What is Leprosy?

Leprosy, also called Hansen’s disease, is a chronic infectious disease caused by the slow-growing bacteria Mycobacterium leprae. It primarily affects the skin, peripheral nerves, eyes, and mucosal surfaces of the upper respiratory tract. Leprosy is broadly categorized into paucibacillary (tuberculoid) and multibacillary (lepromatous) forms, each with distinct clinical presentations and implications. Leprosy symptoms include skin lesions, nerve damage, and muscle weakness. Multi-antibiotic therapy, including drugs like rifampicin and dapsone, is effective in treating leprosy, particularly when diagnosed and treated early.

What is Leprosy Disease?

Definition of Leprosy: Leprosy, also known as Hansen’s disease, is a chronic infectious disease caused by the bacterium Mycobacterium leprae, primarily affecting the skin and peripheral nerves, leading to skin lesions and nerve damage.

Leprosy is characterized by long-term infection with various symptoms like skin lesions, nerve damage, muscle weakness, and numbness and has a long incubation period of 5 to 7 years. If left untreated, it can cause progressive and permanent disabilities. Multi-drug therapy is the standard treatment for leprosy.

Although the disease is rare it still exists and according to WHO about 208,000 people are affected with the disease and most of the cases are found in Africa and Asia. Children are more vulnerable to infection compared to adults.

What Causes Leprosy?

Leprosy is caused by Mycobacterium leprae which was discovered by Gerhard Armauer Hansen in Norway in 1873 as the first bacterium for causing the disease. The disease gets transmitted from the infected person through their respiratory droplets and hence it is an airborne disease. Most people have natural immunity against the bacteria and only 5% are vulnerable to the disease.

Mycobacterium leprae

Mycobacterium leprae is a slow-growing gram-positive rod-shaped bacteria that causes Hensen’s disease by affecting the peripheral system. It has a narrow host range, apart from humans it also affects red squirrels and armadillos.

The bacterium is acid-fast as it has a thick, waxy cell wall that is resistant to certain environmental and chemical stress. One of the main characteristics of the bacteria is that its replication is prolonged and its doubling time is approximately about 14 days. The M. leprae bacteria is an obligate intracellular pathogen that can survive and multiply only inside the cell of the host. The bacterium primarily affects the Schwan cells that are responsible for immune response and nerve function.

How is Leprosy Transmitted?

The primary mode of transmission of leprosy is believed to be through respiratory droplets when an infected person with untreated leprosy coughs or sneezes. However, leprosy is considered to have low contagiousness, and not everyone exposed to the bacteria becomes infected. Leprosy is not easily spread, and early diagnosis and treatment with antibiotics can effectively control the infection. Studies have shown that certain red armadillos carry the leprosy bacteria and spread it to humans.

Leprosy Symptoms

Once the person is affected with the bacteria it takes three to five years for the symptoms to appear and it mainly affects the skin and the peripheral nervous system ( nerves outside the brain and spinal cord). It also affects the eyes and the thin lining of the nose.

The three main symptoms of leprosy are:

• Skin sores, skin lesions, and red patches
• Numbness and tingling sensation in hands and feet
• Muscle weakness

The other symptoms of the disease are:

• Enlarged peripheral nerves
• Thick and stiff skin
• Nosebleeds and nasal congestion
• Loss of eyebrows and eyelashes
• Paralysis
• Permanent damage to hands and feet
• Loss of vision
• Lumps or swellings on the face and ears.

Types of Leprosy Disease

Leprosy is divided into various types as follows:

Based on the immune response of the individual towards the bacteria it is classified into two types:

• Paucibacillary Leprosy (PB): It is characterized by a strong immune response against the bacteria. Patients with this leprosy have a smaller number of skin lesions and these lesions are less severe with a dry appearance and some loss of sensation due to nerve damage. It is less contagious compared to multibacillary leprosy.
• Multibacillary leprosy: It is associated with a weaker immune response leading to an extensive disease with more than six skin lesions. The lesions are more nodular and have severe nerve damage and it is highly contagious.

Based on the Ridley-Jopling classification leprosy is classified into five types:

• Tuberculoid Leprosy: This type is characterized by a strong immune response against the bacterium and the patients have fewer skin lesions and less nerve damage.
• Lepromatous Leprosy: People with weak immune responses towards the bacterium will get this infection. It is severe and highly contagious and is usually characterized by widespread skin bumps, rashes, muscle weakness, and numbness. This type can lead to significant nerve damage and disability.
• Borderline Tuberculoid: This type of leprosy is between tuberculoid and lepromatous type of leprosy and it has the characteristics of both of them. It is further divided into three types:
  • Borderline Tuberculoid: It is closer to tuberculoid leprosy but has more lesions compared to them
  • Mid-borderline (BB): The features are intermediate between lepromatous and tuberculoid leprosy
  • Borderline Lepromatous: It is similar to the lepromatous type, they have numerous lesions and the bacterial load is also very heavy
• Intermediate Leprosy: This is an early transient stage of the disease with less indistinct lesions. At this stage is very difficult to determine the specific type of leprosy as it can either regress, remain stable, or progress into a defined form.
• Primary Neural Leprosy: This is a less common type of leprosy that affects the peripheral nerves but does not cause lesions that are typical in other types of leprosy. It causes nerve damage and loss of function in the affected areas.

