Risk indicators associated with Staphylococcus aureus subclinical mastitis in smallholder dairy cows in Tanzania

A cross sectional study was carried out between June and September 2003 to establish the prevalence and related risks indicators for Staphylococcus aureus (S. aureus) subclinical mastitis on smallholder dairy herds in Dar es Salaam region, Tanzania. 191 lactating cows from 64 randomly selected herds were investigated. However, due to such reasons as aggressive cow, blind quarters and presence of open teat wound, the California mastitis test (CMT) was carried out on 726 (9 cows and 2 quarters were not sampled) quarter milk samples. Herd (at least one positive quarter per cow), cow and quarter level prevalence of subclinical mastitis defined by CMT ≥ + were 100 %, 91.2 % and 85.0 % respectively. S. aureus was isolated in 21.0 % of the 718 (11 cows and 2 quarters were not sampled) - bacteriologically examined quarter milk samples. The cow and quarter level prevalence of sub-clinical mastitis, defined by positive CMT (≥ +) score and S. aureus positive culture, was 97.4 % and 98.0 %, respectively. Water availability, residual suckling, single uddertowel, poor housing sanitation, teat-lesions and the failure to use dry-cow therapy were the most substantial (ρ < 0.05) risk indicators. It is concluded that intensive and continuous farmer education programmes particularly focusing on subclinical mastitis prevalence and ways to reduce or eliminate these infections, are necessary to improve udder health in Tanzania. These issues are discussed at the end of the paper.