The occurrence of commensal rodents in dwellings as revealed by the 1996 English House Condition Survey

1. The presence of commensal rodents was assessed in the 1996 English House Condition Survey (EHCS). Logistic regression techniques were used to identify the key factors that might determine the susceptibility of dwellings to infestation. 2. The overall percentages of dwellings that were infested, weighted to allow for the more intensive sampling used in certain categories of dwellings, were 1.83% for mice Mus domesticus, 0.23% for rats Rattus norvegicus living indoors and 1.60% for rats living outdoors. These figures excluded vacant properties, properties with some commercial use, and purpose-built flats, as these groups showed different patterns of infestation and were therefore excluded from the logistic regressions. 3. The prevalence of both rats and mice was significantly greater for dwellings where pets or livestock were kept in the garden. 4. Dwellings classed as unfit for human habitation were more likely to be infested with mice. 5. Dwellings in areas of low-density housing had a significantly higher prevalence of both rat and mouse infestation. This probably reflects the general suitability of the rural environment for commensal rodents. 6. Older properties had a relatively high prevalence of rats. This may be because their mature gardens provided suitable habitats for colonization. Once other confounding factors were taken into account, the age of the property did not influence the rate of infestation by mice. 7. Dwellings in areas with substantial problems, such as dereliction, litter, vacant properties and unkempt gardens, had a significantly higher prevalence of rats and mice. 8. This study reveals the value of applied ecological techniques, including logistic regression of presence-absence data, in understanding the distribution of commensal rodents in relation to dwellings, with the prospect of more effective management practices being developed as a consequence.