Correlation of clinical, histological and immunological features across the leprosy spectrum.

The Ridley-Jopling system of classification of the variegated clinical pattern of leprosy is based on the specific cell-mediated immunity observed in the histopathology of skin lesions conforming to a spectrum from TT at one end to LL at the other. In this study a fairly large sample of 90 patients was classified on clinical grounds; the histopathology of the skin lesions was studied blind. There was an overall concordance of 90% between the clinical and histological classifications. In addition, the systemic cell-mediated and humoral immune responses were studied. The in vivo cell-mediated immune response, namely the Mitsuda skin response, mostly conformed to the clinical classification. While the in vitro lymphoproliferative responses to BCG and its sonicate were high, the lymphoproliferative responses to Dharmendra lepromin were surprisingly poor. Humoral responses to 35 kDA protein of M. leprae and PGL-1 were good in most LL, BL patients and tapered off towards TT. IgG antibodies to recombinant ML 65 kDa proteins denoted mycobacterial presence.

Poor correlation of systemic immunological parameters with clinical features in macular leprosy.

On the basis of clinical features and bacteriological status, macular skin lesions of nine cases of leprosy were classified as falling within a spectrum between the tuberculoid at one end and the lepromatous at the other. While histologic correlation was seen in 60% of cases, humoral and cellular systemic immunologic features were found to be uncharacteristic. It is suggested that macular lesions form an early stage in the development of leprosy where the systemic immunological response is yet to set in fully.

Sample survey of leprosy after three years of MDT in Bhavani taluk of Periyar District, Tamilnadu.

A sample survey of Bhavani taluk was undertaken in March 1992 three years after the introduction of MDT. Ten percent of the population was taken for the sample. A population of 45,781 was enumerated and 41,554 was examined. The three sectors were stratified according to the prevalence rate and classifying the villages by the size of the population. Villages were selected by random sampling. The sample survey detected 288 new cases of leprosy of which 16 (5.55%) were bacteriologically positive for acid-fast bacilli. The child rate was 13.54% among new cases. According to the sample survey the current prevalence rate per 1000 population was 9.07 (with a new case detection rate of 6.93/1000 population), much higher than that derived from programme data (prevalence rate 3.45) and the expected ten fold reduction of prevalence under MDT. Independent sample surveys of NLEP units after three to five years of implementation of MDT will help to assess deficiencies in the programme and enable us to take remedial measures.