Forty-three trypanosoma isolates from Indonesia were identified as Trypanosoma evansi using a molecular identification algorithm. Further identification showed that 39 isolates were type A and 4 isolates were possibly non-A/B types. The PML, AMN-SB1, and STENT3 isolates were likely non-A/B type Trypanosoma evansi isolated from buffalo, while the PDE isolates were isolated from cattle. Cladistic analysis revealed that Indonesian Trypanosoma evansi was divided into seven clusters based on the gRNA-kDNA minicircle gene. Clusters 6 and 7 are each divided into two sub-clusters. The areas with the highest genetic diversity are the provinces of Banten, Central Java (included Yogyakarta), and East Nusa Tenggara. The Central Java (including Yogyakarta) and East Nusa Tenggara provinces, each have four sub-clusters, while Banten has three.

A Survey on Trypanosoma evansi (Kinetoplastida, Trypanosomatidae) Infection in Domestic Animals in a Surra Endemic Area of Southern Algeria

Background: Trypanosoma (T.) evansi infection is endemic in dromedary camels (Camelus dromedaries) of southern Algeria. Materials and Methods: In order to assess the presence of T. evansi in other domestic animals living together with dromedary camels, a study was conducted in the wilayate of Béchar, El Bayadh, Ouargla and Tamanrasset, between 2015 and 2017. Authorisation to conduct the survey was obtained from the Direction des Services Vétérinaires (DSV, Ministry of Agriculture, Rural Development and Fisheries). A total of 190 animals were sampled, including 42 cattle (Bos taurus), 11 dogs (Canis familiaris), 44 horses (Equus caballus), 3 donkeys (Equus asinus) and 1 mule, 49 goats (Capra hircus) and 40 sheep (Ovis aries). These animals were examined by parasitological (Giemsa stained thin smear, GST), serological (card agglutination test for trypanosomosis (CATT/T. evansi), enzyme-linked immunosorbent assay/Variant Surface Glycoprotein/Rode Trypanozoon antigen type 1.2 [ELISA/VSG RoTat 1.2], immune trypanolysis [TL]) and molecular tests (T. evansi type A specific RoTat 1.2 PCR). Results and Conclusions: The CATT/T. evansi was positive in 10/42 cattle, 0/11 dogs, 2/48 equids, 27/49 goats and 15/40 sheep. On the other hand, 20/38 cattle, 1/9 dogs, 21/42 equids, 17/44 goats and 31/39 sheep were positive in ELISA/VSG RoTat 1.2. However, no single animal was positive in TL. In addition, the T. evansi parasite could not be demonstrated by either GST or RoTat 1.2 PCR in any of the examined animals. This may suggest cross-reactions of CATT/T. evansi and ELISA/VSG RoTat 1.2 with other pathogenic or commensal trypanosome species such as T. vivax or other parasites. Based on these data, in particular taking into account the high specificity of the TL for T. evansi type A, this study does not support the hypothesis that T. evansi circulates in the studied domestic animal species and that they would act as reservoirs for the parasite that causes trypanosomosis in dromedary camels.

Parasitological, Serological and Molecular Prevalence of Trypanosoma evansi among Arabian Camels (Camelus dromedaries) with Evaluation of Antitrypanosomal Drugs

PURPOSE

This study was carried out to assess the prevalence of Trypanosoma evansi infection in naturally diseased Dromedary camels in Dammam, Eastern region of Saudi Arabia. The detection of Trypanosoma evansi was performed using the parasitological, serological, and molecular diagnosis and a comparison between such methods were analyzed. In addition, evaluation of therapeutic efficacy of selected antitrypanosomal drugs, cymelarsan and quinapyrmine (aquin-1.5), was trialed for treatment of diagnosed infected cases.

METHODS

A total 350 randomly selected camels were evaluated using thin blood smear (TBS), RoTat1.2 PCR and CATT/T. evansi techniques.

RESULTS

The total prevalence was 6.9%, 7.7%, and 32.8% by TBS, RoTat1.2 PCR and CATT/T. evansi techniques, respectively. Although PCR detect T. evansi in more samples than TBS, the agreement was good (K = 0.9). Among the CATT/T. evansi results, PCR detect T. evansi in 12 and 15 CATT positive and negative camels, respectively, with low agreement (Kappa = 0.1). The use of cymelarsan and quinapyramine sulfate in the treatment of naturally infected cases demonstrated a very efficient therapeutic response.

CONCLUSION

It was found that 1. Comparing the CATT/T. evansi and PCR results, the positivity of CATT was higher than PCR detection, while the agreement was poor (K = 0.1). 2. Cymelarsan and aquin-1.5 proved to be effective in the treatment of naturally infected camels, but cymelarsan presented with higher effectiveness (100%) than aquin-treated camels (83.3%). a 3. The use of cymelarsan and CATT is recommended for disease treatment and control.

Genotyping of Trypanosoma brucei evansi in Egyptian camels: detection of a different non-RoTat 1.2 Trypanosoma brucei evansi in Egyptian camels

Trypanosoma brucei evansi (T. b. evansi) is an enzootic organism found in Egyptian camels, which genetically classified into types A and B. To detect the parasite genotype circulating in Egyptian camels, we collected 94 blood samples from three distant districts and subjected them to different PCR assays; T. brucei repeat (TBR), internal transcribed spacer-1 (ITS-1), and variable surface glycoproteins (VSG) (RoTat 1. 2, JN 2118Hu) and EVAB PCRs. The highest prevalence was obtained with TBR (80/91; 87.9%), followed by ITS-1 (52/91; 57.1%), VSG JN 2118Hu (42/91; 46.2%), and VSG RoTat 1. 2 (34/91; 37.4%). We reported a different non-RoTat 1. 2 T. b. evansi for the first time in Egyptian camels. Results showed that 47 (58.7%) out of 80 samples were classified as T. b. evansi. Of these, 14 (29.8%) were RoTat 1. 2 type, 13 (27.6%) were non-RoTat 1. 2 type, and 20 (42.6%) samples were from mixed infection with both types. All samples were tested negative with EVAB PCR. RoTat 1. 2 T. b. evansi was the most prevalent in Giza and El Nubariyah, whereas, in Aswan, the only type detected was non-RoTat 1. 2 T. b. evansi. The nucleotide sequences of the VSG RoTat 1.2 and JN 2118Hu PCR products were submitted to DNA Data Bank of Japan (DDBJ) and GenBank under the accession numbers LC738852, and (OP800400-OP800403). Further research is required to increase the sample size and verify the new sequences to corroborate the prevalence of a new variant of non-RoTat 1.2 T. b. evansi in Egypt.

Trypanosoma lewisi in blood of Rattus rattus complex residing in human settlements, Nakhon Si Thammarat, Thailand: Microscopic and molecular investigations

Trypanosomes are blood parasites infected in various mammals, including rats. The presence of rats in human settlements can increase the chance of Trypanosoma transmission to humans. The molecular study of multispacer in Trypanosoma spp. in naturally infected rodents in Thailand is scanty. The objective of this study was to detect Trypanosoma in the blood of the captured rats in Nakhon Si Thammarat, Thailand, using microscopic and molecular techniques. This was a cross-sectional study conducted in human settlement areas. Ninety-nine blood samples were collected using cardiac puncture. A blood sample was smeared on a glass slide and examined using a compound light microscope and a scanning electron microscope. Moreover, polymerase chain reaction was applied to detect Trypanosoma evansi and T. lewisi in the blood. An additional primer set was used to confirm the species of the detected trypanosome. Approximately 18% of the rats had positive Trypanosoma infections. All Trypanosoma-positive blood samples were matched with sequences of T. lewisi. The stumpy form of trypanosome had higher nucleus related parameters than the slender form. Interestingly, the partial sequences of the alpha-tubulin gene of T. lewisi were first reported in the naturally infected RrC in this study. Based on the results obtained, T. lewisi biology, particularly the virulent components and route of transmission, pathogenesis, and in vitro experiments, are strongly recommended for further study.

Morphological, serological, molecular detection, and phylogenetic analysis of Trypanosoma evansi in horses of different regions in Iran

Trypanosoma evansi, the causative agent of "surra" is enzootic in Iran. The current study aimed to detect T. evansi in horses from different regions of Iran using morphological, serological, and molecular methods. In 2021, 400 blood samples were collected from horses in eight regions. Eighty horses showed clinical signs such as cachexia (n = 64), fever (n = 36), foot edema (n = 40), and abdominal edema (n = 32), and 320 horses appeared healthy. All samples from the studied regions were evaluated for the presence of trypanosomes using direct analysis of blood smears, mercuric chloride, and PCR-based tests. In total, 12% (95% CI: ± 3.1%), 21% (95% CI: ± 3.9%), and 21% (84) of animals were positive for Trypanosoma in microscopic, serologic, and molecular analyses, respectively. All animals positive for SSU rDNA PCR were from Qom, Semnan, and Golestan regions. Further molecular analyses on 84 PCR-positive horses revealed that 29 horses scored positive in PCR using primers of trypanozoon species and 5 scored positive in PCR using primers of Trypanosoma evansi type A. All samples (n = 5) were from Qom region. The 205-bp fragments of T. evansi RoTat 1.2VSG (accession numbers: ON017789-93) analyzed and compared to other isolates sequence from GenBank BLAST search. It has close similarities with isolates from Pakistan, Egypt, Malaysia, Kenya, and India. Data herein demonstrated that horses from Iran were at high risk of T. evansi infection. Comprehensive control programs, such as those based on the application of repellants and traps, and also, compliance with quarantine standards are recommended for minimizing the risk of the infection.

