What is hepatitis B? How is it different from other viruses? Can it be cured? What are the symptoms? 2025

Hepatitis B Virus (HBV) is a virus that primarily targets the liver and may lead to serious chronic conditions such as cirrhosis or liver cancer if left undiagnosed and untreated.

Thailand is among the countries with a high prevalence of chronic HBV infection—especially mother-to-child transmission and childhood infections-often without individuals realizing they carry the virus.

This article offers a comprehensive guide covering essential aspects of HBV: what it is, how it’s transmitted, symptoms, diagnosis, treatment, prevention, and long-term implications-so you can protect yourself and your loved ones with informed health choices.

What is Hepatitis B Virus?

Hepatitis B virus (HBV) is a contagious virus that causes liver inflammation. It spreads through blood, sexual contact, or from mother to child during birth. HBV is common worldwide, especially in Asia and Thailand.

Many infected individuals show no symptoms initially, but the virus may remain in the body and become chronic. Without proper care, this can lead to cirrhosis, liver cancer, and even death.

Characteristics of the Virus

• Belongs to the Hepadnaviridae family
• Has a partially double-stranded DNA genome
• The virus can survive outside the body (e.g., on surfaces) for up to 7 days

Why HBV is a Major Concern

• WHO classifies HBV as a global public health threat
• An estimated 254 million people live with chronic HBV worldwide (as of 2022)
• In Thailand, about 3–5 million people live with chronic infection and are at high risk of liver cancer

Why It Deserves Attention

• Almost infected show no symptoms in the early stages
• The virus is transmissible even without symptoms
• It can lead to liver cancer if left untreated

How Is HBV Different from Hepatitis A–E?

Hepatitis viruses are classified into types Hepatitis A, Hepatitis B, C, D, and E. Each type differs in terms of transmission routes, risk of chronic infection, severity, and available treatment or vaccines. Among them, hepatitis B virus (HBV) is one of the most common and potentially dangerous, especially due to its risk of developing into chronic liver disease or liver cancer.

Comparison of Hepatitis Virus Types

Key Points That Make HBV Different

• 90% of Chronic HBV infected since birth
• Greater likelihood of cirrhosis and liver cancer
• Almost 100% Effective vaccine AVAILABLE

What Is HBV Genotype (A–J)?

Hepatitis B virus (HBV) is classified into several genotypes: A through J. These genotypes differ based on geographic distribution, disease severity, treatment response, and the likelihood of progressing to liver cancer.

Common Genotypes in Thailand

• The most prevalent HBV genotypes in Thailand are Genotype B and C.
• Genotype C tends to be more aggressive, with a higher risk of cirrhosis and liver cancer compared to Genotype B.
• People with Genotype C generally respond more slowly to antiviral treatments than those with Genotype B.

Why Genotype Matters

• Helps predict the risk of chronic liver disease, cirrhosis, and liver cancer.
• Guides treatment decisions, such as choosing between antivirals or interferon therapy.
• May influence long-term prognosis and monitoring strategy.

HBV Genotype Distribution by Region

How Is HBV Transmitted?

Hepatitis B virus (HBV) is a highly contagious virus that can be transmitted from person to person through various routes. Some individuals may not show symptoms, making unintentional transmission more likely.

Main Modes of HBV Transmission

• Blood exposure, such as sharing needles, tattooing, body piercing, or receiving contaminated blood product/organ transplant.
• Sexual contact without condom 
• Mother-to-child transmission, either during birth or, in some cases, during pregnancy
• Sharing personal items razors, or nail clippers, that may have traces of blood
• Contact with bodily fluids, particularly through open wounds or mucous membranes

Can HBV Spread Through Kissing or Saliva?

• You CANNOT get HBV by kissing for saliva exchange

What Are the Stages of HBV Infection?

Hepatitis B virus (HBV) infection progresses through several stages—from acute infection to chronic disease and potentially severe complications such as cirrhosis or liver cancer.

