title: Effects of low and high temperatures on infectivity of Cryptosporidium muris oocysts suspended in water.
abstract: Cryptosporidium muris oocysts suspended in 200 microl of water were pipetted into plastic microcentrifuge tubes which were stored at 4 degrees C or frozen at -5 degrees C for 1, 3, 5, 7, and 10 days and at -20 degrees C for 1, 3, 5, and 8h, respectively. Other samples of C. muris oocysts suspended in water were heated in the metal block of a thermal DNA cycler. Block temperatures were set at 5 degrees C incremental temperatures from 40 to 70 degrees C. At each high temperature setting microcentrifuge tubes containing C. muris oocysts were exposed for 1 min. Both, frozen and heated oocyst suspensions as well as untreated control oocyst suspensions were then inoculated into each of four ICR mice by gastric intubation. Untreated, freeze-thawed or heated oocysts were considered infectious when oocysts of C. muris were found microscopically in the faeces of mice after inoculation. All inoculated mice that received oocysts frozen at -5 degrees C for 3, 5, 7, and 10 days and -20 degrees C for 1, 3, 5, and 8h had no oocysts in faeces. In contrast, C. muris oocysts frozen at -5 degrees C for 1 day remained infective for inoculated mice. Our results also indicated that when water containing C. muris oocysts was exposed at a temperature of 55 degrees C or higher for 1 min, the infectivity of oocysts was lost.
authors: Department of Parasitology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences, Brno, Czech Republic.
authors: Helena
authors: H
authors: Neumayerová
authors: Bretislav
authors: B
authors: Koudela
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000662:veterinary; D003080:Cold Temperature; D003457:Cryptosporidiosis / Q000469:parasitology / Q000662:veterinary*; D003458:Cryptosporidium / Q000166:cytology / Q000472:pathogenicity*; D005243:Feces / Q000469:parasitology; D005615:Freezing; D006358:Hot Temperature; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D033661:Oocysts / Q000254:growth & development*; D013997:Time Factors; D014867:Water / Q000469:parasitology*
chemical_list: D014867:Water