Long-Term Survival of Toxoplasma gondii Sporulated Oocysts in Seawater

Toxoplasma gondii is now recognized as an important pathogen in costal marine mammals. Oocysts from cat feces are believed to be washed into seawater and serve as a source of infection via transport hosts. Experimentally, it has been demonstrated that T. gondii oocysts can sporulate in seawater and remain infectious for mice for up to 6 mo. The present study examined the long-term survival of T. gondii in seawater (15 ppt NaCl) kept at 4 C or at room temperature. Oocysts kept at 4 C for 24 mo were orally infectious for mice, while those kept at room temperature for 24 mo were not.