Which specimen is usually used for the diagnosis of Hansen's disease?

Hansen's disease, also known as leprosy, is primarily diagnosed through the examination of skin lesions or affected tissues. The use of tissue juice, which can be harvested from skin biopsies or lesions, allows healthcare providers to directly assess the presence of Mycobacterium leprae, the bacterium responsible for the disease. This method is crucial because the bacteria are not typically found in significant quantities in blood or other fluids, making those samples less effective for diagnosis.

The analysis of tissue samples can reveal characteristic histopathological changes associated with leprosy, as well as the presence of the bacteria itself. This makes tissue juice the most appropriate specimen for accurate diagnosis of Hansen’s disease.

In contrast, while blood can be used in certain tests for other conditions, it does not typically provide the specific information needed for diagnosing leprosy. Sputum is generally evaluated for respiratory infections and might be relevant for other mycobacterial infections, but not for leprosy. Urine also holds little diagnostic value for Hansen's disease. Thus, tissue juice is the best choice for diagnosing this specific bacterial infection.