Abstract
In this report prevalence rates of rodent viruses in laboratory animals are presented based on routine serological screening of mouse and rat colonies from European institutes. The prevalences found during the period 2000–2003 are compared with those reported for 1981–1984 and 1990–1993. It is shown that some infections were eliminated from laboratory animal colonies (e.g. K-virus and polyomavirus) by taking preventative measures whereas other infections such as mouse hepatitis virus and parvoviruses remained at a high rate. Further decreases in prevalence rates in the last 10 years were found for infections such as pneumonia virus of mice, reovirus type 3, Sendai virus, sialodacryoadenitis/rat coronavirus and Mycoplasma pulmonis. The introduction of new detection methods showed that mouse parvovirus and rat parvovirus, both members of the Parvoviridae family, remain a major threat to laboratory mice and rats. Guineapig cytomegalovirus and parainfluenzavirus appeared to be the most prevalent agents among laboratory guineapigs. The importance of a standardized, up-to-date screening programme is discussed.