Comparison of haemagglutination inhibition (HI) and indirect fluorescent antibody (IFA) techniques for the serological diagnosis of certain flavivirus infections.

Paired serum samples from 25 patients having clinical evidence of arboviral infections and 15 controls were examined for antibodies against dengue, Japanese encephalitis and West nile viruses by haemagglutination inhibition (HI) and indirect fluorescent antibody (IFA) methods. The two tests were comparable in specificity but the IFA test was found to be more sensitive than the HI test. Like the HI test, the antibodies detected by IFA test cross-reacted within the flavivirus group under test. Use of IFA test is recommended to detect flavivirus infections as the test is simple, sensitive and can be carried out rapidly.