Giardia cyst and Cryptosporidium oocyst survival in water, soil, and cattle feces

Giardiasis and cryptosporidiosis are gastrointestinal diseases caused by pr otozoan parasites that mag infect domestic animals, wildlife and human bein gs. The ability of cysts and oocysts of these parasites to persist in the e nvironment was determined because agricultural fecal waste has the potentia l to contaminate municipal water supplies. The degradation rate and viabili ty of Giardia cysts and Cryptosporidium oocysts in water, cattle (Bos tauru s) feces, and soil was evaluated at temperatures of -4, 4, and 25 degrees C for up to 12 wk. Cysts and oocysts were enumerated after staining samples with a specific fluorescent monoclonal antibody and the viability was deter mined using propidium iodide dye exclusion and mouse infectivity assays. Gi ardia cysts were noninfective in water, feces, and soil following 1 wk of f reezing to -4 degrees C and within 2 wk at 25 degrees C. At 4 degrees C Gia rdia cysts were infective for 11 wk in water, 7 wk in soil, and 1 wk in cat tle feces. Cryptosporidium oocysts were more environmentally resistant. At -4 and 4 degrees C, the oocysts could survive in water and soil for >12 wk but degradation was accelerated at 25 degrees C. Cryptosporidium oocysts al so were degraded more rapidly in feces and in soil containing natural micro organisms. Contaminated cattle feces should be distributed on fields during warmer weather and after 12 wk of storage to reduce potential waterborne t ransmission following heavy runoffs.