an epidemiological study of listeriosis in dairy cattle

All environmental samples were examined in order to compare the RAPD
patterns with those found in faecal isolates. A comparison of environmental and faecal
isolates obtained at the first three visits and the visit when the highest prevalence of
infection observed is given in the table 6. 20.
Table 6. 20. Comparison of environmental and animals isolates obtained at
different visits.
RAPD patterns obtained at
first three visits peak prevalence
environment animal environment animal
Farm A 1, 2 1 2 , 2, 5 3 3, 4 1, 3, 5 2 , 6 2
Farm B 1, 5, 6 1 3 , 2, 5, 6 5 1 2 , 5 3 , 6, 7 1 3 , 5
Farm C 1 1 2 1 2 , 5, 8, 9 1 3 , 2
Farm D 5 3 ,6 3 1 3 , 2 3 ,5,10 4 5 4 1 5 , 2, 5, 6 2 , 11
Farm E 6 2 1 2 , 5, 7 9 , 12 2 1 4 , 6, 7 1, 5 3 , 6
number refers to the pattern, superscript number refers to the number of times a pattern was detected.
Examination of these isolates failed to reveal any obvious relationship between
environmental and faecal isolates or between faecal isolates present before or at housing
and those at peak excretion (Table 6. 20).
On farm A patterns 1 and 2 were present in animals and the environment at the
first three visits (before housing) and pattern 5 was also present in animals. At the
highest prevalence of infection patterns 1 and 5 were still present in faecal isolates, 2
was not detected and the patterns 3 and 6 had appeared. Patterns 1 and 2 were no longer
present, but 3 and 4 were detected.
On farm B patterns 1, 5, 6 were present in the environment and faeces prior to
housing and pattern 2 was also detected in faecal isolates. At the highest prevalence of
infection patterns 1 and 5 were still present in faecal isolates, 1, 5 and 6 were still
present in the environment and pattern 7 was also detected in the environment.
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