Approach to leprosy responses (type 1 and type 2): updates and clinical management

Abstract

Leprosy is a chronic infectious disease caused by Mycobacterium leprae, primarily affecting the skin and peripheral nerves. Type 1 reactions (T1R) and Type 2 reactions (erythema nodosum leprosum – ENL) are the most severe inflammatory complications of leprosy, responsible for the majority of neuropathies, physical disabilities, and permanent deformities associated with the disease. T1R, prevalent in borderline forms of leprosy, is characterized by acute inflammation of existing skin lesions, localized edema, and neuritis leading to sensory and motor nerve loss. ENL, on the other hand, is an immune complex-mediated reaction with systemic manifestations, such as fever, painful erythematous subcutaneous nodules, arthritis, neuritis, and iridocyclitis, often presenting as a recurrent or chronic condition. This systematic review analyzed studies published in PubMed, LILACS, and Scielo over the past 20 years to evaluate the prevalence, clinical presentations, and management strategies of these reactions. Included therapies range from conventional treatments, such as corticosteroids (prednisolone) and thalidomide, to alternative approaches, like cyclosporine and other immunosuppressants. Results highlight significant gaps in the management of leprosy reactions, including high recurrence rates, drug resistance in chronic cases, and delays in accessing treatment, particularly in remote areas. Furthermore, lack of public awareness and challenges in early diagnosis exacerbate clinical outcomes, leading to irreversible disabilities. It is concluded that further research is crucial to develop diagnostic biomarkers, more effective therapies, and standardized protocols that integrate clinical and preventive management of leprosy reactions, aiming to improve patient quality of life and mitigate the public health burden of leprosy.