Virucidal efficacy of food additive grade calcium hydroxide against surrogate of human norovirus.

An alkaline agent, namely, food additive grade calcium hydroxide (FdCa(OH)2) in the solution, powder and suspension forms was evaluated as a virucidal agent, using a murine norovirus (MNV) as the surrogate for human norovirus. The main constituent of FdCa(OH)2 is Ca(OH)2, which has pH 13 in 0.17% solution. The results showed that 0.17% FdCa(OH)2 solution could inactivate MNV within 30s even in the presence of organic materials (5% fetal bovine serum (FBS)). In a contaminated surface experiment, MNV with 5% FBS was inoculated on rayon sheets, and the result showed FdCa(OH)2 solution could markedly reduce virus titer within 1min. When mouse feces were spiked with MNV and FdCa(OH)2 powder as 10% and 20% w/w was added to the feces, these concentrations could inactivate the virus within 30min and 15min, respectively. Whereas, FdCa(OH)2 suspension at 2.5% and 5% could inactivate the virus within 30min and at 1% within 45min. These and additional results obtained here indicate that FdCa(OH)2 is an effective virucidal agent against MNV, and can serve as a useful alternative disinfectant for inactivation and prevention of human norovirus in house and hospital.