The nasal discharge in leprosy: clinical and bacteriological aspects

Abstract

Nasal discharges containing acid fast bacilli were studied in India, in relation to their clinical setting in 363 patients, and intensively, in London, in relation to their bacteriology. The rarity of such a nasal discharge in borderline leprosy was in striking contrast to its frequency in untreated lepromatous leprosy. In this series the nasal discharge did not develop gradually with the advance of lepromatous leprosy. Highly bacilliferous discharges were encountered in early lepromatous leprosy, indicating nasal involvement far more severe than external appearances suggested. At a later stage the bacteriological importance of the discharge waned, but became once again of great significance with the onset of recrudescence. The typical nasal discharge is an inflammatory exudate rich in both Myco. leprae and macrophages displaying every stage in globus development. The exceptionally high B.I. and high M.I. often encountered in untreated patients in this series frequently exceeded the highest values found in skin. The nasal discharge was encouraged by moist atmospheric conditions and diminished rapidly with even small doses of dapsone. Fresh early morning specimens and 24 h collections of nasal discharges from 31 patients in this series were sent on wet ice to London, together with fresh biopsies of highly infected skin from 11 of these patients. Bacillary isolates from the nasal discharges of all 31 patients produced growth curves in the mouse footpad characteristic for Myco. leprae, indisputable proof that this organism was present in every case. The mean total yield of acid fast bacilli in 24 hr collections was 2.4 x 108, with a morphological index of 12.8. Single nose blow collections showed a mean discharge of 1.1 x 108 acid fast bacilli with a mean morphological index of 16.9. Comparison between the content of acid fast bacilli/g of skin and that of the specimen of nasal discharge from the same patient showed a significantly higher proportion of solidly staining bacilli in the nasal discharge. In 3 patients mouse inoculation tests for dapsone sensitivity of Myco. leprae isolated from the nasal discharge and skin biopsies revealed dapsone resistant bacilli both in the skin and in the nasal discharge. The capacity of Myco. leprae in nasal discharge to survive outside the body was tested in 3 cases, by allowing the discharge to dry in the dark, at room temperature, and sampling for mouse inoculation being undertaken at 1, 1.75, 3, 7, and 10 days. Full survival was found after 24 hr, and 10% after 1.75 days, but none after 3, 7 and 10 days, except in 1 sample in which some growth occurred after 7 days. Similarities with tuberculosis, and the significance of both clinical and bacteriological findings to the transmission of leprosy are discussed.