The hepatitis C virus was discovered in 1989 thanks entirely to the discipline of molecular biology. The hepatitis C virus has never been conclusively seen under the electron microscope, knowledge of its existence being based entirely on cloning of its genetic material.

Prior to the discovery of the hepatitis C virus, one type of infectious hepatitis was referred to as ‘non-A, non-B’ hepatitis. Individuals with this disease had clinical or laboratory evidence of hepatitis without evidence of hepatitis A or B virus infection.

Studies of patients with ‘non-A, non-B’ hepatitis found an association between the disease and a recent history of blood transfusion or injected drug abuse, and in 1989 scientists identified the hepatitis C virus as the pathogen. The discovery of at least six distinct strains (genotypes) of the hepatitis C virus complicates the picture even more.