Volume 77, Issue 1
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645


To investigate the extent of genetic heterogeneity in the genus infecting patients in Thailand, a total of 38 fecal samples containing oocysts from human immunodeficiency virus/acquired immunodeficiency syndrome patients (n = 30), corticosteroid-treated patients (n = 3) and immunocompetent individuals (n = 5) were recruited for analysis. Remarkable variation in the maximum width and length of oocysts both within and between isolates was observed. However, the average length-width ratio of oocysts was within the range for (> 1.2). sporogonic development of freshly passed oocysts in feces from three of these isolates was observed longitudinally, showing that 27% of these oocysts underwent complete sporulation. Interestingly, 95% of sporulated oocysts contained two sporocysts in an oocyst with four sporozoites in each sporocyst, and -like oocysts, characterized by eight sporozoites enclosed by a single sporocyst, were also detected (5%). The small subunit ribosomal RNA (rRNA), 5.8S rRNA, internal transcribed spacer 1 (ITS-1), and ITS-2 were highly conserved, indicating that there were no cryptic species or extensive strain variation.


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  • Received : 29 Dec 2006
  • Accepted : 12 Mar 2007

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