Texas Researchers Find Typhus DNA in Fleas on 6 of 167 Sampled Cats

Texas A&M University researchers detected DNA from the bacterium that causes murine typhus in fleas collected from domestic cats in the Rio Grande Valley, according to a study published in Parasites & Vectors in May 2026. Fleas from six of 167 sampled cats tested positive. The region recorded more than 6,700 cases of flea-borne typhus between 2008 and 2023.

University of Texas Medical Branch researchers identified 149 adults with murine typhus in Galveston from April 2019 through October 2023. Of those patients, 119 required hospitalization and 33 needed intensive care. Two patients died in the ICU from multiorgan failure and hemophagocytic lymphohistiocytosis.

Newsweek reported that a City of San Antonio Metropolitan Health District spokesperson said murine typhus is endemic in Bexar County, with rates in 2023 and 2024 above pre-pandemic levels. Fleas are more active in warm weather, the spokesperson added.

A 2023 University of Texas study found that seroprevalence of past R. Typhi infection in Galveston County rose from 1.2 percent in 2013 to 7.8 percent in 2021. Dr. Sarah Hamer of Texas A&M stated that South Texas is one of the few U.S. places where murine typhus is transmitted with some regularity.

Hamer cited increased numbers of pet and feral cats, socioeconomic barriers to flea protection, and warming temperatures as factors promoting flea infestation and transmission. Murine typhus was nearly eradicated in the U.S. after vector-control campaigns in the 1940s and had appeared to disappear from Galveston for decades before its recent return.