ABSTRACT
A cross-sectional study was carried out from November 2016 to May 2017 in selected districts of Northwest Ethiopia (Jawi, South Achefer, Dembecha and Jabitehenan) with the aim of determining the prevalence of bovine and equine trypanosomosis, estimating the apparent density of vectors and assessing the effectiveness of control measures of the disease. A total of 1257 animals of which 803 bovine and 454 equine were examined for the determination of prevalence using blood sample collected from ear vein of animals. The buffy coat technique was employed to determine the prevalence and the packed cell volume (PCV) value. During sampling animals were categorized into age, body condition score, sex and hair coat color. A total of 40 monoconical traps 10 per district were deployed to estimate the apparent density of vectors. To assess control measures representative number of farmers were interviewed with a prepared questionnaire and using secondary data from veterinary offices. The overall prevalence of trypanosomosis was 7.47% and 4.40% for bovine and equine species, respectively. The prevalence of bovine trypanosomosis was 9.46%, 6.13%, 8.11% and 5.98% while prevalence in equine was 7.8%, 5.3%, 2.7% and 1.8% in Jawi, South Achefer, Dembecha and Jabitehenan districts, respectively. Significance differences in the prevalence of trypanosomosis were observed in hair coat color, age and body condition score in bovine while only body condition was significant in equine. The mean PCV value of parasitemic animals was significantly (P < .001) lower than that of aparasitaemic animals. The apparent densities of vectors were 1.04, 0.97, 0.32 fly/trap/day for Glossina, Stomoxys and Tabanus respectively. Glossina m. submorsitans and G. tachinoides were the species of tsetse identified. The questionnaire response indicated that trypanosomosis was found to be a serious constraint on livestock health in the study areas. The application of continuous trypanosomosis control measures particularly in Jawi and South Achefer districts which were showed an increasing trend in livestock number might be attributed to control effectiveness. In conclusion the presence of trypanosomes and potential vectors necessitate the application of sustainable and integrated control methods in the study areas.
ABSTRACT
The current study was undertaken from December 2015 to May 2016 with the aim of determining and comparing the pathogenicity and response to diminazene aceturate (DA) and isometamidium chloride (ISM) treatment in experimentally infected mice with trypanosome isolates from Jawi and Birsheleko areas of northwest Ethiopia. A total of 42 mice were used for the experiment. These mice were randomly assigned in to 7 groups of 6 mice per group. Three of the groups (Group 1, 4 and 5) were inoculated with trypanosome isolated from Jawi and three other groups (Group-2, 6 and 7) were inoculated with trypanosome isolated from Birsheleko and the remaining one group (Group 3) was negative control. Each experimental mice were received 0.3 ml of positive blood at the 105 parasites/ml from donor animals intraperitoneally while negative control group were received 0.3 ml sterile water. The mice were clinically observed daily during the study period. Parameters including level of parasitaemia, body weight, PCV and hemoglobin value were recorded once per week for ten consecutive weeks post infection. Trypanocidal treatment was given on day 21 post infection when peak parasitaemia was detected in groups (Group 4-DA-Jawi, 5-ISM-Jawi, 6-DA-BRSH and 7-ISM-BRSH). The treatment doses for DA was at 28 mg/kg and for ISM at 4 mg/kg. In all experimental groups during study period when the mice showed severe clinical signs and at the end of the experiment they were euthanized with 70% ethanol for gross and histopathological examinations. The parameters measured during the study period revealed markers leading to pathological changes in all infected groups. Parasitaemia were detected early in the Jawi isolate infected groups compared to the Birsheleko groups. All infected mice showed clear clinical manifestation of depression, weight loss, reduction in feed intake and huddled together in the corner of the cage. Significant (P < 0.05) reduction was observed in the mean PCV and hemoglobin value of s infected mice compared to the negative control. The mean PCV values of Birsheleko isolate infected group was significantly (P < 0.05) lower than Jawi isolate infected group. This study showed that treatment with either DA or ISM were unable to clear parasitaemia indicating the presence of drug resistance problems for both isolates. Relative improvement in clinical and pathological changes was observed as compared with untreated infected groups. Gross and histopathological lesions were observed in infected groups. In conclusion, the current study suggests the presence of strain difference in virulence between isolates and the drugs unable to cure infections indicating the presence of resistance problems necessitate further molecular characterization of the strains and drug resistance detection in the natural host.
