Volume 85, Issue 2
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645



Most infections in humans are caused by or . However, genotyping techniques have identified infections caused by unusual species. has been identified in ≤ 1% of persons with diarrhea, although prevalence is higher in developing nations. We examined the infectivity of in healthy adults. Five volunteers were challenged with 10 oocysts and monitored six weeks for fecal oocysts and clinical manifestations. Four volunteers had diarrhea; three had detectable fecal oocysts; and one infected volunteer remained asymptomatic. Fecal DNA from two volunteers was amplified by using a polymerase chain reaction specific for the small subunit ribosomal RNA gene. Nucleotide sequence of these amplicons was diagnostic for . All infections were self-limited; oocysts were cleared within ≤ 12 days of challenge. These studies establish that healthy adults can be infected and become ill from ingestion of oocysts.


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  • Received : 24 Nov 2010
  • Accepted : 09 May 2011

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