RESUMO
Leprosy is a chronic disease caused by infection with Mycobacterium leprae, which is manifested across a wide clinical spectrum. There is evidence that susceptibility both to leprosy per se and to the clinical type of leprosy is influenced by host genetic factors. This paper describes the application of an identity by descent regression search for genetic determinants of leprosy type among families from Karonga District, Northern Malawi. Suggestive evidence was found for linkage to leprosy type on chr 21q22 (P<0.001). The methodological implications of the approach and the findings are discussed.
Assuntos
Cromossomos Humanos Par 21/genética , Ligação Genética/genética , Predisposição Genética para Doença , Hanseníase/epidemiologia , Feminino , Humanos , Hanseníase/diagnóstico , Hanseníase/genética , Malaui/epidemiologia , Masculino , Linhagem , Análise de RegressãoRESUMO
In this report the methods of the Karonga Prevention Trial, a double-blind leprosy and tuberculosis vaccine trial in Karonga District, Northern Malawi, are described in detail. During a total population house-to-house survey, which lasted from November 1985 until August 1989, 121,008 people (57,892 males and 63,116 females) were vaccinated. A further 5835 people refused vaccination and 5757 were ineligible for vaccination, 2652 of them because they had a history or signs of leprosy, or because they were suspected to have early leprosy. A total of 66,145 individuals, without evidence of prior BCG vaccination, received one of the following: BCG, BCG + 5 x 10(7) killed Mycobacterium leprae, or BCG + 6 x 10(8) killed M. leprae; 54,863 individuals found with a typical or a doubtful BCG scar received either placebo or BCG, or (from mid-1987 onwards) BCG + 6 x 10(8) killed M. leprae. Side-effects were not looked for systematically, but 4 individuals self-reported with glandular abscesses, 9 with large post-vaccination ulcers (> 25 mm in diameter) and 2 with ulcers which persisted for more than 1 year. BCG vials collected from paraffin refrigerators in the field showed satisfactory concentrations of viable BCG throughout the trial. Post-vaccination skin test (RT23 and M. leprae soluble antigen) results and post-vaccination ulcer rates indicate that few mistakes were made in the field when recording the vaccine codes.