Viral genome encodes a single protein, HDAg, that has two isoforms, large and small
Epidemiology
Blood-borne infection transmitted by blood and secretions
Only requires small inoculum to cause infection
Coinfection of about 5% of hepatitis B-infected people
Present worldwide, but more common in the Middle East, Africa, and eastern Europe, as well as older patients from the Mediterranean Basin
Areas with the highest prevalence in the world include parts of Central and West Africa (especially Mauritania and Gabon), parts of the Amazon basin, the Middle East, India, Pakistan, and northern Viet Nam
Higher prevalence among patients coinfected with hepatitis B and HIV
Incubation period of 3 to 7 weeks for superinfection of HDV in a patient already infected with HBV, or 45 to 160 days for new acquisition of both HBV and HDV
Diagnosis
Serology, with anti-HDV IgG, followed by real-time PCR
Viremia fluctuates, so if PCR is negative but suspicion remains, can check anti-HDV IgM
