Rodent vendor apparent source of mouse parvovirus in sentinel mice.

Mouse parvovirus (MPV) has been increasingly prevalent in laboratory animal facilities, and the source of infection often can be difficult to determine. After 4 years of sporadic MPV detected in our sentinel mice and continual failure to identify index cases in colony mice, we developed a regimen to house newly arrived vendor mice in large sterile cages with a high stocking density. Some of these mice were retained in isolation after the remaining mice were deployed as sentinels. After detecting MPV seropositive sentinel mice 4 weeks after introduction to the mouse colonies in one facility, the remaining naïve mice that had been previously housed with those sentinels also tested positive for MPV, despite never having been exposed to colony mice. These results suggest that commercially bred mice intended for use as sentinels may, in fact, arrive at animal facilities already infected with MPV. Depending upon numerous factors, including the health surveillance methods used, it is possible that a low prevalence of MPV may exist undetected at rodent vendors.