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|Title: ||EPIDEMIOLOGY OF BOVINE TRYPANOSOMOSIS IN THE ABBAY BASIN AREAS OF NORTHWEST ETHIOPIA|
|Authors: ||SHIMELIS, DAGNACHEW NIGATU|
|Advisors: ||Dr. Arun K. Sangwan|
Prof. Getachew Abebe
|Keywords: ||Epidemiology/ Bovine/ Trypanosomosis/ Glossina m|
henan/ Northwest Ethiopia
submorsitans/ Drug Resistance/ Survival Analysis/ Season/ Altitude/Abbay Basin/ Dembecha/ Jabite
|Copyright: ||Jul-2004 |
|Date Added: ||10-May-2012 |
|Abstract: ||Tsetse transmitted animal trypanosomosis is a serious constraint to livestock production and
agricultural development in Ethiopia. Part of Abbay basin (Blue Nile) in northwest Ethiopia is
tsetse infested where animal trypanosomosis is a serious threat to economic development. The
objectives of the study were to generate a base line data on epidemiology of tsetse and
trypanosomosis, to assess trypanocidal drug resistance and to know the community awareness
regarding the disease and control methods in the area. The study was conducted between
September 2003 to April 2004 in Dembecha and Jabitehenan weredas of the Abbay basin
areas of northwest Ethiopia. The study methodology was based on questionnaire survey,
seasonal cross-sectional studies of tsetse and trypanosomosis and longitudinal study for the
assessment of trypanocidal drug resistance in the field.
The questionnaire survey indicated that trypanosomosis is the most important problem
affecting the animals and impeding agricultural activity in the area. Entomological survey
revealed that Glossina. m. submorsitans was the only prevalent tsetse fly along with other
biting tabanid and muscid flies. The apparent fly densities were significantly higher (p<0.05)
in the late rainy season (1.08fly/trap/day, 8.78fly/trap/day and 91fly/trap/day) for G. m.
submorsitans, tabanids and muscids respectively than the dry season (0.68fly/trap/day,
0.35fly/trap/day and 7.33fly/trap/day) respectively. In the lowland areas (<1600 m. a. s. l.) the
apparent density for G. m. submorsitans was significantly higher (p<0.05) than the midland
areas (1600-2000 m.a.s.l.) in the both seasons. The altitudinal distribution limit of G. m.
submorsitans was upto 1780 m.a.s.l.The proportion of tsetse flies caught was higher in the
savanna vegetation type followed by riverine, forest, bush and cultivated lands with maize,
teff and horticulture plantations.
In the parasitological survey a total of 1,648 animals, 814 in the late rainy season and 834 in
the dry season were examined with buffy coat technique and the prevalence of
trypanosomosis was 17.07% and 12.35% respectively with a significant difference (p<0.05)
between seasons. Higher infection rates found in the lowland areas below 1600 m.a.s.l.
(19.87% and 17.62%) than the midland areas ≥1600 m.a.s.l.(13.39% and 6.54%) in the late
rainy and dry season respectively with significant difference (p<0.05).The mean PCV values
(%) of parasitaemic and aparasitaemic animals during the late rainy season were 20.7±3.5SD
and 26.6±4.3SD (p<0.001, 95% CI=25.3-25.9) while during the dry season 21.4±3.6SD and
26.6±4.3SD (p<0.001, 95% CI=25.4-25.9) respectively. The regression analysis of herd
average PCV from herd prevalence indicated that herd average PCV decreased with
increasing prevalence of trypanosome infections with a regression coefficient of negative
values in both the seasons.
A total of 100 animals were selected for the assessment of Isometamidium chloride (ISMM)
and Diminazine aceturate resistance, 50 from each of the high risk villages identified in the
area with similar agroecological zones. The selected animals in each village were grouped
into 25 in control and 25 in treatment groups and were identified with ear-tags. At day minus
14 of the study all the 100 cattle were treated with Diminazine aceturate at a dose rate of
7mg/kg bw. After two weeks (day 0) the treatment groups were given ISMM at a dose rate of
1mg/kg bw. Both groups of cattle were examined for trypanosome parasite using buffy coat
technique every 14 days interval until 84 days. The three indices used in assessing ISMM
resistance (the proportion of infection during 8 weeks follow-up period, the 25% survival time
and the ratio of mean hazard rates in the control and treatment groups of cattle) provided
consistent results across the two villages for the occurrence of ISMM resistant trypanosome
infections in the area. There was no significant difference between the Kaplan-Meier survival
curve estimates of the control and treatment groups in both villages (p>0.05).The results of
Diminazine aceturate efficacy showed 16 animals became recurrent infections with T.
congolense but there was no significant difference between trypanosome incidence rate and
trypanosome recurrence rate.
Therefore, trypanosomosis is the most important problem for agricultural activity and animal
production in the Abbay basin areas of northwest Ethiopia (Dembecha and Jabitehenan
weredas of Amhara Region) and the situation is getting worse as the control and prevention of
trypanosomosis is facing a challenge due to limitation of vector control activities and the
development of drug resistance in the area.|
|Appears in:||Thesis - Tropical Veterinary Epidemiology|
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