Leprosy in the United States
Abstract & Commentary
By Philip R. Fischer, MD, DTM&H
Dr. Fischer is Professor of Pediatrics, Department of Pediatric & Adolescent Medicine, Mayo Clinic, Rochester, MN.
Dr. Fischer reports no financial relationships relevant to this field of study.
Synopsis: Hansen disease (leprosy) still occurs in non-tropical areas including the south-central region of the United States. Contact with armadillos is a risk factor for acquisition of infections. Skin lesions are not always anesthetic, and biopsy can be diagnostic.
Source: Abide JM, Webb RM, Jones HL, et al. Three Indigenous Cases of Leprosy in the Mississippi Delta. Southern Medical Journal. 2008;101:635-638.
Abide and colleagues at the University of Mississippi report three patients who presented with skin lesions and were found to have leprosy. A 78-year-old male was noted to have two asymptomatic erythematous lesions on his back during a routine exam. Biopsies revealed granulomatous dermatitis with acid-fast bacilli. Polymerase chain reaction (PCR) testing confirmed the presence of Mycobacterium leprae, and a diagnosis of Hansen disease in the borderline spectrum was made. He was treated with dapsone and rifampin. An 81-year-old woman had a three-week history of an initially itchy plaque-like lesion on an arm. A biopsy showed granulomatous dermatitis with acid-fast bacilli. Borderline tuberculoid leprosy was diagnosed, and she was successfully treated with dapsone and rifampin. Finally, a 73-year-old man presented with a macular, generalized erythematous eruption of two months' duration and had some sensory loss on examination. His biopsy also showed granulomatous dermatitis with acid-fast bacilli. He was diagnosed with borderline lepromatous leprosy and was treated with clofazimine, dapsone, and rifampin. It is interesting that two of these three patients had no anesthetic skin lesions, and at least two of them had not traveled to an area outside the United States where leprosy is endemic. All three patients had either killed or eaten armadillo.
Commentary
Historically, "tropical" diseases have not been confined to patients living or traveling between the Tropics of Cancer and Capricorn. Indeed, yellow fever killed thousands in Philadelphia during the 1790s as America was experiencing its early decades of independence. Even the location of the Mayo Clinic was influenced by a "tropical" disease; bothersome summertime fevers due to malaria prompted Dr. William W. Mayo to move from Indiana's Wabash Valley to what is now Minnesota in 1854. Still, more than 100 cases of leprosy are reported each year in the United States; while most cases occur in immigrants, there are still endemic foci of leprosy in the Gulf Coast states of Texas, Louisiana, and Mississippi.1
Leprosy seems to have arrived in North America during European immigrations of the 1700s.2 Since 1981, human infection with M. leprae has been suspected of being associated with armadillo contact.3 Controversy about the role of armadillos and leprosy actually representing a zoonotic infection continue,2 but a recent case-control study shows that infection is clearly associated with armadillo contact, especially eating them.3 In addition, having lived in Mexico has been identified as a risk factor, and it is suspected that unidentified non-zoonotic factors are still relevant to the transmission of leprosy in the Americas.3
Leprosy has been known for millennia, but confusion about the disease arose after the King James version of the Bible used the word "leprosy" for a variety of contagious skin conditions. To avoid undue stigmatization of affected patients, some clinicians now prefer to refer to leprosy as Hansen's or Hansen disease after the Norwegian, G.A. Hansen, who identified M. leprae in the 1870s.
Currently, the World Health Organization estimates the global prevalence of leprosy to be approximately 1.4 per 10,000 people. There are about 500,000 new cases of leprosy reported each year, and in about a dozen countries leprosy is still endemic (mostly in sub-Saharan Africa but also Brazil, Indonesia, and in parts of South Asia).4
Traditionally, clinicians have been taught to consider a diagnosis of leprosy for someone with an anesthetic skin lesion and a history of travel to an area endemic for leprosy. The cases reported from Mississippi remind us that a wide variety of skin lesions, even those with intact, normal sensation, may be due to leprosy, and that the American Gulf Coast states still represent an endemic area. The diagnosis of leprosy is often unnecessarily delayed5, so a strong index of suspicion is helpful.6 Skin biopsy can provide a definitive diagnosis, with PCR being useful for species confirmation. Treatment depends on the classification of the disease and is effective.6 Expert help is available in the United States when the diagnosis of leprosy is being considered by calling the National Hansen's Disease Program (1-800-642-2477 or 225-578-9841).5
Humans are the main reservoir for M. leprae, and eradication efforts are in progress.4,7 For now, early detection and curative treatment of leprosy infection are the keys to control and, possibly, eventual eradication of this stigmatizing scourge.
References
- Anderson H, Stryjewska B, Boyanton BL, et al. Hansen disease in the United States in the 21st century. Arch Pathol Lab Med 2007;131:982-986.
- Truman R. Armadillos as a source of infection for leprosy. South Med J 2008;101:581-582.
- Clark BM, Murray CK, Horvath LL, et al. Case-control study of armadillo contact and Hansen's disease. Am J Trop Med Hyg 2008;78:962-967.
- Hussain T. Leprosy and tuberculosis: An insight-review. Clin Rev Microbiol 2007;33-15-66.
- Scollard DM. Leprosy is (still) here, but recognition is often delayed. South Med J 2008;101:583.
- Boggild AK, Keystone JS, Kain KC. Leprosy: A primer for Canadian physicians. CMAJ 2004;170:71-78.
- Goulart IMB, Ricardo L. Leprosy: Diagnostic and control challenges for a worldwide disease. Arch Dermatol Res, available online pre-publication, 2008.
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