Hepatitis delta is a major health problem, not only because of the severity of the disease, but also due to the lack of effective antiviral treatment. To improve the current therapeutic options, a better understanding of the pathophysiology is essential. Reliable research in this direction is only possible with large patient study groups. However, given the geographic distribution of hepatitis delta, larger patient cohorts would only be possible through multicenter collaboration.

The hepatitis international network cohort is a multicenter, observational study that will build up a research registry of HDV patients all over the world.

The aims of this project are:

i. Collect clinical information from hepatitis delta patients from multiple centers distributed worldwide in order to build up a large database that will enable and facilitate further research on chronic hepatitis delta.

ii. To better inform patients about their viral infection, present status and evolution of liver disease throughout time. To give them the tools needed to inform other peers and medical professionals about the significance and consequences of a chronic hepatitis delta infection.

iii. To allow the participating physicians to track course of the disease, therapies, signs and symptoms of the hepatitis delta patients included by their center.

Inclusion Criteria:

• Positive HBs antigen and antiHDV for longer than 6 months.

Exclusion Criteria:

Absence of any cause of relevant liver disease other than HDV (i.e. hemochromatosis, autoimmune hepatitis, alcoholic or toxic liver disease, etc.)

Patients with chronic hepatitis delta will be screened regardless of HDV or HBV genotype