Seasonal shedding of multiple Cryptosporidium genotypes in California ground squirrels (Spermophilus beecheyi)

Edward R Atwill, Ralph Phillips, Maria Das Graças C Pereira, Xunde Li, Brenda Mccowan

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28 Citations (Scopus)

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 × 105 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.

Original languageEnglish (US)
Pages (from-to)6748-6752
Number of pages5
JournalApplied and Environmental Microbiology
Volume70
Issue number11
DOIs
StatePublished - Nov 2004

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Spermophilus beecheyi
Sciuridae
Cryptosporidium
squirrels
Oocysts
oocysts
genotype
Genotype
DNA
homology
feces
new species
gene
winter
summer
infection
Geographic Locations
sheds
Infection
DNA Sequence Analysis

ASJC Scopus subject areas

  • Environmental Science(all)
  • Biotechnology
  • Microbiology

Cite this

Seasonal shedding of multiple Cryptosporidium genotypes in California ground squirrels (Spermophilus beecheyi). / Atwill, Edward R; Phillips, Ralph; Pereira, Maria Das Graças C; Li, Xunde; Mccowan, Brenda.

In: Applied and Environmental Microbiology, Vol. 70, No. 11, 11.2004, p. 6748-6752.

Research output: Contribution to journalArticle

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