Public health hazard due to mastitis in dairy cows*

Milk from cows with sub-clinical mastitis accidentally mixed into bulk milk enters food chain and poses a threat to human health. Milk and other dairy products are reported to be frequently infected with Staphylococcus aureus. Also Streptococcus agalactiae has been described as one of the most common agents of invasive infections. The present study was aimed at discussing the economy and public health importance of mastitis in cattle as well as the health hazard of the causative organisms (S. aureus and Str. agalactiae). Seven-hundred-and-four composite milk samples were collected (two or three times per cow per lactation) from 275 cows kept in two herds. The samples were analysed for the presence of S. aureus, Str. agalactiae and other mastitis-causing organisms. For pooled data of latent and subclinical mastitis the frequency of samples containing S. aureus and Str. agalactiae was 16.6 and 1.4%, while of those containing Str. dysgalactiae, Escherichia coli and other mastitis-causing organisms − 4.7, 2.9, and 14.7%, respectively. Quality of milk was found ranging within the European standard. However, high mastitis prevalence in both herds suggests that hygienic control measures should be applied during milk production.