VIABLE CRYPTOSPORIDIUM-PARVUM OOCYSTS EXPOSED TO CHLORINE OR OTHER OXIDIZING CONDITIONS MAY LACK IDENTIFYING EPITOPES

The intestinal protozoan parasite Cryptosporidium parvum is a known ca use of water-borne disease in humans. The detection of Cryptosporidium oocysts in water samples relies upon the use of fluorescently labelle d antibodies, preferably using flow cytometry and epifluorescence micr oscopy. Here we demonstrate that four commercially available antibodie s recognise a similar set of immunodominant epitopes on the oocyst wal l. These epitopes appear to be carbohydrate in nature and are labile t o chlorine treatment and oxidising conditions. Sodium hypochlorite and sodium meta-periodate reduced the ability of the antibodies to detect Cryptosporidium oocysts. Damage to the epitopes did not necessarily r educe the viability of bocysts. This finding may be important for the water industry, where naturally occurring oxidising conditions or sani tising treatments could produce viable oocysts that are undetectable u sing standard protocols. (C) 1998 Australian Society for Parasitology. Published by Elsevier Science Ltd. All rights reserved.