Toward a more accurate estimate of the prevalence of hepatitis C in the United States.

UNLABELLED: Data from the 2003-2010 National Health and Nutrition Examination Survey (NHANES) indicate that about 3.6 million people in the United States have antibodies to the hepatitis C virus, of whom 2.7 million are currently infected. NHANES, however, excludes several high-risk populations from its sampling frame, including people who are incarcerated, homeless, or hospitalized; nursing home residents; active-duty military personnel; and people living on Indian reservations. We undertook a systematic review of peer-reviewed literature and sought out unpublished presentations and data to estimate the prevalence of hepatitis C in these excluded populations and in turn improve the estimate of the number of people with hepatitis C in the United States. The available data do not support a precise result, but we estimated that 1.0 million (range 0.4 million-1.8 million) persons excluded from the NHANES sampling frame have hepatitis C virus antibody, including 500,000 incarcerated people, 220,000 homeless people, 120,000 people living on Indian reservations, and 75,000 people in hospitals. Most are men. An estimated 0.8 million (range 0.3 million-1.5 million) are currently infected. Several additional sources of underestimation, including nonresponse bias and the underrepresentation of other groups at increased risk of hepatitis C that are not excluded from the NHANES sampling frame, were not addressed in this study. CONCLUSION: The number of US residents who have been infected with hepatitis C is unknown but is probably at least 4.6 million (range 3.4 million-6.0 million), and of these, at least 3.5 million (range 2.5 million-4.7 million) are currently infected; additional sources of potential underestimation suggest that the true prevalence could well be higher.

Induction of CXCR3- and CCR5-associated chemokines during acute hepatitis C virus infection.

BACKGROUND & AIMS: Characterization of inflammatory mediators, such as chemokines, during acute hepatitis C virus (HCV) infection might shed some light on viral clearance mechanisms. METHODS: Plasma levels of CXCR3 (CXCL9-11)- and CCR5 (CCL3-4)-associated chemokines, ALT, and HCV RNA were measured in nine injection drug users (median 26 samples/patient) before and during 10 acute (eight primary and two secondary) HCV infections. Using functional data analysis, we estimated smooth long-term trends in chemokine expression levels to obtain the magnitude and timing of overall changes. Residuals were analyzed to characterize short-term fluctuations. RESULTS: CXCL9-11 induction began 38-53days and peaked 72-83days after virus acquisition. Increases in ALT levels followed a similar pattern. Substantial negative auto-correlations of chemokine levels at 1 week lags suggested substantial week-to-week oscillations. Significant correlations were observed between CXCL10 and HCV RNA as well as ALT and CXCR3-associated chemokines measured in the preceding week, CCL3-4 expression levels did not change appreciably during acute HCV infection. CONCLUSIONS: Elevation of CXCR3-associated chemokines late during acute HCV infection suggests a role for cellular immune responses in chemokine induction. Week-to-week oscillations of HCV RNA, chemokines, and ALT suggest frequent, repeated cycles of gain and loss of immune control during acute hepatitis C.

Risk factors for hepatitis C seropositivity among young people who inject drugs in New York City: Implications for prevention.

BACKGROUND: Hepatitis C virus (HCV) infection remains a significant problem in the United States, with people who inject drugs (PWID) disproportionately afflicted. Over the last decade rates of heroin use have more than doubled, with young persons (18-25 years) demonstrating the largest increase. METHODS: We conducted a cross-sectional study in New York City from 2005 to 2012 among young people who injected illicit drugs, and were age 18 to 35 or had injected drugs for ≤5 years, to examine potentially modifiable factors associated with HCV among young adults who began injecting during the era of syringe services. RESULTS: Among 714 participants, the median age was 24 years; the median duration of drug injection was 5 years; 31% were women; 75% identified as white; 69% reported being homeless; and 48% [95% CI 44-52] had HCV antibodies. Factors associated with HCV included older age (adjusted odds ratio [AOR], 1.99 [1.52-2.63]; p<0.001), longer duration of injection drug use (AOR, 1.68 [1.39-2.02]; p<0.001),more frequent injection (AOR, 1.26 [1.09-1.45]; p = 0.001), using a used syringe with more individuals (AOR, 1.26 [1.10-1.46]; p = 0.001), less confidence in remaining uninfected (AOR, 1.32 [1.07-1.63]; p<0.001), injecting primarily in public or outdoors spaces (AOR, 1.90 [1.33-2.72]; p<0.001), and arrest for carrying syringes (AOR, 3.17 [1.95-5.17]; p<0.001). CONCLUSIONS: Despite the availability of harm reduction services, the seroprevalence of HCV in young PWID in New York City remained high and constant during 2005-2012. Age and several injection behaviors conferred independent risk. Individuals were somewhat aware of their own risk. Public and outdoor injection and arrest for possession of a syringe are risk factors for HCV that can be modified through structural interventions.