PAG3 promotes the differentiation of bloodstream forms in Trypanosoma brucei and reveals the evolutionary relationship among the Trypanozoon trypanosomes

Introduction

Trypanosoma brucei, T. evansi and T. equiperdum are members of the subgenus Trypanozoon and are highly similar morphologically and genetically. The main differences between these three species are their differentiation patterns in the hosts and the role of vectors in their life cycles. However, the mechanisms causing these differences are still controversial.

Methods

PAG3 gene was accessed by PCR amplification in 26 strains of Trypanozoon and sequences were then analyzed by BLAST accompanied with T. evansitype B group. RNA interference and CRISPR/Cas9 were used for revealing possible role of PAG3 in slender to stumpy transformation.

Results

The procyclin associated gene 3 (PAG3) can be found in the pleomorphicspecies, T.brucei, which undergoes differentiation of slender forms to the stumpy form. This differentiation process is crucial for transmission to the tsetse fly vector. However, a homologue of PAG3 was not detected in either T. evansi or in the majority of T. equiperdum strains which are allmonomorphic. Furthere xperiments in T. brucei demonstrated that, when PAG3 was down-regulated or absent, there was a significant reduction in the differentiation from slender to stumpy forms.

Conclusion

Therefore, we conclude that PAG3 is a key nuclear gene involved in the slender to stumpy differentiation pathway of T.brucei in the mammalian host. Loss of this gene might also offer a simple evolutionary mechanism explaining why T. evansi and some T. equiperdum have lost the ability to differentiate and have been driven to adapt to transmission cycles that by pass the tsetse vector or mechanical contact.

Diagnosis of animal trypanosomoses: proper use of current tools and future prospects

Reliable diagnostic tools are needed to choose the appropriate treatment and proper control measures for animal trypanosomoses, some of which are pathogenic. Trypanosoma cruzi, for example, is responsible for Chagas disease in Latin America. Similarly, pathogenic animal trypanosomoses of African origin (ATAO), including a variety of Trypanosoma species and subspecies, are currently found in Africa, Latin America and Asia. ATAO limit global livestock productivity and impact food security and the welfare of domestic animals. This review focusses on implementing previously reviewed diagnostic methods, in a complex epizootiological scenario, by critically assessing diagnostic results at the individual or herd level. In most cases, a single diagnostic method applied at a given time does not unequivocally identify the various parasitological and disease statuses of a host. These include "non-infected", "asymptomatic carrier", "sick infected", "cured/not cured" and/or "multi-infected". The diversity of hosts affected by these animal trypanosomoses and their vectors (or other routes of transmission) is such that integrative, diachronic approaches are needed that combine: (i) parasite detection, (ii) DNA, RNA or antigen detection and (iii) antibody detection, along with epizootiological information. The specificity of antibody detection tests is restricted to the genus or subgenus due to cross-reactivity with other Trypanosoma spp. and Trypanosomatidae, but sensitivity is high. The DNA-based methods implemented over the last three decades have yielded higher specificity and sensitivity for active infection detection in hosts and vectors. However, no single diagnostic method can detect all active infections and/or trypanosome species or subspecies. The proposed integrative approach will improve the prevention, surveillance and monitoring of animal trypanosomoses with the available diagnostic tools. However, further developments are required to address specific gaps in diagnostic methods and the sustainable control or elimination of these diseases.

Molecular Analysis of Trypanosome Infections in Algerian Camels

PURPOSE

Surra is an economically important livestock disease in many low- and middle-income countries, including those of Northern Africa. The disease is caused by the biting fly-transmitted subspecies Trypanosoma brucei evansi, which is very closely related to the tsetse-transmitted subspecies T. b. brucei and the sexually transmitted subspecies T. b. equiperdum. At least two phylogenetically distinct groups of T. b. evansi can be distinguished, called type A and type B. These evolved from T. b. brucei independently. The close relationships between the T. brucei subspecies and the multiple evolutionary origins of T. b. evansi pose diagnostic challenges.

METHODS

Here we use previously established and newly developed PCR assays based on nuclear and mitochondrial genetic markers to type the causative agent of recent trypanosome infections of camels in Southern Algeria.

RESULTS/CONCLUSION

We confirm that these infections have been caused by T. b. evansi type A. We also report a newly designed PCR assay specific for T. b. evansi type A that we expect will be of diagnostic use for the community.

Genetic connectivity of trypanosomes between tsetse-infested and tsetse-free areas of Kenya

The prevalence rates of trypanosomes, including those that require cyclical transmission by tsetse flies, are widely distributed in Africa. Trypanosoma brucei and Trypanosoma congolense are actively maintained in regions where there are no tsetse flies although at low frequencies. Whether this could be due to an independent evolutionary origin or multiple introduction of trypanosomes due to continuous movement of livestock between tsetse-free and -infested areas is not known. Thus, the aim of the study was to carry out microsatellite genotyping to explore intra-specific genetic diversity between T. (Trypanozoon), T. congolense and Trypanosoma vivax from the two regions: tsetse infested and tsetse free. Microsatellite genotyping showed geographical origin-based structuring among T. (Trypanozoon) isolates. There was a clear separation between isolates from the two regions signalling the potential of microsatellite markers as diagnostic markers for T. brucei and Trypanosoma evansi isolates. Trypanosoma vivax isolates also clustered largely based on the sampling location with a significant differentiation between the two locations. However, our results revealed that T. congolense isolates from Northern Kenya are not genetically separated from those from Coastal Kenya. Therefore, these isolates are likely introduced in the region through animal movement. Our results demonstrate the occurrence of both genetic connectivity as well as independent evolutionary origin, depending on the trypanosome species between the two ecologies.

A review on the diagnosis of animal trypanosomoses

This review focuses on the most reliable and up-to-date methods for diagnosing trypanosomoses, a group of diseases of wild and domestic mammals, caused by trypanosomes, parasitic zooflagellate protozoans mainly transmitted by insects. In Africa, the Americas and Asia, these diseases, which in some cases affect humans, result in significant illness in animals and cause major economic losses in livestock. A number of pathogens are described in this review, including several Salivarian trypanosomes, such as Trypanosoma brucei sspp. (among which are the agents of sleeping sickness, the human African trypanosomiasis [HAT]), Trypanosoma congolense and Trypanosoma vivax (causing “Nagana” or animal African trypanosomosis [AAT]), Trypanosoma evansi (“Surra”) and Trypanosoma equiperdum (“Dourine”), and Trypanosoma cruzi, a Stercorarian trypanosome, etiological agent of the American trypanosomiasis (Chagas disease). Diagnostic methods for detecting zoonotic trypanosomes causing Chagas disease and HAT in animals, as well as a diagnostic method for detecting animal trypanosomes in humans (the so-called “atypical human infections by animal trypanosomes” [a-HT]), including T. evansi and Trypanosoma lewisi (a rat parasite), are also reviewed. Our goal is to present an integrated view of the various diagnostic methods and techniques, including those for: (i) parasite detection; (ii) DNA detection; and (iii) antibody detection. The discussion covers various other factors that need to be considered, such as the sensitivity and specificity of the various diagnostic methods, critical cross-reactions that may be expected among Trypanosomatidae, additional complementary information, such as clinical observations and epizootiological context, scale of study and logistic and cost constraints. The suitability of examining multiple specimens and samples using several techniques is discussed, as well as risks to technicians, in the context of specific geographical regions and settings. This overview also addresses the challenge of diagnosing mixed infections with different Trypanosoma species and/or kinetoplastid parasites. Improving and strengthening procedures for diagnosing animal trypanosomoses throughout the world will result in a better control of infections and will significantly impact on “One Health,” by advancing and preserving animal, human and environmental health.

Signatures of hybridization in Trypanosoma brucei

Genetic exchange among disease-causing micro-organisms can generate progeny that combine different pathogenic traits. Though sexual reproduction has been described in trypanosomes, its impact on the epidemiology of Human African Trypanosomiasis (HAT) remains controversial. However, human infective and non-human infective strains of Trypanosoma brucei circulate in the same transmission cycles in HAT endemic areas in subsaharan Africa, providing the opportunity for mating during the developmental cycle in the tsetse fly vector. Here we investigated inheritance among progeny from a laboratory cross of T. brucei and then applied these insights to genomic analysis of field-collected isolates to identify signatures of past genetic exchange. Genomes of two parental and four hybrid progeny clones with a range of DNA contents were assembled and analysed by k-mer and single nucleotide polymorphism (SNP) frequencies to determine heterozygosity and chromosomal inheritance. Variant surface glycoprotein (VSG) genes and kinetoplast (mitochondrial) DNA maxi- and minicircles were extracted from each genome to examine how each of these components was inherited in the hybrid progeny. The same bioinformatic approaches were applied to an additional 37 genomes representing the diversity of T. brucei in subsaharan Africa and T. evansi. SNP analysis provided evidence of crossover events affecting all 11 pairs of megabase chromosomes and demonstrated that polyploid hybrids were formed post-meiotically and not by fusion of the parental diploid cells. VSGs and kinetoplast DNA minicircles were inherited biparentally, with approximately equal numbers from each parent, whereas maxicircles were inherited uniparentally. Extrapolation of these findings to field isolates allowed us to distinguish clonal descent from hybridization by comparing maxicircle genotype to VSG and minicircle repertoires. Discordance between maxicircle genotype and VSG and minicircle repertoires indicated inter-lineage hybridization. Significantly, some of the hybridization events we identified involved human infective and non-human infective trypanosomes circulating in the same geographic areas.

