Definition

A leprosy reaction is an inflammatory episode that occurs during the progression of leprosy, representing an immune response to certain bacterial components of Mycobacterium leprae. There are two main types: type 1 reaction and type 2 reaction. These reactions can manifest before, during, or after leprosy treatment.

Causes

Type 1 reaction, also known as the reversal reaction, is an allergic response to parts of the Mycobacterium leprae. This type of reaction most frequently occurs following the start of leprosy treatment but may also arise before or after therapy. It signifies a specific immune response to the M. leprae.

Leprosy reaction type 2, known as erythema nodosum leprosum (ENL), is triggered by the deposition of immune complexes in blood vessels, leading to sudden inflammation. The exact mechanism behind this reaction remains unclear.

Risk factor

Type 1 reaction is unpredictable but tends to occur in:

• Leprosy patients with the borderline type, which represents a transitional phase between tuberculoid and lepromatous leprosy. However, both tuberculoid and lepromatous patients can also experience type 1 reactions.
• Individuals over the age of 15. Type 1 reactions are more commonly observed in those aged 15 and older compared to younger children.
• Patients who have started leprosy treatment. In those who have completed therapy, reactions generally occur within three years post-treatment, though they may appear later.
• Postpartum women. Childbirth is considered a significant factor in the risk of type 1 reactions, as a mother’s immunity typically strengthens after delivery.

Type 2 reactions are often linked to:

• Puberty
• Pregnancy
• Breastfeeding

Symptoms

Type 1 reactions primarily affect the skin and nerves without causing systemic reactions. These reactions typically involve a worsening of pre-existing skin or nerve issues. The skin symptoms associated with Type 1 reactions include:

• Redness and swelling of existing skin lesions
• Severe reactions may result in ulcerations
• Although rare, swelling may occur in the hands, feet, or face

Nerve involvement in Type 1 reactions commonly affects nerves in the elbows, waist, knee creases, face, and neck. This often results in symptoms such as:

• Pain
• Loss of function, experienced as muscle weakness, sensory loss, paralysis, or physical deformities. These symptoms can persist for several days.

Type 1 reactions can be classified as mild or severe. Mild reactions involve several inflamed plaques on the skin without nerve involvement. Severe reactions, on the other hand, are characterized by numerous inflamed plaques accompanied by nerve involvement.

The symptoms of Type 2 Reactions vary based on severity and the affected organs. The skin symptoms of Type 2 reactions include:

• Red patches spreading across various parts of the body, especially on the extremities and face
• Numerous small, painful red nodules
• Pustules
• Ulcers These symptoms may affect only the skin’s surface or extend into deeper layers.

Other possible symptoms of Type 2 Reactions include:

• Eye inflammation
• Inflammation of the scrotum
• Kidney disorders or kidney failure
• Protein leakage into the urine
• Impaired bile salt production
• Fever
• Fatigue
• Enlarged lymph nodes
• Painful and swollen joints

Diagnosis

Type 1 reaction is often suspected in individuals with borderline leprosy who develop symptoms a few months after beginning treatment. Although laboratory tests are not typically required for diagnosis, a skin biopsy can be performed if confirmation is necessary. Nerve function tests may also be conducted to determine the extent of nerve damage and to evaluate the effectiveness of treatment.

Type 2 reaction is usually suspected in patients with lepromatous or borderline lepromatous leprosy who present with symptoms such as fever, fatigue, and the appearance of red patches or lumps accompanied by pain. A diagnosis can be made even if the patient has not yet begun therapy. Blood tests may reveal inflammation and identify complications like kidney and liver disorders. A biopsy is often conducted to confirm the diagnosis of type 2 reaction.

Management

The treatment of leprosy reactions involves the use of immunosuppressive drugs, often in high doses, for a prolonged period to control the reaction.

For type 1 reactions, the goal of therapy is to restore normal nerve function and prevent further nerve damage from inflammation. Oral corticosteroids are the primary treatment for type 1 reactions, as topical corticosteroids and other topical medications, such as tacrolimus, are ineffective. Immediate therapy is necessary for severe type 1 reactions involving nerve damage. Treatment options include:

• First-line therapy consists of corticosteroids to reduce inflammation. Once inflammation has diminished, the dosage is gradually tapered and then discontinued.
• Second-line therapy, for severe reactions unresponsive to corticosteroids, involves the use of cyclosporine.
• Nerve surgery may be necessary to alleviate pressure on the nerves in cases where nerve disorders persist despite treatment.
• Ongoing leprosy therapy, including rifampin, dapsone, and/or clofazimine, should not be interrupted.

For Type 2 Reactions, treatment depends on the severity determined by medical examinations and laboratory results. Mild reactions that affect only the skin, without involvement of other organs, can be treated symptomatically, using pain relievers and antipyretics. Severe reactions may require:

• Corticosteroids
• Clofazimine
• Thalidomide
  Additional drugs considered useful for treating severe Type 2 reactions include cyclosporine, azathioprine, methotrexate, mycophenolate mofetil, and pentoxifylline.

Complications

If type 1 reactions are inadequately treated, they can persist for several months. Skin lesions may continue to swell and eventually merge into larger masses. Nerve damage may worsen, leading to permanent loss of function and disability. Facial nerve involvement can result in eyelid closure problems, potentially causing corneal damage.

Untreated type 2 reactions may lead to severe complications such as kidney failure requiring dialysis, liver failure necessitating a transplant, blindness, and prolonged testicular inflammation that may affect fertility.

Prolonged use of high-dose immunosuppressive drugs for the treatment of leprosy reactions can lead to side effects, including hypertension, diabetes, peptic ulcers, glaucoma, osteoporosis, and increased susceptibility to infections such as tuberculosis.

Prevention

Some studies suggest that corticosteroid medications may prevent leprosy reactions, although this remains a subject of debate.

When to see a doctor?

If you have leprosy and experience symptoms of leprosy reactions or notice worsening of your usual symptoms, it is important to consult a doctor promptly. Early treatment can help prevent complications.

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