What Is the Real Epidemiology of Hepatitis D Virus and Why so Many Mixed Messages?

The disease burden of HDV is poorly understood. Our review identified multiple reasons: (1) HDV infection rates are overestimated in the general population due to limited sample sizes, sampling high-risk populations, and significant regional variations, (2) estimates are based on chronic HBV populations, but HBV burden itself is uncertain, (3) there is a lack of testing in at-risk populations, (4) prevalence testing is based on HDV antibody testing and not HDV RNA, which distinguishes between active infection versus prior exposure, (5) older studies used less reliable testing and (6) HBV vaccination programs have affected HDV prevalence, but is often not accounted for.