In financial terms, mastitis is the most costly disease in the dairy industry, totaling approximately $1.8 billion dollars lost annually. Cost of a single case of mastitis ranges from $104 (Hoblet et al. 1991) to $200 (NMC, 1996). These losses are a result of reduced milk production, discarded milk, replacement costs, extra labor, treatment and veterinary service costs. Increased prevalence of mastitis also results in greater risk of antibiotic residues in human food as well as milk quality issues.