TABLE 3.

Logistic regression model for the likelihood of neonatal-mouse infectivity of intact Cryptosporidium parvum oocysts (bovine genotype A) isolated from one of three in vitro excystation protocols

Factor	Infectivity measured with tissue homogenates			Infectivity measured with histopathology
	Coefficienta	95% CI	Odds ratio	Coefficienta	95% CI	Odds ratio
Protocolb
I	−0.48	−1.46, 0.50	0.62	−0.03	−0.79, 0.72	0.97
II	−0.45	−1.51, 0.61	0.63	−0.27	−1.11, 0.57	0.76
III	−1.45	−2.36, −0.55	0.23	−1.14	−1.85, −0.42	0.32
Positive controlc	0		1.0	0		1.0
Ln (dose)	1.37	0.93, 1.81	3.94	0.80	0.60, 0.99	2.22
Constant	−4.14	−6.18, −2.10	0.02	−2.64	−3.71, −1.57	0.07

^aCoefficient for the log odds or logit, defined as [In(prevalence of infection/1−prevalence of infection)].

^bExcystation protocol I was that of Black et al. (3), protocol II was that of Rennecker et al. (11), and protocol III was that of Atwill et al. (2).

^cReferent category for the different excystation protocols, comprised of fresh bovine C. parvum oocysts.