Bacterial load in the nose and its correlation to the immune response in leprosy patients

[[[ Introduction: ]]] Leprosy, whose etiologic agent is M. leprae, has its clinical manifestations correlated with distinct immunologic forms. The mechanism of infectivity and dissemination of the disease are not completely known, although the nasal mucosa is supposed to have an important role in pathogenesis. [[[ Objective: ]]] To correlate the clinical and bacteriological parameters with that of nasal biopsy and immunological tests, such as lepromin and ML-Flow results, in untreated leprosy patients. [[[ Material and method: ]]] Two hundred and twenty-two patients were evaluated, clinically classified and subjected to skin smear, nasal biopsy, ML-Flow, and Mitsuda test. [[[ Results: ]]] 689% of the cases were borderline cases. Nasal biopsy revealed 91.4% positivity in those who had specific antibodies against M. leprae on blood sample. Lepromatous leprosy cases were 100% positive on ML-flow test, had a large involvement in the nasal mucosa (91%), positive skin smears (100%) and negative Mitsuda test. Nasal bacillary index showed a good correlation with ML-Flow and had similar results when compared to skin smear. The tests agreement was good, revealing that nasal biopsy can be reliable in the diagnosis of multibacillary clinical forms and in the evaluation of the immunological status of leprosy patients. [[[ Conclusion: ]]] The presence of disseminated bacilli in the nasal mucosa was similar to skin involvement, when correlated with Mitsuda test and ML-Flow. As a result, the role of nasal bacillary index may play an important role in the clinical and immunologic characterization of leprosy patients.