Estimating acute viral hepatitis infections from nationally reported cases.

OBJECTIVES

Because only a fraction of patients with acute viral hepatitis A, B, and C are reported through national surveillance to the Centers for Disease Control and Prevention, we estimated the true numbers.

METHODS

We applied a simple probabilistic model to estimate the fraction of patients with acute hepatitis A, hepatitis B, and hepatitis C who would have been symptomatic, would have sought health care tests, and would have been reported to health officials in 2011.

RESULTS

For hepatitis A, the frequencies of symptoms (85%), care seeking (88%), and reporting (69%) yielded an estimate of 2730 infections (2.0 infections per reported case). For hepatitis B, the frequencies of symptoms (39%), care seeking (88%), and reporting (45%) indicated 18 730 infections (6.5 infections per reported case). For hepatitis C, the frequency of symptoms among injection drug users (13%) and those infected otherwise (48%), proportion seeking care (88%), and percentage reported (53%) indicated 17 100 infections (12.3 infections per reported case).

CONCLUSIONS

These adjustment factors will allow state and local health authorities to estimate acute hepatitis infections locally and plan prevention activities accordingly.