Cryptosporidium and Giardia species are enteric protozoa which cause
waterborne disease. The detection of these organisms in water relies on the detection of the oocyst and
cyst forms or stages. Monoclonal and polyclonal
antibodies were compared for their abilities to react with Giardia
cysts and Cryptosporidium oocysts after storage in water, 3.7%
formaldehyde, and 2.5%
potassium dichromate, upon exposure to bleach, and in environmental samples. Three
monoclonal antibodies to Cryptosporidium parvum were evaluated. Each test resulted in an equivalent detection of the oocysts after storage, after exposure to bleach, and in environmental samples. Oocyst levels declined slightly after 20 to 22 weeks of storage in water, and oocyst fluorescence and morphology were dull and atypical. Oocyst counts decreased after exposure to 2,500 mg of
sodium hypochlorite per liter, and fluorescence and phase-contrast counts were similar. Sediment due to algae and
clays found in environmental samples interfered with the detection of oocysts on membrane filters. Two
monoclonal antibodies and a polyclonal antibody directed against Giardia lamblia
cysts were evaluated. From the same seeded preparations, significantly greater counts were obtained with the polyclonal antibody. Of the two
monoclonal antibodies, one resulted in significantly lower
cyst counts. In preliminary studies, the differences between
antibodies were not apparent when used on the environmental
wastewater samples. After 20 to 22 weeks in water,
cyst levels declined significantly by 67%.
Cysts were not detected with
monoclonal antibodies after exposure to approximately 5,000 mg of
sodium hypochlorite per liter.