1. What is Hepatitis D?

     Hepatitis D virus (HDV )is a single-stranded RNA virus of the genus Delta virus. It uses the HBsAg as a viral envelope and shares the same hepatocyte receptor for viral entry . Hepatitis D is caused by the HDV. Compared with mono HBV infection, Hepatitis D is considered the most severe form of viral hepatitis in humans, susceptible of progression to cirrhosis and early decompensation of liver function.

2. How do you get it and how can I protect myself?

       HDV spread like HBV, that is, by parenteral exposure, especially  among injecting drug users.  Vertical transmission from mother to offspring, homosexual promiscuity, and nosocomial exposure  are also  risk factors for the transmission of the HDV. The best way to protect oneself is to be vaccinated. HBV vaccination protects effectively against both HBV and HDV infection.

        3. How common is Hepatitis D in China?

        The global prevalence of Hepatitis D is about  0.8 % in the general population and 13.02% in HBsAg-positive carriers. About   62-72 million people may be infected with HDV worldwide. Asia and Africa are the large reservoirs for HBV infection and accordingly are also the worst-hit areas with respect to HDV burden. China, India, and Nigeria are the top 3 countries with prevalence exceeding 1% in the general population.

4. What are the symptoms of HDV? Would I know if I had it?

        One might feel fatigue, low grade fever, jaundice, loss of appetite, nausea, but there are no specific symptoms telling you that you have HDV or worsening of HBV. Two types of HDV infection exist: simultaneous coinfection with HBV and HDV superinfection of a person chronically carrying HBV. Coinfection can cause liver injury with aminotransferase levels increasing in a  typical biphasic course, corresponding to an initial HBV spread followed by HDV propagation. HDV superinfection of a patient chronically infected with HBV is associated with an episode of acute hepatitis that can be mistaken for a HBV flare. Early detection of anti HDV antibody and HDV RNA will be most helpful.

        5.Who is at risk for getting Hepatitis D?

 HBV carriers  are at risk for HDV, including those with HIV infection, people who inject drugs, men who have sex with men and immigrants from areas of high HDV endemicity .

6. What is acute, chronic, and fulminant HDV?

      HDV infection is defined as acute when less than 6 months; it becomes chronic exceeding 6 months. When acute liver injury occurs, it is called fulminant HDV. Infection with HDV can be an acute or chronic process that occurs only in patients with an HBV infection. Chronic HDV infection  commonly results in the most rapidly progressive form of viral hepatitis; it is the chronic viral infection that is most likely to lead to cirrhosis, and it is associated with an increased risk of  hepatocellular carcinoma.

7. What is HBV/HDV co-infection?

      An HDV coinfection is defined as occurring in an individual not previously exposed to either HBV or HDV. Individuals that have already been infected with HBV if exposed to HDV, it is referred to as a superinfection.The various outcomes of co- and superinfections, can overlap,but on average, they are different. Both can cause an acute infection  that can lead to fulminating hepatitis; however, this outcome is more frequent for superinfections.

8.How is Hepatitis D treated?

     It currently has no satisfactory treatment and a better understanding of its pathogenesis is warranted. Previously pegylated interferon-alpha is the most-commonly used  treatment for chronic hepatitis D, with poor tolerance and low success rate. A  viral entry inhibitor bulevirtide (Myrcludex) was recently approved in Europe as the first drug for the treatment of chronic HDV infection in HDV RNA positive adult patients with compensated liver disease.

References:

1. Mentha N, Clément S, Negro F,et al. A review on hepatitis D: From virology to new therapies. https://doi.org/10.1016/j.jare.2019.03.009.

2. Miao Z, Zhang S,OU X,et al. Estimating the Global Prevalence, Disease Progression, and Clinical Outcome of Hepatitis Delta Virus Infection. he Journal of Infectious Diseases,2020,221,1677–87.

3. Petruzziello A, Marigliano S,  Loquercio G,et al. Global epidemiology of hepatitis C virus infection: an

up-date of the distribution and circulation of hepatitis C virus genotypes. World J Gastroenterol 2016 September 14; 22(34): 7824-7840.

4. Hepatitis C Guidance 2018 Update: AASLD-IDSA Recommendations for Testing, Managing, and Treating Hepatitis C Virus Infection. linical Infectious Diseases® 2018;67(10):1477–92.

5.https://www.mayoclinic.org/medical-professionals/digestive-diseases/news/understanding-hcv-and-evolving-treatment-guidelines/mqc-20437669.