Most impoant in establishing diagnosis of leprosy is: March 2010

Ans. C: Slit smear for AFB Tissue smear testing/slit-skin smears. An incision is made in the skin, and the scalpel blade is used to obtain fluid from a lesion. The fluid is placed on a glass slide and stained by using the Ziehl-Neelsen acid-fast method or the Fite method to look for organisms. The bacterial index (BI) is then determined as the number of organisms at 100X with oil immersion. Skin smears have high specificity but low sensitivity because 70% of all patients with leprosy have negative smear results. However, this test is useful because it detects the most infectious patients. Presence of AFB in suggestive skin lesions, even in the absence of sensory deficit, confirms the diagnosis of leprosy. Lepromin test is not of diagnostic impoance but is of prognostic impoance.