Medically Important DNA Virus: Hepatitis B Virus

Introduction

Hepatitis B Virus (HBV) is a DNA virus belonging to the family Hepadnaviridae. It is a major human pathogen that primarily infects the liver, causing a wide spectrum of liver diseases ranging from acute hepatitis to chronic infection, cirrhosis, and hepatocellular carcinoma (liver cancer). HBV is highly infectious and transmitted through parental, sexual, vertical (from mother to baby).

 

What is Hepatitis B Virus?

Hepatitis B virus is a medically DNA virus that primarily affects the liver and causes the disease hepatitis b. it is a viral disease that can be either acute or chronic and affects millions of people around the world.

 

Clinical significance

1. Acute hepatitis:

Acute hepatitis B virus infection refers to initial phase of infection, typically lasting less six months. Many individuals with acute HBV infection are a symptomatic or have mild flu like symptoms. Most individuals recover from acute hepatitis B without complication

2. Chronic hepatitis:

Chronic hepatitis b virus infection occurs when the virus persist in the body for more than six months. Chronic infection can lead to ongoing liver inflammation, progressive liver damage, and the development of liver cirrhosis over time. Individuals with chronic hepatitis b are at an increased risk of complications, Including Liver failure and hepatocellular carcinoma, a from liver cancer.

3. Liver cirrhosis:

Prolonged inflammation and liver damage caused by chronic HBV infection can lead to the development of liver cirrhosis. Cirrhosis is scarring of the liver from long-term damage. It’s serious, but with early treatment and lifestyle changes, its effects can be reduced.

4. Hepatocellular carcinoma of HBV

IS the most common type primary liver cancer. Chronic HBV infection is a major risk factor for the development of hepatocellular.

 

How transmission hepatitis b virus

HBV is spread when blood, semen, or other body fluids from a person infected with the virus enter the body of someone who is not infected.  

Hepatitis b is a large virus does not cross placenta.  Cannot infect fetus. If not vaccinated at birth they develop a lifelong HBV infection. Hepatitis b virus infection is the only sexually transmitted infection that have a protective vaccine

The main modes of transmission include:

1. Perinatal: HBV can be passed from an infected mother to her baby during childbirth.

2.  Sexual transmission: unprotected sexual contact with an infected person.

3. Horizontal transmission: sharing personal items contaminated with infected blood.   Close contact in households (especially among children in endemic areas).

4. Parenteral transmission: blood transfusion with unscreened or contaminated blood, sharing needles, unsafe  injections with contaminated equipment, needle-stick injuries in healthcare workers, medical procedures done with improperly sterilized instruments, tattooing, piercing, or acupuncture with unsterilized equipment.

Signs and symptoms of hepatitis b infection

1.  Acute hepatitis:

Acute HBV can manifest as an acute illness with a wide spectrum of symptoms. Some people may develop symptoms within 1to 4 months after exposure, but many don’t show any at all.

Symptomatic individual may experience flu-like symptoms such as fatigue, fever, muscle and joint aches, nausea vomiting, and loss of appetite.

Jaundice is a hallmark of acute hepatitis and usually appears after the initial flu-like symptoms.

2.   Fulminant hepatitis: 

Fulminant hepatitis is a rare syndrome created massive necrosis of liver parenchyma tissue and a decrease in liver size.

Fulminant hepatitis is requires urgent medical attention and many necessitate liver transplantation. It’s characterized by rapid and extensive liver cell death, leading to liver failure and encephalopathy.

3.   Chronic hepatitis:

Chronic hepatitis may be silent for years. Symptoms appear only when liver damage is significant. 
Many individuals with chronic HBV infection are asymptomatic and unaware of their infection. Some individuals may experience nonspecific symptoms such as fatigue, mild abdominal discomfort, or intermittent episodes of jaundice. The severity of chronic hepatitis can vary, ranging from mild inflammation to significant liver damage and cirrhosis.

Diagnosis of hepatitis b virus infection

The diagnosis of hepatitis b virus infection is based on clinical evaluation, liver function tests, and most importantly, serologic and virologic testing 

1. Serological tests:

Serological tests are used to detect specific antibodies and antigens associated with hepatitis virus infection. Hepatitis b surface antigen is the primary marker of hepatitis b virus infection. Its presence indicated ongoing HBV infection. Other serological markers include: hepatitis b e antigen, hepatitis b core antibody (anti-HBc). Serological tests help determine the phase of infection (acute, chronic and resolved), assess viral replication, and evaluate immune response.

2. Liver function tests:

    Liver function tests are performed to evaluate liver health and assess the extent of liver damage. Liver function tests measure levels of liver enzymes such as alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyl transferase. Elevated liver enzyme levels indicate liver inflammation and possible liver injury.

    3. Imaging studies:

  Imaging studies such as ultrasound, computed tomography (CT), or magnetic resonance imaging may be performed to assess liver health and detect complications.

3  4. Liver biopsy:

In certain cases, a liver biopsy may be performed to obtain a tissue sample for  microscopic examination. Liver biopsy helps assess the degree of liver inflammation, fibrosis, or cirrhosis. It’s generally reserved for cases where the diagnosis is unclear or when liver biopsy findings may impact treatment decisions.

What are hepatitis B virus treatment?

1. Antiviral therapy:

Antiviral medications are used to suppress HBV replication, reduce liver inflammation, and prevent disease progression. The choice of antiviral medication depends on various factors, including the patient’s hepatitis B e antigen status, viral load, liver function, and presence of liver cirrhosis. Commonly used antiviral drugs include nucleos(t)ide analogs such as entecavir and tenofovir.  Treatment duration and monitoring requirements vary based on individual patient factors.

 

2.  Monitoring and follow-up: 

Regular monitoring of HBV viral load, liver function tests, and serological markers is essential to assess treatment response and disease progression. Monitoring intervals may vary depending on the patient’s clinical status and treatment response. Long-term fallow-up is necessary to ensure sustained viral suppression and to detect any potential complications.

Haw to prevention hepatitis B virus infection

1. Vaccination: is the most effective way to prevent HBV infection

2. Safe injection practices: The use of sterile needles and syringes, can help prevent the transmission of HBV and other blood borne viruses.

3.  Screening and early detection:  Routine screening for HBV infection is important, particularly in high-risk populations. Early detection allows for tamely intervention and appropriate management.

Conclusion

Hepatitis b remains a global health problem, affecting millions worldwide. While it can cause serious complications like like cirrhosis and liver cancer, early detection, vaccination, and proper treatment greatly reduces risks. Universal immunizations and awareness programs are the most powerful tools in eradicating hepatitis B and protecting future generations.