Table 1.

Prevalence and Incidence of MNV, Helicobacter spp., MHV, and Syphacia obvelata in conventional mouse rooms

	Mean (range) of prevalence in conventional colony	Paradigm 1 Incidence			Paradigm 2 Incidence
		Total no. of litters	No. of positive litters	% positive litters	Total no. of litters	No. of positive litters	% positive litters
MNV	85% (73% to 100%)a	57	3 (2 at 4 wk; 1 at 12 wk)d	5%	142	1 at 4 wk	0.7%
Helicobacter spp.	90%b	57	6 (4 at 4 wk; 2 at 8 wk)	11%	142	1 at 4 wk	0.7%
MHV	98% (88% to 100%)	57	7 at 4 wk	12%	142	0	0%
Syphacia obvelata	90%c	2e	2 at 4 wk	100%	1e	1 at 4 wk	100%

^aThe range is 2 standard deviations around the average prevalence of the rooms.

^bEstimate of Helicobacter prevalence in the conventional mice based on our obtained value in the barrier rooms.

^cEstimate of the Syphacia obvelata prevalence in the conventional mice estimated based on historic tape test, fecal flotation, and histopatholgic data

^dIndicates the number of weeks after cross-fostering.

^eNone of the surrogate mothers were fed a diet containing fenbendazole. Pinworm treatment was instituted after the first 3 cross-fostered litters. None of these litters were included the total 287 conventional and barrier litters reported for the other agents.