Genetic Polymorphism among Cryptosporidium parvum Isolates: Evidence of Two Distinct Human Transmission Cycles

Authors

Michael M. Peng, University of Michigan
Lihua Xiao, United States Centers for Disease Control and Prevention
Amanda R. Freeman, United States Centers for Disease Control and Prevention
Michael J. Arrowood, United States Centers for Disease Control and Prevention
Ananias A. Escalante, United States Centers for Disease Control and PreventionFollow
André C. Weltman, Pennsylvania Department of Health
Corinne S.L. Ong, University of British Columbia
William R. Mac Kenzie, United States Centers for Disease Control and Prevention
Altaf A. Lal, United States Centers for Disease Control and Prevention
Charles B. Beard, United States Centers for Disease Control and Prevention

ORCID IDs

Escalante 0000-0002-1532-3430

Document Type

Article

Date of this Version

12-1997

Citation

Emerging Infectious Diseases (1997) 3(4): 567–573

doi: 10.3201/eid0304.970423

Comments

United States government work, public domain

Abstract

We report the results of molecular analysis of 39 isolates of Cryptosporidium parvum from human and bovine sources in nine human outbreaks and from bovine sources from a wide geographic distribution. All 39 isolates could be divided into either of two genotypes, on the basis of genetic polymorphism observed at the thrombospondin-related adhesion protein (TRAP-C2) locus. Genotype 1 was observed only in isolates from humans. Genotype 2, however, was seen in calf isolates and in isolates from a subset of human patients who reported direct exposure to infected cattle or consumed items thought to be contaminated with cattle feces. Furthermore, experimental infection studies showed that genotype 2 isolates were infective to mice or calves under routine laboratory conditions, whereas genotype 1 isolates were not. These results support the occurrence of two distinct transmission cycles of C. parvum in humans.