A new report details the cases of 13 patients who were infected last year at two surgery clinics in Mexico.

The fungus behind a spate of deadly meningitis cases last year linked to medical clinics in Mexico was found to have aggressively attacked the base of patients’ brains, researchers said Wednesday in a report published in The New England Journal of Medicine.

Fungal meningitis was reported in as many as 24 patients from the United States who visited two medical clinics in Matamoros, Mexico. Many came from Texas. Twelve died.

All of the patients had undergone cosmetic procedures — such as breast implants, butt lifts or liposuction — that required epidural anesthesia. It was later discovered that the epidural was contaminated with a fungus called Fusarium solani; the epidural, experts said, introduced the fungus into the patients’ cerebrospinal fluid, a liquid found in and around the spinal cord and brain that provides nourishment and protection and removes waste.