Browsing by Author "Yohannes Tsegaye"

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    Seroprevalence and Risk Factors of Bovine Brucellosis and its Zoonotic Significance in Arsi Zone, Oromia Regional State, Ethiopia
    (Addis Ababa University, 2010-06-01) Yohannes Tsegaye; Moses N. Kyule
    The seroprevalence and risk factors of brucellosis were investigated in cattle kept in intensive and extensive production system, and in human subjects who are occupationally at risk and the general population in Arsi zone, Oromia Regional State, Ethiopia between October 2009 and March 2010. In order to achieve this; on the bases of a one stage cluster sampling technique, sera from a total of 74 clusters consisting of 756 heads of cattle from both system [5 herds consisting 274 animals from intensive system and 69 herds consisting 482 heads of cattle from extensive system (mixed crop-livestock production)] were collected. And on the bases of convenience sampling technique, sera from a total of 183 human subjects (35 from individuals working in government dairy farm/vet lab and the rest 148 from general population or out-patients who came to health centers within the zone) were collected. All cattle and human sera were screened serologically by Rose Bengal Plate Test (RBPT) and sera found positive on RBPT were retested by Complement Fixation Test (CFT). Thus, from RBPT and CFT results, herd and animal level seroprevalence were 9.5% (95% CI: 2.8 - 16.2) and 2.6% (95% CI: 1.5 - 3.7) respectively without considering systems. Herd level seroprevalences were 40% (95% C1: 0.0 - 80.0) in intensive system and 7.3% (95% CI: 1.1 - 13.3) in extensive system . The animal level seroprevalence and within-herd range of brucellosis in cattle in intensive system were 4.4% (95% C1: 2.0 - 6.8) and 0.0 - 7.5%, while for those in extensive system were 1.7% (95% C1: 0.5 - 2.9) and 0.0 - 30%, respectively. According to univatiate logistic regression analysis both herd and animal level seroprevalence were significantly higher (p < 0.05) in the intensive system than in the extensive system. Univariate analysis revealed that, the odds of brucellosis in larger herd size was eleven times (Odds ratio = 11.8) higher than the smaller herds and it was found also to be statistically (p < 0.05) significant. The odds of brucellosis among older cattle (> 3 years) was also five times (OR = 5.00) higher than cattle aged under 3 years for within intensive system and was also statistically (P < 0.05) significant; but not significant (p < 0.05) for within extensive system. Brucellosis seropositivity was observed in 42.9% of the herds with histOlY of previous abortion (n = 7) and in 6.0% of the herds without previous abortion (n = 67) with statistically significant difference (P < 0.05) irrespective of the system of production. In general, the multivariable logistic regression model revealed herd size to be the major risk factor with significant level (p = 0.01) followed by positive influence of production system, sex and age for seropositivity to Brucella antigens; while breed had no influence to seropositivity An overall human brucellosis seroprevalence of 2.2% (95% C1: 1.6 - 2.8) was estimated in this study. Higher seroprevalence-II.4% (95% C1: 0.9 - 21.9) with significant level (p < 0.05) was recorded among occupationally exposed group (among dairy farm/vet lab workers) than among the general population owing to their definite contact with the infected cattle herd confirmed by this study. Specific duties of the seroreactor individuals were two milkers, a barn cleaner and an animal health professional. Seroprevalence in males was higher than females due to their occupation differences that males are employed in such institutions than females. Therefore, the findings of the present study reveal that human brucellosis in Arsi zone is an occupational disease with high impact on persons who, due to their profession, are in direct contact with cattle, animal products and their environments particularly those working under intensive farm. Owing to the statistically significant difference observed in the seroprevalence of bovine brucellosis between intensive and extensive systems; and the seroprevalence of human brucellosis linked to occupational exposure to intensive farms implied some sort of different control strategies need to be addressed in Arsi zone. Thus, implementing a culling practice in the extensive system to eliminate the existing low risk of brucellosis and targeting calves in the intensive systems for vaccination in addition to culling reactors could minimize the economic loss and reduce occupational exposure in particular and the public health in general through production and distTibution of safe agricultmal product