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Hepatitis B: Part 1 - Epidemiology and Clinical Features

Overview 

Hepatitis is an inflammation of the liver that's caused by a variety of contagious viruses and non-infectious agents leading to a range of health problems, some of which can be fatal. There are five main strains of the hepatitis virus, known as types A, B, C, D and E. While their infection results in liver disease, they differ in important ways including modes of transmission, severity of the illness, geographical distribution and prevention methods. 

Particularly types B and C lead to chronic disease in hundreds of millions of people and together are the most common cause of liver cirrhosis, liver cancer and viral hepatitis related deaths. 

An estimated 354 million people worldwide having no access to testing and treatment live with hepatitis B or C. 

Some types of hepatitis are preventable through vaccination. A WHO study found that an estimated 4.5 million premature deaths could be averted in low-and middle- income countries by 2030 through vaccination, individual tests, drugs and education campaigns. WHO’s global hepatitis strategy, championed by all WHO Member States, aims to reduce new hepatitis infections by 90 and deaths by 65 between 2016 and 2030.


Hepatitis B is a potentially life-threatening liver infection caused by the hepatitis B virus (HBV). It can cause chronic infection and puts people at high risk of death from cirrhosis and liver cancer.

In this first part of the article, we shall discuss the following aspects of hepatitis:

  1. Epidemiology, 
  2. Mode of transmission
  3. Sign and symptoms 
  4. Groups at risk
  5. Relationship of HBV and HIV infection H
  6. How to confirm the diagnosis
  7. Sample MCQs

In the second part of the article, you will read about treatment and the prevention of Hepatitis B.

Key Facts

  • Hepatitis B is a viral infection which is caused by hepatitis B virus (HBV).
  • HBV affects the liver and can cause both acute and chronic disease.
  • Chronic liver infection with HBV puts people at high risk of death from cirrhosis of the liver and liver cancer.
  • An estimated death of 1.1 million occurred in 2022, mostly due to cirrhosis and hepatocellular carcinoma (primary liver cancer).
  • More than 686,000 people die every year due to consequences of hepatitis B. (2016 Data)
  • Children less than 6 years of age infected with the hepatitis B virus are most likely to develop chronic infections.
  • HBV is spread by contact with blood or body fluids of an infected person.
  • HBV is 50 to 100 times more infectious than HIV.
  • Hepatitis B can be prevented by vaccine and hepatitis B birth dose is the mainstay of hepatitis B prevention.

Epidemiology

  • Globally, an estimated 240 million people are chronically infected with HBV.
  • More than 686,000 people die every year due to complications of hepatitis B, including cirrhosis and liver cancer. (2016 Data)
  • Hepatitis B prevalence is highest in sub-Saharan Africa and East Asia.
  • In India, the prevalence of hepatitis B surface antigen (HBsAg) is 3-4.2% with over 40 million (4 crore) HBV carriers.
  • Estimates of the prevalence of hepatitis B virus (HBV) markers among men who have sex with men (MSM) range from 5% to 81%, and the prevalence of HBV surface antigen varies from 1% to 11%.
  • Every year over 115,000 Indians die of hepatitis B related complications.
  • There are 10 known HBV genotypes, classified from A to J. The most common genotype in India is D, followed by A and C. The identification of genotypes is important in prognosis and treatment of the patients.

Mode of Transmission

  • HBV is spread by contact with blood or body fluids of an infected person.
  • HBV is 50 to 100 times more infectious than HIV.
  • The main ways of getting infected with HBV are from mother to baby at birth (perinatal), child-to-child (especially in household settings), unsafe injections and transfusions and unprotected sexual contact.
  • Sharing items such as razors or toothbrushes with an infected person, direct contact with the blood or open sores of an infected person, unsafe tattoos/piercings and exposure to blood from needle sticks or other sharps can also lead to HBV transmission.

Signs & Symptoms

  • Many persons are asymptomatic but some persons have acute illness with symptoms that last several weeks, including yellow colour of skin and eyes (jaundice), dark-colour urine, extreme fatigue, nausea, vomiting and abdominal pain.
  • In some persons, the hepatitis B virus can lead to a chronic liver infection that can later develop into cirrhosis of the liver or liver cancer.
  • More than 90% of healthy adults who are infected with the hepatitis B virus will recover and be completely rid of the virus within 6 months.

Risks for chronic HBV

  • Children less than 6 years of age who become infected with the hepatitis B virus are most likely to develop chronic infections.
  • About 80-90% of infants and 30-50% of children infected before the age of 6 years develop chronic infections.
  • Less than 5% of otherwise healthy adults who are infected will develop chronic infection.
  • About 15-25% of adults who become chronically infected during childhood die from hepatitis B related liver cancer or cirrhosis.

Diagnosis

  • It is difficult to diagnose hepatitis solely based on clinical findings.
  • Laboratory diagnosis of hepatitis B infection focuses on the detection of HBsAg.
  • Acute HBV infection is characterized by the presence of HBsAg and immunoglobulin M (IgM) antibody to the core antigen HBcAg.

How to confirm the diagnosis

The diagnosis is based on the serological findings of the patient. See the link for Interpretation of Serological result for HBV infection.
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MCQ

Question: In most people, what are symptoms of hepatitis C when initially infected?

Answer: Most people do not experience symptoms

Explanation: 

Most people (up to 80%) infected with Hepatitis C virus do not have any symptoms in the beginning. When symptoms do occur, they usually happen within 6 to 7 weeks after exposure to the virus. But symptoms can start any time from 2 weeks post-infection up to 6 months.

Early symptoms may include:

  • Fever
  • Abdominal pain
  • Dark urine
  • Fatigue
  • Nausea/vomiting
  • Loss of appetite
  • Clay-colored bowel movements
  • Joint pain
  • Yellow color in the skin or eyes (jaundice)

Question: What is cirrhosis?

Answer: Scarring of the liver

Explanation:

Cirrhosis is scarring of the liver, due to permanent damage to liver tissue. This can occur secondary to infection with many infections, including Hepatitis C virus. HCV damages liver cells, causing them to die. This causes extensive scarring in the liver (fibrosis), which can lead to cirrhosis, a condition in which the liver is unable to function normally. If the damage is severe, liver failure can occur.

Question: Is it possible for the body to rid itself of hepatitis C?

Answer: Yes

Explanation:

Up to one-quarter of people infected with Hepatitis C will rid the virus from their bodies without treatment and not experience chronic infection. It is not understood why this occurs in some patients.

HCV patients need to find a doctor who specializes in HCV monitoring and treatment to avoid progression of the illness. Chronic liver disease can cause complex medical complications and it is important to have a specialist monitor the disease and prescribe any needed medical interventions. There are many new and promising medical treatments for Hepatitis C infection.

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Read further in part 2: Hepatitis B: Treatment & Prevention