EXPERIMENTAL STUDIES ON CLINICO- HEMATOLOGY OF TRYPANOSOMA EQUIPERDUM INFECTED HORSES AND VENEREAL TRANSMISSION IN MICE
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Date
2017-06
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Abstract
Dourine is an endemic venereal transmitted trypanosomosis causing a major health problem threatening the life and productivity of the equine population in Ethiopia. The present experimental study was conducted from November 2016 to June 2017 in Bishoftu, central Oromia, Ethiopia. The objective of the study was to evaluating clinico-hematological profile of horses experimentally infected with Trypanosoma equiperdum, assess the effect of cymelarsan treatment on hematological values of horses infected with T. equiperdum and determine the possibility of venereal transmission of T. equiperdum in mice. The study design was conducted on (n=4) mares and (n=4) stallions. Mares were challenged by insemination of semen originated from non-infected stallion after mixed with T. equiperdum at a dose of 100,000 parasite/ml by artificial insemination whereas stallion group were infected with 2ml of blood that drawn from infected mare at dose of 1x106 parasites /ml via intravenous route. Data on parasitaemia, rectal temperature, serology (CATT/T. evansi test) and hematological were determined before and after infection. Furthermore infected horses were divided into two groups designated as treated and non-treated groups. At weeks 6 of post infection treatment group was injected with cymelarsan® at dose of 0.25mg/kg body weight. Changes in clinical sign, parasitemia and hematological values were monitored. Thirty (n=30) female mice and male (n=12) were involved in experiment to check coital transmission. One infected mouse was co-housed with two healthy female mice at low level of parasitemia (1x101-1x103) in six replications and other one infected male mouse co-housed with two healthy female mice at high level of parasitemia (1x104-1x106) in six replications. Other two infected female co-housed with four healthy female as control. Thereafter the appearance of Parasitemia was monitored daily from female mice. The study revealed that, Dodola strain caused a severe change in blood parameter and a clinical sign in both stallion and mare, infection was predominantly characterized by involvement of genital, nervous and corneal signs. There was significant decrease in mean PCV, Hg, RBC, eosinophil, basophil and monocyte count while mean total WBC and neutrophil count had no significant difference (p>0.05) in animals post-infection when compared to pre-infection values. Lymphocyte and MCHC were significantly (p<0.05) higher at post infection as compared to pre-infection. Cymelarsan treatment at dose of 0.25 mg/kg body weight failed to clear the parasite and improve in clinico-hematological values, rather being relapsed after 21days. Treated group had no significant improvement in RBC, Hgb, and differential leukocyte count whereas PCV and WBC which were significantly (p < 0.05) improved as compared to non-treated group. In healthy female mice co-housed with infected male mice using wet smear no trypanosomes were detected in all female mice and their offspring in wet smear throughout study period. In conclusion the current study revealed that dourine resulted in hematological changes that lead to normocytic hypochromic anemia, thus further elucidative investigation recommended on pathogenesis of the disease. In addition, venereal transmission of T. equiperdum in mice was unsuccessful; hence further molecular based test is essential to ascertain this result.
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MSc Thesis
Keywords
Cymelarsan, Experimental infection, Hematological, Trypanosoma equiperdum