Prevalence of clinical and subclinical mastitis in the Southern Highlands of Tanzania: Results of a cross sectional study

Abstract

A cross-sectional study was conducted between January and March 1999 in Iringa region to determine the prevalence of clinical and subclinical mastitis in smallholder dairy cows. Questionnaire data were collected to assess farmers' awareness of mastitis, including the clinical signs they associated with the disease, and their knowledge of clinical mastitis and its effects on milk production. The California Mastitis Test (CMT) was carried out on milk from each quarter of every lactating cow in the field to determine the prevalence of subclinical mastitis. A total of 739 quarter milk samples from 188 apparently healthy cows, with no clinical signs of mastitis, were further submitted to the laboratory for bacteriological examination and antibiotic sensitivity testing. Questionnaire results indicated that 28% of farms had clinical mastitis in their dairy cows during 1998 but only 71% of farmers treated their affected cows. The prevalence of subclinical mastitis was 80% of all cows, based on a CMT result of=1+. Mastitis pathogens were isolated from 26.9% of all milk samples taken from "normal" quarters. Organisms isolated from milk included Staphylococcus aureus (24.1%), Staph. epidermidis (19.2%) and unidentified Staphylococcus spp. (17.7%). Other isolates were Micrococcus spp. (13.8%), Streptococcus agalactiae (3.9%), unidentified Streptococcus spp. (9.9%), Arcanobacter pyogenes (4.4%), Escherichia coli (2.5%), Klebsiella spp. (3.5%) and others (1.0%). Of the isolates tested, least evidence of resistance was found to erythromycin, lincomycin, methicillin and tetracycline whereas some resistance was found to ampicillin, cloxacillin and penicillin. All isolates were found to be 100% resistant to cephaloridine.