Epidemiology of Acute HCV: In the United States, the CDC estimates that during the 1980s, an average of 230,000 new HCV infections occurred each year. By 1989, however, the annual estimated number of new infections declined more than 80% to 36,000 and in 2013 there were approximately 30,000 new cases. Infection with hepatitis C virus (HCV) occurs among persons of all ages, but the highest incidence is found among persons 20 to 39 years of age. The most common risk factor for new HCV infections in the United States is injection drug use (IDU). In addition, acute HCV infections have been increasingly recognized among men who have sex with men, particularly when engaging in unprotected receptive anal intercourse in the setting of methamphetamine use. Among men who have sex with men, the rate of sexual acquisition of HCV is more than 5-fold higher in HIV-infected men than in HIV-uninfected men. The sexually transmitted HCV infections in the HIV-infected population have been associated with methamphetamine use, the practice of serosorting (according to HIV status), sexual practices that may involve mucosal trauma, multiple sexual partners, concurrent sexually transmitted infections, and CD4 cell count less than 500 cells/mm3 in the person who becomes infected.
Definition of Acute HCV Infection: Most experts define acute hepatitis C infection as the 6-month time period following acquisition of hepatitis C virus. The definition of acute hepatitis C does not depend on the presence or absence of symptoms associated with the acute infection. The preferred accepted laboratory diagnosis of acute includes documentation of either of the two following criteria:
- A positive (detectable) HCV RNA in conjunction with a negative HCV antibody, or
- Positive HCV antibody with documentation of a negative HCV antibody in the past 12 months