title: Cryptosporidium muris: infectivity and illness in healthy adult volunteers.
abstract: Although Cryptosporidium parvum and C. hominis cause the majority of human cryptosporidiosis cases, other Cryptosporidium species are also capable of infecting humans, particularly when individuals are immunocompromised. Ten C. muris cases have been reported, primarily in human immunodeficiency virus (HIV) -positive patients with diarrhea. However, asymptomatic cases were reported in two HIV-negative children, and in another case, age and immune status were not described. This study examines the infectivity of C. muris in six healthy adults. Volunteers were challenged with 10(5) C. muris oocysts and monitored for 6 weeks for infection and/or illness. All six patients became infected. Two patients experienced a self-limited diarrheal illness. Total oocysts shed during the study ranged from 6.7 × 10(6) to 4.1 × 10(8), and the number was slightly higher in volunteers with diarrhea (2.8 × 10(8)) than asymptomatic shedders (4.4 × 10(7)). C. muris-infected subjects shed oocysts longer than occurred with other species studied in healthy volunteers. Three volunteers shed oocysts for 7 months. Physical examinations were normal, with no reported recurrence of diarrhea or other gastrointestinal complaints. Two persistent shedders were treated with nitazoxanide, and the infection was resolved. Thus, healthy adults are susceptible to C. muris, which can cause mild diarrhea and result in persistent, asymptomatic infection.
authors.affiliation: Center for Infectious Diseases, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas; Division of Infectious Diseases, Medical School, University of Texas Health Science Center at Houston, Houston, Texas; Department of Infectious Disease and Global Health, Tufts University Cummings School of Veterinary Medicine, North Grafton, Massachusetts cynthia.l.chappell@uth.tmc.edu.
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Chappell
authors.affiliation: Center for Infectious Diseases, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas; Division of Infectious Diseases, Medical School, University of Texas Health Science Center at Houston, Houston, Texas; Department of Infectious Disease and Global Health, Tufts University Cummings School of Veterinary Medicine, North Grafton, Massachusetts.
authors.forename: Pablo C
authors.initials: PC
authors.lastname: Okhuysen
authors.affiliation: Center for Infectious Diseases, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas; Division of Infectious Diseases, Medical School, University of Texas Health Science Center at Houston, Houston, Texas; Department of Infectious Disease and Global Health, Tufts University Cummings School of Veterinary Medicine, North Grafton, Massachusetts.
authors.forename: Rebecca C
authors.initials: RC
authors.lastname: Langer-Curry
authors.affiliation: Center for Infectious Diseases, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas; Division of Infectious Diseases, Medical School, University of Texas Health Science Center at Houston, Houston, Texas; Department of Infectious Disease and Global Health, Tufts University Cummings School of Veterinary Medicine, North Grafton, Massachusetts.
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Lupo
authors.affiliation: Center for Infectious Diseases, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas; Division of Infectious Diseases, Medical School, University of Texas Health Science Center at Houston, Houston, Texas; Department of Infectious Disease and Global Health, Tufts University Cummings School of Veterinary Medicine, North Grafton, Massachusetts.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Widmer
authors.affiliation: Center for Infectious Diseases, School of Public Health, University of Texas Health Science Center at Houston, Houston, Texas; Division of Infectious Diseases, Medical School, University of Texas Health Science Center at Houston, Houston, Texas; Department of Infectious Disease and Global Health, Tufts University Cummings School of Veterinary Medicine, North Grafton, Massachusetts.
authors.forename: Saul
authors.initials: S
authors.lastname: Tzipori
mesh_terms: D000328:Adult; D000818:Animals; D003458:Cryptosporidium / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D005838:Genotype; D006801:Humans; D007121:Immunocompetence; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D016133:Polymerase Chain Reaction
chemical_list: D007074:Immunoglobulin G; D007075:Immunoglobulin M