Serological tests in 150 cases of leprosy.

Hansen's disease is considered to be one of the well-known infections which upset serological tests for syphilis in patients in whom there has been no past or current treponemal infection. The reason why lepers are biological false positive (B.F.P.) reactors and why this failure in the specificity of lipoidal reactions occurs remains obscure. The frequency of false positive reactions is said to be greater in the lepromatous than in the tuberculoid or dimorphous forms of the disease. Examination of sera from lepers by the treponemal immobilization test (T.P.I.), which is the most specific test available, has lent weight to the criticism of the classical tests. Nelson (1953) studied the sera of 75 patients from the leper colony of Carville, in whom there was no past history and no clinical signs of syphilis, and found that 75 per cent. of the sera gave positive reactions for reagin but that only 16 per cent. were T.P.I. positive. The percentage of positive T.P.I. tests corresponded exactly with the frequency of syphilis in the population under consideration and Nelson concluded that almost 60 per cent. of these lepers were biological false positive reactors. Nelson's conclusions are shared by numerous workers in France and elsewhere. Such a lack of specificity of the classical tests for syphilis in lepers is, however, surprising if one considers the remarkable specificity and the high degree of sensitivity of these reactions in large groups of the population. It is for this reason that we have undertaken a systematic study of the serological reactions of the patients with leprosy in the Institut Marchoux de Bamako. Methods Sera were collected with sterile precautions at the Institut Marchoux; some were examined on the spot by the Kolmer, Kline, and V.D.R.L. tests and the rest were placed in ampoules and transported to Paris, where they