CONCENTRATION: Procedure Notes

1. The gauze should never be more than one (pressed gauze) or two (woven gauze) layers thick; more gauze may trap mucus (containing Cryptosporidium oocysts and/or microsporidial spores).

2. Tap water may be substituted for 0.85% NaCl throughout this procedure, although the addition of water to fresh stool may cause Blastocystis hominis cysts (central body forms) to rupture and is not recommended. In addition to the original 5 or 10% formalin fixation, some workers prefer to use 5 or 10% formalin for all rinses throughout the procedure.

3. Ethyl acetate is widely recommended as a substitute for ether. It can be used in the same way in the procedure and is much safer. Hemo-De can also be used and is felt to be safer than ethyl acetate.