Early detection of M. leprae by qPCR in untreated patients and their contacts: results for nasal swab and palate mucosa scraping.

To verify if the hard palate mucosa can be a site of relevance in the early molecular detection of Mycobacterium leprae in leprosy cases and their household contacts and if there is a correlation of results in nasal swab with those of the scraping of the palate mucosa. The quantitative polymerase chain reaction technique was used. Sample included 78 patients with untreated leprosy (G1), their 54 household contacts (G2), and 80 healthy individuals for the negative control (G3). The presence of M. leprae in both G1 and G2 was observed with the nasal swab and the palate mucosa scrapings methods, and it was shown that the sensitivity between the qPCR exams for RLEP and 85B genes is equivalent, with no statistically significant differences (G1 positivity of 35% in the hard palate mucosa and 44% for the nasal one, p = 0.3731 and for G2 of 31 and 38%, respectively, p = 0.6774). Results support the fact that the buccal mucosa and nasal mucosa may be important sites of primary infection of leprosy with repercussion in the transmission chain and that asymptomatic household contacts are heavily harbored by the causative agent of leprosy, which has a critical significance in the prevention and control action of this disease, since the evaluation of these sites arises as of importance in the early detection of M. leprae. Close monitoring and chemoprophylaxis of household contacts appear to be critical to attain interruption of the transmission of leprosy in endemic countries.