Socioeconomic and environmental risk factors for urban rodent infestation in Sao Paulo, Brazil

This article provides analyses of data on the premises infestation by commensal rodents collected during the 2006 Urban Rodent Survey, in Sao Paulo city, Brazil. A two-stage cluster sample survey was used to visit 23,512 premises, and logistic regression models were estimated in order to understand the relationships among the risk factors and the infestation probability. The premises infestation rates were 23.1% for all rodents, 12.7% for roof rat, 9.4% for Norway rat and 1.7% for house mouse. Factors found to be related to infestation levels were: socioeconomic conditions (human development index and income), premises features (commercial, strictly residential and vacant lots), and environmental resources (access, harborage and food). The analysis of odds ratios showed that access by the building structure favours roof rat and access by the sewage system favours Norway rat. Harborage in ceiling cracks are determinant for roof rat, harborage in wall cracks and in dense bush for Norway rat, and harborage in waste or in building material for house mouse infestations. Available animal food favour all the three species, fruit trees favour Norway and roof rats, human food is important for house mouse: therefore a natural partition of the environmental resources among the species was observed. The results obtained in this article add some knowledge on the biology and behaviour of commensal rodents.