The rate of new diagnoses of Hansen’s disease, or leprosy, in the United States decreased from 0.52 per million in the 1994-1996 period to 0.43 per million in the 2009-2011 period, according to data published in MMWR. The highest incidence was among foreign-born people.
“Because Hansen’s disease is rare, clinicians in the United States are often unfamiliar with it; however, [it] continues to cause morbidity in the United States,” Leisha Nolen, MD, PhD, of the CDC’s Division of High-Consequence Pathogens and Pathology, and colleagues wrote in the report. “Clinicians throughout the United States should familiarize themselves with the signs and symptoms of Hansen’s disease and understand that [it] can occur in the United States.”
The researchers reviewed records from the National Hansen’s Disease Program (NHDP) registry to evaluate trends in Hansen’s disease (HD) and characterize US populations at risk. The data included new diagnoses from 1994 to 2011. The cases were classified as US-born or foreign-born, and the researchers calculated HD rates by country of birth for each year of the study period.
From 1994 to 2011, there were 2,323 new cases of HD, and an average annual incidence rate of 0.45 cases per million (95% CI, 0.43-0.47). Overall, the number of new diagnoses decreased by 17% from 1994-1996 to 2009-2011. Among US-born individuals, the average annual incidence rate from 1994 to 2011 was 0.13 per million (95% CI, 0.12-0.14), with no change in the rate from 1994-1996 to 2009-2011 (0.16 per million).
The average annual incidence rate of HD from 1994 to 2011 among foreign-born individuals was 2.81 cases per million (95% CI, 2.67-2.95). The rate was higher in 1994-1996: 3.66 cases per million vs. 2.29 cases per million for 2009-2011. In the 5-year period of the study when birth country data were collected for the US census (2007-2011), individuals born in Oceania had the highest rate of diagnosis, 556.9 cases per million.
The researchers found that 74% of cases had a delay of less than 3 years between symptom onset and diagnosis, but some “were not diagnosed for many years” after symptom onset.
“HD can lead to severe nerve and tissue damage if treatment is delayed for months or years,” the researchers wrote. “For this reason, it is important to recognize this disease and begin treatment as early as possible. It is important to consider this disease 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.”
Disclosure: The researchers report no relevant financial disclosures.