The basis of nerve damage in leprosy is the unique tendency of Mycobacterium leprae to invade Schwann cells. αβ-Dystroglycan on the basement membrane of Schwann cells binds to laminin α₂, in turn binding to receptors on the M. leprae surface, comprising a histone-like protein and phenoglycolipid-1. When nerve damage during reversal reactions was found to be associated with an abrupt increase in delayed type hypersensitivity against M. leprae antigenic determinants released from Schwann cells, it suggested that the nerve is damaged as an innocent bystander during the immune response. This strongly influenced the introduction of therapy based on immunosuppression combined with continued anti-mycobacterial medication. Lysis of Schwann cells presenting M. leprae antigenic determinants by activated CD4+ T cells and interaction of M. leprae with Toll-like receptors on Schwann cells are additional mechanisms implicated in nerve damage. Persistence of M. leprae antigen in local lesions after regular multiple drug therapy (MDT) is an important risk factor for late reactions. In spite of significant advances in the provision of MDT globally, early diagnosis, together with effective treatment of the disease and associated nerve damage at initial presentation remains a major challenge for the health services. Reduced prevalence as a result of MDT should not be taken to indicate that the challenges of leprosy control are diminished as long as nerve damage is not controlled and new case detection rates are not declining.

The aim of this study was to find predictors of neuropathy and reactions, determine the most sensitive methods for detecting peripheral neuropathy, study the pathogenesis of neuropathy and reactions and create a bank of specimen, backed up by detailed clinical documentation. A multi-centre cohort study of 303 multibacillary leprosy patients in Northern India was followed for 2 years. All newly registered MB patients requiring a full course of MDT, who were smear positive and/or had six or more skin lesions and/or had two or more nerve trunks involved, were eligible. A detailed history was taken and physical and neurological examinations were performed. Nerve function was assessed at each visit with nerve conduction testing, warm and cold detection thresholds, vibrometry, dynamometry, monofilaments and voluntary muscle testing. Because the latter two are widely used in leprosy clinics, they were used as ‘gold standard’ for sensory and motor impairment. Other outcome events were type 1 and 2 reactions and neuritis. All subjects had a skin biopsy at registration, repeated at the time of an outcome event, along with a nerve biopsy. These were examined using a variety of immunohistological techniques. Blood sampling for serological testing was done at every 4-weekly clinic visit. At diagnosis, 115 patients had an outcome event of recent onset. Many people had skin lesions overlying a major nerve trunk, which were shown to be significantly associated with an increased of sensory or motor impairment. The most important adjusted odds ratios for motor impairment were, facial 4.5 (1.3–16) and ulnar 3.5 (1.0–8.5); for sensory impairment they were, ulnar 2.9 (1.3–6.5), median 3.6 (1.1–12) and posterior tibial 4.0 (1.8–8.7). Nerve enlargement was found in 94% of patients, while only 24% and 3% had paraesthesia and nerve tenderness on palpation, respectively. These increased the risk of reactions only marginally. Seven subjects had abnormal tendon reflexes and seven abnormal joint position sense. In all but one case, these impairments were accompanied by abnormalities in two or more other nerve function tests and thus seemed to indicate more severe neuropathy. At diagnosis, 38% of a cohort of newly diagnosed MB leprosy patients had recent or new reactions or nerve damage at the time of intake into the study. The main risk factor for neuropathy found in this baseline analysis was the presence of skin lesions overlying nerve trunks. They increased the risk of sensory or motor impairment in the concerned nerve by 3–4 times. For some nerves, reactional signs in the lesions further increased this risk to 6–8 times the risk of those without such lesions. Patients with skin lesions overlying peripheral nerve trunks should be carefully monitored for development of sensory or motor impairment.

The objective of our research was to identify factors contributing to delay in diagnosis and start of treatment in leprosy, focussing on patients’ narratives of help-seeking behaviour. Our research took place in Purulia, West Bengal, India and in Nilphamari, northern Bangladesh. Between January and August 2000, we conducted semi-structured interviews with 104 patients that explored each individual’s narrative of help-seeking behaviour and the context of beliefs and attitudes towards leprosy. Subsequently we surveyed 356 patients currently receiving treatment for leprosy and recorded specific aspects of each help-seeking action and their reports of local beliefs and attitudes towards leprosy. Delay was estimated from time of first symptoms through to start of effective treatment (mean 18 months, median 9 months in Purulia and mean 20 months, median 12 months in Nilphamari). The number of help-seeking actions ranged from 1 to 7. Time committed to first actions contributed 86% (Nilphamari) and 79% (Purulia) to total delay. The most important contributor to delay in the first action occurred when people simply monitored or ignored first symptoms, 80% in Nilphamari and 67% in Purulia. With delay longer than 12 months as outcome, logistic regression analyses identified age over 35 years, multiple visits to practitioners in traditional medicine and multiple visits to health service practitioners as predictive of delay. Attending a nearby clinic and exposure to health education materials were predictive of early presentation reduced delay.

Reconstructive surgery has made significant advances in correcting deformities in leprosy. However, several patients seem hesitant and unenthusiastic to take advantage of this facility. A study was therefore carried out at the Leprosy Mission Hospital in Kolkata during 1999, to assess patients’ perceptions to reconstructive surgery. Of about 300 patients operated during 1991–1997, 117 were interviewed using a Visual Analogue Scale on their pre-operative expectations and satisfaction after surgery. Nearly 40% had their expectations fully met, another 40% partially, and about 10% perceived benefits more than expected. Less than 5% were not satisfied. Results are presented for surgery on hand, foot and eye among males and females, and the implications for future discussed.