Current epidemiology of leprosy.

Every year around 4,00,000 new cases of leprosy occur in India and India contributes about 80% of the global leprosy case load. The prevalence of leprosy (case load per 1,00,000 population) has come down from 52 per 10,000 in 1981 to 2.4 per 10,000 in July 2004. There is no primary prevention for leprosy. Multidrug therapy is the only intervention available against the disease. As of July 2004 there were about 2,40,000 leprosy cases on record in India. There are thirteen states and union territories in India which have already eliminated leprosy. About 70% of the cases detected in India are paucibacillary which are less or non-infectious. Ever since the start of National Leprosy Eradication Programme in 1983, the number of new cases detected every year has not shown significant change. Leprosy cases are treated for 6 months or 12 months depending on whether they are PB or MB. The treatment completion rates are now found to be 85% for MB and 90% for PB. Phased introduction of MDT services has contributed to a large extent the static level of new case detection. Without complete coverage of MDT, it is difficult to achieve stable level of new case detection. Diagnostic efficiency of the staff is very important external factor influencing case detection rate. The most important factor that could have significant impact or prevalence is the coverage of the entire population with adequate MDT service.

Clinical manifestations, diagnosis and classification of leprosy.

Mycobacterium leprae, the causative organism of leprosy is slow-growing and the reason is its long incubation period of 2-4 years. Males are predominantly affected and deformity is produced in less than 2% of people affected with the disease. The disease manifests in the skin as macules, papules, nodules, plaques or infiltration. Hypopigmented or erythematous skin patches with definite sensory deficit is one of the clinical cardinal signs by which one can make a definite diagnosis. Demonstration of bacilli in the slit skin smear is the bacteriological cardinal sign used to make definite diagnosis of leprosy. Involvement of common cutaneous nerves with thickening and/or tenderness with its dysfunction is the second clinical cardinal sign used to diagnose leprosy. Diagnosis can be made by eliciting definite sensory deficit in the skin lesions (other than nodules and infiltration). In the absence of two clinical cardinal signs and when there is a strong suspicion of leprosy, slit skin smear should be taken from both ear lobes and one of the lesions for demonstration of acid-test bacilli. Clinical classification is based on characteristics like number of lesions, their margin, sensory deficit, satellite lesions, symmetry of lesions, central healing and scaling. Up to 5 lesions are grouped under paucibacillary and six and more are grouped under multibacillary leprosy.