Hepatitis is inflammation of the liver characterized by diffuse or patchy necrosis.
Hepatitis may be acute or chronic (usually defined as lasting > 6 months). Most cases of acute viral hepatitis Overview of Acute Viral Hepatitis Acute viral hepatitis is diffuse liver inflammation caused by specific hepatotropic viruses that have diverse modes of transmission and epidemiologies. A nonspecific viral prodrome is followed... read more resolve spontaneously, but some progress to chronic hepatitis Overview of Chronic Hepatitis Chronic hepatitis is hepatitis that lasts > 6 months. Common causes include hepatitis B and C viruses, nonalcoholic steatohepatitis (NASH), alcohol-related liver disease, and autoimmune liver... read more .
Common Causes of Hepatitis
Common causes of hepatitis include
Specific hepatitis viruses
At least 5 specific viruses appear to be responsible for hepatitis (see table Characteristics of Hepatitis Viruses Characteristics of Hepatitis Viruses ). Other unidentified viruses probably also cause acute viral hepatitis.
Less Common Causes of Hepatitis
Less common causes of hepatitis include autoimmune disorders Autoimmune Disorders In autoimmune disorders, the immune system produces antibodies to an endogenous antigen (autoantigen). The following types of hypersensitivity reactions may be involved: Type II: Antibody-coated... read more , genetic liver disorders, and other viral infections (eg, infectious mononucleosis Infectious Mononucleosis Infectious mononucleosis is caused by Epstein-Barr virus (EBV, human herpesvirus type 4) and is characterized by fatigue, fever, pharyngitis, and lymphadenopathy. Fatigue may persist weeks or... read more , yellow fever Yellow Fever Yellow fever is a mosquito-borne flavivirus infection endemic in tropical South America and sub-Saharan Africa. Symptoms may include sudden onset of fever, relative bradycardia, headache, and... read more , cytomegalovirus infection Cytomegalovirus (CMV) Infection Cytomegalovirus (CMV, human herpesvirus type 5) can cause infections that have a wide range of severity. A syndrome of infectious mononucleosis that lacks severe pharyngitis is common. Severe... read more ) and leptospirosis Leptospirosis Leptospirosis is an infection caused by one of several pathogenic serotypes of the spirochete Leptospira. Symptoms are biphasic. Both phases involve acute febrile episodes; the second... read more .
Parasitic infections (eg, schistosomiasis Schistosomiasis Schistosomiasis is infection with blood flukes of the genus Schistosoma, which are acquired transcutaneously by swimming or wading in contaminated freshwater. The organisms infect the... read more , malaria Malaria Malaria is infection with Plasmodium species. Symptoms and signs include fever (which may be periodic), chills, rigors, sweating, diarrhea, abdominal pain, respiratory distress, confusion... read more , amebiasis Amebiasis Amebiasis is infection with Entamoeba histolytica. It is acquired by fecal-oral transmission. Infection is commonly asymptomatic, but symptoms ranging from mild diarrhea to severe dysentery... read more ), pyogenic infections, and abscesses that affect the liver are not considered hepatitis. Liver involvement with tuberculosis (TB) and other granulomatous infiltrations is sometimes called granulomatous hepatitis, but the clinical, biochemical, and histologic features differ from those of the diffuse liver involvement in hepatitis caused by hepatitis viruses, alcohol, and drugs.
Various systemic infections and other illnesses may produce small focal areas of hepatic inflammation or necrosis. This nonspecific reactive hepatitis can cause minor liver function abnormalities but is usually asymptomatic.
Some types of infectious and noninfectious liver inflammation are summarized in table .
1. Wang Y, Liu S, Zhao J: SARS-CoV-2 infection of the liver directly contributes to hepatic impairment in patients with COVID-19. J Hepatol 73(4):807-816, 2020.