TABLE 2.

Differences in PCR results with DNA extracted from peripheral blood of selected cows with low, intermediate, normal PCVs^a

Agent(s)	No. of positive animals/no. of animals tested (% of positive animals)			Pb
	Group I	Group II	Group III
A. marginale	26c/27 (96)	14/16 (88)	1/15 (7)	<0.0001
Theileria spp.	23/25 (92)	12/16 (75)	1/15 (7)	<0.0001
M. wenyonii	21/27 (78)	1/16 (6)	0/15 (0)	<0.0001
Babesia spp.	12/25 (48)	0/16 (0)	0/15 (0)	<0.0001
A. phagocytophilum	1/27 (4)	2/16 (13)	0/15 (0)	NSd
B. burgdorferi	0/27 (0)	0/16 (0)	0/15 (0)	NS

^aA total of 58 blood samples were tested. Blood samples collected from 12 cows referred to the Animal Hospital in Zurich in 2004 for unrelated reasons, as well as 12 samples from healthy calves, tested negative by PCR for all agents with the exception of M. wenyonii (data not shown). Seven of 12 samples from sick adult cattle, but not from calves, were positive for M. wenyonii. The clinical relevance of this unexpected finding is not yet clear and is the topic of further investigations.

^bP values were determined by chi-square analysis.

^cSee the data for animal 96 in Table 1.

^dNS, not significant.