Occurrence, diversity and distribution of Trypanosoma infections in cattle around the Akagera National Park, Rwanda

BACKGROUND

African Trypanosomiases threaten the life of both humans and animals. Trypanosomes are transmitted by tsetse and other biting flies. In Rwanda, the African Animal Trypanosomiasis (AAT) endemic area is mainly around the tsetse-infested Akagera National Park (NP). The study aimed to identify Trypanosoma species circulating in cattle, their genetic diversity and distribution around the Akagera NP.

METHODOLOGY

A cross-sectional study was carried out in four districts, where 1,037 cattle blood samples were collected. The presence of trypanosomes was determined by microscopy, immunological rapid test VerY Diag and PCR coupled with High-Resolution Melt (HRM) analysis. A parametric test (ANOVA) was used to compare the mean Packed cell Volume (PCV) and trypanosomes occurrence. The Cohen Kappa test was used to compare the level of agreement between the diagnostic methods.

FINDINGS

The overall prevalence of trypanosome infections was 5.6%, 7.1% and 18.7% by thin smear, Buffy coat technique and PCR/HRM respectively. Microscopy showed a low sensitivity while a low specificity was shown by the rapid test (VerY Diag). Trypanosoma (T.) congolense was found at a prevalence of 10.7%, T. vivax 5.2%, T. brucei brucei 2% and T. evansi 0.7% by PCR/HRM. This is the first report of T.evansi in cattle in Rwanda. The non-pathogenic T. theileri was also detected. Lower trypanosome infections were observed in Ankole x Friesian breeds than indigenous Ankole. No human-infective T. brucei rhodesiense was detected. There was no significant difference between the mean PCV of infected and non-infected animals (p>0.162).

CONCLUSIONS

Our study sheds light on the species of animal infective trypanosomes around the Akagera NP, including both pathogenic and non-pathogenic trypanosomes. The PCV estimation is not always an indication of trypanosome infection and the mechanical transmission should not be overlooked. The study confirms that the area around the Akagera NP is affected by AAT, and should, therefore, be targeted by the control activities. AAT impact assessment on cattle production and information on the use of trypanocides are needed to help policymakers prioritise target areas and optimize intervention strategies. Ultimately, these studies will allow Rwanda to advance in the Progressive Control Pathway (PCP) to reduce or eliminate the burden of AAT.

Single nucleotide polymorphisms and copy-number variations in the Trypanosoma brucei repeat (TBR) sequence can be used to enhance amplification and genotyping of Trypanozoon strains

The Trypanosoma brucei repeat (TBR) is a tandem repeat sequence present on the Trypanozoon minichromosomes. Here, we report that the TBR sequence is not as homogenous as previously believed. BLAST analysis of the available T. brucei genomes reveals various TBR sequences of 177 bp and 176 bp in length, which can be sorted into two TBR groups based on a few key single nucleotide polymorphisms. Conventional and quantitative PCR with primers matched to consensus sequences that target either TBR group show substantial copy-number variations in the TBR repertoire within a collection of 77 Trypanozoon strains. We developed the qTBR, a novel PCR consisting of three primers and two probes, to simultaneously amplify target sequences from each of the two TBR groups into one single qPCR reaction. This dual probe setup offers increased analytical sensitivity for the molecular detection of all Trypanozoon taxa, in particular for T.b. gambiense and T. evansi, when compared to existing TBR PCRs. By combining the qTBR with 18S rDNA amplification as an internal standard, the relative copy-number of each TBR target sequence can be calculated and plotted, allowing for further classification of strains into TBR genotypes associated with East, West or Central Africa. Thus, the qTBR takes advantage of the single-nucleotide polymorphisms and copy number variations in the TBR sequences to enhance amplification and genotyping of all Trypanozoon strains, making it a promising tool for prevalence studies of African trypanosomiasis in both humans and animals.

Salivarian Trypanosomes Have Adopted Intricate Host-Pathogen Interaction Mechanisms That Ensure Survival in Plain Sight of the Adaptive Immune System

Salivarian trypanosomes are extracellular parasites affecting humans, livestock and game animals. Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense are human infective sub-species of T. brucei causing human African trypanosomiasis (HAT—sleeping sickness). The related T. b. brucei parasite lacks the resistance to survive in human serum, and only inflicts animal infections. Animal trypanosomiasis (AT) is not restricted to Africa, but is present on all continents. T. congolense and T. vivax are the most widespread pathogenic trypanosomes in sub-Saharan Africa. Through mechanical transmission, T. vivax has also been introduced into South America. T. evansi is a unique animal trypanosome that is found in vast territories around the world and can cause atypical human trypanosomiasis (aHT). All salivarian trypanosomes are well adapted to survival inside the host’s immune system. This is not a hostile environment for these parasites, but the place where they thrive. Here we provide an overview of the latest insights into the host-parasite interaction and the unique survival strategies that allow trypanosomes to outsmart the immune system. In addition, we review new developments in treatment and diagnosis as well as the issues that have hampered the development of field-applicable anti-trypanosome vaccines for the implementation of sustainable disease control.

Exploring Prokaryotic and Eukaryotic Microbiomes Helps in Detecting Tick-Borne Infectious Agents in the Blood of Camels

Dromedary camels (Camelus dromedarius) are widely distributed in Africa, the Middle East and northern India. In this study, we aimed to detect tick-borne pathogens through investigating prokaryotic and eukaryotic microorganisms in camel blood based on a metagenomic approach and then to characterize potentially pathogenic organisms using traditional molecular techniques. We showed that the bacteria circulating in the blood of camels is dominated by Proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria. At the genus level, Sediminibacterium, Hydrotalea, Bradyrhizobium and Anaplasma were the most abundant taxa. Eukaryotic profile was dominated by Fungi, Charophyta and Apicomplexa. At the genus level, Theileria was detected in 10 out of 18 samples, while Sarcocystis, Hoplorhynchus and Stylocephalus were detected in one sample each. Our metagenomic approach was successful in the detection of several pathogens or potential pathogens including Anaplasma sp., Theileria ovis, Th. separata, Th. annulate, Th. mutans-like and uncharacterized Theileria sp. For further characterization, we provided the partial sequences of citrate synthase (gltA) and heat-shock protein (groEL) genes of Candidatus Anaplasma camelii. We also detected Trypanosoma evansi type A using polymerase chain reaction (PCR) targeting the internal transcribed spacer 1 (ITS1) region. This combined metagenomic and traditional approach will contribute to a better understanding of the epidemiology of pathogens including tick-borne bacteria and protozoa in animals.

Development of a loop-mediated isothermal amplification assay based on RoTat1.2 gene for detection of Trypanosoma evansi in domesticated animals

The early containment of trypanosomosis depends on early, sensitive, and accurate diagnosis in endemic areas with low-intensity infections. The study was planned to develop a simple read out loop-mediated isothermal amplification (LAMP) assay targeting a partial RoTat1.2 VSG gene of Trypanosoma evansi with naked eye visualization of LAMP products by adding SYBR® Green I dye. The visual results were further confirmed with those of agarose gel electrophoresis, restriction enzyme digestion of LAMP products with AluI, and sequencing of the PCR products using LAMP outer primers. The LAMP primers did not show cross reactivity and non-specific reactions with regional common hemoparasitic DNA revealing high specificity of the assay. The threshold sensitivity level of the LAMP assay was determined to be 0.003 fg compared to 0.03 fg RoTat1.2 amplified DNA fragments of T. evansi by PCR assay. Moreover, assessment of 500 blood samples collected from unhealthy domestic animals in field suspected for various hemoparasitic infections was carried out for the presence of T. evansi by microscopy, RoTat1.2 VSG PCR, and LAMP assay. LAMP could detect T. evansi in 36 samples, while PCR and microscopy could detect 33 and 12 samples, respectively. All the samples positive by microscopy and PCR were also confirmed positive by the LAMP assay. The current LAMP assay has appealing point of care characteristics to visually monitor the results, lessen the need of post DNA amplification procedure, and enable this method to be applied as a rapid and sensitive molecular diagnostic tool in under resourced laboratories and field setup.

A case of Trypanosoma evansi in a German Shepherd dog in Vietnam

A 2.5-year-old male German Shepherd was presented to a private veterinary clinic in Hanoi, Vietnam showing anorexia, weakness, lethargy, reluctant to go for walks with a recent history of intermittent fever. Clinical examination of the dog showed pale mucous membrane, impaired eyesight, edema of the back legs. Complete blood count revealed severe anemia; red blood cell 3.8 × 10¹²/l, hemoglobin 8.7 g/dl, hematocrit 26.4%, associated with thrombocytopenia 145 × 10⁹/l. Biochemical analysis showed a moderate increase of alanine transaminase (150.7 UI/l) and alkaline phosphatase activities (266 UI/I) with mild hypoglycemia (71.46 mg/dl). Trypanosoma evansi was observed in Giemsa-stained blood smears under microscopic observation which was confirmed by PCR. This is the first report of canine trypanosomiasis caused by T. evansi in Vietnam.