Stages of HBV Infection

1. Incubation Period
   • Time from exposure to the onset of symptoms
   • Typically lasts 60-150 days (average ~90 days)
2. Acute Infection
   • Children younger than 5, immunosuppressed patients will likely not have symptoms
   • Most healthy adults can clear the virus on their own
3. Chronic Infection
   • Infected since birth : 90% turn chronic
   • Infected at age 1-5 : 30% turn chronic
   • Infected in adolecescent : 5% turn chronic
4. Cirrhosis or Liver Cancer
   • Caused by long-term liver inflammation and cell damage
   • Cirrhosis may be asymptomatic at first but leads to severe complications like ascites or hepatocellular carcinoma later in life

What Is an HBV Carrier?

An HBV carrier is someone who has hepatitis B virus in their blood but shows no symptoms and has normal liver enzyme levels. However, they can still transmit the virus to others.

Characteristics of an HBV Carrier

• Presence of HBsAg in the blood for more than 6 months
• No signs or symptoms of illness
• Normal liver enzyme levels (ALT, AST)
• Viral load may be undetectable or very low

Types of HBV Carriers

1. Inactive Carrier
   • Very low or undetectable HBV DNA in the blood
   • Liver remains unaffected
   • requires periodic monitoring
2. Active Carrier (HBeAg-negative chronic hepatitis B)
   • Virus continues to replicate despite no symptoms
   • Higher risk of complications such as cirrhosis
   • May require antiviral treatment

Do HBV Carriers Need Treatment?

• Inactive carriers typically do not need treatment but should have regular check-ups every 6–12 months
• If liver enzymes become elevated or viral load increases, antiviral treatment may be necessary

What Are the Symptoms of Hepatitis B?

Many people infected with HBV may not show symptoms in the early stages—especially infants or young children. Some may experience flu-like symptoms, causing the infection to go unnoticed until liver damage is detected.

Acute Phase Symptoms

• Fatigue or weakness
• Loss of appetite, nausea, vomiting
• Muscle aches 
• Jaundice (yellowing of skin and eyes)
• Cola-Dark urine
• Pale or clay-colored stool
• Fever

Note: These symptoms typically appear within 1–4 months after exposure and may resolve on their own in adults with strong immune systems.

Chronic Phase Symptoms

• May be asymptomatic or present only with persistent fatigue
• Some may develop abnormal liver enzyme levels
• Without treatment, it can progress to cirrhosis or liver cancer

What Are the Types of Hepatitis B Testing?

Diagnosing HBV infection requires blood tests that assess whether the virus is present, determine the stage of infection, evaluate liver function, and measure viral load. These tests guide treatment decisions and long-term monitoring.

Key HBV Tests

1. HBsAg (Hepatitis B surface antigen)
   • Indicates the presence of HBV in the body
   • Positive > 6 months = chronic infection
2. Anti-HBs (Hepatitis B surface antibody)
   • Shows immunity from vaccination or past infection
3. HBeAg (Hepatitis B e antigen)
   • Indicates active viral replication
   • High levels suggest greater infectiousness
4. Anti-HBe (Hepatitis B e antibody)
   • Suggests the immune system is controlling the virus
   • Used to monitor disease progression
5. HBV DNA
   • Measures the amount of virus in the blood
   • Used to assess severity and monitor treatment
6. Liver Function Test (AST, ALT)
   • Evaluates liver inflammation or damage

Why Are Liver Enzymes (AST, ALT) Important?

Liver function tests, especially AST and ALT, indicate whether the liver is inflamed or damaged. In hepatitis B patients, these values help determine disease severity and guide treatment plans.

AST (Aspartate Aminotransferase)

• Found in liver, heart, and muscles
• Elevated AST may signal liver or other organ damage
• Should be interpreted alongside ALT

ALT (Alanine Aminotransferase)

• Found mostly in the liver
• High ALT levels indicate liver inflammation or cell damage
• Key marker for tracking chronic hepatitis B progression

Concerning AST/ALT Levels

• Elevated ALT, especially if persistent, signals active liver inflammation
• Rising levels over time suggest risk of cirrhosis or liver cancer
• Antiviral treatment may be initiated if high ALT is accompanied by active viral replication

How Severe Is Hepatitis B? Can It Lead to Cirrhosis or Liver Cancer?

