|The UK Situation|
The last national survey was carried out across England and Wales in 2004-05 quantified the UK situation with regard to clinical disease incidence and the pathogens involved in both clinical and sub-clinical disease. Of the 125 dairy herds surveyed, 97 returned samples and data to enable analysis to be performed. The incidence rate of clinical mastitis cases (cases per 100 cows per year) from 90 dairy herds across England and Wales is shown in Figure 1, with almost a quarter of herds reporting greater than 100 cases per 100 cows per year.
Figure 1: An illustration of the distribution of clinical mastitis incidence rates in UK dairy herds.
Bacteriology results obtained from 480 clinical mastitis samples submitted for culture revealed Streptococcus uberis and Escherichia coli to be the most commonly isolated organisms, accounting for 23.5% and 19.8% of cases respectively.
Collated national statistics suggest that, at around 200,000 cells/ml, bulk milk somatic cell count (BMSCC) is currently relatively well-controlled. As a broad rule of thumb, for every 100,000 cells/ml increase in BMSCC approximately 8 to 12% of the herd is likely to be infected - i.e. a dairy herd with a BMSCC of 200,000 cells/ml would be expected to have approximately 20% of the cows infected.
From 464 sub-clinical mastitis samples (samples from high somatic cell count cows) collected during the 2004-05 survey, 13.8% cultured S. uberis and 5.2% cultured Staphylococcus aureus although almost 40% returned a diagnosis of no growth, indicating how difficult isolation of major mastitis pathogens can be from persistently infected cases.
Data produced by DairyCo on the hygienic quality of milk can be found here.
The results of the survey led to the conclusion that the incidence of clinical mastitis in dairy herds in England and Wales was somewhere between 47 and 65 cases per 100 cows/year; higher than previously thought. Environmental pathogens (pathogens predominating in the environment) tended to predominate but contagious pathogens (pathogens spreading from cow to cow) remained an important issue in some herds; a clear shift away from the UK situation 50 years ago, as illustrated in Figure 2.
Figure 2: An illustration of the change in the relative contribution of contagious and environmental pathogens to clinical mastitis in the UK.