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87
UDC: 615.035.4
Melenko Svitlana Romanivna,
PhD, Associate Professor of the Department of Infectious Diseases and Epidemiology
Bukovinian State Medical University Bohutska Olha Andriivna student
Bukovinian State Medical University DOI: 10.24412/2520-6990-2023-11170-87-88 PREVENTION AND TREATMENT OF HEPATITIS B
Abstract.
A major reason of morbidity and mortality the whole world is Hepatitis B virus (HBV) infection. The most common and serious diseases to which chronic hepatitis B (CHB) infection leads are cirrhosis, hepatic decompensation and hepatocellular carcinoma (HCC). The chance of developing CHB is related to the age at which infection is acquired, for example, the lowest risk is in adults and >90% in neonates whose mothers are hepatitis B antigen positive. Treatment should be individualized and based on clinical and laboratory criterias.
Keywords: Hepatitis B virus; Treatment; Cirrhosis; Systematic review; Prevention; Chronic hepatitis B infection.
Introduction
According to scientific sources chronic hepatitis B virus (HBV) infection affects an estimated 370 million people worldwide [1].
Epidemiology of chronic hepatitis B (CHB) differs globally. According to statistics data chronic hepatitis B in 30% of cases of all deaths are from cirrhosis and 40% from hepatocellular carcinoma (HCC) [2]. There are more than 2 billion people in the world who are infected with HBV, and about 257 million people have a chronic course [2, 8].
Results
Actually, for hepatitis B, prevention is more effective than therapy. It is still not possible to treat for this infection despite all the progress of antiviral therapy against HBV. That's why, immunization of HBV infection is the best way to prevent HBV-related diseases [3].
To immunize the body against HBV, a person needs three doses of the vaccine; the first dose should be administered immediately after birth, the next after one month and the last at 6 months. The newborns should be vaccinated against HBV as soon as possible after birth. Just a temporary contraindication to administering the vaccine to newborns are severe diseases, such as very low birth weight, severe birth defects, severe asphyxia, and respiratory distress syndrome. The first dose of hepatitis B vaccine should be received after all their vital signs have stabilized [4].
Adults also need immunization, as you know, because as we know chronic HBV typically requires lifelong treatment. Therefore, prevention should be the primary aim. Also mainstays of prevention are not only vaccination, as well as avoiding transmission from infected people via blood supply screening, universal health care precautions, and harm reduction education [5].
Especially, immunologic cure is attainable with current drug therapies that suppress HBV DNA replication and improve liver inflammation and fibrosis. It is defined as the loss of hepatitis B surface antigen with sustained HBV DNA suppression. Also it is mentioned
that, pegylated interferon alfa-2a, entecavir, and tenofovir are recommended as first-line treatment options for chronic hepatitis B [6].
Global guidelines, recommendations and literature reviews report that treatment goals are to maximize long-term inhibition of HBV replication, alleviate the degree of hepatocyte inflammation, reduce necrosis, and hyperplasia of liver fibrous tissue, postponement the occurrence of liver failure, decompensation of liver cirrhosis, HCC and other complications, and to improve the quality of patients' life as well as prolong their survival time. As for treatment: HBsAg remains negative (with or without the presence of anti-HBs), HBV DNA is undetectable, and liver biochemical indicators are normal following withdrawal of the treatment. However, because a covalently closed circular DNA (cccDNA) remains in the nuclei of liver cells, patients are still at risk of HBV reactivation and HCC development [4].
In general, there are 8 drugs approved for the treatment of chronic hepatitis B which can be categorized into two main classes. The first class includes interferon preparations (standard interferon alfa-2b, pegin-terferon alfa 2a [peg-alfa 2a]) and the second is nu-cleos(t)ide analogues (lamivudine, adefovir, entecavir, telbivudine, tenofovir disoproxil fumarate and tenofo-vir alafenamide). The world guidelines recommend initiating treatment with a potent agent. In general it has a high barrier to resistance and a low rate and antiviral resistance. Therefore, in this review, we offer a description of drugs for HBV therapy. So, the first-line therapy for the treatment of chronic HBV infection is entecavir and tenofovir. In fact, entecavir is licensed for use in children older than 2 years and tenofovir in children aged 12 years and older. The American Association for the Study of Liver Diseases (AASLD) also includes tenofovir alafenamide, which is an orally available pro-drug of tenofovir with similar antiviral efficacy but lower renal and bone toxicity [2].
According to the results of the literature review, the researchers claim that interferon alfa-2b or lamivu-dine improved off treatment HBV DNA and HBeAg
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clearance and seroconversion and ALT normalization. Regarding adefovir, the guidelines state that this one improved off treatment ALT normalization and HBV DNA clearance. Compared with lamivudine, pegylated interferon alfa 2-a improved clearance and seroconversion of HBV DNA and HBeAg without treatment, normalized ALT and liver histology. Lamivudine combined with interferon alfa-2b compared with only lamivudine therapy improved post-treatment HBV DNA clearance and HBeAg seroconversion and reduced HBV DNA mutations. Pegylated interferon alfa 2-a plus lamivudine improved HBV and HBeAg DNA clearance, seroconversion, and ALT normalization compared with lamivudine but not pegylated interferon alfa 2-a monotherapy. As for side effects, it is noted that they were common but generally mild and did not result in increased treatment discontinuation. Some factors may modify the treatment effect on intermediate outcomes, they are longer hepatitis duration, male gender, baseline viral load and genotype, HBeAg, and histolog-ical status. It is noted that adefovir and pegylated interferon alfa 2-a with lamivudine improved off treatment viral clearance in HBeAg-negative patients which is a positive response to this therapy [7].
And with that, according to recommendations we have the following: antiviral therapy is indicated for HBV-related compensated cirrhosis patients with positive serum HBV DNA and HBV-related decompen-sated cirrhosis patients with positive HBsAg [4].
Conclusion:
To make a conclusion we can say, the outcome of chronic HBV infection is variable ranging from mild fibrosis to cirrhosis and decompensated liver disease. Numerous studies show us that totally it is estimated that 20% to 30% of those with chronic HBV infection will be at risk for progressive liver fibrosis leading to cirrhosis and an increased risk of HCC. However, most patients will not require antiviral therapy. The primary goal of antiviral therapy is to suppress HBV DNA levels to undetectable, as this endpoint is associated with improvement in liver inflammation and fibrosis and reversal of cirrhosis, a lower risk of HCC and reduced liver-related mortality. However, none of the currently available treatments are curative, and if treatment is started once, it usually needs to be continued for life. Therefore, treatment guidelines emphasize the importance of careful patient selection, initiating therapy
only in those would derive the greatest benefit. Identifying which patients benefit the most from therapy is challenging. The pre-treatment assessment is based on the level of viral replication (HBeAg status and HBV DNA level), degree of inflammation (serum ALT level) and stage of disease (non-invasive test of fibrosis or liver biopsy) and additional factors such as a family history of cirrhosis and HCC, age and presence of comor-bid medical conditions [2].
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