title: Population genetics of Cryptosporidium meleagridis in humans and birds: evidence for cross-species transmission.
abstract: Population genetic studies have been used to understand the transmission of pathogens in humans and animals, especially the role of zoonotic infections and evolution and dispersal of virulent subtypes. In this study, we analysed the genetic diversity and population structure of Cryptosporidium meleagridis, the only known Cryptosporidium species that infects both avian and mammalian hosts and is responsible for approximately 10% of human cryptosporidiosis in some areas. A total of 62 C. meleagridis specimens from children, AIDS patients, and birds in Lima, Peru were characterised by sequence analysis of the ssrRNA gene and five minisatellite, microsatellite and polymorphic markers in chromosome 6, including the 60 kDa glycoprotein (gp60), 47 kDa glycoprotein (CP47), a serine repeat antigen (MSC6-5), retinitis pigmentosa GTPase regulator (RPGR) and thrombospondin protein 8 (TSP8). The multilocus sequence analysis identified concurrent infections with Cryptosporidium hominis in four AIDS patients and three children. Unique subtypes of C. meleagridis ranged from eight at the gp60 locus (gene diversity -Hd=0.651), three at the RPGR (Hd=0.556), three at the MSC6-5 locus (Hd=0.242), two at TSP8 (Hd=0.198), to one at CP47 (monomorphic), much lower than that of C. hominis in the same area. Intragenic linkage disequilibrium was strong and complete at all gene loci. Intergenic linkage disequilibrium was highly significant (P<0.001) for all pairs of polymorphic loci. Two major groups of subtypes were seen, with most subtypes belonging to group 1. Within group 1, there was no clear population segregation, and two of the 14 multilocus subtypes of C. meleagridis were found in both AIDS patients and birds. We believe that these results provide the first evidence of a clonal population structure of C. meleagridis and the likely occurrence of cross-species transmission of C. meleagridis between birds and humans.
authors.affiliation: State Key Laboratory of Bioreactor Engineering, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Yuanfei
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: Wenli
authors.initials: W
authors.lastname: Yang
authors.affiliation: Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
authors.forename: Vitaliano
authors.initials: V
authors.lastname: Cama
authors.affiliation: State Key Laboratory of Bioreactor Engineering, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Asociación Benéfica PRISMA, Lima, Peru.
authors.forename: Lilia
authors.initials: L
authors.lastname: Cabrera
authors.affiliation: Center for Food Safety, University of Georgia, Griffin, GA 30223, USA.
authors.forename: Ynes
authors.initials: Y
authors.lastname: Ortega
authors.affiliation: Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
authors.forename: Caryn
authors.initials: C
authors.lastname: Bern
authors.affiliation: State Key Laboratory of Bioreactor Engineering, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China. Electronic address: yyfeng@ecust.edu.cn.
authors.forename: Yaoyu
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Department of International Health, Johns Hopkins University, Baltimore, MD 21205, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Gilman
authors.affiliation: Division of Foodborne, Waterborne, and Environmental Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. Electronic address: lxiao@cdc.gov.
authors.forename: Lihua
authors.initials: L
authors.lastname: Xiao
mesh_terms: D000818:Animals; D001715:Bird Diseases / Q000469:parasitology; D001717:Birds; D003457:Cryptosporidiosis / Q000469:parasitology*; D003458:Cryptosporidium / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D010568:Peru; D015800:Protozoan Proteins / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D015800:Protozoan Proteins; D012337:RNA, Ribosomal, 18S
keywords: Cryptosporidium meleagridis; Multilocus sequence typing; Population genetics; Subtypes; Zoonosis