Trypanosoma evansi: detection of Trypanosoma evansi DNA in naturally and experimentally infected animals using TBR(1) & TBR(2) primers

Molecular prevalence, associated risk factors and genetic characterization of Trypanosoma evansi in camels

Surra is a major infectious disease of camels being caused by Trypanosoma evansi (T. evansi) in developing countries, including Egypt. However, the identification of changes in the T. evansi prevalence in Egypt is important. In this study, the prevalence of T. evansi and its associated risk factors as well as the genetic characterization of the parasite were estimated. Blood samples were collected from 163 camels from two governorates in Lower Egypt. PCR targeting RoTat 1.2VSG was used for the detection of T. evansi and internal transcribed spacer 1 (ITS-1) was used for sequencing analysis and genetic characterization. Overall prevalence was 19.6% using RoTat 1.2VSG. The risk of the infection in females was 4 times higher than in males (P = 0.0004, OR = 4; 95% CI = 0.79-8.96) and in camels with a history of clinical signs it was 2.3 times higher than camels without clinical signs (P = 0.04, OR = 2.3, 95% CI = 1.035-5.15). Analysis of the ITS-1 sequences of four T. evansi isolates showed little heterogeneity compared to similar sequences in the database. Sequence and phylogenetic analysis, based on the ITS-1 region, confirmed the presence of two distinct genotypes of T. evansi in Egyptian camels with more than 99% similarity with T. evansi isolates from different countries across the ITS-1 region and were closely related to Filipino and Chinese isolates. The results of the study can be used for the observation and prevention of disease and updating the epidemiological data.

Epididymitis in mice experimentally infected with Trypanosoma equiperdum: a histopathological and immunohistochemical study

Trypanosoma equiperdum is a causative agent of dourine in equids and is transmitted from stallions to mares by coitus. Dourine-affected stallions develop orchitis and epididymitis, and these lesions are considered to be responsible for the sexual transmission of T. equiperdum during coitus. However, the parasitic site of trypanosomes in the reproductive organs and the mechanisms underlying transmission have not yet been elucidated histopathologically. We examined the reproductive organs of male mice infected with T. equiperdum histopathologically and identified severe epididymitis with sperm granulomas. Many trypanosomes were detected in the epididymal interstitium and a few were seen within tubular lumen. Interstitial inflammatory cells mainly consisted of Iba1-, iNOS- and CD204-positive cells with a few CD3-, FOXP3- or PAX5-positive cells. There was diffuse immunolabelling of tumour necrosis factor-α (TNF-α) within these inflammatory foci. While caspase-3-positive epithelial cells in the epididymis were not observed in control mice, they were detected multifocally in infected mice and were frequently associated with loss of immunolabelling of zonula occludens-1 (ZO-1), a major protein that forms tight junctions between epididymal epithelial cells. Anti-laminin immunofluorescence revealed an indistinct basement membrane of the epididymal duct. These results suggest that trypanosomes in the epididymal interstitium induce the infiltration of TNF-α-secreting macrophages. Secreted TNF-α may impair the tight junctions of the epididymal duct by inducing apoptosis and downregulating ZO-1 expression.

Spatial-Temporal Variations in Parasitological Prevalence and Host-Related Risk Factors of Camel Trypanosomiasis and Its Vectors in North Eastern Kenya: A Repeated Cross-Sectional Study

Camel trypanosomiasis (Surra) is endemic in the Horn of Africa. Understanding the spatiotemporal variations in Surra prevalence, vector dynamics, and host-related risk factors is important in developing effective control strategies. A repeated cross-sectional study was conducted to determine the Surra parasitological prevalence, livestock reservoirs, vector density/diversity, and host-related risk factors in Kenya. Random samples of 847, 1079, and 824 camels were screened at the start of the dry season, peak dry season, and during the rainy season, respectively. Blood samples were examined using the dark ground/phase contrast buffy-coat technique, and Trypanosoma species were identified based on their movement and morphology in wet and stained thin smears. Reservoir status for Trypanosoma evansi was assessed in 406 cattle and 372 goats. A rainy and dry seasons entomological surveys were conducted to determine the Surra vector abundance/diversity and spatiotemporal density changes. Surra prevalence was 7.1%, 3.4%, and 4.1% at the start of the dry season, peak dry season, and rainy season, respectively. Camel co-infections by Trypanozoon (T. evansi or Trypanosoma brucei brucei) and Trypanosoma vivax were recorded. Spatial variations in Surra prevalence were recorded at the beginning of dry (X _{(7, N = 846)} ² = 110.9, p ≤ 0.001), peak dry (X _{(7, N = 1079)} ² = 42.2, p ≤ 0.001), and rainy (X _{(7, N = 824)} ² = 29.1, p ≤ 0.001) seasons. The screened cattle and goats tested negative for Trypanozoon (T. evansi or T. b. brucei), while two cattle tested positive for Trypanosoma congolense. Biting fly catches were composed of a single species from Tabanus, Atylotus, Philoliche, Chrysops, and Stomoxys genera. The total catches for Philoliche, Chrysops, and Stomoxys were higher in the rainy than dry season consistent with the prevalence results. Surra remains an important camel disease in the region with its prevalence varying in space and time. Camel co-infections by Trypanozoon (T. evansi or T. b. brucei) and T. vivax necessitate proper diagnosis of suspected cases and targeted therapy.

