Hansen's Disease

(Leprosy)
Beatrice Sarpong
Background

▪ An Ancient disease that was widely feared

throughout hist history

▪ Scientists first believed it was hereditary

▪ Gerhard Henrik Amauer Hansen a Norwegian

physician , disproved this by discovering the
specific bacterium associated with the Disease.

▪ Leprosy is a bacterial disease that attacks the

peripheral nervous system (PNS).
– PNS: made up of nerves, composed of bundles
of axons that carry information to and from
the central nervous system ( brain and spinal
cord)

▪ The illness was highlighted stigmatized and those

infected risked having their homes burned down
and being separated from their families.
Figure 1: Gerhard Henrik Amauer Hansen. Adapted
from "Science Photo Library"
Causative Agent and Structure

▪ Two bacterium cause Hansen's Disease: Mycobacterium leprae

and Mycobacterium lepromatosis.
▪ Both bacterium are aerobic, rod-shaped, acid-fast bacteria
▪ Size: ~1-8 µm in length and 0.2-0.5 µm in diameter
▪ Cell Wall: Thick, waxy, and lipid-rich, containing:
– Mycolic acids (making them acid-fast, resistant to Gram staining)
– Peptidoglycan layer (provides structural support)
– Arabinogalactan (links mycolic acids to peptidoglycan)
– Phenolic glycolipids (PGL-1) (important for immune evasion) Figure 2: Mycobacterium leprae in a
Biopsy Specimen. Adapted from Nester's Biology: A Human
– Capsule: Some strains may have a capsule-like outer layer Perspective Anderson, D. G., Salm, S. N., Allen, D. P.
– Intracellular Nature: They primarily infect Schwann cells (nerves) and
macrophages
▪ They both have a 12-13 days generation time = growth rate is very
slow
▪ Prefer cooler temperatures of the body's extremities.
Diseases caused by Mycobacterium leprae
and Mycobacterium lepromatosis

Mycobacterium leprae Mycobacterium lepromatosis

▪ Smaller genome (~3.27 Mb) ▪ Larger genome (~3.9 Mb)

▪ Smaller gen (~3.27 Mb)

▪ Primarily associated with diffuse lepromatous leprosy (DLL)

▪ Causes tuberculoid leprosy.

▪ Occurs when the immune system fails to control the disease
▪ Few skin lesions (dry and numb) consisting of hypopigmented or erythematous macules with
raised erythematous borders and an atrophic center.
▪ Lads to extensive skin involvement and rapid peripheral nerve damage
– Asymmetrical distribution.
– Commonly found on the face, trunk, or extremities. Absent in warm areas (axillae, groin,
perineum, scalp) due to M. leprae’s preference for lower temperatures. ▪ Unnoticed injuries due to massive loss of nerve damage

▪ Most stable form of leprosy that does not progress to borderline or lepromatous leprosy. ▪ Secondary infections cause ulcerations, tissue loss, and malformation of digits
(gingers and toes)
▪ Nerve-related symptoms include:
– Enlarged or tender peripheral nerves (e.g., ulnar, superficial peroneal, greater auricular ▪ The affected digits are absorbed back into the body
nerves).
– Hypoesthesia or anesthesia of the affected skin. Possible muscle atrophy and contractures
due to nerve damage. Affects both humans and armadillos.
▪ More severe cases: thickening of the ears and nose

▪ Humans and armadillos

▪ Nose cartilage collapses

▪ Nasal congestion and bleeding

▪ Deep facial skin wrinkling.

Figure 4: Image of M. Lepromatosis Adapted from Severe Leprosy

Figure 3: Image of M. Leprae. Adapted from Britannica.com Reactions Article.
Signs and Symptoms

▪ Early signs and symptoms:

– Numbness and tingling in hands and feet
– Skin lesions
– Changes skin pigmentation and decreased
sensation

▪ Late signs and symptoms:

– Extensive skin involvement
– Peripheral nerve damage; loss of nerve activity
– Secondar infections: ulceration, and tissue
– Loss malformation of fingers and toes
– Thickening of the nose and ears
– Deep wrinkling of the facial skin
– Saddle nose: nose cartilage collapse
▪ Leads to nasal congestion and bleeding

Figure 5: Image of the effects of Leprosy on the human body.

