Hepatitis B: A widespread but preventable disease

Hepatitis is a general term for inflammation of the liver. Many things can cause hepatitis, such as viral infections, autoimmune diseases, alcohol consumption, toxic chemicals, and certain drugs. Of these, viral infections are the primary cause of hepatitis, and these hepatitis cases are referred to as viral hepatitis. Five major hepatitis viruses exist: HAV, HBV, HCV, HDV, and HEV. These viruses are basically unrelated but are all hepatotropic. Hepatitis B, caused by HBV, is the world’s most common liver infection. Hepatitis B occurs most frequently in the Western Pacific Region and the African Region. Statistics show that 350 million people were infected with HBV in 2005.


HBV is a double-stranded DNA virus. It is a non-retroviral virus but uses reverse transcription as a part of its replication process. Viral DNA gets inside the nucleus of liver cells, and currently no effective ways available to get it out. HBV is highly contagious, and it is much more infectious than HIV. HBV can survive outside the body for up to 1 week. This is one of the reasons why HBV is so contagious.

Transmission of HBV can occur in several ways, including:

  1. Exposure to an infected person’s blood or body fluids containing blood
  2. Unprotected sex with an infected person
  3. Sharing needles and syringes that are contaminated or not sterile
  4. Sharing objects such as a toothbrush, razor, or tools used for manicures, tattoo or body piercing
  5. From an infected woman to her baby during pregnancy and childbirth

Worldwide, mother-to-child transmission, child-to-child transmission, and infections from sharing needles are the most common ways people get infected.


HBV was first identified in the 1960s when a group of scientists discovered a protein that detected the presence of the virus. In the 1970s, the virus was specifically seen by electron microscopy. Before the introduction of the HBV vaccine, almost all children in developing countries used to become infected with the virus. The first HBV vaccine became commercially available in the US in the 1980s. After that, many countries tried to popularize HBV vaccines. At present, the first dose of the HBV vaccine is generally recommended within 24 hours of birth, and two or three more doses are usually given after that.

The use of the HBV vaccine has significantly reduced the prevalence of hepatitis B. But there are still many children remain unvaccinated against HBV in some countries or regions. Why is the HBV vaccine often skipped? There are several possible reasons. First, the severity of the disease has not been fully recognized. Second, hepatitis B is thought to be transmitted mainly by sex, so the need to vaccinate an infant does not exist. In fact, sex transmission is only one of the ways that HBV spreads. Third, the HBV vaccine is difficult to access in some developing countries.


Human bodies may clear HBV without treatment. After the first exposure, infants and children are more likely to develop a chronic HBV infection than adults. Specifically, more than 90% of infants infected, about half of young children infected, and 5-10% of healthy adults infected will develop a chronic HBV infection.

HBV can cause both acute and chronic infections. During the acute infection phase, the majority of people infected do not show any signs or symptoms, while others experience symptoms like poor appetite, nausea, abdomen pain, and jaundice, which resemble symptoms of a mild flu. The acute symptoms of HBV infection are generally not serious. However, a small percentage of people infected can have severe liver damage that is associated with liver failure and even death.

Patients with chronic HBV infection generally have to take medications for a lifetime. In the long-term, a chronic HBV infection may progress to cirrhosis (the scarring of the liver) and liver cancer. Without intervention, about 15-40% individuals with chronic HBV infection will develop cirrhosis, end-stage liver disease or hepatocellular carcinoma, or require liver transplantation. Further, chronic HBV carriers can pass the virus on to other people.


To diagnose hepatitis B, a blood test is usually needed. The detection of viral proteins or antibodies to the virus in blood tests indicates HBV infection. In addition, liver function tests based on blood tests are also used to diagnose HBV infection. Other diagnostic methods include liver ultrasound and liver biopsy, which help doctors evaluate a patient’s liver damage and make a treatment decision. If a person tests positive for HBsAg (an HBV surface antigen) over a period of more than six months, he or she is considered as a chronic HBV carrier.

If you have practiced certain behaviors that put you at high risk of getting infected with HBV, such as having close contact with an infected person or being injured by needles or other sharp objects that you thought are contaminated by an infected person’s blood, you’d better seek medical help immediately. Timely and accurate diagnosis allows for prompt treatment.


No specific treatment for acute HBV infection exists. Most adults are able to clear the virus spontaneously. For chronic HBV infection, there are effective medications to control the virus. The goal of treatment in patients with chronic HBV infection is to prevent the illness from progressing to liver cirrhosis, failure or cancer. Anti-viral medications and interferon injections are two major treatments for patients with chronic hepatitis B. If the patients’ livers have been severely damaged, a liver transplant may be needed.

In addition to medical care, there are things that HBV-infected people can do or should not do in order to reduce the risk of severe complications. HBV-infected people are recommended to have enough rest, eat healthily, and avoid alcohol. Being a night owl and consuming alcohol are both harmful to the liver. Avoiding these things is particularly important for patients with liver disease.

Author Bio

Caroline Liu is an editor at Cusabio, a biotech company committed to providing high-quality life sciences reagents and services for researchers, such as protein expression service. She is focused on topics like infectious diseases.

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