20th century
United States
The National Leprosarium at Carville, Louisiana, known in 1955 as the Louisiana Leper Home, was the only leprosy hospital on the mainland United States. Leprosy patients from all over the United States were sent to Carville in order to be kept in isolation away from the public, as not much about leprosy transmission was known at the time and stigma against those with leprosy was high (see Leprosy stigma). The Carville leprosarium was known for its innovations in reconstructive surgery for those with leprosy. In 1941, 22 patients at Carville underwent trials for a new drug called promin. The results were described as miraculous, and soon after the success of promin came dapsone, a medicine even more effective in the fight against leprosy. Stigma
Despite now effective treatment and education efforts, leprosy stigma continues to be problematic in developing countries where the disease is common. Leprosy is most common amongst impoverished populations where social stigma is likely to be compounded by poverty. Fears of ostracism, loss of employment, or expulsion from family and society may contribute to a delayed diagnosis and treatment.Folk beliefs, lack of education, and religious connotations of the disease continue to influence social perceptions of those affected in many parts of the world.
This incidental transmission was sustained in the armadillo population, and it may be transmitted back to humans, making leprosy a zoonotic disease (spread between humans and animals).Red squirrels (Sciurus vulgaris), a threatened species in Great Britain, were found to carry leprosy in November 2016. It has been suggested that the trade in red squirrel fur, highly prized in the medieval period and intensively traded, may have been responsible for the leprosy epidemic in medieval Europe. A pre-Norman-era skull excavated in Hoxne, Suffolk, in 2017 was found to carry DNA from a strain of Mycobacterium leprae, which closely matched the strain carried by modern red squirrels on Brownsea Island, UK. Risk factors
The greatest risk factor for developing leprosy is contact with another person infected by leprosy. People who are exposed to a person who has leprosy are 5–8 times more likely to develop leprosy than members of the general population. Leprosy also occurs more commonly among those living in poverty. Not all people who are infected with M. leprae develop symptoms.Conditions that reduce immune function, such as malnutrition, other illnesses, or genetic mutations, may increase the risk of developing leprosy. Infection with HIV does not appear to increase the risk of developing leprosy. Certain genetic factors in the person exposed have been associated with developing lepromatous or tuberculoid leprosy. Transmission
Transmission of leprosy occurs during close contact with those who are infected. Transmission of leprosy is through the upper respiratory tract.