The DNA-amplification method using the polymerase chain reaction (PCR) technique appears to be more specific and sensitive for detecting bacilli in the nasal mucosa.7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 Several cohort studies,9,10,14, 15, 16, 17 based on serum positivity (anti-PGL-1) and PCR investigation of bacilli in the nasal mucosa, have shown persistent subclinical infection, especially in highly endemic areas. Here, SDHD is linked to infection.