Hepatitis B is a major risk factor for developing cirrhosis and liver cancer—especially in those with chronic, untreated infection.

HBV and Cirrhosis

• Chronic liver inflammation caused by HBV leads to fibrosis (scarring)
• Accumulated scarring eventually causes cirrhosis, impairing liver function
• Cirrhosis can result in complications such as ascites, esophageal varices, and liver failure

HBV and Liver Cancer

• Chronic HBV carriers are at higher risk for hepatocellular carcinoma (HCC)
• Especially those with positive HBeAg or high viral load
• Liver cancer can develop even without cirrhosis if chronic inflammation is present

Additional Risk Factors

• Alcohol consumption
• Coinfection with hepatitis C virus
• Exposure to aflatoxin (a liver toxin from mold-contaminated food)
• Genetic predisposition or family history of liver cancer

Monitoring Hepatitis B: What Tests and How Often?

Monitoring is essential for hepatitis B patients, especially those with chronic infection or at risk of complications. Regular follow-up helps assess disease progression and guide treatment.

Key Monitoring Tests

• HBV DNA: Measures viral load to assess replication
• ALT and AST: Liver enzyme tests, every 3–6 months
• HBeAg and Anti-HBe: Track disease activity and immune response
• Alpha-fetoprotein (AFP): Tumor marker for liver cancer
• Liver Ultrasound: Detects cirrhosis, tumors, or other complications

Follow-Up Frequency

• Chronic carriers not on treatment: Every 3–6 months
• Patients on antiviral therapy: Every 3 months initially, then every 6 months
• Those with cirrhosis or high cancer risk: AFP and ultrasound every 6 months

How Is Hepatitis B Treated?

The goal of hepatitis B treatment is to suppress the virus, reduce liver inflammation, prevent cirrhosis, and lower the risk of liver cancer. Although a complete cure is not always possible, long-term control is achievable.

Main Treatment Approaches

1. Monitoring Only
   • For inactive carriers or those without liver inflammation
   • Regular check-ups every 6 months are recommended
2. Antiviral Therapy
   
   • For patients with chronic active hepatitis B
   • Common medications include:
     • Tenofovir disoproxil fumarate (TDF)
     • Tenofovir alafenamide (TAF)
     • Entecavir (ETV)
   • These drugs effectively suppress the virus with minimal side effects
3. Interferon Therapy (Pegylated Interferon alpha)
   • An injectable treatment that boosts the immune response
   • Reserved for specific cases due to potential side effects

Duration of Treatment

• Antiviral therapy often requires long-term use
• Discontinuation may be considered when the virus is well-controlled and immune protection is adequate

What Are the Types of Antiviral Drugs for HBV? How Do They Differ?

Antiviral therapy is the mainstay treatment for chronic hepatitis B. It reduces viral load, lowers liver inflammation, and decreases the long-term risks of cirrhosis and liver cancer. There are two main categories of HBV medications:

1. Nucleos(t)ide Analogues (Oral)

• Tenofovir disoproxil fumarate (TDF)
• Tenofovir alafenamide (TAF)
• Entecavir (ETV)

Pros:

• Strong viral suppression
• Well-tolerated, safe for cirrhotic patients
• Fewer side effects

Cautions:

• Requires daily long-term use
• Stopping without medical advice can lead to viral resistance

2. Interferon-Based Therapy (Injection)

• Pegylated Interferon alpha

Pros:

• Stimulates immune system to fight the virus
• Offers a chance of finite therapy if response is strong

Cautions:

• More side effects (fever, chills, depression)
• Not suitable for cirrhotic patients, pregnant women, or certain chronic conditions

Can Hepatitis B Be Completely Cured?

Current treatments for hepatitis B cannot completely eliminate the virus from the body, especially in chronic cases. However, long-term management can keep the infection under control and prevent complications.