Comparison of ITS-1 and TBR-1/2 primer sensitivity for the detection of Trypanosoma evansi local isolates in experimental rats using a polymerase chain reaction

Background and Aim:

Surra is caused by Trypanosoma evansi. The detection method using conventional parasitological tests has not always shown positive results in blood parasite detection, although the livestock has presented with clinical signs. Therefore, a fast and accurate diagnosis is necessary to prevent the disease predominately in field isolates. This study aimed to investigate the sensitivity of molecular detection method using two different specific primers, namely, Internal Transcribed Spacer 1 (ITS-1) and Trypanosoma brucei repeat 1/2 (TBR-1/2) against T. evansi field isolates from Banten Province, Indonesia.

Materials and Methods:

The isolates of T. evansi used in this study were collected from Banten Province and cultured and preserved by the National Research Center for Veterinary Science, Indonesia. Eighteen experimental rats were divided into three equal groups, which were categorized as control, 1 × 10¹, and 1 × 10⁴ infective doses. The isolates were injected into all experimental albino rats intraperitoneally. All samples were tested using conventional blood smear, card agglutination test (CATT), and polymerase chain reaction (PCR) method.

Results:

The results of the CATT examination in all treatments showed negative results. However, PCR results showed that two different primers, namely, ITS-1 and TBR-1/2 had been successfully detected T. evansi from infected experimental rats, proven by positive PCR band appeared in 480 base pairs (bp) and 164 bp, respectively.

Conclusion:

Based on the molecular diagnostic test using PCR method, TBR-1/2 primer is more sensitive to detect T. evansi compared to ITS-1 primer. The present finding provides preliminary data for studying the efficiency of different primers if practically applied as a standard diagnostic test for trypanosomiasis, especially in Indonesian livestock.

Molecular diagnosis of acute and chronic infection of Trypanosoma evansi in experimental male and female mice

Trypanosoma evansi is enzootic in camels in Egypt, and water buffaloes act as a reservoir for camel infection. Molecular techniques have contributed towards understanding the epidemiology of T. evansi. Trypanosoma evansi was detected in acute and chronic stages of the disease in male and female mice by polymerase chain reaction (PCR) using two primers. Two experiments were conducted. In experiment I, two groups consisting of 26 female and 26 male mice received 10⁴ trypanosome by I/P inoculation for each mouse. In experiment II, 42 female and 42 male mice were inoculated I/P with 10² trypanosome/mouse. In addition, five mice were kept as uninfected control for each group. Mice were monitored daily for parasitaemia level during the pre-patent period using the micro-haematocrit centrifugation technique (MHCT) and conventional PCR. The primer pairs, (Trypanosoma brucei) TBR1/2 and TeRoTat1.2 (T. evansi Rode Trypanozoon antigen type [RoTat] 1.2), detected the infection after 24 hours earlier than MHCT in both experiments. The course of infection that was detected by MHCT revealed three waves of parasitaemia in female mice and two waves in male mice in the chronic stage of infection. In addition, PCR was able to detect T. evansi in different organs in the chronic stage (i.e. disappearance of parasite from blood). Application of the two primer sets on blood samples from camels showed that all samples were positive by TBR1/2 primers and only 32 of 44 were positive by TeRoTat1.2 primers. Acutely and chronically Trypanosoma-infected mice were detected by PCR in blood and organs. TBR1/2 primers were more sensitive than TeRoTat1.2 primers in detecting Trypanosoma-infected mice, and more reliable in detecting field-infected camels and excluding carrier animals.

