In January 2012, the Council for State and Territorial Epidemiologists (CSTE) expanded the acute hepatitis C virus (HCV) case definition to include individuals with a documented negative HCV antibody (anti-HCV) or HCV RNA test followed within 6-months by a positive test. In November 2014, health department officials in California were notified of such an anti-HCV seroconversion in an asymptomatic repeat blood donor.
Local health department officials interviewed the index case to assess risk behaviors and exposures, including any health care encounters between last negative test on 9/2/14 and first positive test on 10/28/14. Subsequently, testing for hepatitis B virus (HBV), HCV and human immunodeficiency virus (HIV) was recommended for patients seen at a clinic where the index patient received injections.
The index case denied risk behaviors associated with HCV infection, but reported several healthcare encounters during the exposure window which instigated investigations into three clinics. Of the clinics investigated, unsafe injection practices were noted at a ‘prolotherapy’ (injection of an irritant into joints) clinic, which was subsequently closed. Review of clinic records revealed 399 patients were seen during the 10-month period that began 5-months before documented seroconversion of the index case, and ended with the clinic closure. HCV test results were available for 248 of 399 patients (62%). Including the index case, 8/240 (3.3%) were HCV-positive; 4 of the 8 had acute infection, as defined by the updated CSTE definition. Of the 4 patients with acute infection, 3 were asymptomatic. Three of the acute cases received injections on the same clinic visit day.
Conclusion: Most cases of acute HCV infection identified in this outbreak were asymptomatic and those infected denied risk behaviors; these cases would not have been identified by the pre-2012 CSTE case definition. This outbreak illustrates how a possible healthcare associated exposure is often undetected and uninvestigated since about 70% of new HCV infections are asymptomatic. HCV seroconversion can signal a ‘sentinel’ event in healthcare associated exposure that warrants further investigation.
C. Grigg, None
M. Choi, None
J. Forbi, None
T. Hayden, None
J. Kim, None
P. Batson, None
T. Wada, None
C. Dean, None