Preliminary molecular detection and characterization of Bartonella in small mammals from Malaysian oil palm ecosystems

Abstract

Close contact between humans and wildlife in agricultural landscapes, particularly rodents in oil palm plantations, increases the risk of zoonotic pathogen transmission, with Bartonella spp. emerging as important but understudied cause of febrile illness. The study investigates the presence and genetic characterization of Bartonella in small mammals from Malaysian oil palm plantations to assess the zoonotic risk. A total of 297 animals were trapped and examined, representing five species: Rattus tanezumi R3 mitotype, Rattus tiomanicus, Rattus exulans, Callosciurus notatus, and Tupaia glis. The identification of three Rattus group was further validated using cytochrome c oxidase subunit I (COI) gene analysis. DNA was extracted from the spleen and screened for Bartonella and Rickettsia using conventional PCR targeting the gltA gene followed by sequencing and phylogenetic analysis of positive samples for confirmation and diversity assessment. Molecular screening revealed a 2 % (6/297) prevalence of Bartonella species in five R. tanezumi R3 mitotype and one R. tiomanicus. Conversely, no Rickettsia DNA was amplified from all of the collected samples. All Bartonella-positive samples phylogenetically clustered with Bartonella phoceensis strain 16120, a genotype not currently associated with human disease. However, its detection in predominant rodent reservoir species underscores the utility of a One Health framework. Sustained surveillance using integrated approaches is essential to monitor and mitigate potential zoonotic risks emerging from evolving agricultural landscapes.