Quantitative Shedding of Two Genotypes of
            <i>Cryptosporidium parvum</i>
            in California Ground Squirrels (
            <i>Spermophilus beecheyi</i>
            )

Atwill, Edward R.; Camargo, Sergio Maldonado; Phillips, Ralph L.; Alonso, Laura Herrera; Tate, Kenneth W.; Jensen, Wayne A.; Bennet, J.; Little, Scott; Salmon, Terrell P.

doi:10.1128/aem.67.6.2840-2843.2001

Cited by 38 publications

(36 citation statements)

References 22 publications

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“…This pattern of intraherd transmission of C. parvum within beef calf populations (i.e., a propagating epidemic) would also be created by a wildlife reservoir seeding pastures or rangeland with C. parvum. For example, we have found that California ground squirrels (Spermophilus beecheyi) that inhabit the annual grassland-oak woodland complexes of California can shed substantial numbers of oocysts during spring and summer, with genotypes of C. parvum similar to those obtained from beef calves (6). Similar speculations have been made previously for populations of mice and voles at an agricultural site in Warwickshire, United Kingdom (10).…”

supporting

confidence: 68%

“…What remains unresolved is whether pre-or postparturient cows are the primary biological reservoir for calfhood exposure to C. parvum (3,13,15,34) or, as in the case of beef cattle grazing open range, whether resident wildlife function to contaminate pastures before or after calving. We have found high levels of fecal shedding for California ground squirrels that coinhabit rangeland with beef cattle herds, along with isolates of C. parvum that are indistinguishable from those obtained from infected calves (6).…”

mentioning

confidence: 98%

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Improved Quantitative Estimates of Low Environmental Loading and Sporadic Periparturient Shedding ofCryptosporidium parvumin Adult Beef Cattle

Atwill

Hoar²,

Pereira

et al. 2003

Appl Environ Microbiol

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Our primary goal was to generate an accurate estimate of the daily environmental loading rate of Cryptosporidium parvum oocysts for adult beef cattle, using immunomagnetic separation coupled with direct immunofluorescence microscopy for a highly sensitive diagnostic assay. An additional goal was to measure the prevalence and intensity of fecal shedding of C. parvum oocysts in pre-and postparturient cows as an indicator of their potential to infect young calves. This diagnostic method could detect with a >90% probability oocyst concentrations as low as 3.2 oocysts g of feces ؊1 , with a 54% probability of detecting just one oocyst g of feces ؊1 . Using this diagnostic method, the overall apparent prevalence of adult beef cattle testing positive for C. parvum was 7.1% (17 of 240), with 8.3 and 5.8% of cattle shedding oocysts during the pre-and postcalving periods, respectively. The mean intensity of oocyst shedding for test-positive cattle was 3.38 oocysts g of feces ؊1 . The estimated environmental loading rate of C. parvum ranged from 3,900 to 9,200 oocysts cow ؊1 day ؊1 , which is substantially less than a previous estimate of 1. . Use of this highly sensitive assay functioned to detect a greater proportion of low-intensity shedders in our population of cattle, which reduced the estimated mean intensity of shedding and thereby reduced the associated environmental loading rate compared to those of previous studies.Cryptosporidium parvum has emerged as a ubiquitous waterborne microbial pathogen, with specific genotypes readily transmitted ambidirectionally between livestock and humans (7,9,12,25,28,36). One of the first steps in designing watershed management programs for minimizing the occurrence of C. parvum in drinking water supplies is to identify significant quantitative sources of this parasite. Adult cattle are often considered potential nonpoint sources of environmental contamination for C. parvum, but there is some disagreement over the relative importance that adult cattle have in loading watersheds with significant amounts of C. parvum oocysts. In particular, there is a wide range of reported prevalences of fecal shedding of C. parvum for adult beef and dairy cattle. Numerous investigators have reported mean prevalences of fecal shedding from ϳ20 to ϳ70% in groups of clinically healthy adult cattle (23,31,34), yet several large cross-sectional epidemiologic surveys have observed prevalences of only 2% or less in asymptomatic adult cattle populations (4, 20, 41). Some of this variation in the observed prevalence of fecal shedding can be explained by different investigators using diagnostic assays of differing sensitivity and specificity (11,13,15), but much of the variation is the result of studying different populations of cattle (e.g., beef versus dairy), different age distributions within those populations, and groups of cattle under different management practices, especially when only a single farm or a small sample is examined. For example, we found in two different studies that calving duration fo...

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supporting

confidence: 68%

mentioning

confidence: 98%

Improved Quantitative Estimates of Low Environmental Loading and Sporadic Periparturient Shedding ofCryptosporidium parvumin Adult Beef Cattle

Atwill

Hoar²,

Pereira

et al. 2003

Appl Environ Microbiol

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“…In western USA (California), C. parvum was reported in California ground squirrels (Spermophilus beecheyi); the majority of isolates matched a bovine-murine genotype, with a few isolates resembling a porcine genotype (Atwill et al 2001). Nevertheless, these results solely based on PCR-RFLP are not sufficient for genotyping.…”

Section: Discussionmentioning

confidence: 91%

“…So far, squirrels were reported to be susceptible to several Cryptosporidium species/genotypes of various host specificities and oocyst morphologies (Matsui et al 2000, Atwill et al 2001, Bertolino et al 2003, Hůrková et al 2003, Feng et al 2007). In 17 separate cases of infection, we found two intestinal Cryptosporidium genotypes that had not been previously observed in red squirrels.…”

Section: Discussionmentioning

confidence: 99%

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

Kváč¹,

Hofmannová²,

Bertolino³

et al. 2008

FOLIA PARASIT

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Abstract.We investigated the genotypes of Cryptosporidium infecting red squirrels (Sciurus vulgaris L.) in two areas of the Western Alps in Italy. Examination of 141 faecal samples from 70 red squirrels revealed oocysts of Cryptosporidium in 17 animals (24.3%). Based on 18S rRNA gene sequencing, two genotypes of Cryptosporidium species were found: 15 squirrels were positive for the Cryptosporidium ferret genotype and 2 for the Cryptosporidium chipmunk genotype I. The occurrence and intensity of Cryptosporidium infection did not differ between the study areas or sex. More than 85% of the positive animals were adults; however no difference was found between Cryptosporidium infection in the juvenile and adult age groups. Oocysts of the Cryptosporidium ferret genotype measured 5.5 ± 0.3 × 5.2 ± 0.2 µm (shape index 1.06) and the Cryptosporidium chipmunk genotype I 5.8 ± 0.3 × 5.4 ± 0.3 µm (shape index 1.07). Neonatal and adult CD1 and BABL/c mice inoculated with 1 × 10 3 fresh oocysts of both genotypes did not produce detectable infection.

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“…pal wastewater treatment plants, as well as nonpoint sources such as wildlife (Atwill et al 2001) and intensive and extensive livestock production systems (Atwill et al 2003;Lewis et al 2005).…”

mentioning

confidence: 99%

Management reducesE. coliin irrigated pasture runoff

Knox¹,

Tate²,

Dahlgren³

et al. 2007

Cal Ag

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Quantitative Shedding of Two Genotypes of Cryptosporidium parvum in California Ground Squirrels ( Spermophilus beecheyi )

Cited by 38 publications

References 22 publications

Improved Quantitative Estimates of Low Environmental Loading and Sporadic Periparturient Shedding ofCryptosporidium parvumin Adult Beef Cattle

Improved Quantitative Estimates of Low Environmental Loading and Sporadic Periparturient Shedding ofCryptosporidium parvumin Adult Beef Cattle

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

Management reducesE. coliin irrigated pasture runoff

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