Zoonotic Pathogens of Dromedary Camels in Kenya: A Systematised Review

Kenya is home to Africa’s third largest population of dromedary camels, and production at commercial and local levels are increasingly important. In pastoral and nomadic communities in the arid and semi-arid lands (ASALs), camels play a vital role in food security, while commercial milk production and formalized export markets are rapidly emerging as camel populations expand into non-traditional areas. Until recently, little focus was placed on camels as hosts of zoonotic disease, but the emergence of Middle Eastern respiratory coronavirus (MERS-CoV) in 2012, and the discovery of exposure to the virus in Kenyan camels, highlighted the need for further understanding of this area. This systematised review utilised a robust search strategy to assess the occurrence of camel-associated zoonoses in Kenya and to evaluate the quality of the published literature. Seventy-four studies were identified, covering sixteen pathogens, with an increasing number of good quality studies in recent years. Despite this, the area remains under-researched and there is a lack of robust, high-quality research. Trypanosome spp., Echinococcus granulosus and Brucella spp. appeared most frequently in the literature. Pathogens with the highest reported prevalence were MERS-CoV (0–100%), Echinococcus granulosa (7–60%) and Rift Valley fever virus (7–57%). Exposure to Brucella spp., Coxiella burnetii and Crimean-Congo haemorrhagic fever virus showed higher levels in camel or camel-associated vectors than other livestock species, although brucellosis was the only disease for which there was robust evidence linking camel and human exposure. Zoonotic agents with less severe human health outcomes, such as Dermatophilosus congolensis and contagious ecthyma, were also represented in the literature. This review provides an important summary of the scope and quality of current knowledge. It demonstrates that further research, and improved adherence to robust study design and reporting are essential if the zoonotic risk from camels in Kenya, and elsewhere, is to be better understood.

An Unbiased Immunization Strategy Results in the Identification of Enolase as a Potential Marker for Nanobody-Based Detection of Trypanosoma evansi

Trypanosoma evansi is a widely spread parasite that causes the debilitating disease “surra” in several types of ungulates. This severely challenges livestock rearing and heavily weighs on the socio-economic development in the affected areas, which include countries on five continents. Active case finding requires a sensitive and specific diagnostic test. In this paper, we describe the application of an unbiased immunization strategy to identify potential biomarkers for Nanobody (Nb)-based detection of T. evansi infections. Alpaca immunization with soluble lysates from different T. evansi strains followed by panning against T. evansi secretome resulted in the selection of a single Nb (Nb11). By combining Nb11-mediated immuno-capturing with mass spectrometry, the T. evansi target antigen was identified as the glycolytic enzyme enolase. Four additional anti-enolase binders were subsequently generated by immunizing another alpaca with the recombinant target enzyme. Together with Nb11, these binders were evaluated for their potential use in a heterologous sandwich detection format. Three Nb pairs were identified as candidates for the further development of an antigen-based assay for Nb-mediated diagnosis of T. evansi infection.

Comparison of serological and molecular tests for detection of Trypanosoma evansi in domestic animals from Ghardaïa district, South Algeria

Trypanosoma evansi (T. evansi) is a hemoflagellate parasite that affects a broad range of mammalian hosts and that causes a disease called surra. Diagnosis of surra based on clinical symptoms alone is inaccurate. Therefore, a variety of serological and molecular diagnostic tests are used to assist in the detection of T. evansi infections. The aim of this study was to compare the diagnostic performance of four serological tests (CATT/T.evansi, immune trypanolysis, ELISA with purified variant surface glycoprotein RoTat 1.2 and with whole cell lysate) and two molecular PCR tests targeting sequences within the ribosomal genes locus (ITS1 TD PCR and 18S qPCR). Tests were carried out on blood samples from 161 dromedary camels, 93 horses, 129 goats, 168 sheep, 127 bovines and 76 dogs. Latent class analysis was carried out to calculate the sensitivity and specificity of each diagnostic test. Cohen's Kappa test was used to assess the concordance between the different diagnostic tests. Overall positivity rates observed with the serological tests were as follows: 3.1 % with CATT/T.evansi, 4.9 % with ELISA/RoTat 1.2, 3.4 % with ELISA/whole lysate and 2.0 % with immune trypanolysis (TL). Among the 754 samples tested with the molecular tests, 1.7 % were positive with 18S qPCR and 1.3 % with ITS1 TD PCR. Cohen's Kappa test showed agreement ranging from fair to substantial (k = 0.2-0.8) between serological diagnostic tests. However, it showed a perfect agreement (k = 0.868) between molecular diagnostic tests. Latent class analysis showed that all serological tests were 100 % sensitive, in contrast to the molecular tests with 47 % sensitivity. All tests, though, were highly specific (≥ 97 %). Given the persistence of circulating antibodies after cure, detectable by serological tests, it is recommend combining a serological and a molecular diagnostic test for accurate diagnosis of infection with T. evansi in domestic animals.

Development of a recombinase polymerase amplification lateral flow assay for the detection of active Trypanosoma evansi infections

BACKGROUND

Animal trypanosomosis caused by Trypanosoma evansi is known as "surra" and is a widespread neglected tropical disease affecting wild and domestic animals mainly in South America, the Middle East, North Africa and Asia. An essential necessity for T. evansi infection control is the availability of reliable and sensitive diagnostic tools. While DNA-based PCR detection techniques meet these criteria, most of them require well-trained and experienced users as well as a laboratory environment allowing correct protocol execution. As an alternative, we developed a recombinase polymerase amplification (RPA) test for Type A T. evansi. The technology uses an isothermal nucleic acid amplification approach that is simple, fast, cost-effective and is suitable for use in minimally equipped laboratories and even field settings.

METHODOLOGY/PRINCIPLE FINDINGS

An RPA assay targeting the T. evansi RoTat1.2 VSG gene was designed for the DNA-based detection of T. evansi. Comparing post-amplification visualization by agarose gel electrophoresis and a lateral flow (LF) format reveals that the latter displays a higher sensitivity. The RPA-LF assay is specific for RoTat1.2-expressing strains of T. evansi as it does not detect the genomic DNA of other trypanosomatids. Finally, experimental mouse infection trials demonstrate that the T. evansi specific RPA-LF can be employed as a test-of-cure tool.

CONCLUSIONS/SIGNIFICANCE

Compared to other DNA-based parasite detection methods (such as PCR and LAMP), the T. evansi RPA-LF (TevRPA-LF) described in this paper is an interesting alternative because of its simple read-out (user-friendly), short execution time (15 minutes), experimental sensitivity of 100 fg purified genomic T. evansi DNA, and ability to be carried out at a moderate, constant temperature (39°C). Therefore, the TevRPA-LF is an interesting tool for the detection of active T. evansi infections.

Epidemiological investigations on Trypanosoma evansi infection in dromedary camels in the South of Algeria

An epidemiological study of Trypanosoma evansi (T. evansi) infection in dromedaries was conducted in four wilayate (localities) of Southern Algeria: Béchar, El Bayadh, Ouargla, Tamanrasset. Between February 2014 and April 2016, 1056 camels of different ages and both sexes from 84 herds were sampled. The prevalence was determined through parasitological examination (Giemsa stained thin smear, GST), serological tests (CATT/T. evansi, ELISA/VSG RoTat 1.2, immune trypanolysis), and molecular tests (T. evansi type A specific RoTat 1.2 PCR and T. evansi type B specific EVAB PCR). The overall prevalence was 2.4 % with GST, 32.4% with CATT/T. evansi, 23.1% with ELISA/VSG RoTat 1.2, 21.0% with immune trypanolysis (TL), 11.2 % with RoTat 1.2 PCR and 0% with EVAB PCR. El Bayadh was the most affected wilaya with 11.8% positives in GST, 74.9% in CATT/T. evansi, 70.1% in ELISA/VSG RoTat 1.2 and 62.2% in immune trypanolysis. Only in Béchar, a non-significantly higher prevalence (13.6%) was observed with RoTat1.2 PCR than in El Bayadh (13.0%). We didn't find any evidence of the presence of T. evansi type B in the study area.

Equine trypanosomosis: enigmas and diagnostic challenges

Equine trypanosomosis is a complex of infectious diseases called dourine, nagana and surra. It is caused by several species of the genus Trypanosoma that are transmitted cyclically by tsetse flies, mechanically by other haematophagous flies, or sexually. Trypanosoma congolense (subgenus Nannomonas) and T. vivax (subgenus Dutonella) are genetically and morphologically distinct from T. brucei, T. equiperdum and T. evansi (subgenus Trypanozoon). It remains controversial whether the three latter taxa should be considered distinct species. Recent outbreaks of surra and dourine in Europe illustrate the risk and consequences of importation of equine trypanosomosis with infected animals into non-endemic countries. Knowledge on the epidemiological situation is fragmentary since many endemic countries do not report the diseases to the World Organisation for Animal Health, OIE. Other major obstacles to the control of equine trypanosomosis are the lack of vaccines, the inability of drugs to cure the neurological stage of the disease, the inconsistent case definition and the limitations of current diagnostics. Especially in view of the ever-increasing movement of horses around the globe, there is not only the obvious need for reliable curative and prophylactic drugs but also for accurate diagnostic tests and algorithms. Unfortunately, clinical signs are not pathognomonic, parasitological tests are not sufficiently sensitive, serological tests miss sensitivity or specificity, and molecular tests cannot distinguish the taxa within the Trypanozoon subgenus. To address the limitations of the current diagnostics for equine trypanosomosis, we recommend studies into improved molecular and serological tests with the highest possible sensitivity and specificity. We realise that this is an ambitious goal, but it is dictated by needs at the point of care. However, depending on available treatment options, it may not always be necessary to identify which trypanosome taxon is responsible for a given infection.

