Immunofluorescence and morphology of Giardia lamblia cysts exposed to chlorine.

Giardia cyst-like objects detected by immunofluorescence in chlorinated water samples often cannot be positively identified by their morphological appearance. To determine the effect of chlorine on cyst immunofluorescence and morphology, Giardia lamblia cysts were exposed to chlorine for 48 h. The majority of cysts exposed to chlorine concentrations of 1 to 11 mg/liter at 5 and 15 degrees C lost their internal morphological characteristics necessary for identification, but most of them were still detectable by immunofluorescence.