Leprosy, a terrible flesh-eating disease that ravaged the world for thousands of years, may still be around today were it not for the pioneering work of dermatologist Dr. Thomas Rea. According to a report from the Los Angeles Times, Dr. Rea has died at the age of 86 at his home in California.

Dr. Rea’s work helped lead to a dramatic drop in leprosy cases throughout the 20^th century. Along with his colleague Dr. Robert Modlin, Rea was able to harness the human body’s immune system to attack the bacterial infection known for causing nasty skin lesions and growths. Researchers had suspected that the immune system may be the key to halting the disease for years, but Rea’s work paved the way for effective treatments for the disease.

One of the biggest problems with leprosy is that it had the ability to spread as a result of even the slightest human contact. Throughout history, the disease ate away at the flesh of sufferers and carried a massive social stigma due to its tendency to spread. One of Dr. Rea’s biggest breakthroughs was rendering the disease non-contagious, allowing other treatments to address the symptoms without fear of transmission.

Almost instantly, the disease that once posed a massive global health issue was rendered “entirely controllable.” Gone were the days of quarantine and “leper” colonies, which had been humanity’s best defense against the disease for thousands of years.

Leprosy is characterized by skin lesions that take on a reddish or copper hue. They can be flat, raised, or nodular, and are typically accompanied by sensory loss. Sensory loss is one of the key identifying factors of a leprosy infection, and is not a symptom of other infections that can produce similar lesions.

The disease is caused by two types of bacteria, M. leprae and M. lepromatosis. The latter is a relatively new identification, discovered after a fatal case of diffuse lepromatous leprosy that occurred in 2008. The two bacteria are extremely difficult to culture in a laboratory setting, and effective research on the species was difficult until more modern molecular genetic analysis techniques became available.

Dr. Rea’s work led to the development of a new drug to treat leprosy, called thalidomide. The U.S. FDA banned the drug due to its tendency to cause birth defects, but Dr. Rea’s lobbying efforts led to the acceptance of limited use in cases of leprosy.

Dr. Rea headed the University of Southern California’s dermatology department from 1981 to 1986, and continued his research on leprosy, or Hansen’s disease, up until a few months before his death. Rea was known for his fearless approach to leprosy patients, working just as hard to remove the social stigma from the disease as he did to find an effective treatment.

Rea served in the U.S. Army Medical Corps in Korea, and then went to work at the dermatology department at New York University. This is where he came into contact with Hansen’s disease patients for the first time, and he moved to Los Angeles by 1970.

Dr. Hansen will be remembered for his outstanding contributions to the understanding of a disease that affected humanity for countless generations. He is survived by his wife, two sons, and four grandchildren.