A patient who recently died of rabies in Maryland contracted the illness from a kidney transplant received over a year ago, the CDC reported on Friday. The lengthy incubation period, while longer than the typical 1 to 3 months, is unusual but not unprecedented.

Tests on tissue samples from the patient and donor confirmed that they were both infected with raccoon-type rabies. The three other patients who received organs from the donor have been identified and are receiving anti-rabies shots.

The CDC notes: “If rabies is not clinically suspected [in a potential donor], laboratory testing for rabies is not routinely performed, as it is difficult for doctors to confirm results in the short window of time they have to keep the organs viable for the recipient.”

Source: CDC