Two Types of HBV Recovery

1. Clinical Cure
   • Undetectable HBV DNA in blood
   • Normal liver enzymes (ALT, AST)
   • No liver inflammation
   • Viral genetic material may still persist in liver cells
2. Functional Cure
   • Undetectable HBV DNA and HBsAg
   • Immune system controls the virus without medication
   • Very low risk of liver complications
   • Considered the optimal goal in HBV treatment

No “Sterilizing Cure” Yet

• This would mean complete eradication of the virus from the body
• Medical science hasn’t reached this stage yet
• However, new therapies and vaccines are under development to pursue this goal

When Can Antiviral Treatment Be Stopped? Is It Lifelong?

Antiviral therapy for chronic hepatitis B is typically long-term, and in many cases, lifelong. Discontinuation should only be considered under strict medical guidance.

Criteria for Stopping Antiviral Therapy

1. Stable immune control with undetectable HBV DNA for over 2 years
2. Loss of HBeAg and HBsAg, indicating near-functional cure
3. No cirrhosis or liver complications present
4. Capacity for regular follow-up after stopping medication (due to risk of viral flare)

When Not to Stop Antiviral Therapy

• Patients with cirrhosis
• Detectable viral load in blood
• Pregnant women or those planning pregnancy soon
• Inability to maintain regular follow-up with a specialist

Discontinuation Requires Physician Oversight

• Never stop medication without professional advice
• Frequent blood tests are required every 1–3 months after stopping
• If viral rebound occurs, treatment must resume

How Often Should Liver Health Be Monitored in HBV? Is There a Risk of Liver Cancer?

Even without symptoms, hepatitis B carriers—especially those with chronic infection—are at risk of developing cirrhosis or liver cancer. Regular liver surveillance is essential.

Risk of Liver Cancer

• Chronic hepatitis B is a major risk factor for liver cancer
• Asymptomatic carriers still have a measurable risk
• Risk increases with cirrhosis or genetic predisposition

Liver Monitoring Guidelines

1. Abdominal Ultrasound
   • Detects liver nodules or abnormalities
   • Recommended every 6 months for high-risk patients
2. Alpha-fetoprotein (AFP) Test
   • Tumor marker for liver cancer
   • Often combined with ultrasound every 6 months
3. FibroScan or Liver Stiffness Measurement
   • Assesses liver fibrosis or cirrhosis
4. CT Scan or MRI (if needed)
   • For suspicious lesions or inconclusive ultrasound findings

How Should You Take Care of Yourself If Diagnosed with HBV?

After being diagnosed with hepatitis B, self-care plays a crucial role in managing the disease, preventing liver damage, and supporting treatment outcomes.

Self-Care Guidelines

1. Attend Regular Medical Follow-ups
   • Adhere to appointments, liver tests, and blood work
   • Do not stop medication without medical advice
2. Avoid Alcohol Consumption
   • Alcohol accelerates liver damage and inflammation
   • Increases risk of cirrhosis and liver cancer
3. Avoid Hepatotoxic Drugs
   • Includes certain painkillers and anti-inflammatory medications
   • Never self-medicate without consulting a physician
4. Adopt a Liver-Friendly Diet
   • Avoid foods contaminated with aflatoxin (e.g., stored peanuts, chili powder)
   • Focus on clean, well-cooked, and nutritionally balanced meals
5. Engage in Appropriate Exercise
   • Regular activity helps boost immunity and support liver health
6. Inform Partner and Family for Screening
   • HBV can be transmitted via blood and sexual contact
   • Encourage loved ones to get tested and vaccinated

Can People with HBV Have Children? Can It Be Passed to the Baby?

Yes, individuals with hepatitis B can have children, but careful planning and close medical supervision are essential to prevent mother-to-child transmission—a common route of HBV infection in Thailand.

Pregnancy Planning for HBV-Positive Individuals

• HBV DNA levels should be tested before pregnancy
• If the viral load is high, safe antiviral medication may be prescribed in the second or third trimester
• Consultation with a specialist 3–6 months prior to conception is advised

Preventing Mother-to-Child Transmission

• Newborns should receive the hepatitis B vaccine within 12 hours of birth
• Also administer HBIG (Hepatitis B Immune Globulin) immediately
• Follow-up doses at month 1 and 6 complete the immunization schedule

Monitoring the Infant After Birth

• At age 9–12 months, test for immunity (Anti-HBs) and check for infection (HBsAg)
• If protection is inadequate, a booster vaccine may be necessary

Should You Get the HBV Vaccine? What If You’ve Had It Before?

