This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
[{'content': "Napier's aldehyde test is used in diagnosis of: \nSelect and explain. \nA. Malaria, B. Typhus fever, C. Kala azar, D. Enteric fever", 'role': 'user'}, {'content': 'Answer: C \nExplanation: In the Kala-azar endemic areas of India, Napieris aldehyde test has been used for a long time. The test relies on the jellification caused by the binding of the serum globulins to the formaldehyde. The serum globulins increase in a variety of infections and thus this test is rather non-specific. A positive reaction may also be seen in diseases like, tuberculosis, cirrhosis of liver, malaria, etc. Fuher, in kala-azar, the test becomes positive only when infection is atleast three months old and may remain positive even after six months of cure. Ref:', 'role': 'assistant'}]