Introduction : 

A chronic infection caused by the acid-fast, rod-shaped Mycobacterium leprae bacillus is leprosy. Leprosy is also known as Hansen’s disease. Two related diseases that mainly affect superficial tissues, especially the skin and peripheral nerves, maybe leprosy. A mycobacterial infection initially triggers a broad array of cellular immune responses. The second component of the condition, peripheral neuropathy with possible long-term effects, is then elicited by these immunologic events.

As a highly infectious and debilitating disease, leprosy was once feared, but nowadays, it does not spread quickly, and treatment is very successful. However, nerve damage can result in hands and feet being crippled, paralysis, and blindness if left untreated.

Classification of Leprosy :

The number and sort of skin sores have determined leprosy. The type of leprosy depends on specific symptoms and treatment. The forms are: 

Tuberculoid:  A moderate type of leprosy, which is less severe. People with this type only have one or a few patches (paucibacillary leprosy) of flat, pale-colored skin. Owing to nerve damage underneath, the affected region of the skin can feel numb. It is less infectious to tuberculoid leprosy than other types. 

Lepromatous:  Come on. A more extreme form of the disorder. It brings widespread skin bumps and rashes, numbness, and muscle weakness (multibacillary leprosy). It can also impact the nose, kidneys, and male reproductive organs. It is more infectious than leprosy caused by tuberculosis. 

Borderline: The tuberculoid and lepromatous symptoms are present for people with borderline leprosy. 

You can hear physicians use this simplified classification as well: 

Paucibacillary – single lesion (SLPB): One lesion 

Paucibacillary (PB): lesions from two to five 

Multibacillary (MB): Six lesions or more

Incubation period :

The incubation period is called the interval between contact with the bacteria and the appearance of symptoms. Symptoms typically take about 3 to 5 years to appear after coming into contact with the leprosy-causing bacteria. Up to 20 years later, some individuals do not show symptoms. The long incubation period of leprosy makes it very hard for doctors to determine when and where a person with leprosy has been infected.

Pathophysiology :

Depending on the host’s reaction to the organism, leprosy can manifest in various ways. 

1. The tuberculoid type of the disease that usually affects the skin and peripheral nerves are present in individuals who have a robust cellular immune response to M leprae. 

2. They tend to be dry and hypoesthetic, and the number of skin lesions is small. 

3. Typically, nerve activity is asymmetric. Owing to the low number of bacteria in the skin lesions, i.e., < 5 skin lesions, with no organisms on the smear, this type of the disease is often referred to as paucibacillary leprosy. 

4. In these people, the findings of skin tests with antigens from killed species are positive.

5. The lepromatous type of the disease, characterized by extensive skin involvement, is for individuals with limited cellular immune response. 

6. Infiltrated nodules and plaques are often identified as skin lesions, and nerve involvement appears to be symmetric in distribution. 

7. The organism grows best at 27-30 ° C; therefore, skin lesions tend to develop in the body’s colder areas, with sparing of the groin, axilla, and scalp. 

8. Owing to no small number of bacteria present in the lesions, i.e.,> 6 lesions, with potential bacilli visualization on the smear, this type of disease is often referred to as multibacillary leprosy. 

9. Skin test results for antigens from killed species are non-reactive.

Patients can also have symptoms of both types (indeterminate or borderline leprosy) but typically evolve to one or the other over time. Interestingly, most people exposed to leprosy never contract the disease, possibly because more than 95 percent of individuals are naturally immune to this disease.

Epidemiology :

In 2018, 208,619 new leprosy cases were reported globally, according to WHO estimates based on data from 159 countries. The worldwide prevalence was 184,212 cases (rate, 0.2/10,000) reported at the end of 2018. In 2018, 79.6 percent of all new leprosy cases were in Brazil, Indonesia, and India. Furthermore, in 2018, 23 priority countries accounted for 96 percent of cases globally.

a. Mortality/Morbidity :

Leprosy is never lethal. The nerve damage and crippling sequelae are the main consequences of infection. 33-56 percent of newly diagnosed patients have already demonstrated symptoms of compromised nerve function[11], according to one report. According to reports, three million individuals who have undergone multidrug treatment for leprosy have suffered impairment due to nerve damage. While the skin and peripheral nerves are involved in both lepromatous leprosy and tuberculoid leprosy, tuberculoid leprosy has more severe manifestations. Nerve involvement contributes to sensory and motor loss of control, leading to repeated trauma and amputation. Most generally, the ulnar nerve is involved. 

Damage to the following nerves is related to characteristic leprosy impairment: 

i. Ulnar and Median-Hand Clawed 

ii. Tibial posterior-Plantar insensitivity and clawed toes 

iii. Peroneal Common-Foot Drop 

iv. Radial nerves of the cutaneous, nasal, and greater auricular

b. Race : 

Leprosy was once globally endemic, although no predilection for the race is recognized. The incidence of leprosy fell significantly in northern Europe and North America in the late 1800s, and the disease is now recorded mainly in tropical areas. 

c. Gender :

In males, leprosy is typically more common than in females, with a 2:1 male-to-female ratio. The prevalence of leprosy among females is equal to or greater than that of males in some areas of Africa. 

d. Age :

Leprosy can occur at any age, but the age-specific occurrence of leprosy in developed countries peaks in children younger than ten years, accounting for 20 percent of leprosy cases. In infants, leprosy is very rare; however, they are at relatively high risk of maternal leprosy, particularly in cases of lepromatous leprosy or mid borderline leprosy.

e. HIV Coinfection :

Preliminary data suggest that, unlike tuberculosis, HIV coinfection does not appear to affect leprosy. Besides, coinfection with HIV does not seem to affect the lepromatous to tuberculoid leprosy ratio.

