Submitted to: Journal of Eukaryotic Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/20/2006
Publication Date: 11/1/2006
Citation: Li, X., Fayer, R. 2006. Infectivity of Microsporidian spores exposed to temperature extremes and chemical disinfectants. Journal of Eukaryotic Microbiology. 53(1):77-79. Interpretive Summary: Spores of 13 species of the protozoa Microsporidia are infectious for humans and many animals. To determine how best to disinfect them, 3 species of spores in water were heated to boiling or exposed to chlorine or 70% alcohol and others were frozen. After each treatment, spores were inoculated into cell cultures to test for infectivity. Exposure for 10 min to low levels of chlorine, 70% alcohol, or boiling rendered all spores noninfectious. Freezing at -20 C for 8 hours also rendered them noninfectious. These findings provide useful data for disinfection of contaminated water and items exposed to contaminated water.
Technical Abstract: Spores of Encephalitozoon hellem, Encephalitozoon cuniculi, and Encephalitozoon intestinalis were heated to temperatures up to boiling or exposed to chlorine or70% ethanol and others were frozen. After each treatment, spores were inoculated into cell cultures to test for infectivity. After exposure to 0.54, 2.55, and 25.7 mg/L chlorine for 10 min infectivity of E. hellem, E. cuniculi, and E. intestinalis was markedly reduced or eliminated. Ethanol rendered E. cuniculi and E. intestinalis noninfectious after exposure for 5 min and E. hellem for 10 min. After freezing in water at -20 C for 8 h all 3 species were rendered noninfectious. Inhibition of E. cuniculi, E. intestinalis and E. hellem required exposure for 2, 5, and 10 min, respectively, at 100 C. These data indicate that ethanol is effective for surface disinfection of microsporidia and chlorine is useful for water disinfection. Freezing and heating in water reduce microsporidia infectivity but are time and temperature related.