# Bartonella infection in small mammals and their ectoparasites from the Central Highlands of Madagascar: diversity and implication in future zoonotic surveillance

## TL;DR

This study found high Bartonella infection rates in small mammals and fleas in Madagascar, identifying two potential zoonotic species that could impact public health.

## Contribution

The study reports new Bartonella diversity and zoonotic potential in Madagascar's Central Highlands using molecular methods.

## Key findings

- 60.1% of small mammals and 15.9% of fleas tested positive for Bartonella.
- Rattus rattus and Synopsyllus fonquerniei showed the highest infection rates.
- Two potential zoonotic Bartonella species (B. elizabethae and B. kosoyi) were identified.

## Abstract

This research aimed to investigate the prevalence and diversity of Bartonella in small mammals and their ectoparasites from the Central Highlands of Madagascar and to refine existing information on potential associated zoonotic diseases.

A retrospective analysis was performed on mammals and their ectoparasites collected in the Fandriana and Ankazobe districts, including 253 spleen samples from seven small mammal species and 183 individual ectoparasites (132 fleas and 51 ticks). Genomic DNA was extracted and amplified by polymerase chain reaction (PCR) targeting the nuoG gene (346 bp). Sanger sequencing of the PCR products was performed to assess Bartonella diversity using phylogenetic analysis.

In total, 60.1% (152/253) of small mammals and 15.9% (21/132) of fleas tested positive for Bartonella, with Rattus rattus (69.1%, 137/198) and the associated flea Synopsyllus fonquerniei (21.2%, 14/66) having the highest infection rates. At the same sampled locations, adult R. rattus were more frequently infected with Bartonella than juveniles. Phylogenetic analysis revealed five associated clades of Bartonella with two clades recognized as a potential zoonotic species (B. elizabethae and B. kosoyi).

Using molecular tools, we report a high prevalence of Bartonella in small mammals and their fleas in the Central Highlands of Madagascar. Two potential Bartonella zoonotic species were identified in R. rattus and their fleas. As these bacteria are generally vector-borne, they could have a significant impact on public health in the vicinity of our study areas and, in general, in Madagascar, and merit further investigation.

The online version contains supplementary material available at 10.1186/s13071-025-07233-9.