Adapted from Pathogenesis, clinical manifestations, and
treatment of leprosy
Pathogenesis and Virulence

▪ Pathogenesis: the process by which a disease develops, from the initial infection to the final outcome.

▪ M. leprae and M. lepromatosis are preferentially infect cells of the peripheral nervous system.

▪ Tuberculoid leprosy is cell-mediated immunity develops against invading bacteria and then activated macrophages limit their
spread
– Chronically infected cells, however are progressively damaged by attacking immune cells
– The disease then stops progressing
– Nerves damage does not worsen but is permanent
– Tuberculoid leprosy is rarely transmissible to others

▪ Lepromatous leprosy occurs when cell-mediated immunity to the pathogen fails to develop or is suppressed.
– Unrestricted cell growth occurs
– Bacteria first multiply in skin macrophages and cells of the PNS, then later spread to the rest of the body

– Virulence:
▪ Mucus of the nose and throat contain high numbers of the bacterium
▪ Hugh numbers of the pathogen in the mucus of the nose and that which make it easily transmitted to others.
▪ Tissue damage leads to disabling deformities, resorption or cartilage and bone and skin ulcerations

▪ Hansen’s disease is driven by M. leprae and M. lepromatosis's ability to survive intracellularly, evade immune responses, and
preferentially infect nerves, leading to chronic infections with progressive nerve damage and disfigurement if untreated.
Virulence Factors:

Virulence Facotrs: Function

Phenolic Glycolipid-1 (PGL-1) Aids in bacterial entry into Schwann cells and
suppresses the immune response.
Lipoarabinomannan (LAM) Inhibits macrophage activation and prevents
bacterial destruction.

Slow Growth Rate Evades immune detection by dividing very

slowly.

Intracellular Survival in Macrophages Resists degradation inside immune cells.

Schwann Cell Tropism Causes nerve damage, leading to anesthesia

and deformities.
Epidemiology

▪ Transmission: person to person via contact with nasal secretions

▪ Most immune systems can control the disease by immune defenses and only a small percentage
are exposed
▪ M. leprae can also occur in wild armadillos and human contact can cause the illness to spread
from armadillo to human.
– Leads to incidences of the disease being present even when individuals did not travel to areas of the world where
the disease is prevalent

▪ Currently less than 1 case per 10,000 individuals in most countries.

▪ World Health Organization (WHO) with the "Global Leprosy Strategy 2021-2030
– Aims at interrupting transmission via active detection and prompt treatment of new cases.
– Expanding the management of leprosy to include the mental well-being of the patient.

▪ Global Prevalence:
– Remains an endemic in several countries especially in India, Brazil, Indonesia. With few cases
reported in countries in Asia, Africa and the Americas
 Diagnosis

▪ Diagnosis involves clinical evaluation, laboratory tests, and historical considerations

▪ Diagnosis is based on recognition of characteristic symptoms
▪ Clinical evaluations:
– Skin lesions: hypopigmented, raised, or numb
▪ Well-defined lesions and can appear on face, arms, and legs
– Nerve damage: weakness, and loss of motor function can occur in peripheral nerves
– Thickened nerves: visibly enlarged peripheral nerves, especially, around the elbows, wrists and knees

▪ Laboratory Diagnosis:
– Laboratory tests can confirm and classify the diagnosis and classify the disease more accurately
– Skin smear is often taken from skin lesions to examine to the presence of M. leprae
– Ziehl-Neelsen staining detects acid-fast bacilli (AFB).
▪ They appear as red rods
– Skin Biopsy: when smears are negative, but suspicion of leprosy remains high, skin biopsies are taken
▪ Positive findings: granulomas or nerves surrounded by inflammation
– Nerve Biopsy: don’ to assess nerve involvement in leprosy, especially when thickened nerves not clearly palpable
– Polymerase Chain Reaction (PCR):
▪ Sensitive molecular test can detect the DNA of the mycobacterium in skin lesions, blood\
▪ PCR testing is useful method there is a negative smear test
Diagnosis (part 2)

▪ Serological Tests: antibody-based tests have been developed in research settings.

