Hepatitis A cannot be distinguished from other types of viral hepatitis on the basis of clinical or epidemiologic features alone. Serologic testing is required and acute Hepatitis A infection is confirmed by the presence of IgM anti-Hepatitis A in serum.
Antibodies generally become detectable 5-10 days before the onset of disease. In situations that serological testing cannot be performed or gives inconclusive results, molecular methods can also be a good tool for diagnosing Hepatitis A infection.
Molecular detection (RT-PCR) can be done in sera, plasma, faeces and in some situations in “saliva”. Quantification and genotyping of Hepatitis A RNA are carried out primarily in serum samples because faeces can contain inhibitors that interfere with the PCR detection.