Monitoring the dynamic nature and magnitude of the mastitis challenge, prevalence and incidence within the modern dairy herd is becoming common place around the developed dairy industries of the world. The iterative process of regular interpretation of prevalence data (Individual Cow Somatic Cell Counts [ICSCC]), incidence data (Clinical Mastitis Records) and how these data change over time both within lactation and over the dry period can give much information about the transmission patterns and likely origin and duration of intramammary infections within a dairy herd