City officials say one person has died and two others became ill from a rare bacterial disease carried by rats. All three sickened individuals lived within the same one-block radius in the Concourse section of The Bronx.

The disease, leptospirosis, is extremely rare in humans, and a spokesperson with the Department of Health told Gothamist the city sees only one to three cases a year. There were only 26 reported cases of leptospirosis reported in NYC from 2006 to 2016. Still, Demetre Daskalakis, acting deputy commissioner of the Health Department, told the NY Post that the proximity of the cases was unusual. “This is the first time a cluster of cases has been identified," he told the paper.

Daskalakis also noted that the patient who died had suffered an infection, but though all three were hospitalized with acute renal [kidney] and hepatic [liver] failure, the two surviving patients have completely recovered. A spokesperson with the Health Department told Gothamist two patients were diagnosed in December and one was diagnosed in February. One patient, Braulio Balbuena Flores, told the Post he was hospitalized for two weeks. “I had a fever,” he said. “I couldn’t eat, couldn’t sleep, whole body hurt.”

Flores lives in a basement apartment at 750 Grand Concourse—city officials issued a vacate order for basement apartments in that building on Tuesday. The Health Department says it is working with the Housing Preservation and Development and Buildings Departments to mitigate rodent infestations in the area.

The Health Department says leptospirosis is spread by animal urine, and is rarely spread from human to human. The bacteria gets into the human body through open wounds or cuts, or through the eyes, nose or mouth; symptoms include fever, headache, chills, muscle aches, vomiting or diarrhea, though more serious cases can involve infections in the kidneys and liver. The disease is treatable with antibiotics.