Optimization of spatial accessibility to vaccination points of 2009 rabies vaccination campaign in Sao Paulo city, Brazil

Abstract

São Paulo city has more than 2.5 million dogs and 560 thousand cats. These populations are distributed irregularly through the territory, making it difficult to allocate health services. One of the most important health interventions over the animal population is the vaccination against rabies, presumably responsible for the ending of the rabies epidemics in dogs and cats in 1983. The aim of this study is to evaluate the accessibility to vaccination points during the 2009 mass vaccination campaign. To achieve this, we used a two-step floating catchment area (2SFCA) method implemented in a geographic information system environment, under the hypothesis of optimal distribution of vaccination points to assure the potential use of the service by 100% of the target population. Areas with low accessibility were observed, especially in dense populated areas, for both dogs and cats. An algorithm to optimize the vaccination point location was created in order to improve accessibility, and scenarios with lower number of vaccination points were created. This methodology can be used to offer vaccination against rabies evenly to the entire population of animals, especially after the halt of this control strategy from 2010 and 2011. The model considered the same location of vaccination points for dogs and cats, when appropriate.