The anatomical distribution of single leprosy lesions in an African population; and its implications for the pathogenesis of leprosy

Data on the anatomical sites of single leprosy lesions found in 635 newly diagnosed and biopsy-confirmed leprosy patients are presented. These patients were found during total population surveys carried out by the Lepra Evaluation Project; a prospective longitudinal study of the epidemiology of leprosy in Karonga District; Northern Malawi. There was a striking excess of single lesions on the face and the back of the arms; compared to the distribution of skin surface area; and a deficit on the legs; regardless of age. There is some evidence for a sex difference in lesion distribution among adults; with facial and arm lesions being relatively more common in females and back lesions being more common in males. The excess of lesions on the face compared to the lower limbs is similar to data from Uganda; but very unlike data from Burma and elsewhere in Asia. Overall; the distribution of lesions does not suggest a pattern reflecting entry of Mycobacterium leprae; nor does it suggest an association with anatomical distribution of the nervous or vascular system. It is argued that the distribution reflects the influence of some 'local' environmental or behavioural factors. Author.90.Z1-542-363-300901121

The distribution and implications of BCG scars in northern Malawi

"Reported are data on the BCG scar status of more than 112;000 individuals who were surveyed in Karonga District; northern Malawi; between 1979 and 1984. The age and sex patterns of apparent BCG scars reflect the history of BCG vaccination activities in the district. Repeated independent examinations of large numbers of people revealed that the proportions remaining with the same observed scar status among those initially classified as being scar ""positive"" or scar ""negative"" were each approximately 90 percent . The repeatability of positive scar reading was lower among children and older adults than among young adults aged 15-24 years; and blind follow-up of children known to have been vaccinated as infants in child health clinics indicated that less than 60 percent had a detectable scar 3 years after receiving the vaccine. ""Negative"" repeatability increased consistently with age. The implications of these findings for estimating BCG vaccine uptake and for assessing its efficacy in case-control and cohort studies are discussed. The finding that BCG scars may be difficult to read suggests there is a danger of observer bias that could lead to distortion--in particular; to overestimates of vaccine efficacy."

Protective efficacy of BCG against leprosy in Northern Malawi

The effectiveness of a BCG vaccination programme in protecting against leprosy was assessed by case-control and cohort analyses of data from the Lepra Evaluation Project in Karonga District; Northern Malawi. Results indicate that BCG provides at least 50 percent protection against leprosy in this population and that protection is independent of age; sex; schooling status; or location within the project area. Agreement between these findings and those from a controlled trial in Uganda indicates that BCG is sufficiently effective against leprosy in East and Central Africa to be considered an important element of leprosy control in that region