A single test approach for accurate and sensitive detection and taxonomic characterization of Trypanosomes by comprehensive analysis of internal transcribed spacer 1 amplicons

To improve our knowledge on the epidemiological status of African trypanosomiasis, better tools are required to monitor Trypanosome genotypes circulating in both mammalian hosts and tsetse fly vectors. This is important in determining the diversity of Trypanosomes and understanding how environmental factors and control efforts affect Trypanosome evolution. We present a single test approach for molecular detection of different Trypanosome species and subspecies using newly designed primers to amplify the Internal Transcribed Spacer 1 region of ribosomal RNA genes, coupled to Illumina sequencing of the amplicons. The protocol is based on Illumina's widely used 16s bacterial metagenomic analysis procedure that makes use of multiplex PCR and dual indexing. Results from analysis of wild tsetse flies collected from Zambia and Zimbabwe show that conventional methods for Trypanosome species detection based on band size comparisons on gels is not always able to accurately distinguish between T. vivax and T. godfreyi. Additionally, this approach shows increased sensitivity in the detection of Trypanosomes at species level with the exception of the Trypanozoon subgenus. We identified subspecies of T. congolense, T. simiae, T. vivax, and T. godfreyi without the need for additional tests. Results show T. congolense Kilifi subspecies is more closely related to T. simiae than to other T. congolense subspecies. This agrees with previous studies using satellite DNA and 18s RNA analysis. While current classification does not list any subspecies for T. godfreyi, we observed two distinct clusters for these species. Interestingly, sequences matching T. congolense Tsavo (now classified as T. simiae Tsavo) clusters distinctly from other T. simiae Tsavo sequences suggesting the Nannomonas group is more divergent than currently thought thus the need for better classification criteria. This method presents a simple but comprehensive way of identification of Trypanosome species and subspecies-specific using one PCR assay for molecular epidemiology of trypanosomes.

Molecular characterization and phylogenetic analysis of Trypanosoma evansi from Northern India based on 18S ribosomal gene

Six Trypanosoma evansi isolates were collected from ponies (PH1 and PK6), camel (CB2), donkeys (DJ3 and DH4) and cattle (CK5) from different States of Northern India (Haryana, Rajasthan, Uttar Pradesh and Gujarat) for molecular characterization based on 18S rRNA gene. The 18S rRNA gene (2251 bp) of different isolates was amplified, cloned and custom sequenced separately. Based on sequence and phylogenetic analysis of all six isolates, collected from different hosts as well as geographical areas, were having high identity among Indian T. evansi strains (99.7%) and with other strains of T. evansi (99.2%) distributed worldwide. There is less genetic diversity among different salivarian strains of T. evansi except few nucleotide changes at significant locations in one Indian isolate of camel origin (CB2). All Indian T. evansi isolates were grouped in salivarian clade with high bootstrap values and remained far away from stercorarian clade having 88-90% nucleotide identity. The study will be helpful in understanding the evolutionary relationship, molecular epidemiology and variation in disease pathogenesis among different T. evansi strains. Further, more studies are required on large number of isolates collected from diverse host and geographical areas to reaffirm the present finding.

Isometamidium chloride and homidium chloride fail to cure mice infected with Ethiopian Trypanosoma evansi type A and B

Background

Trypanosoma evansi is mechanically transmitted by biting flies and affects camels, equines, and other domestic and wild animals in which it causes a disease called surra. At least two types of Trypanosoma evansi circulate in Ethiopia: type A, which is present in Africa, Latin America and Asia, and type B, which is prevalent in Eastern Africa. Currently, no information is available about the drug sensitivity of any Ethiopian T. evansi type.

Methodology/principal findings

This study was conducted with the objective of determining the in vivo drug sensitivity of two T. evansi type A and two type B stocks that were isolated from camels from the Tigray and Afar regions of Northern Ethiopia. We investigated the efficacy of four trypanocidal drugs to cure T. evansi infected mice: melarsamine hydrochloride (Cymelarsan), diminazene diaceturate (Veriben and Sequzene), isometamidium chloride (Veridium) and homidium chloride (Bovidium). Per experimental group, 6 mice were inoculated intraperitoneally with trypanosomes, treated at first peak parasitemia by daily drug injections for 4 consecutive days and followed-up for 60 days. Cymelarsan at 2 mg/kg and Veriben at 20 mg/kg cured all mice infected with any T. evansi stock, while Sequzene at 20 mg/kg caused relapses in all T. evansi stocks. In contrast, Veridium and Bovidium at 1 mg/kg failed to cure any T. evansi infection in mice.

Conclusions/significance

We conclude that mice infected with Ethiopian T. evansi can be cured with Cymelarsan and Veriben regardless of T. evansi type. In contrast, Veridium and Bovidium are not efficacious to cure any T. evansi type. Although innate resistance to phenanthridines was previously described for T. evansi type A, this report is the first study to show that this phenomenom also occurs in T. evansi type B infections.

Surra is a vector borne disease in camels, horses, water buffaloes, cattle and other domestic animals caused by Trypanosoma (T.) evansi. This protozoan parasite is transmitted by biting flies such as tabanids and stable flies and is endemic in many countries in Northern and Eastern Africa, Latin America and Asia. Surra is responsible for high economic losses due to mortality and morbidity of draught animals and leads to animal trade restrictions in endemic regions. Control of surra is mainly based on the treatment of sick animals presenting clinical symptoms. In Ethiopia two different types of T. evansi (A and B) have been described, yet no data existed about the drug sensitivity of any T. evansi type. In this study, we show for the first time that T. evansi type B is naturally in vivo resistant to the phenanthridine class of trypanocidal drugs, a phenonomen that was previously described for T. evansi type A. All Ethiopian T. evansi types are sensitive to melarsamine hydrochloride and diminazene diaceturate. Unfortunately, the most efficacious drugs are either not registered in Ethiopia or escape quality control of the active substance in commercial drug formulations. Furthermore, the inefficacious drugs remain accessible on the market despite their toxicity for animals.

Development and validation of direct dry loop mediated isothermal amplification for diagnosis of Trypanosoma evansi

Non-tsetse transmitted Trypanosoma evansi infection (Surra) is one of the most important diseases of camels in north and east Africa and of buffalo and cattle in Asia. Early, accurate and feasible diagnosis is a crucial step towards the control of Surra. Dry format of loop-mediated isothermal amplification (LAMP) diagnostics for the detection of T. evansi was developed, where the detection limit was determined as to equivalent to one parasite per reaction. The assay was validated by testing blood from 48 camels clinically diagnosed to have Surra, which all tested negative microscopically and revealed 43 (89.6%) to be positive for T. evansi when tested by the dry-LAMP. Furthermore, DNA extracted from a randomly selected subset of 20 of these blood samples were then subjected to RoTat1.2-PCR (TaKara Ex Taq), with 14 matching results, with six that were positive by dry-LAMP and negative by PCR. The kappa value of dry-LAMP applied to direct blood was 0.4211, indicating moderate agreement to RoTat 1.2-PCR. In addition, 103 genomic DNA extracted from camels' blood were tested by both dry-LAMP and RoTat1.2-PCR revealed 67 matching results and 31 positive by dry-LAMP and negative by PCR and a further five positives by PCR and negative by dry-LAMP. This novel dry-LAMP method is more sensitive than conventional PCR, direct (without DNA extraction step), is user friendly and does not require cold chain or highly trained personnel.

Parasitological and Molecular Detection of Canine Trypanosomiasis From Riyadh Province, Saudi Arabia

Trypanosoma evansi is the most widespread of the pathogenic salivarian trypanosomes; it causes a serious disease called surra that affects domestic animals such as camels, horses, and dogs, and often leads to reduced productivity and economic losses. Therefore, the objectives of the present study were to determine the prevalence rates of trypanosomiasis using 3 parasitological tests (wet blood film, Giemsa staining, and microhematocrit centrifugation technique) and polymerase chain reaction (PCR) among stray dogs from Riyadh Province, Saudi Arabia. In the current study, 117 dog blood samples collected from certain districts of Riyadh Province showed that 5 of 117 dogs (4.3%) were positive for the genus Trypanosoma. In addition, the findings indicated no effect of dog gender or age on parasite infection. For a more specific diagnosis, PCR amplification of the RoTat 1.2 VSG gene in 5 internal transcribed spacer1-positive samples diagnosed with Trypanosoma indicated that 2 were positive for RoTat 1.2 T. evansi. The absence of the RoTat 1.2 VSG gene in 3 of the 5 T. evansi-positive samples could be explained by the circulation of T. evansi type B in dogs from Saudi Arabia. Thus, this is the first study demonstrating T. evansi type B outside of Africa.

