The World Health Organization (WHO) and the International Agency for Research on Cancer (IARC) have officially classified the Hepatitis D virus (HDV) as carcinogenic to humans. This places HDV alongside Hepatitis B and Hepatitis C as major causes of liver cancer, cirrhosis, and chronic liver disease progression.The reclassification is based on increasing evidence of HDV’s severe health risks, especially its role in accelerating liver damage and cancer in co-infected individuals. This important update emphasises the urgent need for better awareness, expanded testing, early diagnosis, vaccination strategies, and improved treatment options to combat HDV and reduce the global burden of liver cancer and liver-related deaths.Understanding Hepatitis D Virus (HDV) and its symptomsHepatitis D is a unique and dangerous virus that requires the presence of Hepatitis B virus (HBV) to infect and replicate. HDV cannot infect people on its own; it "hijacks" the HBV infection process, resulting in more severe liver disease when both viruses coexist.Symptoms of HDV infection often overlap with other liver diseases and can be easily overlooked. Common signs include:Fatigue and weaknessNausea and loss of appetiteAbdominal pain or discomfort, especially in the upper right sideDark-coloured urineYellowing of the skin and eyes (jaundice)Unexplained weight lossFeverBecause symptoms may be mild or mistaken for other illnesses, many individuals delay seeking medical care, increasing the risk of serious liver damage.What causes Hepatitis D virus infectionHDV spreads primarily through direct contact with infected blood or bodily fluids. Common modes of transmission include:Infected blood transfusions or blood productsUnprotected sexual contact with an infected personSharing needles or syringes among people who inject drugsUnsafe medical procedures involving non-sterile equipmentMother-to-child transmission during childbirth (less common)Because HDV can only infect individuals already carrying HBV, anyone with chronic hepatitis B is at risk of contracting HDV.Who is at risk of Hepatitis D InfectionPopulations at higher risk for HDV infection include:People living in regions with high HBV prevalence such as parts of Asia, Africa, and the Amazon BasinPeople who inject drugs and share needlesPatients receiving haemodialysis or undergoing frequent blood transfusionsIndividuals with multiple sexual partners or those who engage in unprotected sexInfants born to mothers infected with both HBV and HDVAwareness and screening in these groups are essential for early detectionGlobal impact: How widespread is Hepatitis DAccording to the WHO, over 300 million people worldwide are infected with hepatitis B, C, or D, contributing to about 1.3 million deaths annually, mostly from liver cirrhosis and liver cancer complications and limited access to early diagnosis or effective treatment. About 5% of chronic HBV carriers, roughly 12 million people worldwide, are co-infected with HDV.Why is Hepatitis D considered dangerousCo-infection with HDV dramatically worsens liver health outcomes. Research shows:HDV increases the risk of liver cancer by two to six times compared with HBV infection alone.Up to 75% of chronic HDV patients develop liver cirrhosis within 15 years, which is significantly higher than HBV-only cases.HDV accelerates liver inflammation and damage, raising the risk of severe complications and death.Current treatment options for Hepatitis DWhile chronic HBV infection can be managed with lifelong antiviral therapies, treatment options for HDV are limited but improving:Bulevirtide: Approved in Europe, this antiviral helps block HDV entry into liver cells, improving outcomes, especially when combined with pegylated interferon.Pegylated interferon: Sometimes used to suppress HDV replication, but effectiveness varies.No specific hepatitis D vaccine exists; prevention depends on hepatitis B vaccination, which protects against both HBV and HDV infections.Progress in global hepatitis B vaccination and testingVaccination remains the most effective prevention method. As of 2025:129 countries have adopted hepatitis B testing for pregnant women (up from 106 in 2024).147 countries provide the hepatitis B birth dose vaccine (up from 138 in 2022).These efforts are critical to preventing HBV and consequently HDV transmission.Expert recommendations to combat Hepatitis DTo achieve WHO’s hepatitis elimination goals by 2030, health authorities must:Scale up hepatitis B vaccination coverage worldwideEnsure universal testing of HBV-positive individuals for HDVExpand access to novel HDV therapies and affordable medicinesStrengthen healthcare infrastructure and data systemsCombat stigma and discrimination around viral hepatitis to encourage testing and treatmentMeeting these goals could save 2.8 million lives and prevent 9.8 million new infections by 2030.Also read | Testicular cancer symptoms men often miss: Know the risks, treatment options, and what to watch for