The hepatitis C virus (HCV) is a common virus of world-wide distribution af
fecting up to 3% of the world's population. Its genetic diversity, with mul
tiple subtypes, and existence in the form of quasispecies in individual hos
e, is, in part, responsible for high rates of chronic infection. Individual
s with HCV infection will undoubtedly present to rheumatologists and other
health care professionals with rheumatic and other immunological disorders
related to what was usually a remote and asymptomatic acute infection. The
goals of this review are: (I) to summarize clinical observations regarding
rheumatological and immunological diseases linked with HCV infection; (2) t
o provide relevant information on the molecular biology of HCV; (3) to disc
uss the state of the art regarding the use of diagnostic studies; (4) to co
nsider the differential diagnosis of liver disease and rheumatic disorders;
and (5) to provide a practical guide to the history, physical examination,
laboratory work-up, disease monitoring, and therapy of HCV patients with r
heumatic disorders.