A extensive six-year study in Boston has revealed a concerning public health threat: rats are spreading a perhaps fatal strain of leptospirosis, dubbed ‘leptosbury’. The research underscores the importance of understanding and managing urban rat populations to mitigate disease transmission.

Leptospirosis spreads primarily through contact with the urine of infected animals, often found in soil, puddles, or stagnant water. Humans, pets, and other animals can become infected when exposed to these contaminated environments.

Symptoms of leptospirosis can include high fever, headache, bleeding, muscle pain, tremors, eye redness, and vomiting. If left untreated, the infection can lead to severe kidney and liver damage, highlighting the need for prompt medical attention.

While traditionally associated with tropical climates, leptospirosis is increasingly observed in cooler regions, a trend potentially linked to global warming and changing environmental conditions.

Key Findings: 18% of rats Carried Leptospira Bacteria

A collaborative effort involving Tufts University, the University of Northern Arizona, the U.S.Department of agriculture (USDA), and the Centers for Disease Control and Prevention (CDC) analyzed kidney samples from 328 rats captured at 17 locations across boston between 2016 and 2022. the results were alarming: 18% of the rats tested positive for leptospira bacteria.

• Genetic Similarity: Researchers discovered that a leptospirosis case reported in Boston in 2018 shared a near-identical genetic fingerprint with leptospira samples taken from rats in the same geographic area.
• Source Identification: This close genetic match provides strong evidence that the city’s rat population is a important source of leptospirosis transmission.
• Advanced Analysis: Scientists employed specialized DNA capture techniques to conduct a comprehensive analysis of the leptospira bacteria’s genetic sequence.

According to Dr. Dave Wagner, professor at Northern Arizona University, this research marks a significant advancement in the field: We can now watch in detail how the bacteria spread among the spacing populations in the city.

Implications for Urban Rat Control

The study’s findings underscore the challenges of managing rat populations in urban environments and the need for targeted intervention strategies.

It is not possible to completely destroy the rats in cities. We need to better understand the effects of interventions for rating control on both animal populations and disease spread.

Dr. Marieke Rosenbaum, Tufts University

The research, published in *PLOS Neglected Tropical Diseases*, also revealed key insights into rat behaviour and population dynamics:

• Genetic Diversity: Rat populations in Boston exhibit genetic diversity, with each region harboring its own distinct bacterial strain over time.
• Movement Patterns: Rats can travel up to approximately 600 meters, utilizing green spaces and biological corridors for movement. However, multi-lane roads can act as barriers, limiting their dispersal.