Transmission of mouse parvovirus by fomites

Abstract

The goal of the current studies was to determine the risk of transmission of mouse parvovirus (MPV) by caging and husbandry practices. To determine whether MPV can be transmitted during cage changes in a biologic safety cabinet without the use of disinfectants, 14 cages of Swiss Webster mice were inoculated with MPV. Cages containing infected mice were interspersed among 14 cages housing naïve Swiss Webster mice. At 1, 2, and 4 wk after inoculation of the mice, cages were changed across each row. All naïve mice housed adjacent to infected mice remained seronegative. To determine the risk of environmental contamination, nesting pads that were used to sample the room floor during husbandry procedures at 1, 2, 4, and 6 wk after inoculation of the mice were placed in cages with naïve mice. None of the mice exposed to the pads became MPV seropositive. To determine whether components from cages that had housed MPV-infected mice could transmit MPV, Swiss Webster mice were exposed to soiled bedding or used cages, drinking valves, food, cage bottoms, wire bars and filter tops, nesting material, or shelters. With the exception of drinking valves, all mice exposed to other components became MPV seropositive. Fourteen cages that had housed MPV-infected mice were washed but not autoclaved; mice housed in the washed cages did not become MPV seropositive. In conclusion, all cage components can serve as fomites, with the drinking valve being the least risky. Cage washing alone was sufficient to remove or inactivate MPV.

Figure 1.

Number of sentinels (among a total of 14 mice) that were seropositive for MPV 3 wk after a 1-wk exposure to water valves that had been used by MPV-inoculated mice for 1 wk; to cages that had housed MPV-inoculated mice for 1 wk; or to soiled bedding collected at 1, 2, 4, or 6 wk after index mice were inoculated with MPV.

Figure 2.

Number of sentinels (among a total of 7 mice) that were seropositive for MPV 3 wk after a 1-wk exposure at 1, 2, 3, 4, 5, or 6 wk to nesting material from cages housing an MPV-infected index mouse, a breeding pair, and a litter of mice.

Figure 3.

Number of sentinels (among a total of 14 mice) that were seropositive for MPV 3 wk after a 1-wk exposure to components from cages that had housed MPV-inoculated mice for 1 wk.