By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University
SYNOPSIS: Six patients in California were found to have leprosy in the absence of a known exposure.
SOURCE: Belzer A, Ochoa MT, Adler BL. Autochthonous leprosy in the United States. N Engl J Med 2023;388:2485-2487.
Belzer and colleagues studied the cases of six patients with leprosy first diagnosed in California between 2017 and 2022, which they indicate may have been locally acquired. Their mean age was 68.3 years and all were male. None had a prior known exposure to an infected individual, while one of the six reported having been exposed to an armadillo more than five decades previously. Most had a history of travel to Gulf Coast states, and all had international travel that included countries where leprosy is present. All had borderline or lepromatous leprosy with all infections confirmed by polymerase chain reaction (PCR). The interval from symptom onset to diagnosis ranged from six months to 11 years.
COMMENTARY
In 2020, 159 cases of leprosy were newly diagnosed in the United States, with 69% reported in one of six states: Florida, California, Louisiana, Hawaii, New York, and Texas.1 Most cases had an apparent exposure history, which, in some instances, was with armadillos. Armadillos were first noted in 1970 to be infected with Mycobacterium leprae, and evidence has accumulated since of their role as a potential source of human infection in the United States.2 Only one of the six patients reported by Belzer et al recalled an armadillo exposure and that occurred more than 50 years prior to the diagnosis of leprosy. In Great Britain, red squirrels also have been identified as potential carriers of M. leprae.
There is no definitive proof that these infections were acquired in the United States. Nonetheless, it is imperative that clinicians maintain alertness to the fact that patients may present with leprosy in the absence of a known exposure history.
REFERENCES
- Health Resources & Services Administration. National Hansen’s Disease (Leprosy) Program Caring and Curing Since 1894. https://www.hrsa.gov/hansens-disease
- Sharma R, Singh P, Loughry WJ, et al. Zoonotic leprosy in the Southeastern United States. Emerg Infect Dis 2015;21:2127-2134.
