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Objectives: Studies on the pathogenesis and immune responses of Cryptosporidium infection and development of drugs and vaccines use mostly immunocompromised mouse models. In this study, we establish an immunocompetent mouse model of cryptosporidiosis with high intensity and long duration of infection.Methods: We have obtained a Cryptosporidium tyzzeri isolate from laboratory mice, and infect adult C57BL/6 J mice experimentally with the isolate for determinations of infectivity, infection patterns, pathological changes, and transcriptomic responses.Results: The isolate has an ID50 of 5.2 oocysts, with oocyst shedding lasting at high levels for >2 months. The oocyst shedding is boosted by immunosuppression of animals and suppressed by paromomycin treatment. The isolate induces strong inflammatory and acquired immune responses, but down-regulates the expression of α-defensins in epithelium. Comparative genomics analysis has revealed significant sequence differences from other isolates in subtelomeric genes. The down-regulation of the expression of α-defensins may be responsible for the high-intensity and long-lasting infection in this animal model.Conclusions: The immunocompetent mouse model of cryptosporidiosis developed has the advantages of high oocyst shedding intensity and long oocyst shedding duration. It provides an effective mechanism for the propagation of Cryptosporidium, evaluations of potential therapeutics, and studies of pathogen biology and immune responses. [ABSTRACT FROM AUTHOR]

[Display omitted] • No detection of zoonotic Cryptosporidium spp. or Giardia duodenalis from amphibians. • Reptiles are predominantly infected with host-specific Cryptosporidium. • Overall prevalence of zoonotic Cryptosporidium and Giardia duodenalis in reptiles is low. • Detection of zoonotic species in reptiles is likely due to mechanical carriage. • There is a paucity of studies on Giardia from reptiles and amphibians. The zoonotic potential of the protist parasites Cryptosporidium spp. and Giardia duodenalis in amphibians and reptiles raises public health concerns due to their growing popularity as pets. This review examines the prevalence and diversity of these parasites in wild and captive amphibians and reptiles to better understand the zoonotic risk. Research on Giardia in both groups is limited, and zoonotic forms of Cryptosporidium or Giardia have not been reported in amphibians. Host-adapted Cryptosporidium species dominate in reptiles, albeit some reptiles have been found to carry zoonotic (C. hominis and C. parvum) and rodent-associated (C. tyzzeri , C. muris and C. andersoni) species, primarily through mechanical carriage. Similarly, the limited reports of Giardia duodenalis (assemblages A, B and E) in reptiles may also be due to mechanical carriage. Thus, the available evidence indicates minimal zoonotic risk associated with these organisms in wild and captive frogs and reptiles. The exact transmission routes for these infections within reptile populations remain poorly understood, particularly regarding the importance of mechanical carriage. Although the risk appears minimal, continued research and surveillance efforts are necessary to gain a more comprehensive understanding of the transmission dynamics and ultimately improve our ability to safeguard human and animal health. [ABSTRACT FROM AUTHOR]

Octomitus is a diplomonad genus known to inhabit the intestinal tracts of rodents. Ultrastructural morphology and 18S rDNA gene sequence analysis support the placement of Octomitus as the closest sister lineage to Giardia , a parasite which causes diarrheal disease in humans and animals worldwide. However, further information on the ecology and diversity of Octomitus is currently scarce. Expanding the available database of characterized sequences for this organism would therefore be helpful to studies of Diplomonad ecology, evolution, and epidemiology, particularly related to the evolution of parasitism in Giardia and Spironucleus, another related Diplomonad common in commercial fish farming. In order to study the prevalence and genotypic diversity of Octomitus , we developed a nested PCR assay specific to Octomitus and optimized to detect genotypes in fecal samples collected from wildlife in a New York watershed, and sequenced a portion of the small subunit ribosomal DNA (18S rDNA) gene to identify samples to species level. Molecular evidence suggested that Octomitus genotypes display similar prevalence to Cryptosporidium and microsporidian pathogens in wildlife as well as strong host preference for rodent and opossum hosts. Phylogenetic analysis showed strong support for 14 Octomitus genotypes, 13 of these novel, and patterns of host-parasite co-evolution. [Display omitted] • First molecular detection assay for novel Octomitus genotypes. • 13 new Octomitus genotypes are identified in diverse rodent hosts and a marsupial. • Comparable prevalence of Octomitus in wildlife to Cryptosporidium and microsporidia (24.3%). • Octomitus likely has little, if any, public health impact. [ABSTRACT FROM AUTHOR]

