Leprosy

Updated August 08, 2024

NCCID Disease Debriefs provide Canadian public health practitioners and clinicians with up-to-date reviews of essential information on prominent infectious diseases for Canadian public health practice. While not a formal literature review, information is gathered from key sources including the Public Health Agency of Canada (PHAC), the USA Centers for Disease Control and Prevention (CDC), the World Health Organization (WHO) and peer-reviewed literature.

This disease debrief was prepared by Danait Hailemariam. Questions, comments, and suggestions regarding this disease brief are most welcome and can be sent to nccid@manitoba.ca

What are Disease Debriefs? To find out more about how information is collected, see our page dedicated to the Disease Debriefs.

Questions Addressed in this debrief:

What are the important characteristics of leprosy?
What is the current risk for Canadians from leprosy?
What is the prevalence of leprosy in Canada?
What measures should be taken for a suspected leprosy case or contact?

What are the important characteristics of leprosy?

Cause

Leprosy, also known as Hansen’s disease, is caused by the bacterium Mycobacterium leprae. This chronic infection primarily targets the skin, peripheral nerves, mucosa of the upper respiratory tract, and ocular tissues, leading to disfiguring sores and nerve damage. Historically feared as highly contagious, leprosy is now recognized as difficult to transmit and easily treatable upon diagnosis. Despite medical advancements, stigma and discrimination against those affected persist in many parts of the world.

U.S. Centers for Disease Control and Prevention – About Hansen’s Disease (Leprosy)

World Health Organization- Leprosy

Public Health Ontario- Infectious Diseases Surveillance Reports

Chen, K. H., Lin, C. Y., Su, S. B., & Chen, K. T. (2022). Leprosy: A Review of Epidemiology, Clinical Diagnosis, and Management. Journal of tropical medicine, 2022, 8652062. https://doi.org/10.1155/2022/8652062

Signs and Symptoms:

Infection with Mycobacterium leprae primarily affects the skin, peripheral nerves, upper respiratory tract, and eyes. Early signs include skin lesions that are lighter or redder than the surrounding skin; these lesions often have reduced sensation or a burning feeling. Skin symptoms include discolored patches, nodules, thick or dry skin, painless ulcers on the feet, swelling or lumps on the face or earlobes, and loss of eyebrows or eyelashes.

If the disease progresses untreated, individuals may experience muscle weakness, numbness, enlarged nerves, and more severe skin damage. Nerve damage may lead to injuries like burns, leading to further complications. Advanced cases can lead to paralysis of hands and feet, shortening of toes and fingers, chronic ulcers, and disfigurement of the nose. Vision problems related to nerve damage and blindness can also occur. Mucous membrane symptoms include nasal congestion and nosebleeds.

U.S. Centers for Disease Control and Prevention – About Hansen’s Disease (Leprosy)

World Health Organization- Leprosy

Severity and Complications:

Untreated leprosy can lead to severe complications and long-term disabilities. Some potential complications associated with advanced leprosy include:

– Paralysis and crippling: Nerve damage can result in paralysis and crippling of the hands and feet, leading to difficulty in performing daily activities and potentially permanent disability.

– Deformities: The disease can weaken bones and soft tissues, causing shortening of toes and fingers due to reabsorption. Chronic non-healing ulcers on the soles of the feet can lead to further deformities and functional limitations. Characteristic facial features of advanced leprosy include loss of eyebrows and nose disfigurement.

– Blindness: Eye problems due to facial nerve involvement can progress to blindness.

– Painful nerves: Affected nerves can become painful or tender, leading to discomfort and reduced mobility. Redness, pain, and a burning sensation in the skin around the affected nerves are common.

– Chronic ulcers: Non-healing ulcers on the skin, particularly on the bottoms of the feet, can develop due to nerve damage and reduced sensation. These ulcers are prone to infection and can lead to further complications if not properly managed.

While treatment with multidrug therapy (MDT) can effectively cure leprosy and prevent disease progression, it cannot reverse existing nerve damage or physical deformities. Early diagnosis and prompt initiation of treatment are crucial to prevent severe complications and minimize long-term disability associated with leprosy. Regular monitoring and comprehensive care are essential in managing the disease and improving the quality of life for affected individuals.

U.S. Centers for Disease Control and Prevention – About Hansen’s Disease (Leprosy)

Pan American Health Organization- Leprosy

Bhandari, J., Awais, M., Robbins, B. A., & Gupta, V. (2024). Leprosy. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK559307/

Transmission:

Leprosy is primarily transmitted through respiratory droplets from untreated individuals. Close and frequent contact with an untreated person is typically necessary for transmission. Casual contact, such as shaking hands or sitting next to someone with leprosy, does not spread the disease. Around 95% of people have natural immunity to the bacterium and will not develop leprosy even if exposed. The bacterium can also be found in some animals, such as armadillos. The incubation period can range from 2 to 20 years or longer. The specific risk of contracting leprosy is not significantly higher for immunocompromised people compared to the general population due to the low contagion rate of the disease.

World Health Organization- Leprosy

Pan American Health Organization- Leprosy

Bhandari, J., Awais, M., Robbins, B. A., & Gupta, V. (2024). Leprosy. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK559307/

Epidemiology:

General

Leprosy continues to pose public health challenges globally. Each year, approximately 250,000 people worldwide are diagnosed with leprosy. India, Brazil, and Indonesia report the highest number of new cases annually. An average of 225 individuals in the United States are diagnosed each year. Canada has a very low incidence rate of leprosy, fewer than 12 cases annually, which are diagnosed primarily among immigrants or travelers from endemic regions. Numbers are not available for all provinces, but Ontario reported just 5 cases in 7 years (2017 – 2023), and Alberta reported 26 cases in 20 years (2000 – 2020).