Frequency and factors associated with Theileria equi, Babesia caballi and Trypanosoma evansi in equids from Bahia (Northeast Brazil)

The aim of this study was to determine the frequency and factors associated to Babesia caballi, Theileria equi and Trypanosoma evansi in naturally infected equids from the northeast Brazil. Blood samples from 569 equids (528 horses, 8 mules, and 33 donkeys) were collected and tested for the presence of DNA of each of these protozoan parasites by PCR. Generalized linear models were used to evaluate risk factors associated with the infection. The frequency of T. equi infection was 83.5% (475/569) - 84.3% in horses, and 73.2% in donkeys and mules. The results of the final model indicated that age (senior group) and animal species (mule and donkey group) were protective factors against this pathogen. The frequency of B. caballi infection was 24.3% (138/569) - 23.5% in horses and 34.1% in donkeys and mules. Age (adult and senior group) was considered a protective factor against B. caballi infection whereas animal species (donkey and mule group) were considered a risk factor for the infection. Trypanosoma evansi infection was not detected in any of animals. Our results suggest that equids from the area studied may be infected earlier in life with the etiological agents of equine piroplasmosis and become asymptomatic carriers.

Systematic review and meta-analysis on the global distribution, host range, and prevalence of Trypanosoma evansi

BACKGROUND

Surra is an animal trypanosomosis, caused by infection with Trypanosoma evansi and leading to severe economic loss due to mortality and morbidity. Compared to tsetse-transmitted animal trypanosomoses, little attention is given to the epidemiology and control of surra. Understanding its epidemiology is a first step in local and global efforts to control the disease. We conducted a systematic review and meta-analysis of published studies on distribution, host ranges and prevalence of T. evansi infection.

METHODS

Four electronic databases were searched for publications on T. evansi that met our inclusion criteria for the systematic review. Subsets of publications were subjected to meta-analysis for the pooled prevalence of T. evansi in various hosts as determined by multiple detection methods.

RESULTS

A total of 272 references published between 1906-2017 were included. Trypanosoma evansi was reported from 48 countries; largely confined to Africa and Asia with publications on natural T. evansi infections from 77% (n = 48) of countries, contrasting with seven countries in South America, and four in Europe where T. evansi is not endemic but was imported with infected animals. Although surra is a notifiable disease, many countries do not report surra cases to OIE. Trypanosoma evansi was mainly reported from dromedary camels in Africa and the Middle East, water buffaloes, cattle, dogs and horses in East and Southeast Asia. In South America, the acute form of the disease was reported in horses and dogs. Surra was also reported in a wide range of wild animals. Some rare human cases occurred in India and Vietnam. Meta-analysis on a subset of 165 publications indicated pooled prevalence of T. evansi in domestic animals ranging from 14-31%, 6-28% and 2-9% using respectively antibody detection, molecular and parasitological tests, with camels as the most affected, followed by buffalo and cattle.

CONCLUSIONS

This study illustrates that T. evansi affects a wide range of domestic and wild animals in Africa, Asia and South America with highest prevalence observed in dromedary camels. For successful control of T. evansi, both locally and globally, the role of wild animals in the epidemiology of surra needs further investigation.

Molecular survey and characterization of Trypanosoma evansi in naturally infected camels with suspicion of a Trypanozoon infection in horses by molecular detection in Egypt

In Egypt, although the Trypanosoma evansi has been reported frequently among domestic animals, there is no published data on T. evansi in horses. Therefore, this study aimed to assess the prevalence and characterization of T. evansi in three governorates by examining blood samples from 40 local camels, 35 imported camels, 25 horses and 10 donkeys by PCR targeting the sequences of TBR and RoTat 1.2VSG. The overall prevalence of T. evansi was 54.5% and 21.8% by TBR PCR and RoTat 1.2VSG PCR, respectively. The TBR PCR detected T. evansi in 60% and 71.4%, respectively, of local and imported camels and in 10% and 40% of donkeys and horses, respectively. For RoTat 1.2VSG PCR, T. evansi was detected in 32.5% and 31.4 of local and imported camels, respectively. All horses and donkeys were negative by RoTat 1.2VSG PCR. TBR PCR was superior to RoTat 1.2VSG PCR in T. evansi infection detection. Statistically significant differences in the prevalence of the infection were observed on the basis of body condition and location. Sequencing and phylogenetic analysis, based on RoTat 1.2VSG, confirmed the presence of T. evansi, which was closely related to Egyptian and Indian isolates. In conclusion, TBR PCR is the best assay to monitor T. evansi infections in camels, horses, and donkeys. The presence of T. evansi in horses and donkeys possibly play a role in the transport of the infection to camels. This is the first report of T. evansi infection in horses in Egypt using TBR PCR.