Room Decontamination Using Ionized Hydrogen Peroxide Fog and Mist Reduces Hatching Rates of Syphacia obvelata Ova

This study evaluated the efficacy of ionized hydrogen peroxide (iHP) fog and mist for environmental and surface decontamination of Syphacia obvelata ova in rodent rooms. Ova were collected by perianal tape impression from S. obvelata infected mice. In experiment 1, ova were exposed to iHP using a whole-room fogging decontamination system with a 15 min initial fog application cycle in unoccupied rodent rooms. Ova were removed from the fogged environment after a 15 min, 30 min, 90 min, or 240 min iHP exposure time. In experiment 2, a second cohort of ova were exposed to iHP using the whole-room fogging decontamination system. Ova were removed after 3, 4 or 6 continuous fog application cycles with 45 min dwelling time between each cycle and 15 h dwelling time for the last time point. In experiment 3, a third set of ova was exposed to an iHP surface misting unit with 1, 2, or 3 iHP mist applications. A 7 min contact time followed each application. After exposure, ova were incubated in a hatching medium for 6 h. Control ova were maintained at room temperature without iHP exposure before incubation in the hatching medium. After incubation, the number of ova hatched was assessed by microscopic examination. For experiment 1, results ranged from 46% to 57% of exposed ova hatched. For experiment 2, results ranged from 43% to 49% of ova hatched. For experiment 3, 37% to 46% of exposed ova hatched. Conversely, for the control groups above 80% of ova hatched for all 3 experiments. These data suggest that exposure to iHP fog and mist has variable effectiveness in reducing viability of S. obvelata ova at the time points tracked. Further studies are needed to identify iHP exposures that will further reduce or eliminate the hatching of rodent pinworm ova.