Seasonal Shedding of MultipleCryptosporidiumGenotypes in California Ground Squirrels (Spermophilus beecheyi)

Abstract

Twelve percent of 853 California ground squirrels (Spermophilus beecheyi) from six different geographic locations in Kern County, Calif., were found to be shedding on average 44,482 oocysts g of feces ؊1 . The mean annual environmental loading rate of Cryptosporidium oocysts was 57,882 oocysts squirrel ؊1 day ؊1 , with seasonal patterns of fecal shedding ranging from <10,000 oocysts squirrel ؊1 day ؊1 in fall, winter, and spring to levels of 2 ؋ 10 5 oocysts squirrel ؊1 day ؊1 in summer. Juveniles were about twice as likely as adult squirrels to be infected and shed higher concentrations of oocysts than adults did, with particularly high levels of infection and shedding being found among juvenile male squirrels. Based on DNA sequencing of a portion of the 18S small-subunit rRNA gene, there existed three genotypes of Cryptosporidium species in these populations of squirrels (Sbey03a, Sbey03b, and Sbey03c; accession numbers AY462231 to AY462233, respectively). These unique DNA sequences were most closely related (96 to 97% homology) to porcine C. parvum (AF115377) and C. wrairi (AF115378). Inoculating BALB/c neonatal mice with up to 10,000 Sbey03b or Sbey03c fresh oocysts from different infected hosts did not produce detectable levels of infection, suggesting that this common genotype shed by California ground squirrels is not infectious for mice and may constitute a new species of Cryptosporidium.

Natural infection with two genotypes of Cryptosporidium in red squirrels (Sciurus vulgaris) in Italy

“…Bertolino et al (2003) reported that the probability of infection increased at higher densities and in young red squirrels. However, in this and other studies on squirrels, Cryptosporidium was commonly found also in adults (Atwill et al 2004). In our experiments, neither the Cryptosporidium ferret genotype nor the chipmunk genotype I was infectious for adult CD1 and BALB/c mice, which is in accordance with the noninfectivity of Sbey03b and Sbey03c genotypes for BALB/c mice (Atwill et al 2004).…”

“…However, in this and other studies on squirrels, Cryptosporidium was commonly found also in adults (Atwill et al 2004). In our experiments, neither the Cryptosporidium ferret genotype nor the chipmunk genotype I was infectious for adult CD1 and BALB/c mice, which is in accordance with the noninfectivity of Sbey03b and Sbey03c genotypes for BALB/c mice (Atwill et al 2004). On the contrary, adult SCID or BALB/c mice were susceptible to C. parvum-type oocysts and C. muris that originated from the Siberian chipmunk (Matsui et al 2000, Hůrková et al 2003.…”

“…Recent studies have shown that natural cryptosporidiosis in the family Sciuridae could be caused by various species and genotypes of both gastric and intestinal Cryptosporidium (Matsui et al 2000, Perz and Blancq 2001, Bertolino et al 2003, Hůrková et al 2003, Atwill et al 2004, Feng et al 2007. The presence of Cryptosporidium in red squirrels (Sciurus vulgaris L.) was previously reported from populations in the Western Italian Alps; however, the genotypes of these Cryptosporidium were not investigated Canestri-Trotti 2001, Bertolino et al 2003).…”

Capture and Retention of Cryptosporidium parvum Oocysts by Pseudomonas aeruginosa Biofilms

“…Outside its host, C. parvum exists as a nonreproductive oocyst, ϳ5 m in diameter, that is resistant to typical environmental stresses (6,29,39,40). C. parvum oocysts originate from the waste of infected hosts and are discharged in large quantities from municipal wastewater treatment facilities, animal agriculture, and wildlife populations (2,18,26,47). Because oocysts are persistent in the environment, the transmission of viable oocysts from sources to public water supplies can result in human infection even over long transport distances.…”

90-Kilodalton Heat Shock Protein, Hsp90, as a Target for Genotyping Cryptosporidium spp. Known To Infect Humans

“…One disadvantage of the SSU rRNA gene is that there are minor sequence differences among different copies of the gene, which sometimes can lead to variation in RFLP for certain Cryptosporidium species or genotypes (8,25). In such situations, it is very important to differentiate intragenotypic variations among isolates from sequence variations between different copies of the gene (2) and to have a tool that confirms the genotype. Although there are other genes available which can differentiate the two major human-pathogenic species, C. parvum and C. hominis, these cannot distinguish genetically divergent species of Cryptosporidium, i.e., C. canis, C. felis, C. suis, and C. muris, from them (10,16,21).…”