ABSTRACT
The Northwestern region of Ethiopia is affected by both tsetse and non-tsetse transmitted trypanosomosis with a significant impact on livestock productivity. The control of trypanosomosis in Ethiopia relies on either curative or prophylactic treatment of animals with diminazene aceturate (DA) or isometamidium chloride (ISM). In the present work; questionnaire survey, cross-sectional and experimental studies were carried out to; a) assess the utilization of trypanocidal drugs; b) determine the prevalence of bovine trypanosomosis and; c) assess the drug resistant problems respectively in Tsetse and non-tsetse infested areas on NW Ethiopia. A total of 100 respondents were included for the survey and the questionnaires focused on the drug utilization practices for the control of Trypanosomosis. Blood from cattle 640 (324 cattle tested in 2011, 316 cattle tested in 2012) and 795 (390 cattle tested in 2011, 405 cattle tested in 2012) were examined from tsetse infested and non-tsetse infested areas respectively using the buffy coat technique and thin blood smear for the detection of trypanosomes and measurement of packed cell volume (PCV). For the assessment of trypanocidal drug resistance three isolates, one from tsetse (TT) and two from non-tsetse (NT) areas were used on thirty six trypanosome naïve calves. The experimental animals were divided randomly into six groups of six animals (TT-ETBS2-DA, TT-ETBS2-ISM, NT-ETBD2-DA, NT-ETBD2-ISM, NT-ETBD3-DA and NT-ETBD3-ISM), which were infected with T. vivax isolated from a tsetse-infested or non-tsetse infested area with 2 × 106 trypanosomes from donor animals, and in each case treated with higher dose of DA or ISM. The results of the questionnaire survey showed trypanosomosis was a significant animal health constraint for 84% and 100% of the farmers questioned in non-tsetse and tsetse infested areas of Northwest Ethiopia respectively. Responses on trypanocidal drug utilization practices indicated that risk factors for the development of drug resistance are common and treatment failures are frequently seen. Accordingly, the majority of farmers in tsetse infested area get trypanocides from drug stores and unauthorized sources whereas those from non-tsetse area get from veterinary clinics. Moreover, treatment administration is mainly by animal health personnel and treatment frequency is a maximum of three times/year/animal in non-tsetse area whereas it is administered mainly by the farmers more than seven times/year/animal in tsetse infested area. The prevalence of trypanosomosis varied from 17.59% in 2011 to 25.0% in 2012 in tsetse infested areas with a significant (P = 0.023) difference. Similarly, in non-tsetse infested area the prevalence was varied from 3.85% in 2011 to 5.93% in 2012 without significant rise. Trypanosoma congolense (75%) was the most prevalent followed by T. vivax (20.58%) and mixed infections (4.41%) in tsetse infested area while in non-tsetse infested area only T. vivax was detected. The overall mean PCV in parasitaemic animals (20 ± 2.3 SD) was significantly (P < 0.001) lower than that of aparasitaemic animals (27 ± 4.3 SD). The assessment of trypanocidal drug resistance tests revealed one isolate of non-tsetse infested area against DA in group NT-ETBD2-DA is resistant to the higher dose used with 3 relapsing animals (50% relapses) in the group. Another two relapses were detected one against ISM for the isolate from tsetse infested area (TT-ETBS2-ISM) and one against DA for another isolate (NT-ETBD3-DA) from the non-tsetse area. In conclusion, trypanosomosis is widely prevalent in both study areas causing significant reduction in the mean PCV values. Farmers' trypanocidal utilization practices appear to pose risks of drug resistance problems. The in vivo drug resistance tests indicated the presence of resistant parasites with the higher dose against DA for NT-ETBD2 isolate and suspected resistance problems were detected against ISM and DA for TT-ETBS2 and NT-ETBD3 isolates respectively. Therefore, trypanosomosis is a major constraint in Northwest Ethiopia and drug resistance is a threat in the control of trypanosomosis in both study areas.
