Friday, August 19, 2011

Hepatitis C

What is Hepatitis C?
Hepatitis C infection is an infection of the liver caused by the hepatitis C virus (HCV). It is difficult for the human immune system to eliminate HCV from the body, and infection with HCV usually becomes chronic. Over decades, chronic infection with HCV damages the liver and can cause liver failure. Although the basic structure is common to all hepatitis C viruses, there are at least six distinctly different strains of the virus which have different genetic profiles (genotypes).The genetic diversity of HCV is one reason that it has been difficult to develop an effective vaccine since the vaccine must protect against all genotypes.

What causes Hepatitis C?
The exact causes of hepatitis c, for any particular hepatitis patient, are never conclusively proven. Unsafe blood transfusions, drug usage, unprotected sex and inadequate sterilizations are some of the causes.

Who is at risk of contracting Hepatitis C?
Currently, screening for HCV is not recommended as part of a routine physical examination. Rather, testing should be done among:
  • Individuals at high risk for infection including current and past users of injectable drugs and persons exposed to infected blood or organs from infected persons
  • Children born to chronically infected mothers
  • People who received blood, blood products, or transplanted organs prior to 1992
  • Persons with abnormal levels of liver enzymes in the blood.

What are the symptoms?
About 75% of people have no symptoms when they first acquire HCV infection. The remaining 25% may complain of fatigue, loss of appetite, muscle aches or fever. Yellowing of the skin or eyes (jaundice) is rare at this early stage of infection.
As cirrhosis develops, symptoms increase and may include: weakness, loss of appetite, weight loss, breast enlargement in men, a rash on the palms, difficulty with the clotting of blood, and spider-like blood vessels on the skin.
In patients with advanced cirrhosis, the liver begins to fail. This is a life-threatening problem. Confusion and even coma (encephalopathy) may result from the inability of the liver to process certain toxic substances.
Increased pressure in the blood vessels of the liver (portal hypertension) may cause fluid to build up in the abdominal cavity (ascites) and result in engorged veins in the swallowing tube (esophageal varices) that tear easily and can bleed suddenly and massively. Portal hypertension also can cause kidney failure or an enlarged spleen resulting in a decrease of blood cells and the development of (anemia), or the development of low platelets (thrombocytopenia), which can promote bleeding. In advanced cirrhosis, liver failure causes decreased production of clotting factors.

How is it diagnosed?
Screening tests are tests that are used to diagnose a condition or disease among individuals not known to have the disease. They are particularly useful for individuals who have risk factors for the condition or disease.
Recombinant immunoblot assay (RIBA) is used to confirm the positive results of EIAs since occasionally a positive EIA is a false positive, that is, the test is positive when HCV is not present. Although the direct detection of HCV RNA (HCV PCR) also is widely used to confirm the HCV infection, RIBA is still useful to differentiate false positive results in the few individuals whose immune systems have eliminated the virus but still have antibodies left over from the resolved infection.
Several tests (assays) are available to measure the amount of HCV RNA in a person's blood. These tests are referred to as molecular tests because they examine the virus at the molecular level. A single negative test for RNA does not mean that there is no infection because the virus may appear in the blood intermittently or may exist in small amounts. Newer tests have helped by detecting smaller and smaller amounts of virus in the blood.

How is it treated?
Patients with HCV infection should discuss treatment options with a physician who is experienced in treating the disease. Treatment is recommended in patients at increased risk for cirrhosis unless there are reasons that would make treatment unsafe. the decision regarding antiviral therapy in chronic HCV infection should be tailored to the individual patient with careful consideration of the risks and benefits.
All patients with HCV should be vaccinated against hepatitis B and hepatitis A. They also should be counseled on measures to prevent the spread of HCV and eliminating alcohol use. Finally, risk behaviors for HCV overlap with those of HIV, and all patients with HCV should be tested for HIV.

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