Viral Hepatitis

Viral hepatitis means an inflammation caused by a viral infection in the liver. It is caused by a variety of viral agents. The common viruses are Hepatitis A virus (HAV), Hepatitis B virus (HBV), Hepatitis C virus (HCV), Hepatitis D virus (HDV), Hepatitis E virus (HEV), Cytomegalovirus (CMV), Epstein-Barr virus (EBV), etc. Different viruses have different transmission routes, clinical presentation, and outcome.

Hepatitis A virus (HAV)

Close contact with a person that has a HAV infection or consumption of contaminated food or water is usually the route of transmission, i.e. the fecal-oral route. It takes about 4 weeks to develop symptoms after infected with the virus. A HAV infection is almost always a one-time infection that does not result in chronic infection or chronic liver disease. Vaccination is available and the most effective means of preventing HAV transmission. Person at risk, such as travel to an endemic area, should receive a HAV vaccination.

Hepatitis B virus (HBV)

HBV is transmitted through blood, sexual contact, or mother to newborn routes. In a HBV infected individual, blood has the highest concentration of the virus while other body fluids (e.g., semen, vaginal secretions, and wound exudates) have lower concentrations. Symptoms usually develop from 6 weeks to 6 months after exposure to the virus. Most of the HBV infection (~95%) in adults is a one-time infection and the rest become chronic. The outcome is the opposite in infants: 90% will be chronic. Chronic HBV infection can lead to liver cirrhosis and liver cancer. Vaccination is available and highly effective. All children and individuals at risk are recommended to get a HBV vaccination.

Hepatitis C virus (HCV)

HCV infection is the most common chronic blood borne infection in the United States. It is mostly transmitted through blood, such as blood transfusion, needle puncture, use of injecting drugs, etc. Occupational exposures, sexual contact, and mother to newborn routes can also result in transmission of HCV. Most of the newly infected people usually have no symptoms or barely recognizable illness. Only a small portion (15-20%) of hepatitis C infection is a one-time infection. Most of the HCV infections progress to chronic. Chronic HCV infection can cause liver cirrhosis and liver cancer. No HCV vaccine is available today to prevent HCV infection.

Hepatitis D virus (HDV)

Hepatitis D infection is rare. HDV only infects people with HBV infection. It can be acute or chronic.

Hepatitis E virus (HEV)

Hepatitis E virus is also rare. It has a similar transmission route to HAV. It usually results in an acute infection, and does not lead to a chronic infection.

Cytomegalovirus (CMV) and Epstein-Barr virus (EBV)

Cytomegalovirus (CMV), Epstein-Barr virus (EBV), and other virus can also cause inflammation in liver, especially in immune compromised person.

Symptoms and Signs

Hepatitis can be acute or chronic. Acute hepatitis means it lasts less than six months and chronic means it persists longer.

Acute hepatitis

Patient may have no symptom at all. Most people acute hepatitis will have nonspecific flu-like symptoms initially, such as mild fever, headache, nausea, vomiting, malaise, muscle and joint aches, diarrhea, etc. Abdominal discomfort or pain, loss of appetite, dark urine, yellowing of the skin and eyes, which is called jaundice, can also happen. Sometimes, enlarged liver, spleen, or lymph notes can occur. Rarely, it can lead to acute liver failure and even death without prompt liver transplant.

Chronic hepatitis

Patient with chronic hepatitis may have no symptoms. A lot of people only experience symptoms such as fatigue, vague abdominal discomfort or pain, decreased appetite, tiredness, weakness, etc. If jaundice occurs, the patient usually has a lot of liver damage from chronic inflammation, such as scarring. A lot of scarring in the liver is called cirrhosis, which is a serious liver condition. Once cirrhosis happens, the patient has tendency to have bleeding, infection, fluid in the belly, swelling in legs, yellow skin and eyes, confusion and coma, renal failure, difficulty breathing, cancer, etc. Patient with cirrhosis should be evaluated for liver transplant.

Diagnosis and Treatment

Diagnosis is to detect the infected virus, which type, how much; to assess liver damage and effects to other organs. This usually involves one or more of the following tests:

  • Blood works
  • Paracentesis
  • Abdominal ultrasound
  • CT scan
  • MRI/MRCP
  • Liver biopsy
  • Endoscopy
  • ERCP
  • EUS

Treatment is based on the type of virus, acute vs chronic, how much liver damage, complications, etc.

References:

  1. PubMed Health.
  2. Wikipedia.
  3. Mayo clinic online health information.
  4. Sleisenger and Fordtran's Gastrointestinal and Liver Disease- by Mark Feldman MD, et al.
  5. The Little Black Book of Gastroenterology-by David W. Hay.
  6. Principles of Clinical Gastroenterology by Tadataka Yamada, et al.


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