"WASHINGTON — Rat infestation in many world cities appears to be soaring, especially in Washington, and a new study blames warming temperatures, urbanization and other human actions.

A first-of-its-kind examination of trends and reasons in hard-to-count rat populations uses rat sighting reports in 16 cities around the world. In 11 of those cities, rat complaints have increased, according to a study in Friday’s journal Science Advances.

Based on individual trends within cities, Washington was by far the leader in rat increases, followed by San Francisco, Toronto, New York City and Amsterdam. Washington’s rising rat reporting trend was three times greater than Boston’s and 50% more than New York’s, the study said. Washington city officials did not respond to requests for comment.

Only three cities saw significant decreasing trends — New Orleans, Louisville and Tokyo — with the home of Mardi Gras showing the biggest drop in rat reporting. Experts said the Louisiana city can teach others how to combat the rat problem."

Seth Borenstein reports for the Associated Press January 31, 2025. [2]