Journal of the American Medical Association (07/21/99) Vol.
An estimated 4 million people in the United States and 202
million people worldwide may carry the hepatitis C virus
(HCV). As such, HCV will likely be a serious public health
threat well into the 21st century. HCV is the leading cause
of liver transplants in the United States, and it causes
cirrhosis and hepatocellular carcinoma. The virus is usually
asymptomatic for years, so many do not know they are infected
until after they have sustained irreparable liver damage.
Experts are unsure whether all who are infected with HCV will
develop a progressive disease. HCV, which has proven
difficult to study because it does not grow well in
laboratories, is a positive single-stranded RNA with six
different genotypes and 100 subtypes. A single patient may
have many closely-related but distinct viral variants, called
quasispecies. Quasispecies may elude the body's immune
surveillance, worsening chronic infections and causing a lack
of immunity after infection. Quasispecies may also be
associated with the progression of HCV and may influence
treatment. High risk factors for HCV include blood
transfusions or blood products given before 1990, intravenous
drug use, and multiple sex partners.