Lest anyone think that I have misrepresented the data, I have searched for several days for ANY reference of chlorine to disinfect nosema spores in combs. There is plenty of evidence to show that soaking spores in chlorinated water is effective. However, as these data show, the time and strength has a lot to do with effectiveness. Also, different species of Microsporidian react differently; Randy mentioned that N. ceranae may be more sensitive than N. apis.

Infectivity of Microsporidian Spores Exposed to Temperature Extremes and Chemical Disinfectants
J. Eukaryot. Microbiol., 53(S1), 2006 pp. S77–S79

> The present studies were designed to investigate the effects of ethanol, chlorine, heating and freezing on infectivity of Encephalitozoon intestinalis, E. hellem, and E. cuniculi spores using cell culture as a bioassay. 

> Commercial laundry bleach (5.25% sodium hypochlorite) was diluted 1:50,000, 1:10,000 and 1:1,000 with deionized water (v:v). The pH value was measured with an ATI Orion pH meter (model 330, Orion, Boston, MA). Free available chlorine and total residual chlorine were measured using a digital chlorine colorimeter kit (model DC1100, LaMotte Co., Chestertown, MD).   

> Spores of each species were placed in 13 microcentrifuge tubes and 1ml of chlorine solution was added to 12 tubes.Spores were exposed at 22 1C for 10, 30, 60, and 120min, washed three times with HBSS as above, suspended in culture medium, and inoculated into MDBK cell cultures.  

> After E. hellem spores were exposed to laundry bleach diluted 1:50,000 for 10 min, growth in MDCK cells was inhibited 100%. Spores of E. cuniculi had to be exposed at the same dilution for 30 min or in laundry bleach diluted 1:10,000 for 10min before they were 100% inhibited. Although E. intestinalis spores exposed to laundry bleach diluted 1:50,000 for 10 min resulted in 98%+ inhibition, exposure at a dilution of 1:1,000 for 10 min was required to obtain 100% inhibition. 

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