– Phenolic glycolipid (PGL-1): a molecule found on M. leprae
▪ The presence pf these antibodies suggest exposure to the bacteria
▪ Not a definitive diagnostic tool for leprosy
– PCR-based serological tests: detect genetic markers or specific antigens are
▪ Available for research purposes
▪ Not routine in clinical diagnosis

▪ Differential Diagnosis
– Used to rule out other illnesses that present with skin lesion or peripheral neuropathy similar
to leprosy
▪ Examples of other conditions: tuberculosis, chronic dermatitis, syphilis, and sarcoidosis

▪ Immunological testing
– Lepromin test: skin test that assesses a patient's immune response
▪ Positive result: indicates a more tuberculoid form of leprosy
▪ Not used in routine clinical practice because it is very sensitive
Treatment, Control, and Prevention

▪ No vaccines are currently available to control the disease

▪ The World Health Organization (WHO) recommends: a multidrug therapy (MDT) regime for treating leprosy.

▪ The goal of treatment is to cure disease, prevent disability, and reduce transmission

▪ Treatment for tuberculoid Leprosy: a combination of anti-biotics dapsone and rifampin in 12 months

▪ Treatment for Lepromatous Leprosy: anti-biotic combination therapy with dapsone, rifampin, and clofazimine
for 2 years.

▪ Prophylactic treatment with an anti-mycobacterial agent is recommended for close contact with patients

▪ Preventive measures includes:

– Early detection, effective treatment, and regular monitoring are crucial
– Providing education to reduce stigma and ensure those infected receive support and care.
– Regular screening and the use of preventative antibiotics can reduce transmission
– Contact tracing and chemoprophylaxis for those at high risk
Competing Perspectives on the Treatment,
Control, and Prevention of Hansen's Disease

▪ Multidrug Therapy (MDT) vs. Alternative Therapies

– In Favor of MDT: WHO supports MDT as the standard treatment, proven to cure
leprosy and reduce transmission.
– Rival Position (Alternative Therapies): Some proponents suggest herbal or
alternative remedies alongside MDT, despite limited scientific evidence.

▪ Stigma Reduction through Integration vs. Separation of Leprosy

Patients
– In Favor of Integration: Advocates emphasize reducing stigma by integrating
patients into society to improve mental health and long-term outcomes.
– Rival Position (Separation): Some experts argue for isolation to prevent
transmission, especially in high-endemic areas.
Competing Perspectives on the Treatment, Control,
and Prevention of Hansen's Disease (Pt. 2)

▪ Mass Chemoprophylaxis vs. Targeted Chemoprophylaxis

– In Favor of Mass Chemoprophylaxis: The WHO and a lot of supporters suggest giving
preventive antibiotics to entire populations or high-risk groups to control transmission.
– Rival Position (Targeted Chemoprophylaxis): Others argue for targeting only high-risk
groups to ensure cost-effectiveness and reduce side effects.
▪ Focus on Early Detection vs. Focus on Social Determinants of Health
– In Favor of Early Detection: Early diagnosis and intervention are crucial to prevent disability
and reduce transmission.
– Rival Position (Social Determinants of Health): Advocates argue that addressing the root
causes of health inequality, like poverty and poor access to healthcare, is key to controlling
leprosy.
▪ Government-Led vs. Community-Led Initiatives
– In Favor of Government-Led Control: Proponents of government-led initiatives argue that
top-down approaches ensure resources and large-scale organization.
– Rival Position (Community-Led Control): Supporters of community-led initiatives believe
local involvement ensures better cultural sensitivity and treatment acceptance.
 Hansen's Disease in the News

▪ WHO Announcement: Vital leprosy drugs are expected to arrive in Nigeria after a
year-long delay.

▪ Cause of Delay: The delay was due to new regulations introduced by Nigeria’s drug
authority, which held up the drugs.

▪ Impact: Nigeria reports over 2,000 new cases of leprosy annually. Patients have been
sent home from hospitals without treatment.
▪ Transmission Risk: Lack of drugs increases the risk of leprosy spreading, as the
medication suppresses transmission.

▪ Expert Opinion: Dr. Samimu Msheliza, a public health expert, emphasized the urgent
need for the medication to prevent further transmission and suffering.