The hepatitis B vaccine is one of the most effective ways to prevent infection—especially for people at risk or those without natural immunity.

Who Should Get the HBV Vaccine?

• Newborns (as part of routine immunization)
• Adults who’ve never been vaccinated or lack immunity
• High-risk groups (e.g., multiple partners, IV drug users)
• Healthcare professionals
• Household contacts of HBV carriers

How Long Does the Vaccine Last?

• A 3-dose series (at 0, 1, and 6 months) offers long-term protection
• Routine boosters are generally unnecessary except in specific high-risk situations

If You’ve Had HBV, Do You Still Need the Vaccine?

• No. If you’ve had HBV, your body already has natural antibodies
• Focus should be on liver monitoring and viral load management

Can You Check Immunity Before Vaccination?

• Yes. Blood tests for Anti-HBs and HBsAg are available
• If Anti-HBs is >10 mIU/mL, you’re considered protected and don’t need the vaccine

Can You Have Sex If You Have HBV? Should You Use Protection?

People with hepatitis B can engage in normal sexual activity—but always use condoms if your partner has not been vaccinated or lacks immunity, since HBV can be transmitted through sexual contact.

How to Prevent Transmission to Your Partner

• Always use condoms during intercourse
• Your partner should get tested for Anti-HBs and HBsAg to assess immunity
• If no immunity is found, they should get vaccinated promptly

What If You Had Sex Without Knowing You’re Infected?

• If your partner lacks immunity and had recent exposure (within 7 days):
  → They should receive the HBV vaccine + HBIG (immune globulin) to prevent infection

Summary

• HBV is not a barrier to having sex
• But proper protection is crucial to prevent transmission to your partner

Can People with HBV Live with Others? Do They Need to Separate Personal Items?

Yes. People with hepatitis B can safely live with family or others without isolation or special separation, because the virus doesn’t spread through casual contact like sharing meals or bathrooms.

Non-Risk Transmission Scenarios

• Not transmitted through coughing, sneezing, or breathing
• Not spread by sharing bathrooms
• Not spread through shared meals or utensils
• Not transmitted by hugging, handshakes, or regular daily contact

Preventing Household Transmission

• Do not share sharp personal items (e.g., razors, nail clippers, toothbrushes)
• Keep open wounds covered to avoid accidental blood contact
• Encourage all household members to check their immunity and get vaccinated

Can HBV Be Detected in an Annual Check-Up? What Tests Are Needed?

Yes—hepatitis B can be detected during a health check-up, but only if HBV-specific markers are included, such as HBsAg or Anti-HBs, which aren’t always part of standard panels.

Health Check-Up Tests That May Reveal HBV

• HBsAg: A positive result means active HBV infection
• Anti-HBs: >10 mIU/mL indicates immunity
• Anti-HBc: Shows past infection or exposure to the virus

Additional Tests If HBV Is Found

• Liver function tests (AST, ALT)
• HBV DNA quantification (viral load)
• Liver imaging (ultrasound or FibroScan)

Summary

• Always request HBV-specific tests when getting a health check
• Not all packages include them, so be sure to confirm in advance

What Are the Complications of HBV?

People with hepatitis B—especially those with chronic infections—may develop serious liver-related complications, which often take years to manifest.

Major Complications of Hepatitis B

1. Chronic Hepatitis B
   • Occurs when the immune system fails to clear the virus
   • Leads to ongoing liver inflammation
2. Cirrhosis
   • Scarring of the liver impairs its function
   • Increases risk of liver failure and gastrointestinal bleeding
3. Liver Cancer (Hepatocellular Carcinoma)
   • Can occur even without prior cirrhosis
   • More common in patients with high viral loads or untreated cases
4. Extrahepatic Manifestations
   • Includes kidney inflammation, vasculitis, abnormal blood clotting, etc.

What Is Chronic HBV? How Is It Different from Acute Infection?

