Urban rats fuel disease spread in Boston, study finds

A six-year study led by Tufts University has found that migrating urban rats are spreading leptospirosis, a potentially deadly bacterial disease. Researchers tested 328 rat kidney samples from 17 Boston sites, with 59 testing positive for Leptospira.

Genetic sequencing revealed rats maintain distinct local bacterial strains but can transmit them when displaced. One human case was genetically linked to local rats. The study, published in PLOS Neglected Tropical Diseases, highlights how construction, roads, and greenways influence rat movement and disease spread.

Researchers hope the findings will support improved public health strategies and rat control efforts in urban environments.