Viral hepatitis is primarily caused by hepatitis A, B, C, D, and E viruses. However, its diagnosis is mainly confirmed through blood tests by examining serological results. It is generally difficult to differentiate clinically because conditions like hepatitis A and E have very similar clinical manifestations. Similarly, hepatitis B and C can show similar symptoms during certain stages of the disease. Therefore, the examination of viral hepatitis primarily involves blood tests for serological studies of the hepatitis virus.