(CNN) Leprosy is a disease most people think ended in the Middle Ages, but a new study shows that it's not a thing of the past.

Mayo Clinic researchers wanted to understand how common it was in their clinic after a patient was diagnosed with the disease in March 2017. In the clinic's electronic health records, they found nine patients diagnosed with leprosy over a 23-year period.

The study authors emphasized that, though it's rare, the disease should still be considered when diagnosing patients.

"This is not a disease that the average person in the United States has to worry about, but if they develop a rash and have extensive travel to a place where it is common, then they should bring it to the attention of their provider," said study author and dermatologist Dr. Spencer A. Bezalel.

According to the World Health Organization , those places include the Democratic Republic of Congo, Ethiopia, Madagascar, Mozambique, Nigeria, Tanzania, Bangladesh, India, Indonesia, Myanmar, Nepal, the Philippines, Sri Lanka and Brazil. Each of those countries reported 1,000 new cases of leprosy, also known as Hansen's disease, in the past five years.

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