Hepatitis is inflammation of the liver due to a viral infection. Even though the liver is involved in all types of hepatitis, the virus type, route of transmission, natural history and treatment protocols are different between the types of hepatitis. This article will discuss the virus type, route of transmission, signs and symptoms, investigation and diagnosis, natural history, and treatment protocols of each type of hepatitis and compare them to differentiate one from the other.
Hepatitis A is a food and water borne infection. Hepatitis A virus is a RNA virus. Usually travelers to tropical countries fall victim to this infection. Children get this infection easily. Virus enters the body via food or water and incubates for 3 to 6 weeks before causing prodromal symptoms like fever, ill health, lethargy, body ache, joint pains. During the active phase, yellowish discoloration of eyes develops with liver, spleen and lymph node enlargement.
Full blood count shows low white blood cell count and low platelets. Serum transaminases rise during the active phase. AST and ALT rise are more than ALP rise. ALT rises more than AST. Serum IgM rises after 25 days of exposure to indicate recent infection. After sero-conversion IgG remains detectable for life.
Treatment is supportive. Food hygiene, strict individual use of crockery to limit the spread, fluid intake, maintaining good renal function, and avoiding alcohol are important steps. There are various preventive methods. Passive immunization with immunoglobulin provides protection for 3 months and is recommended for travelers. Active immunization with a purified protein from the virus gives immunity for 1 year. If a booster dose is administered 6 months after the first dose, there will be immunity for 10 years. (Difference Between Active and Passive Immunity)
Hepatitis A is self-limiting but fulminant hepatitis is a rare possibility. Chronic hepatitis does not occur with hepatitis A.
Hepatitis B is a blood borne infection. Blood transfusion, unprotected sexual contact, hemodialysis, intravenous drug abuse are known risk factors. After the virus enters the body, it remains dormant for 1 to 6 months before giving rise to prodromal symptoms like fever and lethargy. Extra-hepatic features are more common in hepatitis B. During the acute stage liver and spleen enlargement occur.
Full blood count may show lymphocytic leukocytosis. AST levels rise 2 to 4 months after exposure and returns to baseline after the 5th month. HBsAg is positive in serum from 1-6 months. If HBsAg is positive after 6 months, it suggests chronic career state. HBeAg is positive in serum from 2 to 4 months and denotes a high infective state. In liver biopsy, immunofluorescence HBcAg and HBeAg are positive from 2 to 4 months. Antibodies against HBsAg appear 6 months after exposure, and anti-HBsAg is the only marker that is positive in vaccinated individuals. Anti-HBeAg becomes positive after 4 months. If anti-HBCAg is positive, it denotes a past infection. Complications include carrier state, relapse, chronic hepatitis, cirrhosis, superinfection with hepatitis D, glomerulonephritis, and hepatocellular carcinoma. If HBsAg is positive, the risk increases 10 fold. If both HBsAg and HBeAg are positive, the risk increases 60 fold. Fulminant hepatitis is rare.
Treatment is supportive. Alcohol avoidance is essential.
Hepatitis C is a RNA virus. It is also blood borne. Intravenous drug abuse, hemodialysis, blood transfusion, and sexual contact increase the risk of contracting the disease. Chronic hepatitis is very common after hepatitis C infection. Around 20% get cirrhosis. Hepatocellular carcinoma risk is also high with hepatitis C. Presentations are similar to hepatitis B.
AST and ALT both increase, but AST remains lower than ALT till cirrhosis develops. Hepatitis C Ag is positive during active infection. Treatment is supportive. In chronic hepatitis, interferon Alfa and ribavirin may be used. Peginterferone Alfa may be more effective than interferon Alfa. Evidence suggests that interferon Alfa reduces the progression into a chronic state when given during the acute stage.
Hepatitis D and E
Hepatitis D only exists with hepatitis B and increases the risk of hepatocellular carcinoma. Hepatitis E is similar to hepatitis A and causes a high degree of mortality in pregnancy.
What is the difference between Hepatitis A, B and C?
• Hepatitis A and C are RNA viruses while hepatitis B is a DNA virus.
• Hepatitis B and C are blood borne while A is food borne.
• Hepatitis B and C cause chronic hepatitis while A does not.
• Hepatitis B and C increase the risk of hepatocellular carcinoma while A does not.
• All three types may cause fulminant hepatitis.