Abstract
In Brazil, rabies surveillance is based on monitoring domestic and wild animals, although the most prevalent lineage of the rabies virus (RABV) currently diagnosed in Brazil is associated with bats, particularly non-haematophagous bats. Disease control is based on the mass vaccination of dogs and cats. We used data collected by the passive surveillance system of the city of Campinas from 2011 to 2015, to describe the temporal and geographic distributions of the bat specimens and RABV and discuss the current rabies surveillance with the advent of the declaration of canine and feline rabies-free areas in Brazil. We described the species, locations and health statuses of the collected bat specimens. Moreover, all samples were submitted for RABV diagnosis. Then, we performed a time series decomposition for each bat family. Additionally, we determined the spatiotemporal relative risk for RABV infection using the ratio of the kernel-smoothed estimates of spatiotemporal densities of RABV-positive and RABV-negative bats. From the 2537 bat specimens, the most numerous family was Molossidae (72%), followed by Vespertilionidae (14%) and Phyllostomidae (13%). The bat families behaved differently in terms of seasonal and spatial patterns. The distribution of bats varied geographically in the urban environment, with Molossidae and Phyllostomidae being observed downtown and Vespertilionidae being observed in peripheral zones. Concurrently, a significant relative risk of RABV infection was observed downtown for Vespertilionidae and in peripheral zones for Molossidae. No RABV-positive sample clusters were observed. As a result of the official declaration of RABV-free areas in southern Brazil, mass dog and cat vaccinations are expected to halt in the near future. This stoppage would make most dog and cat populations susceptible to other RABV lineages, such as those maintained by non-haematophagous bats. In this scenario, all information available on bats and RABV distribution in urban areas is essential. Currently, few studies have been conducted. Some local health authorities, such as that in Campinas, are spontaneously basing their surveillance efforts on bat rabies, which is the alternative in reality scenario of increased susceptibility to bat-associated RABV that is developing in Brazil.
Highlights
Bats are among the taxa that can adapt to the urban environment [1,2,3]
The current work was based on records of a passive bat rabies surveillance system in the city of Campinas, Brazil
The findings showed that bat family densities varied in space and time
Summary
Bats are among the taxa that can adapt to the urban environment [1,2,3]. Of the 178 bat species recorded in Brazil [4], at least 84 (47.2%) occur in urban areas [5]. The increased abundance of bats in urban areas may generate conflicts with humans and domestic animals, both as a nuisance and, more importantly, in the transmission of diseases, those caused by RNA viruses, including the rabies virus (RABV), Ebola virus, SARS-CoV, Hendra virus and Nipah virus [6, 7]. Several lineages or antigenic variants (AgV) of the RABV occur that are adapted to specific taxa, such as carnivores, bats or non-human primates [11]. Spillover of these specific lineages, including bat-associated lineages infecting other mammals, to other taxa is common [6, 12]
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