Current mastitis control programs are based primarily on hygiene including teat disinfection, antibiotic therapy and culling of chronically infected cows. Acceptance and application of these measures has led to considerable progress in controlling contagious mastitis pathogens. However current mastitis control procedures are less effective against environmental pathogens Environmental streptococci account for a significant number of both subclimcal and clmica intramammary infections (IMI) in lactating and nonlactating cows. Among the environmental streptococci, Streptococcus uberis and Streptococcus dysgalactiae subsp. dysgalactiae appear to be the most prevalent, infecting mammary glands as favorable conditions arise. In spite of the economic impact caused by the high prevalence of environmental streptococci in many well-managed dairy herds, virulence factors associated with pathogenesis of environmental streptococcal mastitis in dairy cows are not well understood. Consequently, strategies for controlling mastitis caused by environmental streptococci are poorly defined and currently inadequate.
展开▼