U.S. Centers for Disease Control and Prevention – About Hansen’s Disease (Leprosy)

Public Health Ontario- Infectious Diseases Surveillance Reports

Alberta Government- Alberta Public Health Disease Management Guidelines, Leprosy

Clinical and Laboratory Diagnosis:

Early diagnosis is crucial to prevent complications and transmission. Diagnosis is primarily clinical, based on characteristic skin lesions and sensory loss, and confirmed by laboratory tests, including skin smears or biopsies showing acid-fast bacilli. Molecular tests, such as PCR, can also detect Mycobacterium leprae DNA. Based on the above, leprosy cases are categorized into two types for treatment: Paucibacillary (PB) and Multibacillary (MB).

Paucibacillary (PB) case: This type involves 1 to 5 skin lesions, with no bacilli detected in a skin smear.

Multibacillary (MB) case: This type involves more than five skin lesions, nerve involvement (either pure neuritis or any number of skin lesions combined with neuritis), or the presence of bacilli in a slit-skin smear, regardless of the number of skin lesions.

U.S. Centers for Disease Control and Prevention – About Hansen’s Disease (Leprosy)

World Health Organization- Leprosy

Public Health Agency of Canada- Leprosy

Prevention and Control:

Effective prevention and control of leprosy require a multifaceted approach. While case detection and treatment with multidrug therapy (MDT) are fundamental, additional measures are necessary to enhance prevention. The World Health Organization (WHO) recommends a comprehensive strategy that includes active case finding and thorough contact tracing within affected communities. This involves identifying individuals at high risk of developing leprosy, such as household, neighborhood, and social contacts of known cases. Since Leprosy is a notifiable disease in Canada, all confirmed and probable cases should be reported to the Medical Officer of Health (MOH) (or designate) of the zone by mail, fax, or electronic transfer within 48 hours (two business days). Preventive chemotherapy, typically a single dose of rifampicin, should be administered to close contacts of the index case.

World Health Organization- Leprosy

Alberta Health- Alberta Public Health Disease Management Guidelines, Leprosy

Public Health Agency of Canada- Leprosy

Vaccination:

Currently, Canada does not have an approved vaccine for leprosy, and there is no globally recognized vaccine. The Bacillus Calmette-Guérin (BCG) vaccine, primarily used for tuberculosis (TB) prevention, provides some level of protection against leprosy. However, the BCG vaccine is not routinely administered in Canada except in certain high-risk populations or specific regions with higher rates of TB.

World Health Organization- Guidelines for the diagnosis, treatment, and prevention of leprosy

World Health Organization- Leprosy/Hansen disease: Contact tracing and post-exposure prophylaxi

Treatment:

Leprosy is treatable with multidrug therapy (MDT), which includes dapsone, rifampicin, and clofazimine. The treatment duration is typically 6 months for paucibacillary and 12 months or more for multibacillary leprosy. Early treatment prevents disease progression and complications, and patients quickly become non-infectious.

World Health Organization- Leprosy

U.S. Centers for Disease Control and Prevention – About Hansen’s Disease (Leprosy)

Public Health Ontario- Infectious Diseases Surveillance Reports

What is happening with current outbreaks?

Globally, the incidence of leprosy has significantly decreased due to the widespread use of MDT. However, it persists in some regions, particularly in developing countries. Recent data and reports indicate:

– Global: India, Brazil, and Indonesia report the highest number of new cases annually, with over 10,000 new cases annually.

– United States: The number of leprosy cases remains very low, with about 225 new cases reported each year, primarily among immigrants or individuals who have traveled to endemic areas.

– Canada: Leprosy is extremely rare, with fewer than 12 cases reported annually, primarily among immigrants or travelers from endemic regions.

Office for Science and Society- Leprosy and Its Stigma Are Both Curable

World Health Organization- Global leprosy (Hansen disease) update, 2022: New paradigm – control to elimination

U.S. Centers for Disease Control and Prevention – About Hansen’s Disease (Leprosy)

What is the current risk for Canadians?

The risk of leprosy for Canadians remains very low. The risk can be minimized by avoiding prolonged close contact with untreated individuals, ensuring prompt treatment, maintaining good hygiene, and following recommended health guidelines.

What measures should be taken for a suspected case or contact?

For a suspected case of leprosy, a clinical evaluation and dermatological examination are conducted, followed by diagnostic tests such as skin smears and biopsies. The patient is then referred to a specialist and initiated on WHO-recommended multidrug therapy (MDT), with regular monitoring for treatment response and complications. Contacts of leprosy patients are identified and screened periodically, with consideration given to BCG vaccination and single-dose rifampicin as preventive measures, along with providing education and psychosocial support. Public health measures include reporting cases, raising community awareness, and adhering to infection control protocols in healthcare settings.

All new leprosy index cases are identified and recorded to guide subsequent activities. These index cases receive counseling about the disease, its curability, and the importance of contact screening, with consent sought to disclose their status to facilitate the tracing of family and close contacts. Contacts include household members, neighbors, and social contacts who have had significant exposure to an untreated index case.

Government of Canada – National case definition: Leprosy

The Lancet- Leprosy

World Health Organization- Leprosy/Hansen disease: Contact tracing and post-exposure prophylaxis

Alberta Government- Alberta Public Health Disease Management Guidelines, Leprosy