Slit Skin Smear and Staining for Acid-Fast Bacilli

The normal habitat of the Mycobacterium leprae in the human host is the skin, the nasal mucous membrane and the nerve tissue. It is possible to demonstrate M leprae depending on the type of leprosy. Slit skin smear and staining are useful, cost-effective tools in the screening and diagnosis of leprosy in suspected cases, to diagnose a relapse of leprosy, and to assess the prognosis of the disease. Although they have been done away with in the National Leprosy Eradication Programme in India, there are calls from the leprology community to re-introduce them in the field for their usefulness, as the presence of acid-fast bacilli in slit skin smear is one of the cardinal signs in the diagnosis of Hansen’s disease. This method was first described by Wade in 1935.