The Epidemiology of Bovine Brucellosis in Intra and Peri-Urban Dairy Production Sysems in and Around Addis Ababa
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Date
1998-01
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Addis Ababa Universty
Abstract
Bovine brucellosis is an infectious disease of economic importance by causing abortions and infertility. Bovint: brucellos is considered a zoonosis.
infprmation on the extent of bovine brucellosis. however. is scarce for the expanding intra- and peri- urban dairy enterprise in Ethiopia. The purpose of this study was to investigate the status of bovine brucellosis and its impact on reproduction in some intra- and peri-urban dairy production systems
in Ethiopia. A cross-sectional investigation of bovine brucellosis was carried out from Jun to October 1917 on -42 dairy farms located in Debre Zeit, Kalili, Sebela, and Addis Ababa. The farms represent peri-urban systems. Intra-urban systems in secondary towns and intra-urban production systems. Bulk milk samples were collected from each farm (herd ) in June, August, and
October Blood samples from 950 non-vaccinated breeding animals above six months of age were collected once in June. The milk Ring Test (WRT), the Rose Bengal Plate Test (ROPT). and the Complement Fixation Test (CFT) were carried out on milk and serum samples. Farm management parameters and zoonotic aspects were cullected by administering a questionnaire . An overall herd infection rate of 33.3% was determined. With respect to the production systems 100%. 30%, and 12.5% of the farms were infected in peri-u rban. intra.-urbun stecondary town. and intra -urban systems, respectively. The within herd prevalence ranged from 0-16.7%. At least one or two reactors were idemilied in 64.3% of the farrms. An overall prevalence rate of 811% was found on individual animals. A prevalence rate of 9.8 % was observed in the age group 2 to 4 years. A prevalence rale af 9.1 % and 3.3% was identified in fams that keep more than 100 animals, and less than 50 animals, respectively. Significant difference in prevalence rate was observed in animals aged below and above 2 yeas and between no arturition and at least one parturition. A significant difference in prevalence rate
was also observed between farms that keep below 50 and above 100 animals. Odds ratios (OR) of 2.1 4 (1.04·483) between age and brucellosis infection and 2.99 ( 1.29· 8.06) between herd size and brucellosis infection were determined. Significant differences in prevalence rates were not observed among the production systems and districts in indvidual animals.
Agreement (kappa values) between RBPT +/'CFT+ and MRT tests were 0.31 (first MRT result ), 0.43 (first and second MRT results pooled), and 0.58 (first. second and third MRT results pooled). Moderate agreement (k=0.44) was found between RBPT+ and CFT +and good agreement (k=O.74) was found between RBPT+ and RBPT +ICFT + testing procedure Considering positive results in both RBPT and CFT as gold standnrd the sensitivity (SE) and specificity (SP) of the pooled MRT were 57.1% and 89.3%respectively). Sensitivty and specilicity, of RBPT were 100% and 94.6%. respectively.
Associations betweer reproductive and production parameters and brucellosis infection could not be established for individual animals. However. on the basis of questionnaire .answers, previous abortions and use of natural service were associated with Brucellar infection: OR of 15.58 (1.72-79.16) and 0.06(0·0.61) were calculated respectively·. Abortions were recorded in 56.1 % of the farms. Lack of knowledge of brucellosis was recorded in 87.8% of the farms. Cleaning and disinfection was done regularly in 29.3,% removal of infected animals was farm practice in 14.6%provision of maternity pens was found in 4,9% of the farms, and 21.9% of the farms obtained repbcement stock from outside source. Prokmged fever was observed in nine persons interviewed . They were attending cows for at
least six months. Absence of vaccination . herd size, cuttle density, lack of knowledge of brucellosis, and poor manogement and husbandry practices are likely factors responsibl to explain the relaively high prevalence rate observed in his study. Due to its impact on production and lfor its 'Zoonotic significance. Awareness of brucellosis in urban farming should be given priority. Conclusions and recommendations in this regard, emphasizing control of brucellosis are given.
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The Epidemiology of Bovine