efficacy of different concentrations of sodium hypochlorite on the in vitro excystation of sporozoites of cryptosporidium baileyi

sodium hypochlorite has been used for disinfecting of cryptosporidium in some contaminated environments by this parasite and also in laboratory works it has been used for the purification of the parasite from bacteria and as a treatment for facilitating of releasing the sporozoites of cryptosporidium (excystation). the excystation is a critical stage of life cycle of the parasite. the purpose of this study was to determine the efficacy of sodium hypochlorite on the laboratory excystation of sporozoites of cryptosporidium baileyi. c. baileyi oocysts have been isolated and identified from the bursa of fabricus of naturally infected 30- day- old broiler chickens in shiraz area. the oocysts were propagated in sensitive 2-day-old chicks and purified by modified sheater’s sugar flotation method. oocysts were exposed to various concentrations of bleach and incubated at various temperatures for 15 min prior to being washed by centrifuging. then the oocysts were exposed to the appropriate excystation fluid and releasing the sporozoites were observed by light microscopy. complete excystation inhibition was seen by 2.5% and 5% sodium hypochlorite at 37 º c for 15 min. treatment of oocysts with 1.25% sodium hypochlorite at 4 º c had no effect on laboratory excystation. in other cases there were some degree of excystation inhibition. the results indicate that 25% commercial bleach or 1.25% sodium hypochlorite at 4 º c for 10-15 min may be suitable for purification and sterilization of oocysts and also this treatment facilitates and enhances in vitro sporozoite releasing from the oocysts.