Mitochondrial DNA is critical for longevity and metabolism of transmission stage Trypanosoma brucei

The sleeping sickness parasite Trypanosoma brucei has a complex life cycle, alternating between a mammalian host and the tsetse fly vector. A tightly controlled developmental programme ensures parasite transmission between hosts as well as survival within them and involves strict regulation of mitochondrial activities. In the glucose-rich bloodstream, the replicative 'slender' stage is thought to produce ATP exclusively via glycolysis and uses the mitochondrial F1FO-ATP synthase as an ATP hydrolysis-driven proton pump to generate the mitochondrial membrane potential (ΔΨm). The 'procyclic' stage in the glucose-poor tsetse midgut depends on mitochondrial catabolism of amino acids for energy production, which involves oxidative phosphorylation with ATP production via the F1FO-ATP synthase. Both modes of the F1FO enzyme critically depend on FO subunit a, which is encoded in the parasite's mitochondrial DNA (kinetoplast or kDNA). Comparatively little is known about mitochondrial function and the role of kDNA in non-replicative 'stumpy' bloodstream forms, a developmental stage essential for disease transmission. Here we show that the L262P mutation in the nuclear-encoded F1 subunit γ that permits survival of 'slender' bloodstream forms lacking kDNA ('akinetoplastic' forms), via FO-independent generation of ΔΨm, also permits their differentiation into stumpy forms. However, these akinetoplastic stumpy cells lack a ΔΨm and have a reduced lifespan in vitro and in mice, which significantly alters the within-host dynamics of the parasite. We further show that generation of ΔΨm in stumpy parasites and their ability to use α-ketoglutarate to sustain viability depend on F1-ATPase activity. Surprisingly, however, loss of ΔΨm does not reduce stumpy life span. We conclude that the L262P γ subunit mutation does not enable FO-independent generation of ΔΨm in stumpy cells, most likely as a consequence of mitochondrial ATP production in these cells. In addition, kDNA-encoded genes other than FO subunit a are important for stumpy form viability.

Trypanosoma brucei Plimmer & Bradford, 1899 is a synonym of T. evansi (Steel, 1885) according to current knowledge and by application of nomenclature rules

Proper application of the principles of biological nomenclature is fundamental for scientific and technical communication about organisms. As other scientific disciplines, taxonomy inherently is open to change, thus species names cannot be final and immutable. Nevertheless, altering the names of organisms of high economical, medical, or veterinary importance can become a complex challenge between the scientific need to have correct classifications, and the practical ideal of having fixed classifications. Trypanosoma evansi (Steel, 1885), T. brucei Plimmer & Bradford, 1899 and T. equiperdum Doflein, 1901 are important parasites of mammals. According to current knowledge, the three names are synonyms of a single trypanosome species, the valid name of which should be T. evansi by the mandatory application of the Principle of Priority of zoological nomenclature. Subspecies known as T. brucei brucei Plimmer & Bradford, 1899, T. b. gambiense Dutton, 1902 and T. b. rhodesiense Stephens & Fantham, 1910 should be referred to respectively as T. evansi evansi (Steel, 1885), T. e. gambiense and T. e. rhodesiense. The polyphyletic groupings so far known as T. evansi and T. equiperdum should be referred respectively to as surra- and dourine-causing strains of T. e. evansi. Likewise, trypanosomes so far known as T. b. brucei should be referred to as nagana-causing strains of T. e. evansi. Though it modifies the scientific names of flagship human and animal parasites, the amended nomenclature proposed herein should be adopted because it reflects phylogenetic and biological advancements, fixes errors, and is simpler than the existing classificatory system.

Differential virulence of camel Trypanosoma evansi isolates in mice

This study assessed the virulence of Trypanosoma evansi, the causative agent of camel trypanosomiasis (surra), affecting mainly camels among other hosts in Africa, Asia and South America, with high mortality and morbidity. Using Swiss white mice, we assessed virulence of 17 T. evansi isolates collected from surra endemic countries. We determined parasitaemia, live body weight, packed cell volume (PCV) and survivorship in mice, for a period of 60 days' post infection. Based on survivorship, the 17 isolates were classified into three virulence categories; low (31-60 days), moderate (11-30 days) and high (0-10 days). Differences in survivorship, PCV and bodyweights between categories were significant and correlated (P < 0.05). Of the 10 Kenyan isolates, four were of low, five moderate and one (Type B) of high virulence. These findings suggest differential virulence between T. evansi isolates. In conclusion, these results show that the virulence of T. evansi may be region specific, the phenotype of the circulating parasite should be considered in the management of surra. There is also need to collect more isolates from other surra endemic regions to confirm this observation.

Multiple evolutionary origins of Trypanosoma evansi in Kenya

Trypanosoma evansi is the parasite causing surra, a form of trypanosomiasis in camels and other livestock, and a serious economic burden in Kenya and many other parts of the world. Trypanosoma evansi transmission can be sustained mechanically by tabanid and Stomoxys biting flies, whereas the closely related African trypanosomes T. brucei brucei and T. b. rhodesiense require cyclical development in tsetse flies (genus Glossina) for transmission. In this study, we investigated the evolutionary origins of T. evansi. We used 15 polymorphic microsatellites to quantify levels and patterns of genetic diversity among 41 T. evansi isolates and 66 isolates of T. b. brucei (n = 51) and T. b. rhodesiense (n = 15), including many from Kenya, a region where T. evansi may have evolved from T. brucei. We found that T. evansi strains belong to at least two distinct T. brucei genetic units and contain genetic diversity that is similar to that in T. brucei strains. Results indicated that the 41 T. evansi isolates originated from multiple T. brucei strains from different genetic backgrounds, implying independent origins of T. evansi from T. brucei strains. This surprising finding further suggested that the acquisition of the ability of T. evansi to be transmitted mechanically, and thus the ability to escape the obligate link with the African tsetse fly vector, has occurred repeatedly. These findings, if confirmed, have epidemiological implications, as T. brucei strains from different genetic backgrounds can become either causative agents of a dangerous, cosmopolitan livestock disease or of a lethal human disease, like for T. b. rhodesiense.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): Trypanosoma evansi infections (including Surra)

Trypanosoma evansi infections (including Surra) have been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on the eligibility of T. evansi infections (including Surra) to be listed, Article 9 for the categorisation of T. evansi infections (including Surra) according to disease prevention and control rules as in Annex IV and Article 8 on the list of animal species related to T. evansi infections (including Surra). The assessment has been performed following a methodology composed of information collection and compilation, expert judgement on each criterion at individual and, if no consensus was reached before, also at collective level. The output is composed of the categorical answer, and for the questions where no consensus was reached, the different supporting views are reported. Details on the methodology used for this assessment are explained in a separate opinion. According to the assessment performed, it is inconclusive whether T. evansi infections (including Surra) can be considered eligible to be listed for Union intervention as laid down in Article 5(3) of the AHL because there was no full consensus on the criterion 5 A(v). Consequently, the assessment on compliance of T. evansi infections (including Surra) with the criteria as in sections 4 and 5 of Annex IV of the AHL, for the application of the disease prevention and control rules referred to in points (d) and (e) of Article 9(1) is also inconclusive, as well as which animal species can be considered to be listed for T. evansi infections (including Surra) according to Article 8(3) of the AHL.

A Clinical and Epidemiological Investigation of the First Reported Human Infection With the Zoonotic Parasite Trypanosoma evansi in Southeast Asia

BACKGROUND

Trypanosomais a genus of unicellular parasitic flagellate protozoa.Trypanosoma bruceispecies and Trypanosoma cruziare the major agents of human trypanosomiasis; other Trypanosomaspecies can cause human disease, but are rare. In March 2015, a 38-year-old woman presented to a healthcare facility in southern Vietnam with fever, headache, and arthralgia. Microscopic examination of blood revealed infection with Trypanosoma

METHODS

Microscopic observation, polymerase chain reaction (PCR) amplification of blood samples, and serological testing were performed to identify the infecting species. The patient's blood was screened for the trypanocidal protein apolipoprotein L1 (APOL1), and a field investigation was performed to identify the zoonotic source.

RESULTS

PCR amplification and serological testing identified the infecting species as Trypanosoma evansi.Despite relapsing 6 weeks after completing amphotericin B therapy, the patient made a complete recovery after 5 weeks of suramin. The patient was found to have 2 wild-type APOL1 alleles and a normal serum APOL1 concentration. After responsive animal sampling in the presumed location of exposure, cattle and/or buffalo were determined to be the most likely source of the infection, with 14 of 30 (47%) animal blood samples testing PCR positive forT. evansi.

CONCLUSIONS

We report the first laboratory-confirmed case ofT. evansiin a previously healthy individual without APOL1 deficiency, potentially contracted via a wound while butchering raw beef, and successfully treated with suramin. A linked epidemiological investigation revealed widespread and previously unidentified burden ofT. evansiin local cattle, highlighting the need for surveillance of this infection in animals and the possibility of further human cases.

New Trypanosoma evansi Type B Isolates from Ethiopian Dromedary Camels

BACKGROUND

Trypanosoma (T.) evansi is a dyskinetoplastic variant of T. brucei that has gained the ability to be transmitted by all sorts of biting flies. T. evansi can be divided into type A, which is the most abundant and found in Africa, Asia and Latin America and type B, which has so far been isolated only from Kenyan dromedary camels. This study aimed at the isolation and the genetic and phenotypic characterisation of type A and B T. evansi stocks from camels in Northern Ethiopia.

