Affiliation:
1. Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California—Davis, Tulare
2. University of California Cooperative Extension, Bakersfield, California
Abstract
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
.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
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4. Quantitative Shedding of Two Genotypes of
Cryptosporidium parvum
in California Ground Squirrels (
Spermophilus beecheyi
)
5. Transport of
Cryptosporidium parvum
Oocysts through Vegetated Buffer Strips and Estimated Filtration Efficiency
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