A fairly common systemic disease, viral hepatitis is marked by hepatocellular destruction, necrosis, and autolysis, leading to anorexia, jaundice, and hepatomegaly. In most patients, hepatic cells eventually regenerate with little or no residual damage. Advanced age and serious underlying disorders make complications more likely. The prognosis is poor if edema and end-stage liver disease develop.
There are six types of hepatitis:
Type A (infectious or short-incubation hepatitis) is rising among homosexuals and in people with immunosuppression related to human immunodeficiency virus (HIV) infection. It’s usually self-limiting and without a chronic form. About 40% of cases in the United States result from hepatitis A virus.
Type B (serum or long-incubation hepatitis) is also increasing among HIV-positive individuals.
Hepatitis B is considered a sexually transmitted disease because of its high incidence and rate of transmission by this route.
Routine screening of donor blood for the hepatitis B surface antigen (HBsAg) has decreased the incidence of posttransfusion cases, but transmission by needles shared by drug abusers remains a major problem. Acute signs and symptoms usually begin insidiously and last for 1 to 4 weeks. Urticaria or arthralgia that’s experienced before any signs of jaundice is highly suggestive of hepatitis B infection. A chronic, potentially infectious state develops in about 10% of infected adults and in 70% to 90% of infected infants. This chronic state is associated with progressive liver disease in some individuals. Fulminant hepatitis can ensue, and there’s an increased risk of primary hepatocellular carcinoma.
Type C accounts for about 20% of all viral hepatitis cases and is primarily transmitted through blood and body fluids or obtained during tattooing.
Type D (delta hepatitis) is responsible for about 50% of all cases of fulminant hepatitis, which has a high mortality. Developing in 1% of patients, fulminant hepatitis causes unremitting liver failure with encephalopathy. It progresses to coma and commonly leads to death within 2 weeks.
In the United States, type D hepatitis is confined to people who are frequently exposed to blood and blood products, such as I.V. drug users and hemophiliacs. It’s transmitted parenterally and, less commonly, sexually.
Type E (formerly grouped with type C under the name non-A, non-B hepatitis) occurs primarily in people who have recently returned from an endemic area (such as India, Africa, Asia, or Central America); it’s more common in young adults and more severe in pregnant women.
The major forms of viral hepatitis result from infection with the causative viruses: A, B, C, D, E, or G.
Type A hepatitis
Hepatitis A is highly contagious and usually transmitted by the fecal-oral route. It may also be transmitted parenterally.
I.V. drug abusers and recipients of multiple blood product transfusions are at increased risk for hepatitis A.
Hepatitis A usually results from ingestion of contaminated food, milk, or water. Outbreaks of this type are commonly traced to ingestion of seafood from polluted water.
Type B hepatitis
Once thought to be transmitted only by the direct exchange of contaminated blood, hepatitis B is now also known to be transmitted by contact with human secretions and stool passed by health care workers, recipients of plasma-derived products, and hemodialysis patients. As a result, nurses, physicians, laboratory technicians, and dentists are frequently exposed to type B hepatitis, commonly as a result of wearing defective gloves.
Transmission also occurs during intimate sexual contact and through perinatal transmission.
Type C hepatitis
Although hepatitis C viruses have been isolated, only a small percentage of patients have tested positive for them, perhaps reflecting the test’s poor specificity. Usually, this type of hepatitis is transmitted through transfused blood from asymptomatic donors and receiving tattoos.