Submitted to: International Society of Protistologists
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2006
Publication Date: June 20, 2006
Citation: Li, X., Fayer, R. 2006. Infectivity of Microsporidian Spores after exposure to temperature extremes and chemical disinfectants. International Society of Protistologists Workshop on Opportunistic Pathogens. June 20-24, 2006, Lisbon, Portugal. p.2.
Although Encephalitozoan intestinalis, E. hellem, and E. cuniculi infect humans and animals, reservoirs and routes of spread remain largely unknown. Detection of spores in surface, ditch, recreational, and drinking water and outbreaks (possibly water related) strongly suggest the importance of waterborne transmission. Rendering spores noninfective is extremely important for safety of water, food and facility management but disinfection data are sparse. The present study investigated the effects of ethanol, chlorine, heating and freezing on spore infectivity. After E. intestinalis and E. cuniculi spores were exposed to 70% ethanol for 5 min and E. hellem spores were exposed for 20 min spores were not infective for cultured MDBK cells. E. hellem spores exposed to laundry bleach diluted 1:50,000 for 10 min and E. cuniculi, spores similarly exposed for 30 min were not infective for cultured MDBK cells. To obtain 100% inhibition of E. intestinalis, spores required exposure at a dilution of 1:1,000 for 10 min. When E. intestinalis and E. hellem spores in water without cryoprotectants were held at -20 'C for 24 h, and E. cuniculi spores were similarly held for 2 h, spores were not infective for cultured MDBK cells. Spores of E. cuniculi held at 100 'C for 1 min failed to grow in cell culture but E. intestinalis and E. hellem spores had to be held for 5 and 10 min, respectively, to obtain 100% inhibition of growth in cultured cells. These findings provide basic data applicable to food, water and environmental disinfection strategies.