Diagnosis of Leprosy

Leprosy or Hensen’s disease can be diagnosed by looking for one of the following signs:

• A red or pale skin patch that has lost sensation
• Thick or enlarged peripheral nerve
• Microscopic detection of the bacteria

To confirm the diagnosis biopsy is conducted, and the infected nerve or the skin sample is taken and viewed under the microscope. The tests used in the diagnosis of leprosy are

• Modified acid-fast stain
• Lepromin skin test
• NAT-HANS Test
• OnSite Leprosy Ab Rapid test

What are the Complications of Leprosy?

If the disease is not treated on time it can lead to various complications like permanent damage to skin, feet, nerves, legs, and eyes. The other complications include:

• Hair loss
• Infertility
• Vision loss or glaucoma
• Iritis
• Disfiguration of the face that includes permanent swelling, lumps, and bumps
• Muscle weakness that causes claw-like hands and feet also loses flexibility
• Chronic nose-bleeds due to the permanent damage caused to the inner lining of the nose
• Kidney failure
• Nerve damage causes loss of sensation

Leprosy Treatment

Leprosy is treated with a combination of antibiotics: two or three antibiotics are used at the same time, it is known as multi-drug therapy. This was introduced by World Health Organization (WHO) in the 1980s. This treatment is highly effective in curing patients and stopping the transmission of the disease. Some of the key components of leprosy treatment are:

Multi-Drug Treatment for Leprosy

This therapy involves a combination of antibiotics to ensure that the bacterium is fully eradicated and to prevent the development of drug resistance. Some of the medicines used in this treatment are Dapson, Rifampicin, and Clofazimine. The duration of the drugs is specific to the patient’s response.

In addition to multi-drug treatment other supportive treatments are also given to manage complications and to prevent disability. The treatments are

• Corticosteroids and anti-inflammatory drugs to treat nerve damage and inflammation
• Painkillers are used to manage pain that is caused due to nerve damage
• Physiotherapy and rehabilitation to maintain muscle strength and joint mobility
• Surgical interventions to correct deformities or to relieve never-catch
• Psychosocial support is important for patients dealing with the psychological impact of leprosy
• Regular follow-up is important to monitor the results of treatment and to prevent further complications

Conclusion: Causes, Symptoms, Treatment and Types Of Leprosy

Leprosy also known as Hensen’s disease is a chronic infectious disease caused by the Mycobacterium leprae that primarily affects the skin, peripheral nerves, eyes, and lining of the mucous membrane. It has a wide range of symptoms like skin lesions, loss of vision, muscle weakness, numbness, and permanent damage to the legs and arms. It can be treated and prevented by multi-drug therapy and supportive treatment.

FAQs on Causes, Symptoms, Treatment and Types Of Leprosy

What is the Main Cause of Leprosy?

Leprosy is an infectious disease caused by the bacteria Mycobacterium leprae that affects the peripheral nerves, eyes, skin, and mucous membrane causing skin lesions and nerve damage.

What is the Main Treatment for Leprosy?

Leprosy is treated with a combination of antibiotics, usually two to three antibiotics at a time. The antibiotics used are dapsone, rifampicin, and clofazimine.

What are the Three Main Symptoms of Leprosy?

The main symptoms of leprosy are skin ulcers, nerve damage, and muscle weakness. If not treated it can cause severe disfigurement and disability.

What is the Classification of Leprosy?

Leprosy types are classified into 5 types by Ridley and Jopling based on the immunological and histological features. They are – Tuberculoid (TT), Boberline tuberculoid (BT), Mid borderline (BB), Borderline lepromatous (BL), and Borderline lepromatous (BL).

How to Prevent Leprosy?

Leprosy spread can be prevented by early diagnosis and treatment for infected people, household contacts should have immediate and annual examinations for at least five years after the last contact with the infected person.

What is the Cure for Leprosy?

Leprosy is treated with a combination of antibiotics over a prolonged period for several months to years, under medical supervision. Multidrug therapy is the standard treatment regimen recommended by the World Health Organization (WHO) to cure leprosy effectively.

Is Leprosy Contagious?

Yes, leprosy is mildly contagious and is transmitted through prolonged close contact with untreated individuals with the disease. However, it is not highly infectious and can be effectively treated with antibiotics.