Facts and Figures
In the United States, hepatitis delta is estimated to affect approximately 5-10% of people already living with chronic hepatitis B, correlating to fewer than 250,000 coinfections, and classifying it as a rare disease by the National Institutes of Health (NIH). Hepatitis B and delta coinfection is more common in certain parts of the world including Mongolia, Romania, Russia, India, Pakistan, the Middle East, Georgia, Turkey, West and Central Africa, and the Amazonian river basin. Globally 15-20 million people are thought to be affected, although a recent meta-analysis suggested there may be as many as 62–72 million coinfections.
The risk of progression to cirrhosis, including the risk of liver cancer, need for liver transplant, and death is in the 70% range.
Genotypes
There are at least 8 different types of hepatitis delta, called “genotypes,” which are associated with distinct disease progression. In general, a more severe disease occurs in genotypes 1 and 3, and a milder disease in genotype 2. Although a single genotype tends to dominate in an infected person, multiple genotypes can occur in those at high risk for repeated exposure to the virus.
Prevalence and Genotypes of Hepatitis D Around the World
Wedemeyer, Journal of Hepatology, 2018
- Genotype 1– most common and found worldwide, especially in Europe, the Middle East, North America and North Africa
- Genotype 2 – found in Japan, Taiwan and Russia
- Genotype 3 – found exclusively in Amazonian region of South America
- Genotype 4 – found in Japan and Taiwan
- Genotypes 5 - 8 – found primarily in Africa
Genotype testing for hepatitis delta is available from the Centers for Disease Control and Prevention (CDC).
Prevalence in Europe
Geographic areas declared as HDV endemic by the World Health Organization include parts of Africa, Asia, Pacific Islands, the Middle East, Eastern Europe, and Greenland. In Europe, HDV prevalence varies among countries, with lower rates in countries like Austria, Belgium, and France, and higher rates in countries such as Romania, Eastern Turkey, Russia, and Greenland. The prevalence in European countries has been impacted by immigration from endemic regions, contributing to stabilization or increase in HDV prevalence in some areas.
2024 Updated Prevalence Study in 25 Countries
A new study assessed HDV prevalence among HBV-infected individuals across 25 countries/territories, refining earlier estimates. Anti-HDV prevalence varied widely, with the highest rate in Mongolia (60.1%). Adjustments for regional and population heterogeneity led to changes in prevalence estimates in 19 of the 25 countries. While Mongolia had the highest percentage, China reported the largest number of HDV RNA+ cases due to its large HBV-infected population. The findings revealed lower HDV prevalence rates than prior studies, which often focused on high-risk groups. These updated prevalence data provide critical insights for targeting HDV screening and care strategies globally.
Read more here: Adjusted estimate of the prevalence of hepatitis delta virus in 25 countries and territories