TABLE 1.

C. parvum isolates used in this investigation

Isolate	Host	Source	Oocyst age (days)a	Excystation rate (%)b
Iowa	Cow	H. Moon, National Animal Disease Center, Ames, Iowa	8-15	95
TAMU	Horse	C. L. Chappell, University of Texas Health Science Center, Houston	12-49	95
Moredun	Deer	S. E. Wright, Moredun Research Institute, Peniculk, Scotland	11-37	98
Maine	Humanc	M. J. Arrowood, Centers for Disease Control, Atlanta, Ga.	6	97
Glasgow	Humand	H. V. Smith, Scottish Parasite Diagnostic Laboratory, Glasgow, Scotland	8	98
Peru-HIV2	Humane	R. Gilman, Johns Hopkins University, Baltimore, Md.	62	81

^aOocyst age at the time of infection.

^bIn vitro excystation rate determined within 10 days after shedding (except Peru-HIV2 [62 days]).

^cIsolated during an outbreak traced to contaminated apple cider.

^dIsolated during an outbreak traced to contaminated drinking water.

^eIsolated from a human immunodeficiency virus patient attending a clinic in Lima, Peru.