TY - JOUR AU - Peng, Michael M. AU - Xiao, Lihua AU - Freeman, Amanda R. AU - Arrowood, Michael J. AU - Escalante, Ananias A. AU - Weltman, André C. AU - Ong, Corinne S.L. AU - Mac Kenzie, William R. AU - Lal, Altaf A. AU - Beard, Charles B. T1 - Genetic Polymorphism Among Cryptosporidium parvum Isolates: Evidence of Two Distinct Human Transmission Cycles T2 - Emerging Infectious Disease journal PY - 1997 VL - 3 IS - 4 SP - 567 SN - 1080-6059 AB - 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. KW - Canada KW - United States DO - 10.3201/eid0304.970423 UR - https://wwwnc.cdc.gov/eid/article/3/4/97-0423_article ER - End of Reference