The tattooing paradox: are studies of acute hepatitis adequate to identify routes of transmission of subclinical hepatitis C infection?

BACKGROUND: The Hepatitis Branch of the Centers for Disease Control and Prevention does not recommend routine regulation and inspection of tattoo parlors because surveillance of hepatitis C virus (HCV)-positive acute hepatitis cases rarely identifies tattooing in the incubation period. However, the majority of seroepidemiological studies agree that tattooing is a strong, independent risk factor for subclinical HCV seropositivity. We postulated that this paradox might be explained if transmission of HCV by tattooing generally caused subclinical HCV seropositivity without the acute hepatitis syndrome.
METHODS: We reanalyzed data from a prior seroepidemiological study of 626 consecutive patients who were unaware of their HCV serologic status and whose risk factors were ascertained by interview of an internist. Separate multiple logistic regression models were developed to predict a history of the acute hepatitis syndrome and HCV seropositivity.
RESULTS: A history of injection-drug use was strongly associated with both HCV seropositivity (adjusted odds ratio [AOR], 7.2; 95% confidence interval [CI], 3.1-16.5) and a history of acute hepatitis (AOR, 5.9; 95% CI, 2.5-13.8), whereas having a commercially applied tattoo was strongly associated with HCV seropositivity (AOR, 6.5; 95% CI, 2.9-14.4) but not with a history of acute hepatitis (AOR, 1.2; 95% CI, 0.5-3.3).
CONCLUSIONS: Intravenous injection of relatively large quantities of innocula of HCV may be more likely to result in the relatively rare acute HCV hepatitis syndrome, whereas intradermal exposure to small quantities of innocula may cause only subclinical HCV infections. If so, public policy on regulation and inspection of tattoo parlors should be determined by seroepidemiological studies rather than by the Sentinel Counties Study of acute hepatitis cases.