Symptoms of Leprosy 

Leprosy mostly affects the skin and nerves, called the peripheral nerves, beyond the brain and spinal cord. 

Disfiguring skin sores, bumps, or lumps that do not go down for several weeks or months is leprosy’s principal symptom. The sores on the skin are pale-colored. Nerve damage leads to loss of sensation in legs and arms, weakness of muscles.

Causes :

Exactly how leprosy is transmitted is not clear. When an individual coughs or sneezes with leprosy, they can spread droplets containing M. The leprosy bacteria that someone else breathes in. For leprosy to be transmitted, near physical contact with an infected individual is required. Shaking hands, kissing, or sitting beside them during a meal on a bus or at a table, do not transmit the disease.

Pregnant leprosy mothers are unable to pass it on to their newborn babies. Neither is it spread through sexual touch.

Risk Factors :

Leprosy can permanently damage skin, nerves, arms, legs, feet, and eyes without care. 

Leprosy complications may include: 

Glaucoma or blindness 


Loss of hair 

For infertility 

Facial disfigurement (including permanent swelling, bumps, and lumps) 

Erectile dysfunction in males and infertility 

Failure of the kidney 

Weakness in the muscles contributing to claw-like hands or not being able to stretch feet 

The inside of the nose is permanently damaged, which can lead to nosebleeds and a chronic stuffy nose 

Permanent nerve damage, including those in the arms, legs, and feet, outside the brain and spinal cord 

Damage to the nerves can lead to a dangerous loss of feeling. Do not experience pain when one gets cuts, burns, or other injuries to hands, legs, or feet if they have leprosy-related nerve damage.

Diagnosis :

It is possible to distinguish Hansen’s disease by the presence of skin patches that may look lighter or darker than normal skin. The skin areas affected can often be reddish. The lack of sensation is prominent in these skin patches. For a needle, one cannot feel a light brush or a prick. 

The physician will take a sample of skin or nerve (through skin or nerve biopsy) and check for bacteria under the microscope and confirm your diagnosis, and may even conduct tests to rule out any skin diseases.

Treatment :

It is possible to treat leprosy. 16 million people with leprosy have been healed in the last 2 decades. The World Health Organization provides free care for all people with leprosy. 

Therapy relies on the type of leprosy they have. For treatment, antibiotics are used. Doctors recommend treatment on a long-term basis, usually for 6 months to a year. You may need to take antibiotics longer if you are suffering from severe leprosy. The nerve damage that comes with leprosy cannot be treated with antibiotics. 

A standard treatment for leprosy that combines antibiotics is multidrug therapy (MDT). That means you are going to take two or more drugs, mostly antibiotics: 

Paucibacillary leprosy: Two antibiotics, such as dapsone, are used every day, and rifampicin is used once a month. 

Multibacillary leprosy: In addition to daily dapsone and monthly rifampicin, you can take a daily dose of the antibiotic clofazimine. For 1-2 years, you will undergo multidrug treatment, and then you will be healed.

Antibiotics: The bacteria causing leprosy can be destroyed by antibiotics used during treatment. However, though medication may cure the condition and keep it from getting worse, nerve damage or physical disfigurement may have existed before a diagnosis is not reversed. Thus, before any irreversible nerve damage occurs, the condition must be detected as soon as possible.

Transmission : 

The exact way Hansen’s disease spreads between people is not understood. Scientists claim that it can happen if a person with Hansen’s disease coughs or sneezes, and a healthy person breathes in the droplets that contain the bacteria. Prolonged close contact is required with someone with untreated leprosy for several months. 

You do not get leprosy from casual contact with a person who has Hansen’s disease, such as: shaking or hugging palms, sitting for a meal together, sitting on the bus next to each other. 

During pregnancy, Hansen’s disease is also not transmitted from a mother to her unborn baby, and it does not spread by sexual contact. It is often challenging to locate the infection source due to the bacteria’s slow-growing nature and the long time to cause symptoms of the disease.

For general health purposes, if possible, avoid contact with armadillos. Speak to your physician if you have come into touch with an armadillo and are anxious about having Hansen’s disease. Over time, the doctor will follow up with you and conduct annual skin tests to see if the disease progresses. 

Prevention : 

In high-risk areas, awareness campaigns on leprosy are essential to enable patients and their families, who have been traditionally shunned from their communities, to come forward and receive care. 

Early diagnosis and multidrug therapy treatment is the most effective way to avoid leprosy disabilities and avoid further disease spread. However, the Bacille Calmette-Guérin ( BCG) vaccine is partially protective against leprosy.

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