Hepatitis B infection can occur in two main forms: acute and chronic—each with distinct clinical courses and implications.

Acute Hepatitis B Infection

• Occurs within 6 months of initial exposure
• Most people clear the virus naturally without treatment
• May present with symptoms (e.g., jaundice) or be asymptomatic

Chronic Hepatitis B Infection

• Defined as the presence of HBV in the body for more than 6 months
• Common in individuals infected at birth or early childhood
• Associated with risks of chronic liver inflammation, cirrhosis, and liver cancer

Summary of Differences

HBV and Pregnancy: Does It Affect the Baby?

Pregnant women with hepatitis B can pass the virus to their newborns—especially if not properly screened or treated. However, with the right prevention steps, transmission can be nearly 100% avoided.

How Is HBV Passed from Mother to Child?

• Transmission usually occurs “during delivery”
• High maternal viral load increases the risk of transmission

What Should Newborns Receive Immediately?

• First dose of HBV vaccine within 12 hours of birth
• HBIG (Hepatitis B Immune Globulin) for added protection
• Complete the vaccine series at 1 and 6 months of age

What Should Pregnant Women Do?

• Get tested for HBV at the first prenatal visit
• If HBsAg is positive, antiviral treatment may be recommended in the third trimester
• Breastfeeding is safe if the baby receives both the vaccine and HBIG

HBV and the Vaccine: Who Needs It? How Long Does Protection Last?

The hepatitis B vaccine is highly effective in preventing infection and is recommended for all newborns, unvaccinated adults, and people in high-risk groups.

Who Should Get Vaccinated?

• All newborns
• Unvaccinated adults or those lacking immunity
• People living with HBV-positive individuals
• Healthcare workers
• Partners of people with HBV
• People with risk behaviors (e.g., sharing needles, multiple sex partners)

How Many Doses Are Needed?

• 3 doses at 0, 1, and 6 months
• Accelerated schedules are available for high-risk groups

How Long Does Immunity Last?

• If Anti-HBs ≥ 10 mIU/mL after vaccination
  → Protection can last decades or even a lifetime
• No booster needed unless you’re high-risk and immunity doesn’t develop

HBV and Liver Cancer: What’s the Link?

Chronic hepatitis B infection is one of the leading causes of liver cancer, particularly in people who are unaware of their infection or don’t receive proper long-term care.

How Does HBV Increase Liver Cancer Risk?

• The virus causes chronic liver inflammation and fibrosis
• Chronic inflammation leads to cirrhosis, a precursor to cancer
• HBV can integrate into liver cell DNA, causing mutations

Who’s at Risk of Liver Cancer from HBV?

• People with long-term HBV infection, especially asymptomatic carriers
• Those who don’t receive or continue antiviral treatment
• People with additional risks like alcohol use or smoking
• Those with a family history of liver cancer

How to Prevent Liver Cancer in HBV Patients?

• Adhere to treatment and follow-up schedules
• Avoid liver toxins (e.g., alcohol, non-prescribed medications)
• Undergo liver cancer screening every 6–12 months

Can HBV Be Cured? Is Lifetime Medication Necessary?

Not everyone with hepatitis B needs lifelong treatment—and not everyone will be cured. It depends on the type of infection, liver condition, and how the body responds to therapy.

Acute Infection

• Most adults (~90–95%) clear the virus naturally
• No antiviral meds needed; the immune system controls the virus
• Those who recover develop antibodies (Anti-HBs)

Chronic Infection

• Some patients have inactive virus → only need monitoring
• Others require antiviral treatment due to viral replication and liver damage
• Regular reassessments every 3–6 months are essential

Is Lifelong Medication Required?

• Some people need antivirals for years or even for life
• Others may stop treatment if the virus is well-controlled
• Stopping treatment must always be supervised by a doctor

Conclusion

Hepatitis B is a manageable disease when detected early and treated appropriately. Although not all cases can be completely cured, modern prevention and treatment options offer highly effective solutions.

Widespread vaccination, regular health checkups, and risk-reducing lifestyle choices are key to stopping HBV transmission and preventing long-term liver complications.

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