Diagnosis of Viral Hepatitis
Zhi Q. Yao
Viral hepatitis refers to a group of viral infections that primarily cause liver inflammation. The most common types include hepatitis A, hepatitis B, and hepatitis C. Hepatitis D occurs in the presence of hepatitis B. Hepatitis E, like hepatitis A, is transmitted by the fecal-oral route and only leads to an acute hepatitis. The differential diagnosis of liver inflammation is broad:
Differential Diagnosis
Viral hepatitis: A, B, C, D, and E
Other infections: Epsterin-Barr Virus (EBV), cytomegalovirus (CMV), herpes simplex virus (HSV), leptospirosis, tuberculosis (TB), and toxoplasmosis
Autoimmune hepatitis
Drug-induced hepatitis: acetaminophen, alcohol, isoniazid, azoles, and statins
Hemodynamic liver injury: sepsis, ischemia, heart failure, and vascular occlusion
Nonalcoholic fatty liver disease (NAFLD)
Cholestatic liver disease: primary biliary cirrhosis, primary sclerosing cholangitis, gallstones, and acute cholecystitis
Metabolic/genetic: hemochromatosis, Wilson disease, and α1-antitrypsin deficiency
Pregnancy-related liver diseases
Hepatic tumors, cysts, abscesses, and biliary tract neoplasms
HEPATITIS A
Hepatitis A virus (HAV) causes approximately half of the cases of acute hepatitis in the United States. Major routes of infection include ingestion of contaminated food or water and close contact with an infected person. Persons at high risk include men who have sex with men and those who travel to endemic areas. Typical incubation period is 2 to 3 weeks.
Clinically, patients infected with hepatitis A may or may not exhibit the following typical symptoms or signs: fatigue, anorexia, jaundice, and nonspecific gastrointestinal symptoms such as nausea, poor appetite, and abdominal pain that are indistinguishable from other causes of hepatitis.
The diagnosis of acute hepatitis A depends on serology: detecting an IgM anti-HAV; positive IgG anti-HAV antibody indicates prior infection and immunity, while the presence of both IgM and IgG antibodies suggests infection within the prior 2 to 6 months; the absence of both IgM and IgG anti-HAV antibodies indicates susceptibility to HAV.
There is no chronic state of HAV infection.
HEPATITIS B
An estimated 350 million persons worldwide are infected with hepatitis B virus (HBV), a double-strained DNA virus that is coated with a surface antigen (HBsAg) and has a central core (with HBV core and e antigens) containing the HBV DNA. HBV causes approximately one-third of acute viral hepatitis and approximately 15% of cases of chronic viral hepatitis in the United States.
Hepatitis B is transmitted parenterally by percutaneous exposure; by sharing needles in drug use; by intimate person-to-person contact with an infected person, including sexual contact; and by mother-to-infant vertical transmission. The virus is found in blood as well as in body fluids such as saliva, milk, urine, or stool.
The incubation period of HBV infection ranges from 6 weeks to 6 months after exposure. Symptoms are similar to those of hepatitis A and may include other nonspecific constitutional complaints.
In most adult patients (>90%), the acute infection resolves within 6 months, whereas most infant HBV infection (>90%) leads to a chronic carrier status.
Patients with persistent HBsAg positivity beyond 6 months are deemed a chronic infection. Patients with established chronic infection must be monitored for the development of cirrhosis and hepatocellular carcinoma (HCC) with ultrasonography and measurement of serum α-fetoprotein at an interval of every 6 to 12 months.
The diagnosis of hepatitis B depends on accurately interpreting serologic tests according to the natural history of infection. The patient with immunetolerance— acquired HBV perinatally will be HBeAg positive and have high levels of HBV DNA; the risk for active hepatitis increases with age.Related posts:
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