HCV is transmitted primarily through percutaneous (parenteral) exposure that can result from injection drug use, needle stick injuries, and inadequate infection control in health-care settings. Much less often, HCV transmission occurs among
HIV-positive persons, especially MSM, as a result of sexual contact with an HCV-infected partner (29, 30), among persons who receive
tattoos in unregulated settings (30), and among infants born to HCV-infected mothers (31).
After adjustment for non-sampled populations in NHANES, there are an estimated 3.2 million chronically HCV-infected persons in the United States (32). After adjustment for populations not sampled in the NHANES household surveys (32), such as the incarcerated and homeless, there are an estimated 3.2 million chronically HCV-infected persons in the United States (11).
A single positive anti-HCV result cannot distinguish between acute and chronic HCV infection or between current or cleared HCV infection. Approximately 75%-85% of newly infected adults and adolescents develop chronic infection and making this distinction requires a health department to follow-up with a provider to determine if there were symptoms for reporting purposes. Laboratory criteria in the 2012 case definition for past or present HCV infection require one or more of the following: anti-HCV positive (repeatedly reactive) by EIA, verified by at least one more specific assay, or HCV RIBA positive, or HCV nucleic acid test (NAT) positive, or anti-HCV screening-test positive with an assay-specific signal-to-cutoff ratio predictive of a true case. In 2013, the RIBA test was phased out in the United States and the revised testing algorithm has been published (33). This assessment requires, on average, review Division of Viral Hepatitis, CDC of at least 4 records by hepatitis surveillance staff in health departments (34). No clinical symptoms are required; however, the case must be known to not be an acute case.
Because of the high burden of current HCV infection in the United States and because no vaccine is available for preventing infection,
national recommendations (35) emphasize other primary prevention activities, including screening and testing blood donors, inactivating HCV in plasma-derived products, testing persons at risk for HCV infection and providing them with risk-reduction counseling, and consistently implementing and practicing infection control in healthcare settings.
In 2010, the FDA approved point-of-care tests for HCV infection, which meant that patients could receive HCV test results within the same visit and faster referral to care (36). In 2012, CDC augmented existing risk-based recommendations for HCV testing by recommending one-time screening for HCV infection among all those born during 1945-1965 (37). It is estimated that persons born during these years have a 3% prevalence of HCV antibodies, which is five times higher than the prevalence seen in adults born in other years. Of all persons living with HCV infection, about 75% were born during 1945-1965; a similar percentage of HCV-associated deaths can be attributed to this birth cohort (37). The goal of birth-cohort HCV testing
is to identify unrecognized infections among the segment of the population with the largest risk of HCV-associated morbidity and mortality, thereby increasing opportunities for persons infected with HCV to benefit from appropriate care and treatment.
Linkage to care and treatment is critical to improving health outcomes for persons found to be infected with HCV. Such linkage is particularly important in light of the major advancements that have been made in HCV treatments. For patients infected with HCV, treatment has previously consisted of pegylated interferon combined with oral doses of ribavirin (38). Approximately 40%-50% of HCV-infected patients receiving this therapy cleared their infection (38).
However, HCV treatment improved drastically in 2011 with the development of the initial direct-acting oral agents, telaprevir and boceprevir, which were capable of achieving a sustained virologic response rate of >80% (38, 39). These two drugs were available during the reporting period in 2013 that this Surveillance Report covers, but are now discontinued in the United States because of the development of newer all-oral direct-acting antiviral agents.
In 2013, the FDA approved the use of simeprevir and sofosbuvir (40). When given in combination with pegylated interferon and ribavirin or together as an all-oral combination regimen for a shorter duration of 8-12 weeks, these agents increase virologic cure rates to >90% (41, 42).
In 2014, two new all-oral regimens, Harvoni (ledipasvir/sofosbuvir) and Viekira Pak (ombitasvir, paritaprevir, and ritonavir tablets; dasabuvir tablets), were licensed for the treatment of HCV. These four agents are now the standard-of-care for HCV treatment in the United States.
Evidence-based guidance is available from AASLD/IDSA to assist providers caring for HCV-infected patients (43). The AASLD/IDSA HCV gui
dance is continuously updated to incorporate new information regarding HCV testing, linkage to care, and treatment (https://www.hcvguidelines.org).