A field study to estimate the prevalence of Trypanosoma equiperdum in Mongolian horses.
Abstract: From May to July 2000, a cross-sectional study was conducted to estimate the prevalence of Trypanosoma equiperdum in the horse population of the central province (Tuv aimag) of Mongolia. On average, four herds were selected from each of the 29 aimag subdivisions (119 herds). From each herd, 10 horses were sampled in proportion to sex and age categories in the respective herds (1190 horses). Sera from 1122 horses were analysed for T. equiperdum antibodies using two serological assays, the complement fixation test (CFT) and the enzyme-linked immunosorbent assay (ELISA). The crude estimate of the CFT and the ELISA seroprevalence was 7.6 and 6.7%, respectively. Concordance between the CFT and ELISA results was high (96%). The highest number of CFT positive animals was detected in one herd in Möngönmorit (6/10), followed by herds in Bayandelger (5/10) and in Bayantsagaan (5/10). Poor body condition was significantly correlated with positive serological status in both CFT and ELISA. A history of abortion appeared to be a risk factor for both CFT and ELISA seropositivity. Blood samples of all horses belonging to herds with at least three (3/10) seropositive animals (CFT and/or ELISA) were analysed by light microscopy and by PCR using a Trypanosoma (Trypanozoon) brucei specific primer pair. No trypanosomes or any other haemoparasites could be detected in Giemsa stained thin blood smears. Eight out of the 130 samples (6.2%) analysed by PCR gave positive signals. Seven out of the eight PCR positive horses were also serologically positive. One PCR (and ELISA) positive stallion from Möngönmorit showed emaciation, scrotal and preputial oedema and an oedematous skin plaque. From the serological and DNA-based results it is concluded, that trypanosome infections occur in horses in the Tuv aimag of Mongolia. Since at present neither serological nor DNA-based tests allow a subspecies specific identification within the subgenus Trypanozoon, no definitive diagnosis can be given for T. equiperdum. Whether the examined herds are infected with T. equiperdum or with T. evansi, the causative agent of surra, remains an open question. However, based on the clinical findings, the negative parasitological results and the concentration of conspicuous seroprevalences in single herds, circumstantial evidence supports the existence of infections with the causative agent of dourine.
Publication Date: 2003-07-16 PubMed ID: 12860063DOI: 10.1016/s0304-4017(03)00160-2Google Scholar: Lookup
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Summary
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The research study conducted from May to July 2000 aimed to understand the prevalence of Trypanosoma equiperdum, a parasitic species, in the horse population of Central Mongolia, specifically Tuv aimag province. Horses with a poor body condition and a history of abortion appeared to have an increased risk of infection in the study.
Sampling and Methodology
- The study was a cross-sectional survey conducted with the aim of estimating the prevalence of Trypanosoma equiperdum in Mongolia’s horse population.
- The researchers survey was carried out in the Tuv aimag province, central Mongolia, wherein 119 horse herds were randomly selected from 29 subdivisions, selecting an average of four herds from each subdivision.
- From every selected herd, 10 horses were sampled categorically based on their sex and age, resulting in a total sample of 1190 horses.
- Upon collecting the samples, antibodies of T. equiperdum was tested in the sera of 1122 horses using two distinct tests – the complement fixation test (CFT) and the enzyme-linked immunosorbent assay (ELISA).
Results and Findings
- The estimated prevalence rate of T. equiperdum, as determined by the CFT and ELISA tests, was found to be 7.6% and 6.7%, respectively.
- There was a high match between the results derived from these two assays, with a concordance of 96%.
- The maximum number of CFT-positive animals was discovered in a herd located in Mongonmorit, followed by herds in Bayandelger and Bayantsagaan.
- Poor body condition and a history of abortion were identified as significant risk factors for both CFT and ELISA seropositivity.
- Unlike the serological tests, no parasites or haemoparasites were detected in the light microscopy examination of the thin blood smears.
Implications of the Findings
- Based on the serological and DNA-based test results, it was concluded that trypanosome infections are present in horses belonging to the Tuv aimag province of Mongolia.
- However, the study also highlighted a lacuna in the existing serological and DNA-based tests as they failed to specifically identify the subtype within the genus Trypanozoon.
- This left an open question regarding the exact infection type affecting the surveyed herds – whether they were infected with T. equiperdum or T. evansi, the causative agent of surra, a similar parasitic disease.
- While the exact subtype remains unidentified, based on clinical symptoms, negative parasitology tests, and the high prevalence in specific herds, the researchers suggested that the infection could be Dourine, a sexually-transmitted disease in horses caused by T. equiperdum.
Cite This Article
APA
Clausen PH, Chuluun S, Sodnomdarjaa R, Greiner M, Noeckler K, Staak C, Zessin KH, Schein E.
(2003).
A field study to estimate the prevalence of Trypanosoma equiperdum in Mongolian horses.
Vet Parasitol, 115(1), 9-18.
https://doi.org/10.1016/s0304-4017(03)00160-2 Publication
Researcher Affiliations
- Freie Universitaet Berlin (FU-Berlin), Institute for Parasitology and International Animal Health, Koenigsweg 67, D-14163 Berlin, Germany. tropvetm@zedat.fu-berlin.de
MeSH Terms
- Animals
- Antibodies, Protozoan / blood
- Complement Fixation Tests / veterinary
- Cross-Sectional Studies
- DNA, Protozoan / chemistry
- DNA, Protozoan / genetics
- Dourine / blood
- Dourine / epidemiology
- Dourine / parasitology
- Enzyme-Linked Immunosorbent Assay / veterinary
- Female
- Horse Diseases / epidemiology
- Horse Diseases / parasitology
- Horses
- Male
- Mongolia / epidemiology
- Polymerase Chain Reaction / veterinary
- Seroepidemiologic Studies
- Surveys and Questionnaires
- Trypanosoma / genetics
- Trypanosoma / isolation & purification
- Trypanosomiasis / blood
- Trypanosomiasis / epidemiology
- Trypanosomiasis / parasitology
- Trypanosomiasis / veterinary
Citations
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