METHODOLOGY/PRINCIPAL FINDINGS

T. evansi was isolated in mice by inoculation with the cryopreserved buffy coat of parasitologically confirmed animals. Fourteen stocks were thus isolated and subject to genotyping with PCRs targeting type-specific variant surface glycoprotein genes, mitochondrial minicircles and maxicircles, minisatellite markers and the F1-ATP synthase γ subunit gene. Nine stocks corresponded to type A, two stocks were type B and three stocks represented mixed infections between A and B, but not hybrids. One T. evansi type A stock was completely akinetoplastic. Five stocks were adapted to in vitro culture and subjected to a drug sensitivity assay with melarsomine dihydrochloride, diminazene diaceturate, isometamidium chloride and suramin. In vitro adaptation induced some loss of kinetoplasts within 60 days. No correlation between drug sensitivity and absence of the kinetoplast was observed. Sequencing the full coding sequence of the F1-ATP synthase γ subunit revealed new type-specific single nucleotide polymorphisms and deletions.

CONCLUSIONS/SIGNIFICANCE

This study addresses some limitations of current molecular markers for T. evansi genotyping. Polymorphism within the F1-ATP synthase γ subunit gene may provide new markers to identify the T. evansi type that do not rely on variant surface glycoprotein genes or kinetoplast DNA.

Parasitological, serological and molecular survey of Trypanosoma evansi infection in dromedary camels from Cholistan Desert, Pakistan

Background

Surra, a vector borne disease caused by Trypanosoma (T.) evansi, affects the health, productivity and working capacity of camels. Since clinical signs are not pathognomonic, diagnosis must be confirmed by laboratory methods. This is a first study on the prevalence of surra in Cholistan Desert, Pakistan using a broad variety of diagnostic tests thereby emphasizing it as a risk for the dromedaries of Pakistan.

Methods

In a cross sectional study, 1005 dromedary camels from three districts in the Cholistan Desert were sampled to assess the prevalence of trypanosomosis due to T. evansi by means of parasitological (Giemsa stained thin smear), serological (formol gel test, CATT/T. evansi, ELISA/VSG RoTat 1.2, immune trypanolysis) and molecular tests (TBR1/2 PCR and RoTat 1.2 PCR). Kappa was calculated to assess the degree of agreement between different tests whereas chi-square test along with odds ratios and their 95 % confidence intervals were used to study influence of breed, gender, age and locality on disease prevalence.

Results

Overall prevalence was 0.7 % with Giemsa stained thin smears (GST), 40.1 % with formol gel test (FGT), 47.7 % with CATT/T. evansi, 44.2 % with ELISA/VSG RoTat 1.2, 39.9 % with immune trypanolysis (TL), 31.9 % with TBR1/2 PCR and 30.5 % with RoTat1.2 PCR. Based on these results, the Cholistan Desert appears to be a high risk area for surra. According to TL and TBR1/2 PCR, camels at Bahawalpur are approximately two times more likely to be infected than those in Bahawalnagar (OR = 1.8; 95 % CI: 1.38-2.42) and Rahim Yar Khan (OR = 1.9; 95 % CI: 1.30-2.75). Test agreement of TL was moderate with CATT/T. evansi (k = 0.43; 95 % CI: 0.378-0.489) and ELISA/VSG RoTat 1.2 (k = 0.54; 95 % CI: 0.489-0.594) and poor with the other tests. Test agreement between TBR1/2 PCR and RoTat1.2 PCR was almost perfect (k = 0.96; 95 % CI: 0.950-0.984). We didn't find evidence for the presence of T. evansi type B in the studied population.

Conclusion

Our study supports using antibody detection tests, rather than parasitological and molecular examination, to assess surra prevalence in camels. It also calls for implementation of measures to control surra in the Cholistan Desert.

Trypanosome infection in dromedary camels in Eastern Ethiopia: Prevalence, relative performance of diagnostic tools and host related risk factors

A cross-sectional study was conducted in Chifra and Dewe districts of Afar region, Eastern Ethiopia, to determine the prevalence, agreement between diagnostic tests and host related risk factors of trypanosome infection in camel. An overall prevalence of 2%, 24.1%, 21.3%, 9.5% and 7.8% was recorded with respectively Giemsa stained thin blood smear, CATT/T. evansi, RoTat1.2 PCR, 18S PCR and ITS-1PCR in a cohort of 399 animals. Only one T. vivax infection was confirmed by TvPRAC PCR indicating T. evansi as the predominant species affecting camels in the study area. No single animal was positive when tested with T. evansi type B specific EVAB PCR. There was slight agreement between the CATT/T. evansi and the molecular tests. Among the PCR methods, RoTat 1.2 PCR yielded a significantly higher positivity rate compared to 18S PCR and ITS-1 PCR. There was no significant difference in the positivity rate observed in each gender of camels (p>0.05). The positivity rate was significantly higher in camels with poor body condition and in older animals when tested using the CATT/T.evansi or RoTat 1.2 PCR (p>0.05). Camels that tested positive with all tests had significantly lower PCV's (p<0.05). This study provides further evidence that T. evansi is endemic in the Afar region of Ethiopia. The latent class analysis indicated an estimate overall prevalence of 19% (95% CI: 13-28). Moreover, the model indicated low sensitivity of CATT/T. evansi (43%) and the PCR tests (39-53%) but higher specificity of the PCR tests (86-99%) and low specificity of CATT/T. evansi (80%). This study suggests that improved sensitivity and reliability of the tests would help diagnosis of trypanosomosis. Further studies are required to determine the prevalence of clinical disease and losses due to trypanosomosis.

Epidemiology of Trypanosoma evansi and Trypanosoma vivax in domestic animals from selected districts of Tigray and Afar regions, Northern Ethiopia

Background

African animal trypanosomosis, transmitted cyclically by tsetse flies or mechanically by other biting flies, causes serious inflictions to livestock health. This study investigates the extent of non-tsetse transmitted animal trypanosomosis (NTTAT) by Trypanosoma (T.) evansi and T. vivax in domestic animals in the tsetse-free regions of Northern Ethiopia, Afar and Tigray.

Methods

A cross sectional study was conducted on 754 dromedary camels, 493 cattle, 264 goats, 181 sheep, 84 donkeys, 25 horses and 10 mules. The microhaematocrit centrifugation technique was used as parasitological test. Plasma was collected for serodiagnosis with CATT/T.evansi and RoTat 1.2 immune trypanolysis (ITL) while buffy coat specimens were collected for molecular diagnosis with T. evansi type A specific RoTat 1.2 PCR, T. evansi type B specific EVAB PCR and T. vivax specific TvPRAC PCR.

Results

The parasitological prevalence was 4.7% in Tigray and 2.7% in Afar and significantly higher (z = 2.53, p = 0.011) in cattle (7.3%) than in the other hosts. Seroprevalence in CATT/T.evansi was 24.6% in Tigray and 13.9% in Afar and was significantly higher (z = 9.39, p < 0.001) in cattle (37.3%) than in the other hosts. On the other hand, seroprevalence assessed by ITL was only 1.9% suggesting cross reaction of CATT/T.evansi with T. vivax or other trypanosome infections. Molecular prevalence of T. evansi type A was 8.0% in Tigray and in Afar and varied from 28.0% in horses to 2.2% in sheep. It was also significantly higher (p < 0.001) in camel (11.7%) than in cattle (6.1%), donkey (6%), goat (3.8%), and sheep (2.2%). Four camels were positive for T. evansi type B. Molecular prevalence of T. vivax was 3.0% and was similar in Tigray and Afar. It didn’t differ significantly among the host species except that it was not detected in horses and mules.

Conclusions

NTTAT caused by T. vivax and T. evansi, is an important threat to animal health in Tigray and Afar. For the first time, we confirm the presence of T. evansi type B in Ethiopian camels. Unexplained results obtained with the current diagnostic tests in bovines warrant particular efforts to isolate and characterise trypanosome strains that circulate in Northern Ethiopia.

Genome and phylogenetic analyses of Trypanosoma evansi reveal extensive similarity to T. brucei and multiple independent origins for dyskinetoplasty

Two key biological features distinguish Trypanosoma evansi from the T. brucei group: independence from the tsetse fly as obligatory vector, and independence from the need for functional mitochondrial DNA (kinetoplast or kDNA). In an effort to better understand the molecular causes and consequences of these differences, we sequenced the genome of an akinetoplastic T. evansi strain from China and compared it to the T. b. brucei reference strain. The annotated T. evansi genome shows extensive similarity to the reference, with 94.9% of the predicted T. b. brucei coding sequences (CDS) having an ortholog in T. evansi, and 94.6% of the non-repetitive orthologs having a nucleotide identity of 95% or greater. Interestingly, several procyclin-associated genes (PAGs) were disrupted or not found in this T. evansi strain, suggesting a selective loss of function in the absence of the insect life-cycle stage. Surprisingly, orthologous sequences were found in T. evansi for all 978 nuclear CDS predicted to represent the mitochondrial proteome in T. brucei, although a small number of these may have lost functionality. Consistent with previous results, the F1FO-ATP synthase γ subunit was found to have an A281 deletion, which is involved in generation of a mitochondrial membrane potential in the absence of kDNA. Candidates for CDS that are absent from the reference genome were identified in supplementary de novo assemblies of T. evansi reads. Phylogenetic analyses show that the sequenced strain belongs to a dominant group of clonal T. evansi strains with worldwide distribution that also includes isolates classified as T. equiperdum. At least three other types of T. evansi or T. equiperdum have emerged independently. Overall, the elucidation of the T. evansi genome sequence reveals extensive similarity of T. brucei and supports the contention that T. evansi should be classified as a subspecies of T. brucei.

