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CDC Report: Leprosy Still Occurs in U.S.
Hansen’s disease –– commonly known as leprosy –– continues to occur in the U.S., in both U.S.-born and foreign-born persons, according to new research by the Centers for Disease Control and Prevention (CDC), published October 31 in Morbidity and Mortality Weekly Report.
Many clinicians are not familiar with the disease or its manifestations and treatments, the report says, but Mycobacterium leprae is an important pathogen to consider when caring for patients with chronic skin disorders of unknown cause.
Known since Biblical times, leprosy is a chronic infection of the skin and nerves, commonly presenting as pale or reddish skin patches with diminished sensation. Without treatment, it can progress to a severely debilitating disease with nerve damage, tissue destruction, and functional loss.
An important factor in limiting the morbidity of leprosy is early diagnosis and prompt initiation of therapy, the CDC notes. But because leprosy is rare, U.S. clinicians are often unfamiliar with it.
Although not highly contagious, leprosy is thought to be transmitted through nasal secretions. The normal incubation period ranges from 3 to 7 years. The initial presentation is often one or more chronic anesthetic macular or maculopapular skin lesions. Leprosy can progress to involve peripheral nerves, resulting in sensory and motor loss, and ultimately to permanent disability.
For its report, the CDC examined the National Hansen’s Disease Program (NHDP) registry of new leprosy diagnoses during 1994–2011. The population was divided into U.S.-born and foreign-born persons.
During 1994–2011, there were 2,323 new cases of leprosy, with an average annual incidence rate of 0.45 cases per 1 million persons. A 17% decrease in the rate of new diagnoses was observed in the U.S. population overall, from 0.52 during 1994–1996 to 0.43 during 2009–2011. During 1994–2011, U.S.-born persons had an average annual rate of 0.13, but foreign-born persons had an average rate of 2.81.
The analysis regarding country of birth was limited to 2007–2011. During this 5-year period, persons born in Oceania had the highest rate of leprosy diagnoses, with an average annual rate of 556.9 cases per 1 million population –– more than 10 times the rate observed for any other region. Almost half (48.9%) of the persons with leprosy from Oceania were diagnosed in Hawaii.
In the U.S., leprosy is mostly confined to areas where the disease is still found, such as Texas and Louisiana, according to past research. In these states, the bacteria can be found on armadillos, which can pass the infection to humans.
To reduce the occurrence of leprosy in the U.S., diagnosis and treatment need to be improved among persons who were born in foreign countries where there is a high prevalence of the disease and in those countries themselves, the CDC says. Moreover, clinicians throughout the U.S. should be aware of the signs and symptoms of the disease and know that it exists in the U.S. According to the CDC, it is important to consider leprosy when evaluating chronic skin conditions, especially those with associated loss of sensation. By diagnosing and treating patients early, it is possible to prevent further transmission and lifelong disability.
Sources: CDC; October 31, 2014; and MedicalXpress; October 30, 2014.