Urban rats have been found to spread a deadly bacteria as they migrate within cities, potentially leading to a life-threatening disease in humans. A recent six-year study conducted by researchers at Tufts University and their collaborators shed light on this phenomenon, also uncovering a groundbreaking technique for testing rat kidneys.
The disease in question is leptospirosis, caused by a type of bacteria commonly found in rats. This bacteria is excreted in rat urine, contaminating the environment and posing a risk of infection to humans, dogs, and other species. While leptospirosis is more prevalent in tropical regions, the changing climate could lead to an increase in cases in colder regions as temperatures rise.
In Boston, leptospirosis is present in local rat populations, with different strains of the bacteria moving around the city as rat groups migrate. The study, led by Marieke Rosenbaum, M.P.H., D.V.M., and her team at Tufts University, along with collaborators from Northern Arizona University, the USDA, and the CDC, analyzed genetic data from rat populations in Boston to track the spread of leptospirosis.
Through advanced molecular techniques, the researchers were able to identify the specific strains of leptospirosis present in rat kidneys collected from various sites in Boston. By culturing the bacteria from rat kidneys, including frozen samples, the team obtained valuable isolates for analysis. This process allowed for a detailed examination of the genetic relatedness of different strains within the rat population.
The findings of the study, published in the journal PLOS Neglected Tropical Diseases, provide crucial insights into rat control and human leptospirosis mitigation efforts in urban areas. By understanding how rat populations migrate and transmit the bacteria, public health interventions can be better targeted to prevent the spread of the disease.
One key discovery from the study was the link between a human leptospirosis case in Boston and rats as the source of infection. Genetic sequencing of bacteria isolated from a patient revealed a close match to strains found in rats from the same location, confirming rats as a significant source of human infection.
Rats in urban environments exhibit distinct genetic populations, with limited intermingling between groups. However, when rats disperse, they can carry leptospirosis with them, potentially spreading the bacteria to new areas. Factors such as construction activities and road networks can disrupt rat populations, influencing the transmission of the disease.
Moving forward, the researchers emphasize the importance of understanding how pest control interventions impact rat migrations and disease transmission. While extermination may not be a feasible solution, targeted interventions can help reduce the risk of leptospirosis spreading among rat populations and to humans.
Overall, the study highlights the complex interactions between urban rats, the bacteria they carry, and human health. By unraveling these dynamics, researchers aim to improve strategies for managing rat populations and minimizing the threat of leptospirosis in urban settings.