Variant surface glycoproteins from Venezuelan trypanosome isolates are recognized by sera from animals infected with either Trypanosoma evansi or Trypanosoma vivax

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Soluble forms of VSGs from seven Venezuelan animal trypanosomes were purified and characterized.

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All purified soluble VSGs exhibited cross-reactivity with Trypanosoma vivax.

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Anti-VSG antibodies behaved as markers of infection for non-tsetse transmitted trypanosomes.

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All purified soluble VSGs can be used as diagnostic reagents for bovine trypanosomosis.

Salivarian trypanosomes sequentially express only one variant surface glycoprotein (VSG) on their cell surface from a large repertoire of VSG genes. Seven cryopreserved animal trypanosome isolates known as TeAp-ElFrio01, TEVA1 (or TeAp-N/D1), TeGu-N/D1, TeAp-Mantecal01, TeGu-TerecayTrino, TeGu-Terecay03 and TeGu-Terecay323, which had been isolated from different hosts identified in several geographical areas of Venezuela were expanded using adult albino rats. Soluble forms of predominant VSGs expressed during the early infection stages were purified and corresponded to concanavalin A-binding proteins with molecular masses of 48–67 kDa by sodium dodecyl sulfate-polyacrylamide gel electropohoresis, and pI values between 6.1 and 7.5. The biochemical characterization of all purified soluble VSGs revealed that they were dimers in their native form and represented different gene products. Sequencing of some of these proteins yielded peptides homologous to VSGs from Trypanosoma (Trypanozoon) brucei and Trypanosoma (Trypanozoon) evansi and established that they most likely are mosaics generated by homologous recombination. Western blot analysis showed that all purified VSGs were cross-reacting antigens that were recognized by sera from animals infected with either T. evansi or Trypanosoma (Dutonella) vivax. The VSG glycosyl-phosphatidylinositol cross-reacting determinant epitope was only partially responsible for the cross-reactivity of the purified proteins, and antibodies appeared to recognize cross-reacting conformational epitopes from the various soluble VSGs. ELISA experiments were performed using infected bovine sera collected from cattle in a Venezuelan trypanosome-endemic area. In particular, soluble VSGs from two trypanosome isolates, TeGu-N/D1 and TeGu-TeracayTrino, were recognized by 93.38% and 73.55% of naturally T. vivax-infected bovine sera, respectively. However, approximately 70% of the sera samples did not recognize all seven purified proteins. Hence, the use of a combination of various VSGs for the diagnosis of animal trypanosomosis is recommended.

Trypanosoma evansi and surra: a review and perspectives on origin, history, distribution, taxonomy, morphology, hosts, and pathogenic effects

Trypanosoma evansi, the agent of "surra," is a salivarian trypanosome, originating from Africa. It is thought to derive from Trypanosoma brucei by deletion of the maxicircle kinetoplastic DNA (genetic material required for cyclical development in tsetse flies). It is mostly mechanically transmitted by tabanids and stomoxes, initially to camels, in sub-Saharan area. The disease spread from North Africa towards the Middle East, Turkey, India, up to 53° North in Russia, across all South-East Asia, down to Indonesia and the Philippines, and it was also introduced by the conquistadores into Latin America. It can affect a very large range of domestic and wild hosts including camelids, equines, cattle, buffaloes, sheep, goats, pigs, dogs and other carnivores, deer, gazelles, and elephants. It found a new large range of wild and domestic hosts in Latin America, including reservoirs (capybaras) and biological vectors (vampire bats). Surra is a major disease in camels, equines, and dogs, in which it can often be fatal in the absence of treatment, and exhibits nonspecific clinical signs (anaemia, loss of weight, abortion, and death), which are variable from one host and one place to another; however, its immunosuppressive effects interfering with intercurrent diseases or vaccination campaigns might be its most significant and questionable aspect.

Single point mutations in ATP synthase compensate for mitochondrial genome loss in trypanosomes

Viability of the tsetse fly-transmitted African trypanosome Trypanosoma brucei depends on maintenance and expression of its kinetoplast (kDNA), the mitochondrial genome of this parasite and a putative target for veterinary and human antitrypanosomatid drugs. However, the closely related animal pathogens T. evansi and T. equiperdum are transmitted independently of tsetse flies and survive without a functional kinetoplast for reasons that have remained unclear. Here, we provide definitive evidence that single amino acid changes in the nuclearly encoded F1FO-ATPase subunit γ can compensate for complete physical loss of kDNA in these parasites. Our results provide insight into the molecular mechanism of compensation for kDNA loss by showing FO-independent generation of the mitochondrial membrane potential with increased dependence on the ADP/ATP carrier. Our findings also suggest that, in the pathogenic bloodstream stage of T. brucei, the huge and energetically demanding apparatus required for kDNA maintenance and expression serves the production of a single F1FO-ATPase subunit. These results have important implications for drug discovery and our understanding of the evolution of these parasites.

The typing of Trypanosoma evansi isolates using mobile genetic element (MGE) PCR

The mobile genetic element PCR (MGE-PCR) is a simple and sensitive technique that can be used to detect genetic variability in Trypanosoma brucei ssp. To investigate the reliability of MGE-PCR in genotyping Trypanosoma evansi, stocks that were isolated directly from camels and after their respective passage in mice were analyzed. Construction of a dendrogram using the MGE-PCR banding profiles revealed a clear distinction between T. evansi and T. brucei, as well as discriminating the T. evansi strains (T. evansi with minicircle types B and A). A minor host-dependent clustering shows a genetic difference of <15%. Changes in the banding profiles were observed after serial passage of T. evansi type B in mice, while those of T. evansi type A were identical. It is apparent that significant random insertion mobile element positional variation occurs when T. evansi isolates are introduced into a new host, a factor that needs to be considered when MGE-PCR is used to determine genetic variation in T. evansi isolates that have different host origins.

Loop-mediated Isothermal Amplification (LAMP) test for detection of Trypanosoma evansi strain B

Camel Trypanosomiasis (Surra) is mainly caused by Trypanosoma evansi strains that express variable surface glycoprotein (VSG) RoTat 1.2. However, in Kenya a second causative strain that does not express RoTat 1.2 VSG (T. evansi type B) has been identified. The prevalence of T. evansi type B largely remains unknown due to inadequate diagnostic assay. This work reports the development of a sensitive and specific diagnostic assay capable of detecting T. evansi type B based on the strategy of Loop-mediated Isothermal Amplification (LAMP) of DNA. The test is rapid and amplification is achieved within 20-25min at 63 degrees C using a real time PCR machine. Restriction enzyme AluI digestion of the amplicon gave the predicted 83bp and 89bp sized bands and the LAMP product melt curves showed consistent melting temperature (T(m)) of approximately 89 degrees C. The assay analytical sensitivity is approximately 0.1tryps/ml while that of classical PCR test targeting the same gene is approximately 10tryps/ml. There was a 100% agreement in detection of the LAMP amplification product in real time, gel electrophoresis, on addition of SYBR Green I, and when using chromatographic Lateral Flow Dipstick (LFD) format. The use of the LAMP test revealed nine more T. evansi type B DNA samples that were not initially detected through PCR. The robustness and higher sensitivity of the T. evansi type B LAMP assay coupled with the visual detection of the amplification product indicate that the technique has strong potential as a point-of-use test in surra endemic areas.

African trypanosomiasis: sensitive and rapid detection of the sub-genus Trypanozoon by loop-mediated isothermal amplification (LAMP) of parasite DNA

Control of human African trypanosomiasis (HAT) is dependent on accurate diagnosis and treatment of infected patients. However, sensitivities of tests in routine use are unsatisfactory, due to the characteristically low parasitaemias in naturally infected individuals. We have identified a conserved sequence in the repetitive insertion mobile element (RIME) of the sub-genus Trypanozoon and used it to design primers for a highly specific loop-mediated isothermal amplification (LAMP) test. The test was used to analyse Trypanozoon isolates and clinical samples from HAT patients. The RIME LAMP assay was performed at 62 degrees C using real-time PCR and a water bath. DNA amplification was detectable within 25min. All positive samples detected by gel electrophoresis or in real-time using SYTO-9 fluorescence dye could also be detected visually by addition of SYBR Green I to the product. The amplicon was unequivocally confirmed through restriction enzyme NdeI digestion, analysis of melt curves and sequencing. The analytical sensitivity of the RIME LAMP assay was equivalent to 0.001 trypanosomes/ml while that of classical PCR tests ranged from 0.1 to 1000 trypanosomes/ml. LAMP detected all 75 Trypanozoon isolates while TBR1 and two primers (specific for sub-genus Trypanozoon) showed a sensitivity of 86.9%. The SRA gene PCR detected 21 out of 40 Trypanosoma brucei rhodesiense isolates while Trypanosoma gambiense-specific glycoprotein primers (TgsGP) detected 11 out of 13 T. b. gambiense isolates. Using clinical samples, the LAMP test detected parasite DNA in 18 out of 20 samples which included using supernatant prepared from boiled blood, CSF and direct native serum. The sensitivity and reproducibility of the LAMP assay coupled with the ability to detect the results visually without the need for sophisticated equipment indicate that the technique has strong potential for detection of HAT in clinical settings. Since the LAMP test shows a high tolerance to different biological substances, determination of the appropriate protocols for processing the template to make it a user-friendly technique, prior to large scale evaluation, is needed.