Leprosy in America May be Transmitted by Armadillos

Author: Health Resources and Services Administration (HRSA)
Published: 2011/04/28 - Updated: 2025/01/24
Publication Type: Research, Study, Analysis
Peer-Reviewed: Yes
Topic: Americas - Publications List

Page Content: Synopsis - Introduction - Main

Synopsis: Study on leprosy bacteria reports that armadillos may be a source of infection in the Southern United States.

Why it matters: This article presents findings from a study led by Dr. Richard W. Truman, published in the New England Journal of Medicine, which identifies armadillos as a potential source of leprosy infections in the southern United States. The research reveals that 64% of human samples and 85% of armadillo samples shared a unique genotype of Mycobacterium leprae, suggesting zoonotic transmission. While the risk of acquiring leprosy from armadillos remains extremely low, this insight enhances understanding of leprosy's transmission dynamics and underscores the importance of considering environmental reservoirs in disease monitoring and prevention efforts - Disabled World (DW).

Defining Leprosy (Hansen's Disease)

Leprosy (Hansen's Disease): Leprosy, also referred to as Hansen's disease (HD), stems from a persistent infection caused by the bacteria Mycobacterium leprae or Mycobacterium lepromatosis. Primarily affecting the skin and peripheral nerves, the condition can result in lasting disabilities if left untreated. Damage to nerves may lead to insensitivity to pain, increasing the risk of limb loss due to unnoticed injuries or infections. While once dreaded for its perceived high contagiousness, it's now understood that leprosy doesn't spread easily, and effective treatments are available. Transmission occurs through droplets from the nose and mouth, requiring prolonged, close contact over months with an untreated individual. However, casual interactions like handshakes, hugs, meal-sharing, or sitting together pose no risk of transmission. Globally, the prevalence of leprosy has dramatically declined from 5.2 million cases in the 1980s to fewer than 200,000 by 2020, thanks to the efficacy of multidrug therapy (MDT) in curing the disease.

Introduction

The collaboration between scientists at the Health Resources and Services Administration's (HRSA) National Hansen's Disease Program (NHDP) in Baton Rouge, La., the Ecole Polytechnique Federale de Lausanne and Institute Pasteur in Europe, and the Instituto de Biomedicina in Venezuela sheds light on the potential risk of transmission of leprosy bacteria between armadillos and humans. The risk of transmission is extremely low.

Main Item

The study, led by Richard W. Truman, Ph.D., Research Scientist at NHDP, and published in the April 28 issue of the New England Journal of Medicine, was partially supported by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health.

"Leprosy has been feared throughout human history, and there are still regions in several countries, including in the southern United States, where new cases of this disease continue to occur," said Dr. Truman. "The results of this study will help us better understand where some of these infections originate."

Caused by the bacterium Mycobacterium leprae, leprosy, also known as Hansen's disease, primarily affects the skin and peripheral nerves. It is a chronic infection that afflicts more than 2 million persons worldwide with nerve damage, deformity or disability. Today, leprosy is found mostly in tropical regions of the world; at least 250,000 new cases are reported globally every year, with 150-250 cases occurring in the United States. Leprosy is treatable with antibiotics but is easily misdiagnosed, and delays in therapy increase the likelihood of disability and deformity.

Leprosy was thought to be spread only between humans via respiratory droplets. Armadillos are the only other known natural hosts of leprosy bacteria. These data confirm a long-suspected link between armadillos and the 30 to 40 new cases of leprosy seen each year in U.S. born Americans who have never traveled abroad to regions where the disease is prevalent.

The new study, scientists compared the gene sequences of M. leprae samples taken from humans and armadillos in the United States. They found that 64% of the human samples had a particular genotype that had never been seen before, and 85% of samples from armadillos shared that same genotype.

"These findings do not change the risk of acquiring leprosy from armadillos, which remains extremely low," said Dr. James Krahenbuhl, director of NHDP. "Armadillos have been suspected as a source of human infection in the Gulf Coast area for 40 years."

"Genetics and genomics have become important tools for studying how diseases behave in natural settings," said Christine Sizemore, Ph.D., chief of the Tuberculosis and Other Mycobacterial Diseases Section at NIAID. "The data and methods used in this study can be applied in other areas of the world to monitor leprosy transmission and identify other possible environmental reservoirs."

NIAID conducts and supports research at NIH, throughout the United States, and worldwide to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses.

Related Information

Rare Leprosy Case in Ireland Highlights Need for Improved Guidelines and Awareness in Low-Incidence Regions: A rare case of leprosy in Ireland, highlights diagnostic challenges, the need for tailored public health guidelines, and strategies to reduce stigma in low-incidence regions.
Transmission of Leprosy Between Red Squirrels and Humans in Medieval England: Ancient Mycobacterium leprae genome reveals medieval English red squirrels as animal leprosy host.

Attribution/Source(s): This peer reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally authored by Health Resources and Services Administration (HRSA) and published on 2011/04/28, this content may have been edited for style, clarity, or brevity. For further details or clarifications, Health Resources and Services Administration (HRSA) can be contacted at hrsa.gov NOTE: Disabled World does not provide any warranties or endorsements related to this article.