Leprosy: Diagnosis (Davidsons)

Lepramatous and borderline leprosy are diagnosed by appearance of M leprae in slit skin smears. The dermis is scraped with a blade sent off for microscopy. The stain used is Ziehl-Neelsen method. Nasal smears may also be used to show evidence of lepramatous leprosy.

The lepromin test is like the tuberculin test, but read after 4 weeks. The degree of cell immunity is evident, and is useful in classification of disease and the type of treatment and prognosis that can be estimated.

Serological diagnosis can be achieved because M leprae has a characteristic surface lipid (PGL I) which can be detected in tissue by monoclonal antibody – i.e.: antibody binds to this therefore we know M leprae is present.

Treatment: Sulphones (eg: Dapsone), Rifampicin, lofazimine. The former two used together to prevent resistance.

Category: Microbiology Notes