an epidemiological study of listeriosis in dairy cattle

CHAPTER 7
Conclusion
The aim of this study was to identify risk factors at both the farm level and the
individual animal level which were associated with Listeriosis and L. monocytogenes
infection in dairy cattle. An ultimate aim of epidemiological studies is to control
disease. This can be achieved by a better understanding of the factors associated with
infection and clinical disease.
In this study two observational studies, cross-sectional and longitudinal, were
conducted to determine:
a) the frequency of clinical listeriosis in dairy cattle, its clinical characteristic and risk
factors associated with disease at farm level;
b) the infection rate in individual animals, risk factors associated with it, the degree of
environmental contamination and the source of infection.
In the cross sectional study, a postal survey, was carried out. 12% of dairy
farmers reported clinical Listeriosis and on these farms around 5 out of 100 cattle were
at risk of contracting the disease each year (Chapter 2). The most frequently reported
clinical sign was silage eye. This corresponds with the recent increased number of field
reports of this disease. However there is a need for a detailed investigation to establish
the exact relationship between silage eye and L. monocytogenes and the dynamics of
this relationship.
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