Page 107 - JSOM Winter 2019

An Ongoing Series

Leprosy (Hansen’s Disease)

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Elena M. Crecelius, MD *; Mark W. Burnett, MD 2

Introduction

There are few infectious diseases that are as stigmatic and disease is more common. People infected with leprosy are no
misunderstood as leprosy. Also known as Hansen’s Disease, longer infectious to others after just a few days of taking the
leprosy is caused by Mycobacterium leprae bacteria and is appropriate antibiotic therapy.
most commonly seen in tropical regions of the world. More
than 200,000 newly diagnosed cases of leprosy occurred in Leprosy infects the peripheral nerves, skin, and mucosal mem-
2017, the majority in South and Southeast Asia, Africa, and branes. Leprosy causes skin lesions that are usually chronic,
the Pacific Islands. In the United States, there were 178 new painless, and numb and may include flat discolored patches,
cases reported in 2015, with most cases occurring in those thick or dry skin, nodules, or swollen lumps under the skin.
who were foreign-born, primarily from Oceania. Leprosy can It may also cause loss of eyebrows and eyelashes or painless
cause permanent disability and nerve damage but is curable; ulcers on the feet. Medical providers should suspect leprosy
if caught early and treated appropriately, it may resolve with- when a patient has a rash that is partially or entirely numb,
out long-lasting consequences. Unfortunately, approximately especially if it has not improved after treatment for other
2 million people worldwide have permanent disabilities due to possible causes. Leprosy in its early stages is often misdiag-
leprosy. Because leprosy is not common in the United States, nosed as tinea corporis (ringworm), eczema, psoriasis, or
the diagnosis can be easily missed if clinicians do not think to vitiligo.
look for it.
The number of lesions a patient develops depends on the
strength of the patient’s immune response and the number
Background and Clinical Presentation
of bacteria present. Leprosy is defined as paucibacillary (also
Leprosy is not highly infectious. Human-to-human transmis- known as tuberculoid) when fewer than six lesions are present
sion usually occurs after prolonged (weeks to months), close and multibacillary (also known as lepromatous) when six or
contact with an infected person, likely via respiratory secre- more lesions are present.
tions. Only people who carry specific genes are thought to
be able to contract leprosy, with less than 5% of the general Acute changes in symptoms, known as leprosy reactions, can
population believed to be susceptible to infection. Biological occur in untreated patients or during the course of treatment.
relatives who share the same household as someone with un- In patients with paucibacillary leprosy, this usually causes ten-
treated leprosy are at the highest risk for infection. However, derness and swelling at previous lesions and the development
anyone who is susceptible to infection with leprosy and is ex- of new lesions and is known as a type 1, or reversal, reaction.
posed to the bacteria may become infected, especially those Patients with multibacillary disease may develop erythema no-
who are immunosuppressed. People who live or travel in areas dosum leprosum (ENL), or a type 2 reaction, with tender, red
where leprosy is more common are at higher risk of infection. bumps under the skin, high fever, multiple painful joints, and
Transmission to humans may also occur after touching or eat- painful swelling of lymph nodes and the spleen.
ing certain species of armadillos in the southern United States
or Central and South America. Permanent damage from leprosy occurs from repetitive, un-
noticed injuries, secondary to numbness from nerve involve-
Physical findings and symptoms of leprosy can appear 1 to ment. Chronic manifestations commonly include permanent
20 years after exposure to an untreated, infected person or an numbness, nonhealing ulcers, muscle weakness, broken bones,
infected armadillo. Shorter incubation periods are associated resorption of fingers and toes, and nasal disfigurement. Ulcers
with more intense exposure to M leprae, as in areas where the that occur on the surface of the eye may lead to blindness.
*Correspondence to elena.m.crecelius.mil@mail.mil
1 CPT Crecelius is a resident physician in pediatrics at Tripler Army Medical Center in Hawaii. She is a graduate of the Indiana University School
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of Medicine. COL Burnett is currently chief of pediatrics at Tripler Army Medical Center in Hawaii and is the pediatric subspecialties consultant
to the US Army surgeon general. He is board certified in pediatrics and pediatric infectious diseases and has served overseas in Korea, Germany,
Kosovo, Iraq, Afghanistan, and Kuwait and as the JSOTF-P surgeon in the Philippines. He is a graduate of the University of Wisconsin-Madison
and the Medical College of Wisconsin.
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