Non-specific factors that influence susceptibility to leprosy

Abstract

While these T-deficient animal models were important in suggesting the important role of CMI in human leprosy infections, they also indicate that CMI deficiency, non-specifically derived, would be likely to increase the risk factor of infection in man, as well as immunologically determining the outcome of the infection once established in man. Since we do not know why a proportion of nine-banded armadillos is highly susceptible to infections with M. leprae the question of native-susceptibility must be re-considered. Leprosy is undoubtedly a serious risk factor in pregnancy, necessitating optimum chemotherapy for women with active leprosy and prophylactic therapy for those with 'cured' leprosy, and for all to be fed a high protein diet throughout pregnancy and lactation. Though there is ever increasing evidence that leprosy is an airborne infection and therefore the portal of entry may be via the lung following the inhalation of M. leprae-infected nuclei, as in tuberculosis, much of the evidence for this route of transmission stemmed from intensive studies on nasal discharges from patients with active lepromatous leprosy. From one of the studies it was shown that M. leprae remained viable in dried nasal secretions for periods up to 10 days, but that survival was optimal at high humidities. Therefore if the lung is not the only portal of entry the risk of indirect transmission would be greatest in areas with high humidities.