▪ Patient Impact: A woman in Nasarawa state described worsening symptoms due to

the lack of treatment, with irreversible nerve damage.

▪ Regulatory Issue: Nigeria’s drug authority introduced new measures to combat

counterfeit drugs, but these delayed the arrival of necessary treatments. Figure 6: Image of Leprosy patient seeking treatment in Nigeria.
Adapted from
▪ WHO Request: The WHO has asked Nigeria to temporarily lift the new testing policy
to allow the drugs to arrive from India.

▪ Leprosy Treatment: Leprosy is curable with antibiotics, but untreated cases lead to
sores, nerve damage, and deformities.
Christian Worldview Leviticus 13-14 Luke
17:12-19
▪ Matthew 25:35-40 (NIV): "For I was hungry and you gave me something to eat, I was thirsty and you gave me something
to drink, I was a stranger and you invited me in, I needed clothes and you clothed me, I was sick and you looked after me, I
was in prison and you came to visit me."

▪ "Then the righteous will answer him, 'Lord, when did we see you hungry and feed you, or thirsty and give you something to
drink? When did we see you a stranger and invite you in, or needing clothes and clothe you? When did we see you sick or in
prison and go to visit you?' "The King will reply, 'Truly I tell you, whatever you did for one of the least of these brothers and
sisters of mine, you did for me.'"
– The Bible does not specifically address microbes or germs, as modern scientific knowledge did not exist at the
time, but it consistently encourages believers to care for the body and health as part of honoring God’s creation.

▪ Leprosy, in biblical times, was considered not only a physical affliction but also a social and spiritual challenge. In
Leviticus 13, the disease was heavily associated with impurity, and individuals with leprosy were often isolated.
However, the New Testament reveals Jesus' compassion toward lepers, showing that the disease was not to be viewed
as a moral failure but as an opportunity to demonstrate Christ-like mercy.

▪ Mark 1:40-42 (NIV): "A man with leprosy came to him and begged him on his knees, 'If you are willing, you can make me
clean.' Jesus was indignant. He reached out his hand and touched the man. 'I am willing,' he said. 'Be clean!' Immediately
the leprosy left him and he was cleansed."

– This passage highlights Jesus' willingness to care for and heal the suffering, showing that even individuals
suffering from diseases caused by microbes are worthy of love, care, and healing. Figure 7. Jesus heals the leper. Adapted from
"Lessons of a Leper" by J. Augus
▪ The Christian worldview calls for treating those affected by diseases like Hansen's disease with compassion, dignity,
and mercy. While microbes, such as the bacteria that cause leprosy, can be harmful, they are part of a fallen world, and
Christians are called to serve those who suffer due to such illnesses. The example of Jesus healing lepers teaches
believers to offer practical help, show kindness, and reflect God's love to the suffering, regardless of the physical or
social stigma associated with the disease.
Works Cited

▪ Bhat, J. R., & Babu, R. P. (2 017). Community-based a pproaches for leprosy control: The role of local engagement and education. Leprosy Review, 88(1), 32-42. https: //doi. org/10.4727

▪ Ernst, J. D. (2 012 ). Leprosy (Hansen's Disease). In L. Goldman & A. I. Schafer (Eds.), *Goldman's Cecil Medicine* (24th ed., pp. 1950-1954). W.B. Saunders. https: //doi. org/10.1016 /B9 78-1-4377-1604-7.00334-1

▪ Fenner, F., & Brown, D. W. (2019). Chemoprophyla xis and leprosy: A public health approa ch to reducing transmission. Journ al of In fectious Diseases, 16(4 ), 285-290 . https: //doi. org/10.1093/jid/jiz0 02

▪ Han, X. Y., Sizer, K. C., & Tan, H. H. (200 8). Mycobacterium lepromatosis sp. nov., a newly identified cause of leprosy. International Journal of Systematic and Evolutionary Microbiology, 58(11), 2466-2470. https: //doi. org/10.1099/ijs.0 .65824-0

▪ Kumar, A., & Garg, R. (202 0). Targeted che moprophy laxis for leprosy: A cost-effectiveness a nalysis. Leprosy Review, 91(3), 302-310 . https: //doi. org/10.47276/lr.91.3.302

