Problems in the collection and analysis of data in leprosy studies

Abstract

Several studies have shown that incidence rates are higher among household contacts of multibacillary cases of leprosy than among any other group. But the rarity of multibacillary cases in many endemic communities means that most new leprosy cases have no apparent connection with the known bacilliferous cases. This means that: either much M. leprae transmission is attributable to individuals whom we do not recognize as bacilliferous cases; or transmission does originate chiefly from bacilliferous cases but it requires only minimal - and not prolonged or intimate - contact. A major international collaborative study should be encouraged to assess comparability of diagnosis and classification between different clinicians and histopathologists. Publications should be fully explicit on procedures for diagnosis and classification of cases. Greater emphasis should be placed upon improving and documenting field ascertainment methods than on institutionalizing poor routine data. Immunological measures of infection should be applied in population-based studies of the epidemiology of M. leprae infection. Case control methods should be applied to studies of risk factors for infection and for disease.