# Molecular epidemiology of rodent-borne Leptospira spp. in Sri Lanka: identification of novel sequence types and previously unrecognized reservoir animals

## TL;DR

This study explores the genetic diversity of Leptospira in rodents in Sri Lanka, identifying new strains and reservoir animals linked to human infections.

## Contribution

The study identifies novel Leptospira sequence types and newly recognized rodent reservoirs in Sri Lanka.

## Key findings

- Pathogenic Leptospira DNA was detected in 12.8% of rodent kidney samples from four species.
- Five Leptospira sequence types were identified, including two novel types: ST389 and ST392.
- Rattus rattus and Mus booduga were newly identified as sources of human Leptospira infections.

## Abstract

Introduction. Leptospirosis is an important zoonotic disease globally, which is most prevalent in tropical regions. This disease is endemic in Sri Lanka, where the complex ecology of Leptospira spp., reservoir animals and environmental and occupational factors has resulted in a public health problem.

Gap Statement. Although genomic analysis of Leptospira isolates has recently revealed the diversity of Leptospira spp. in Sri Lanka, the genetic relationship between human patients and reservoir animals remains unclear.

Aim. This study investigated the genetic diversity of Leptospira spp. circulating in rodent populations in three districts of Sri Lanka: Kurunegala, Anuradhapura and Badulla.

Methodology.
Leptospira DNA was detected from rodent kidney tissue samples by real-time PCR, from which positive samples were subjected to flaB sequencing and multilocus sequencing typing (MLST).

Results. Pathogenic Leptospira DNA was detected by real-time PCR in 33 of 257 kidney tissue samples (12.8%) from 4 rodent species: Bandicota bengalensis, Mus booduga, Rattus rattus and Vandeleuria sp. MLST and partial flaB sequencing of real-time PCR-positive samples identified Leptospira borgpetersenii, Leptospira interrogans, Leptospira kirschneri and Leptospira licerasiae in the rodent population. Five sequence types (STs), including two novel STs, ST389 and ST392, were identified. The novel STs of L. interrogans and L. kirschneri were genetically distinct from other STs detected in Sri Lanka. R. rattus and M. booduga were newly identified as the source of L. interrogans ST49 and of L. borgpetersenii ST144 and L. licerasiae infections in humans, respectively.

Conclusion. This study identified the genetic diversity of Leptospira spp. in rodent populations and reservoir animals for human infections in Sri Lanka.