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United States Department of Agriculture

Agricultural Research Service

Title: Infectivity of Microsporidia Spores Stored in Water at Environmental Temperature

Authors
item Li, Xunde - USDA, ARS, VISITING SCI
item Palmer, Robert
item Trout, James
item Fayer, Ronald

Submitted to: Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 14, 2002
Publication Date: February 1, 2003
Citation: Li, X., Palmer, R.C., Trout, J.M., Fayer, R. 2003. Infectivity of microsporidia spores stored in water at environmental temperature. Applied and Environmental Microbiology. Vol. 89:185-188.

Interpretive Summary: Of the 13 species of microsporidia that infect humans, Encephalitozoon cuniculi, E. hellem, and E. intestinalis have been detected in surface water, a potential source for transmission of the spore stage of these parasites. To determine how long waterborne spores of these species could survive in the environment, culture derived spores were stored in water at 10, 15, 20, 25 and 30 C and tested for infectivity at weekly and monthly intervals by inoculation into cultured mammalian cells. For all species, spores lost infectivity faster at higher temperatures. At 10 C spores of E. intestinalis, E. hellem, and E. cuniculi were still infectious after 12, 9, and 3 months, respectively. At 25 C spores of the 3 species survived for 3 weeks to 3 months. At 30 C spores of the 3 species survived for 1 week to 1 month. These findings indicate that spores of different species differ in their longevity and temperature tolerance but all 3 have the potential to remain infectious in the environment long enough to become widely dispersed.

Technical Abstract: To determine how long waterborne spores of Encephalitozoon cuniculi, Encephalitozoon hellem, and Encephalitozoon intestinalis could survive in the environment, culture derived spores were stored in water at 10, 15, 20, 25 and 30 C and tested for infectivity at weekly and monthly intervals by inoculation into monolayers of MDBK cells. Infectivity was based on the ability of stored spores to infect cells and produce intracellular cluster of microsporidia detectable by gram-chromotrope staining and light microscopy. For all species, spores lost infectivity faster at higher temperatures. At 10 C spores of E. intestinalis were still infectious after 12 months whereas those of E. hellem and E. cuniculi remained infective for 9 and 3 months, respectively. At 25 C spores of the 3 species survived for 3 weeks to 3 months. At 30 C spores of the 3 species survived for 1 week to 1 month. These findings indicate that spores of different species differ in their longevity and temperature tolerance but at temperatures from 10 C to 30 C all 3 have the potential to remain infectious in the environment long enough to become widely dispersed.

Last Modified: 7/25/2014