# First report of pathogenic Leptospira in Sri Lankan bats: A potential reservoir risk?

## TL;DR

This study is the first to find pathogenic Leptospira in Sri Lankan bats, suggesting they may contribute to the spread of leptospirosis, a serious disease in tropical regions.

## Contribution

The first molecular evidence of pathogenic Leptospira in Sri Lankan bats, highlighting their potential role as disease reservoirs.

## Key findings

- Leptospira was detected in 16 bat urine samples from three species in Wavulgalge cave.
- Leptospira borgpetersenii was identified in Miniopterus fuliginosus, a known pathogenic species.
- One genetically distinct Leptospira species was found in Rousettus leschenaultii.

## Abstract

The genus Leptospira, classified under the phylum Spirochaetes, includes saprophytic, intermediate, and pathogenic species. Pathogenic Leptospira spp. are the causative agents of leptospirosis, a widespread and often neglected zoonotic disease that causes severe illness in humans, particularly in tropical and subtropical regions. In Sri Lanka, leptospirosis causes annual outbreaks, especially during the monsoon seasons. While rodents are recognized as primary reservoirs, bats have also been identified as potential reservoir hosts. This study aimed to detect and characterize Leptospira species in bats roosting in Wavulgalge cave, Sri Lanka.

Urine samples (n = 148) were collected during natural urination from four bat species: Miniopterus fuliginosus (n = 117), Hipposideros speoris (n = 8), Rousettus leschenaultii (n = 10), and Rhinolophus rouxii (n = 13). DNA was extracted and screened for Leptospira using real-time PCR targeting the lipL32 gene. Sixteen samples tested positive, including 14 from M. fuliginosus, one from H. speoris, and one from R. leschenaultii. Positive samples were further analyzed by amplifying additional loci (flaB, secY, and rrs2) for Sanger sequencing and phylogenetic analysis. Sequences were obtained from 12 samples. Leptospira borgpetersenii was identified in M. fuliginosus, while the sequence from R. leschenaultii represented a genetically distinct Leptospira species. Phylogenetic analysis showed clustering with sequences from the same bat host genera reported in other countries, and one L. borgpetersenii sequence clustered with strains previously detected in Sri Lankan hosts, including humans.

This study provides the first molecular evidence of Leptospira in Sri Lankan bats and highlights their potential role as reservoirs contributing to the environmental circulation of pathogenic Leptospira.

Leptospira are spiral-shaped bacteria that can cause leptospirosis, a serious disease affecting both humans and animals, particularly in tropical regions such as Sri Lanka. The disease spreads through contact with water or soil contaminated by the urine of infected animals. In Sri Lanka, leptospirosis poses a major public health challenge, with frequent outbreaks during the rainy season. While rodents and domestic animals are well-known sources of infection, the role of bats has received far less attention.

In this study, we investigated whether bats in Sri Lanka can carry Leptospira bacteria that may contribute to disease transmission. We examined urine samples from bats living in Wavulgalge cave and tested 148 samples using molecular detection methods. We found genetic evidence of Leptospira in 16 samples from three bat species. Most of these belonged to Leptospira borgpetersenii, a pathogenic species previously associated with infections in animals and humans. This is the first molecular evidence of Leptospira in bats from Sri Lanka.

Our findings suggest that bats may act as natural reservoirs for these bacteria. Because bats play important ecological roles, such as pollination and insect control, it is important to balance disease surveillance with bat conservation when assessing potential risks to human health.