Napier's aldehyde test is used in diagnosis of:

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: