Viral hepatitis is an inflammatory liver condition that most commonly arises from hepatitis A virus (HAV), hepatitis B virus (HBV), hepatitis C virus (HCV), hepatitis D virus (HDV), and hepatitis E virus (HEV). The prevalence of these viruses varies geographically.
The clinical picture of acute viral hepatitis is variable and is dependent on the type of the virus and the individual circumstances . This is often a self-limiting disease as a majority of patients will exhibit no/mild symptoms . However, a few may develop a rapid onset of fulminant liver failure.
There are 4 phases of viral hepatitis. In the viral replication stage, the infection is not clinically apparent although the serology is positive. This is followed by the prodromal period, which is characterized by acute manifestations such as fatigue, malaise, fever, anorexia, nausea, emesis, abdominal pain, urticaria, and arthralgia. In the icteric phase, the patients develop jaundice, gastrointestinal disturbance, dark urine, gray-colored stools, right upper quadrant pain, and hepatomegaly. Finally, recovery of the symptoms and liver enzymes occurs in the convalescence stage.
The workup consists of the assessment of the clinical presentation, history and risk factors, physical examination, and the pertinent tests.
Patients suspected to have viral hepatitis should undergo serology studies to determine the presence of antibodies to the virus. Interpretation of serology markers takes into account differentiation between acute and chronic infection as well as what constitutes an immune status. Also, the clinician must consider the window period for the specific viral subtypes.
An acute infection with HAV is associated with immunoglobulin M (IgM) anti-HAV antibodies , which persists for a few months whereas immunoglobulin G (IgG) antibodies reflect a history of infection.
Diagnosis of hepatitis B is based on numerous markers. An acute infection is represented by the detection of HBsAg, anti-HBc (total- IgM and IgG antibodies), IgM anti-HBc, and negative anti-HBs .
Chronic hepatitis B infection is characterized by the presence of HBsAg that has persisted for more than 6 months , positive anti-HBc (total), and negative IgM anti-HBc and anti-HBs . Also, HBV DNA levels are increased . Additionally, alanine transaminase (ALT) and aspartate transaminase (AST) levels are consistently or intermittently elevated .
Patients who are immune due to past exposure exhibit negative HBsAg but positive anti-HBc and anti-HBs while those who have received vaccination for hepatitis B demonstrate negative HBsAg and anti-HBc with a positive anti-HBs .
Also, HBeAg is present when viral replication is taking place while anti-HBe is detectable when HBeAg subsides.
In addition to serology, HCV RNA testing and liver biopsy also helpful for diagnosis of hepatitis C. A reactive HCV antibody test does not determine whether the infection is acute or chronic  , hence further evaluation with HCV RNA testing is warranted. If the latter is detected, then the infection is currently active  . Moreover, liver enzymes should be obtained.
This disease is diagnosed with the detection of IgM anti-HDV and IgG anti-HDV.
HEV infection is diagnosed by IgM anti-HEV and IgG anti-HEV. Moreover, blood and stool samples may be positive for HEV RNA.