Hepatitis C Nucleic Acid Amplification Testing (NAAT) for Acute Case Detection: A Historical Protocol Repurposed to Combat a Current Outbreak.

Background. In 2011, the Indiana State Department of Health (ISDH) noted an increase of acute Hepatitis C (HCV) infections among young patients (<50 years) with a history of illegal drug use. Due to these observations, the ISDH evaluated the use of pooled NAAT (nucleic acid amplification test) as a strategy for detection of early-acute HCV. This strategy was evaluated over a nine-month period in 2013, with 19 HCV NAAT positive, antibody negative cases detected during this time. These cases were later confirmed by seroconversion, demonstrating the efficacy and benefit of this testing strategy. Due to time and cost restraints, however, this pilot project ended in December 2013. Method. In 2015, a HIV-outbreak in rural southeast Indiana provided refreshed interest in acute HCV diagnostics due to shared risk factors (i.e. injection drug use). Between February-June 2015, outbreak-associated specimens from the outbreak and surrounding counties were tested for both HIV and HCV. Of 1322 specimens, 38.5% (n = 509) were positive for HCV (21.4% were co-infected with HIV, n = 109). The pooled NAAT protocol was revived and adapted for outbreak testing beginning in May 2015. Serum received from 284 HCV antibody-negative samples were pooled into intermediate pools of eight samples. Six intermediate pools were combined into one master pool of 48 samples. Reactive master pools triggered reflex intermediate pool testing, followed by individual specimen assessment from the reactive intermediate pool. Finally, secondary specimen collection was requested to confirm the individual reactive sample. Result. Six NAAT-positive, antibody-negative cases (2.11% of antibody-negative outbreak-associated specimens) were diagnosed with this methodology. This represents a higher prevalence than the 2013 state-wide pilot, which was 0.16%. These results indicate a sustained risk factor in this community, and heightened HCV/HIV testing may be warranted. Conclusion. These data demonstrate the efficacy of pooled NAAT testing for the detection of acute HCV infection in a high risk population. In the future, acute-HCV screening through pooled NAAT may be seen as a useful barometer for the assessment of injection drug usage and risk of HIV-acquisition throughout Indiana. Disclosures. All authors: No reported disclosures.