CDC update on Hansen’s Disease
The latest issue of the CDC’s Morbidity Mortality Weekly Report has brought to my attention an update on Hansen’s Disease (aka Leprosy) in the United States for the past 15 years. Leprosy is a sporadic disease in the US, with an annual incidence rate of about 1 case per million people. The incidence outside of the US is higher. It is caused by the acid-fast bacterium Mycobacterium leprae, and according to this recent review article, seems to be transmitted via nasal secretions although only poorly. The incubation period for the development of disease is long; generally about 3 to 7 years, and initially presents with numbness in the peripheral nerves and flat skin lesions. Because of the very long incubation period, diagnosis is frequently delayed and at that point the treatment options become limited.
The World Health Organization is leading a global effort to eliminate Hansen’s Disease, and is beginning to show some marked success. To facilitate this effort, epidemiologists from the CDC examined reported data for the period from 1994 to 2011. They found that overall the rate of leprosy has declined during that time period, however the rate among people not born (but diagnosed in) the US was about 10 times higher than the rate for people born in the US. Clinicians noted that many of the cases were in patients from nations in the Southern Pacific (Oceania); indeed Hansen’s Disease is one that immigrants are screened for when they enter the US, however if they do not apply for Permanent Residency, they forego that screening. The CDC recommends that to effectively eliminate Hansen’s Disease clinicians here need to be further educated about the disease and its symptoms among high risk populations in order to monitor recent immigrants. Resources also should be expanded to enable clinicians outside the US to diagnose the disease earlier. The CDC notes that an early diagnosis of Hansen’s Disease is critical to prevent further transmission, and to prevent lifelong disability from the disease.