Several species of wild mammals are farmed in China as part of the rural development and poverty alleviation, including fur animals, bamboo rats, and macaque monkeys. Concerns have been raised on the potential dispersal of pathogens to humans and other farm animals brought in from native habitats. Numerous studies have been conducted on the genetic identity and public health potential of Cryptosporidium spp., Giardia duodenalis , and Enterocytozoon bieneusi in these newly farmed exotic animals. The data generated have shown a high prevalence of the pathogens in farmed wildlife, probably due to the stress from the short captivity and congregation of large numbers of susceptible animals. Host adaptation at species/genotype and subtype levels has reduced the potential for cross-species and zoonotic transmission of pathogens, but the farm environment appears to favor the transmission of some species, genotypes, and subtypes, with reduced pathogen diversity compared with their wild relatives. Most genotypes and subtypes of the pathogens detected appear to be brought in from their native habitats. A few of the subtypes have emerged as human pathogens. One Health measures should be developed to slow the dispersal of indigenous pathogens among farmed exotic animals and prevent their spillover to other farm animals and humans. [Display omitted] • Cryptosporidium spp., Giardia duodenalis , and Enterocytozoon bieneusi are prevalent in farmed exotic animals. • Divergent species/genotypes and subtypes are found in these enteric pathogens. • The farm environment appears to favor the transmission of some species, genotypes, and subtypes. • Most genotypes and subtypes of the pathogens detected appear to be brought in from the native habitats of animals. • One Health measures should be implemented to control spillover infections of other farm animals and humans. [ABSTRACT FROM AUTHOR]

Abstract Few data are available on the distribution and human infective potential of Cryptosporidium and Enterocytozoon bieneusi genotypes in bats. In this preliminary study, we collected 109 fecal specimens during April–July 2011 from a colony of straw-colored fruit bats (Eidolon helvum) in an urban park (Agodi Gardens) of Ibadan, Nigeria, and analyzed for Cryptosporidium spp., Giardia duodenalis and E. bieneusi using PCR targeting the small subunit rRNA gene, triosephosphate isomerase gene, and ribosomal internal transcribed spacer, respectively. Genotypes of these enteric parasites were determined by DNA sequencing of the PCR products. Altogether, 6 (5.5%), 0 and 16 (14.7%) specimens were positive for Cryptosporidium spp., G. duodenalis , and E. bieneusi , respectively. DNA sequence analysis of the PCR products indicated the presence of two novel Cryptosporidium genotypes named as bat genotype XIV (in 5 specimens) and bat genotype XV (in 1 specimen) and one known E. bieneusi genotype (Type IV in 1 specimen) and two novel E. bieneusi genotypes (Bat1 in 13 specimens and Bat2 in 2 specimens). In phylogenetic analysis of DNA sequences, the two novel Cryptosporidium genotypes were genetically related to Bat genotype II previously identified in fruit bats in China and Philippines, whereas the two novel E. bieneusi genotypes were genetically related to Group 5, which contains several known genotypes from primates. With the exception of Type IV, none of the Cryptosporidium and E. bieneusi genotypes found in bats in this study are known human pathogens. Thus, straw-colored fruit bats in Nigeria are mainly infected with host-adapted Cryptosporidium and E. bieneusi genotypes. Graphical abstract Image 1 Highlights • Two novel Cryptosporidium genotypes were identified in fruit bats in Nigeria. • One known and two novel Enterocytozoon bieneusi genotypes were further detected. • Most Cryptosporidium and E. bieneusi genotypes in fruit bats are host adapted in nature. [ABSTRACT FROM AUTHOR]