The effect of temperature and deposition in reservoir sediments or water on the viability of cultured Giardia lamblia cysts, as determined by fluorogenic dyes

The impact of the pathogenic parasite Giardia lamblia on man and other mammals has been recognized for many centuries. Its trophozoite in the small intestine can lead to giardiasis with diarrhea the common symptom. The cyst forms from the trophozoite in the host, is expelled into the environment and if is ingested, giardiasis can occur. Except for the diagnosis of giardiasis, little was known about the biology of either the cyst or the trophozoite until they were able to be grown in culture starting 5 years ago. The period of viability of the cyst defines its environmental impact but cyst viability has only been studied in water. No information is available about cyst viability in sediments, which have been shown to affect the viability of bacteria.; The major goals of this investigation were to: (1) Determine if cysts had different viability in reservoir sediments versus water and (2) See if commercially available monoclonal antibodies could be used for labels of cysts in environmental studies.; 1. In the first set of experiments cysts were placed in 8 chambers of 2 microcosms, which were comprised of 4 glass chambers which were all connected through a common stainless steel chamber. The cysts were placed into dialysis bags, which were placed in either sediments or water (n = 4) filled chambers of the microcosm and maintained at 25{dollar}spcirc{dollar}C for 8 days. At the end of 8 days, the number of cysts determined to be viable by fluorogenic dyes were counted. A significantly (p {dollar}<{dollar}.05) greater number of viable cysts were found in the sediment than the water chambers.; 2. In the second set of experiments, the cysts were exposed to 25{dollar}spcirc{dollar}C for 8 days, but the cysts were labeled with monoclonal antibodies with a fluorogenic dye attached. This set of experiments had the same results as the above, significantly (p {dollar}<{dollar}.01) more cysts were still viable in the sediments (62% of the original number) than in the water (46%) chambers. In the last set of experiments, the monoclonal antibody labels were used and the cysts were exposed to 31{dollar}spcirc{dollar}C for 8 days. In this set of experiments, significantly (p {dollar}<{dollar}.005) more cysts were still viable in the sediments (38%) than in the water (21%) chambers. Significantly more cysts survived in both the water (p {dollar}<{dollar}.001) and the sediments (p {dollar}<{dollar}.001) after 8 days at 25 versus 31{dollar}spcirc{dollar}C. In both these sets of experiments the monoclonal antibody labels remained attached and helped with the identification of the cysts.