▪ Lobo, L. D. , & Alves, M. S. (2017). Social stigma and integration of individuals with Hansen’s disease in Brazil. Social Science & Medicine, 189, 174-182. https: //doi. org/10.1016/j.socscimed. 2017.07.037

▪ Matsuoka, M., & Hayashi, K. (2016). Alte rnative the ra pies in leprosy : The cha llenge of integrating traditional medicine with conventional tre atment . Leprosy Review, 87(2 ), 10 0-108. https: //doi. org/10.47276/lr.87.2.100

▪ Martinez, R. A., & Garcia, M. F. (2019). Government-led strategies for controlling le prosy: A review of national programs. Leprosy Review, 90(2 ), 112-120. https: //doi. org/10.47276/lr.90 .2.112

▪ Parkinson, J. L., & Wilson, R. S. (2018). Isolate or integrate? Ethical perspectives on the management of leprosy in the 21st century. Leprosy Review, 89(1), 45-54. https: //doi. org/10.47276/lr.89.1. 45

▪ Ross, W., & Okafor, M. (2025, March 7). Vital leprosy drugs due in Nigeria after y ear delay. BBC News. https: //www.bbc.com/news/articles/cm2 nz3ejk72o#

▪ Scollard, D. M., Adams, L. B., Gillis, T. P., Krahe nbuhl, J. L., Truman, R. W., & Williams, D. L. (2006). The continu ing challenges of leprosy. Clinical Microbiology Reviews, 19(2), 338-381. https: //doi. org/10.1128 /CMR.19.2.338-381.2006

▪ Smith, J. D., & Thompson, L. M. (2019). Diagnostic methods for leprosy in the 21s t century. Journ al of T ropical Medicine and Hygien e, 103(4), 245-250. https: //doi. org/10.1016/j.jtmh.2019.03.00 4

▪ Stein, G. A., & Mathew, S. A. (2018). Social determinants of health in leprosy : The role of poverty and he althcare access. International Journal of Public Health, 63(6), 747-753. https: //doi. org/10.1007/s00038-018-114 2-9

▪ World Health Organization. (2 020). Globa l leprosy stra tegy 2021–2030: Accelerating towards a leprosy-free world. https: //www.who. int/publications/i/item/97892 400684 44

▪ World Health Organization. (2 019). Le prosy. https: //www.who. int/news-room/fact-sheets/detail/leprosy

Works cited: Images

▪ Figure 1: Science Photo Library. (n.d.). Gerhard Hansen [Photograph]. Science Photo
Gallery. https://sciencephotogallery.com/featured/gerhard-hansen-national-library-of-medicine.html

▪ Figure 2: Anderson, D. G., Salm, S. N., & Allen, D. P. (2024). Chapter 27: Nester's microbiology: A human
perspective with Connect (2024 Release). McGraw-Hill. ISBN-13: 9781266296727.

▪ Figure 3: Encyclopaedia Britannica. (n.d.). Mycobacterium leprae. Encyclopaedia

Britannica. https://www.britannica.com/science/Mycobacterium-leprae

▪ Figure 4: Han, X. Y., & Jessurun, J. (2013). Severe leprosy reactions due to Mycobacterium lepromatosis. The
American Journal of the Medical Sciences, 345(1), 65-69. https://doi.org/10.1097/MAJ.0b013e31826af5fb

▪ Figure 5: Mennuru, N. B., Birudala, R., & Birudala, G. (2023). Pathogenesis, clinical manifestations, and
treatment of leprosy. In D. Bagchi, A. Das, & B. W. Downs (Eds.), Viral, parasitic, bacterial, and fungal
infections (pp. 609-615). Academic Press. https://doi.org/10.1016/B978-0-323-85730-7.00042-4

▪ Figure 6: BBC News. (2025, March 8). Title of article. BBC

News. https://www.bbc.com/news/articles/cm2nz3ejk72o

▪ Figure 7: Agus, J. (2024, February 10). Lessons of a leper. JJ's

Outlook. https://jjsoutlook.com/2024/02/10/lessons-of-a-leper/