Hepatitis B: Symptoms, Transmission, Testing, Treatment, and Prevention

Hepatitis B is being detected in Thailand's population at a steadily increasing rate, because the hepatitis B virus is a cause of inflammation of the liver cells and destruction of those cells. If it continues chronically, fibrosis of the liver develops, which can lead to cirrhosis and liver cancer, the most common type of cancer among Thai people.

What Is the Hepatitis B Virus?

Hepatitis B (Hepatitis B) is caused by infection with the hepatitis B virus (Hepatitis B virus; HBV), an extremely dangerous virus. If a person becomes infected and does not receive treatment, it may lead to chronic inflammation, liver failure, cirrhosis, and liver cancer. It can be transmitted through childbirth, contact with the blood or open wounds of an infected person, sexual contact with an infected person, and the sharing of sharp instruments or personal items such as syringes, razors, or toothbrushes.

Symptoms of the Hepatitis B Virus Can Be Divided Into 2 Stages

1. Acute-stage hepatitis B, with symptoms lasting 6 months or less
2. Chronic-stage hepatitis B, with symptoms lasting longer than 6 months

Symptoms that may be found in each stage

Acute-Stage Hepatitis B

• Fever
• Fatigue
• Loss of appetite
• Nausea and vomiting
• Abdominal pain
• Dark yellow urine
• Yellowing of the eyes
• Jaundice
• Chronic-stage hepatitis B
• Fatigue
• Loss of appetite
• Abdominal pain
• Weight loss
• Jaundice

If left untreated, there is a risk of cirrhosis and liver cancer.

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How Is Hepatitis B Transmitted?

• The hepatitis B virus can be transmitted through sex with an infected person without using a condom
• The hepatitis B virus can be transmitted to a baby during childbirth from a mother who carries the virus (with up to a 90% chance of infection) if she does not receive testing and treatment before planning to have a child
• The hepatitis B virus can be transmitted through sharing needles
• The hepatitis B virus can be transmitted through sharing piercing needles and tattoo equipment, and through ear piercing done with equipment that has not been sterilized to a proper standard
• The hepatitis B virus can be transmitted through sharing toothbrushes, razors, or nail clippers with others
• The hepatitis B virus can be transmitted through accidental needlestick injuries at work, in the case of medical personnel
• The hepatitis B virus can be transmitted through contact with blood or bodily fluids that enter through a wound

Common Misconceptions About Hepatitis B

• The hepatitis B virus is not transmitted through hugging
• The hepatitis B virus is not transmitted through sharing a bathroom
• The hepatitis B virus is not transmitted through sharing a swimming pool
• The hepatitis B virus is not transmitted through eating together and sharing utensils

Diagnosing the Hepatitis B Virus

A blood test evaluates HBeAg and HBeAb, which indicate whether the disease is in a stage where the virus is actively replicating or has passed the replication stage. An ALT (alanine aminotransferase) test measures an enzyme found in liver cells. If the value is within the normal range, ALT should be monitored every 3 - 6 months. In cases where HBeAg is negative but the patient has an abnormal ALT, or has risk factors for liver disease, for example, a man older than 40 years, a family history of cirrhosis and liver cancer, physical examination showing signs of chronic liver disease, an ALT greater than half above the normal value, or an ultrasound showing abnormal liver features, the amount of hepatitis B virus should also be measured, along with a blood test of liver function (liver function test).

Blood Tests to Detect the Hepatitis B Virus

• HBsAg (hepatitis B virus antigen): A positive result means the patient currently has the hepatitis B virus
• Anti-HBS (immunity to HBsAg): A positive result means the patient has immunity to the hepatitis B virus. This immunity develops only after the patient has been vaccinated, or has previously been infected with the hepatitis virus and recovered. Therefore, a patient with immunity does not transmit the virus to others and will not be infected with the hepatitis B virus again

To diagnose chronic hepatitis B, a blood test must be repeated 6 months after a diagnosis of acute hepatitis B. If it is found that the body cannot eliminate the hepatitis B virus and cannot develop immunity, then a diagnosis of "chronic hepatitis B" is made. Liver biopsy: The doctor uses a needle inserted through the skin to collect tissue from the liver. This examination is not performed on every patient; it is done only in patients with chronic hepatitis who need to monitor the progression of the disease, for example, to determine the extent of liver fibrosis and inflammation of the liver cells, which affects the decision to begin treatment, or when liver cancer is suspected.

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Treatment of the Hepatitis B Virus

Currently, the medications used to treat the hepatitis B virus fall into 2 groups: the injectable pegylated-interferon alpha and oral medications (oral nucleoside/nucleotide analogs). The differing characteristics of treatment with these 2 methods are as follows:

Injectable pegylated-interferon alpha

• Acts as an immunomodulator, aiming to achieve long-term immunological control, so there is no problem with HBV resistance
• Has a defined treatment duration
• Side effects are common, such as flu-like symptoms, fatigue, mood disturbances, cytopenias, and autoimmune disorder
• Cannot be used in patients with decompensated cirrhosis
• The decision to treat with this group of medications should be supported by other information, such as HBV DNA, HBeAg, or HBsAg titer, to help assess the likelihood of response to treatment

Oral medications of the oral nucleoside/nucleotide analog type

• Acts by inhibiting viral replication, so HBV resistance may develop after a period of treatment. This group of medications is further divided into 2 subgroups according to the likelihood of developing HBV
• resistance: low barrier to resistance (namely lamivudine, adefovir, and telbivudine) and high barrier to resistance (namely entecavir, tenofovir disoproxil
• fumarate (TDF) and tenofovir alafenamide (TAF)
• Has no fixed treatment duration; the medication is taken until reaching the treatment endpoint, which is HBeAg seroconversion in HBeAg-positive patients, or HBsAg
• loss/seroconversion in HBeAg-negative patients
• Side effects may occur but are usually not severe, such as with lamivudine (causing pancreatitis, lactic acidosis) or TDF (nephropathy, Fanconi syndrome, osteomalacia, lactic acidosis)

How to Prevent the Hepatitis B Virus

The hepatitis B virus can be prevented through vaccination. The group most eligible to receive the hepatitis B vaccine is newborn infants. However, adults who do not yet have immunity, or who were not vaccinated as children, should be tested for the hepatitis B virus and have their hepatitis B immunity checked before being vaccinated. The truly at-risk groups that doctors emphasize should be vaccinated are people who live in the same household as a hepatitis B patient, those who are frequently exposed to risk, and those who frequently have sex without a condom. The vaccine must be given as a complete series of 3 doses in order to protect against the hepatitis B virus. The symptoms of the hepatitis B virus depend on the stage of the disease. Most patients in the acute stage have no symptoms or only mild symptoms. Patients in the chronic stage may experience fatigue, loss of appetite, abdominal pain, weight loss, and jaundice. Complications that may arise from the hepatitis B virus include cirrhosis, liver cancer, and liver failure. Prevention of the hepatitis B virus includes vaccination against the hepatitis B virus, having safe sex, and avoiding contact with the blood and bodily fluids of others.

Verified references

Hepatitis B is caused by hepatitis B virus (HBV). Acute infection often causes no symptoms, while chronic infection can damage the liver over time. Vaccination, testing, and appropriate care prevent many complications.

1. WHO: Hepatitis B fact sheet Accessed 13 August 2026