All about hepatitis D, deadly viral hepatitis given a ‘cancer' tag by WHO

The Print

3 days ago

Hepatitis D or HDV, which only affects individuals infected with hepatitis B, is associated with a two- to six-fold higher risk of liver cancer compared to hepatitis B alone, according to the IARC.
Viral hepatitis, characterised by inflammation of the liver, can be caused by the five known hepatitis viruses—A, B, C, D and E. Among these, only hepatitis B, C, and D can lead to chronic infections that significantly increase the risk of cirrhosis, liver failure, or liver cancer.
New Delhi: The World Health Organisation-International Agency for Research in Cancer (WHO-IARC) has now declared hepatitis D, a little-known but deadly viral hepatitis, as carcinogenic, expressing hope that this will lead to more screening and access to new treatments.
It is estimated that globally, 48 million people are affected with HDV, which in combination with the hepatitis B virus, has the highest fatality rate of all the hepatitis infections, at 20 percent.
Its prevalence is highest in low- and middle-income regions in Africa and Asia, apart from the Amazon basin and India. Scientific evidence has shown that 8-37 percent, depending on the region, of those infected with hepatitis B, also have HDV.
A 2024 report by the WHO had said that India had over 3.5 crore cases of viral hepatitis—including 2.98 crore hepatitis B cases—in 2022, accounting for 11.6 percent of the total disease burden globally that year.
Over 1.25 lakh people, the report suggested, had died due to hepatitis B and C in India that year.
Senior gastroenterologists and public health professionals suggested that HDV is largely undetected in the country, mainly because of lack of screening, and is more prevalent in some parts of east India and among people infected with HBV.
'From a public health perspective, this classification by WHO-IARC highlights the importance of incorporating HDV awareness, screening, and prevention into the existing hepatitis B prevention programme,' Dr Saswata Chatterjee, gastroenterologist with the Calcutta Medical Research Institute (CMRI), told ThePrint.
With liver cancer becoming a challenging burden, screening and early detection of co-infections, such as HDV, will be crucial in reducing chronic complications of viral hepatitis, he added.
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HBV triggers rapid progression to end-stage liver failure
Dr Piyush Ranjan, senior gastroenterologist with Sir Ganga Ram Hospital in Delhi, explained that HDV is a satellite virus that requires hepatitis B virus (HBV) for replication, causing the most aggressive form of viral hepatitis.
Compared to hepatitis B and C, HDV leads to more rapid progression to cirrhosis and liver cancer. In clinical terms, explained CMRI's Dr Chatterjee, HDV occurs as a co-infection—when it is contracted simultaneously with HBV—or a superinfection—when an individual who is chronically infected with HBV becomes infected with HDV.
While HBV increases the risk of developing liver complications, HDV increases this risk substantially, accelerating the progression of liver fibrosis, cirrhosis and malignancy.
The mode of transmission of this hepatitis virus is similar to hepatitis B and C—through contaminated injections, mother to child, and sexual contact.
Dr Vibhor Sharma, a medical oncologist with Asian Hospital, highlighted that co-dependency of HDV on HBV leads to making hepatitis worse in patients.
'HDV-triggered liver disease is more severe as it can result in end-stage liver failure in less than ten years,' he said, adding that as compared to the general population in India, this form of hepatitis is seen more commonly in intravenous drug users, HIV/AIDS patients and those with chronic HBV.
The declaration by the WHO-IARC is crucial, said the medical oncologist as HDV, despite its aggressiveness in triggering liver cancers, is mostly undiagnosed and is grossly underreported in developing countries such as India.
Prevention and management
Clinicians say HDV is preventable at a low cost, through immunisation. The effective methods to prevent both HBV and HDV are the vaccines against hepatitis B, safe blood practices, sterilisation of medical equipment, and safe sex practices, said Dr Chatterjee.
The HBV vaccine in India, as part of the Union government 's Universal Immunization Programme, was piloted in 2002-03 and then scaled up in the entire country in 2010 to protect children from the acute infection.
It is now provided as part of the pentavalent vaccine at 6, 10 & 14 weeks apart from the birth dose of hepatitis B vaccine.
However, a 2020 study from India said that although the coverage of third-dose hepatitis B vaccine has reached 86 percent in the country, the birth dose coverage was under 50 percent in 2015 despite high rates of institutional deliveries.
The WHO says that while treatment with oral medicine can cure hepatitis C within 2 to 3 months and effectively suppress hepatitis B with life-long therapy, treatment options for hepatitis D are evolving.
Sir Ganga Ram's Dr Ranjan maintained that for those already infected, management is challenging, with limited approved therapies, though newer agents like bulevirtide—an antiviral therapy especially developed against the condition—offer promise.
'The carcinogen tag will hopefully intensify global surveillance, funding, and research to curb the burden of HDV-associated liver cancer,' said the gastroenterologist.
(Edited by Gitanjali Das)
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