Cryptosporidium parvum oocysts were stored in 1-ml aliquots of filtered river water at −20, 4, 10, and 21–23 C in the dark. Oocysts were also added to filter-sterilized river water samples and stored at 21–23 C. The infectivity of oocysts stored under different conditions was assayed at weekly intervals through infection of human adenocarcinoma ileocecal (HCT-8) cell monolayers. Wells containing between 10 and 100 foci of infection were enumerated by immunofluorescent microscopy, and the number of infective oocysts was calculated. No infectious oocysts were detected after 1 wk at −20 C. The number of infective oocysts stored at 4 C decreased 5-fold, and the number of those stored at 10 C decreased 2.5-fold after 14 wk. The infectivity of oocysts stored in potassium dichromate (positive control) at 4 C decreased 2-fold over 14 wk. The number of infective oocysts in filter-sterilized and non–filter-sterilized river water stored at 21–23 C decreased by 3.3 and 2.6 log units, respectively, over 12 wk, and no foci of infection were detected at 14 wk. The results show that as temperature increased from 4 to 23 C, the duration of oocyst infectivity decreased.
Influence of Temperature on Cryptosporidium parvum Oocyst Infectivity in River Water Samples as Detected by Tissue Culture Assay
- Views Icon Views
- Share Icon Share
- Search Site
Nicholas J. Pokorny, Susan C. Weir, Ramon A. Carreno, Jack T. Trevors, Hung Lee; Influence of Temperature on Cryptosporidium parvum Oocyst Infectivity in River Water Samples as Detected by Tissue Culture Assay. J Parasitol 1 June 2002; 88 (3): 641–643. doi: https://doi.org/10.1645/0022-3395(2002)088[0641:IOTOCP]2.0.CO;2
Download citation file: