Epidemiology of Acute HCV
In the United States, during the 1980s, an estimated average of 230,000 new hepatitis C virus (HCV) infections occurred each year.[1] After 1989, however, the annual estimated number of acute (new) HCV infections steadily declined until 2005, followed by a leveling off between 2006 through 2010, and then a steady increase from 2010 through 2018 (Figure 1).[2] The Centers for Disease Control and Prevention (CDC) data shows an increase of approximately 4-fold in the estimated annual number of acute (new) HCV infections in the United States from 2010 through 2018, with a peak of 50,300 new infections in 2018 (Figure 2).[2] Among different age groups, persons 20 to 29 and 30 to 39 had the highest number (Figure 3) and rate (Figure 4) of reported acute new HCV infections in 2018.[2] The current opioid epidemic in the United States is the predominant force driving the increase in new HCV infections, particularly in young adults.[3,4] In addition, an increase in acute HCV infections has been recognized among men who have sex with men, particularly men living with HIV infection who engage in condomless anal sex and use methamphetamine associated with sex.[5]
Definition of Acute HCV Infection
Most experts define acute HCV infection as the 6-month time period following acquisition of HCV.[6,7,8] The definition of acute HCV infection does not depend on the presence or absence of symptoms associated with the acute HCV infection because most infections are subclinical. The preferred accepted laboratory diagnosis of acute HCV infection 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