Survival of Toxoplasma gondii tissue cysts in 0.85-6% NaCl solutions at 4-20 C

The effect of storage of Toxoplasma gondii tissue cysts in various NaCl solutions at different temperatures was studied. Tissue cysts from rodent brains were suspended in 0.85%, 2.0%, 3.3%, and 6.0% aqueous NaCl solutions. After storage at 4-20 C for various time intervals, brains were bioassayed in mice for viability of T. gondii. At 4 C, tissue cysts survived for at least 56 days in 0.85% NaCl, for 49 days in 2.0% NaCl, and for 21 days in 3.3% NaCl solutions. At 10 C, tissue cysts survived for at least 21 days in 0.85%, 2.0%, and 3.3% NaCl solutions. At 15 C, tissue cysts survived for at least 21 days in 0.85% NaCl, 14 days in 2.0%, and 3.3% NaCl solutions. At 20 C, tissue cysts survived for 14 days in 0.85% NaCl, 7 days in 2.0% NaCl, and 3 days in 3.3% NaCl solutions. Tissue cysts generally did not survive in 6.0% NaCl solution at any temperature.