Hepatitis B

Hepatitis B is an infection of the liver caused by the Hepatitis B virus (HBV). HBV is a Deoxyribonucleic Acid (DNA) virus meaning its genetic material in made from DNA. This virus can cause both acute and chronic liver infection. Chronic Hepatitis is associated with carriage of the virus in the blood stream with long term damage to the liver. An estimated 257 million individuals are chronically infected with HBV world over.

Transmission of HBV

The virus is transmitted in the following ways

• Direct contact with blood or open wounds of an infected individual
• Through sexual intercourse
• During birth, a baby can acquire HBV from their infected mother
• Receiving blood products from an infected individual
• Direct contact from contaminated needlestick or sharp injuries

Symptoms of HBV Infection

The infection most commonly presents as an acute viral hepatitis (90%) which resolves completely with no carrier state. In some infected patients (1-10%), chronic HBV infection develops and they carry the virus in their blood. When infected as a neonate (in first month of life), the risk of chronic infection rises to 90%. Immunocompromised states are also associated with an increased risk.

Acute Hepatitis

The symptoms appear around 2 to 3 months after infection. Some patients may even remain asymptomatic.

• Fever
• Fatigue
• Muscle and joint pains
• Jaundice with yellowing of skin and whites of the eyes
• Dark coloring of the urine
• Abdominal pain in the right upper region with tenderness

Chronic Hepatitis

This involves continued or recurrent flares of acute infection for a duration longer than 6 months. Some individuals may have progressed to a chronic state even without any acute symptoms. Later they develop symptoms of chronic liver failure. Apart from liver involvement, they may have involvement of other organs such as the musculoskeletal system and the kidneys

Symptoms experienced are as follows

• Fatigue
• Decrease appetite and weight loss
• Loss of hair
• Skin rash
• Joint pains and inflammation
• Hematuria or blood in the urine if kidneys have inflammation (glomerulonephritis)

Complications of HBV

• Acute Fulminant Hepatitis: About 1% of recently infected individuals can progress to fulminant hepatitis with risk of acute liver failure. They may have hepatic encephalopathy from rise in blood ammonia levels and bleeding abnormalities. Liver transplant may be needed for survival
• Cirrhosis: Chronic HBV can lead to scarring and fibrosis of the liver. This can result in vascular resistance in the veins supplying the liver with back pressure to the abdomen organs. They develop ascites or fluid in the abdominal cavity and an increase in the size of the spleen along with other symptoms of chronic liver failure.
• Hepatocellular Cancer or cancer of the liver: Chronic HBV increases the risk of cancer. Infection at infancy increases this risk further.

Diagnosis of HBV Infection

The following tests are done to evaluate for HBV infection and to confirm the diagnosis.

1. Serum Antibody testing: There are multiple different types of antibodies associated with HBV. In the acute state, the IgM type is increased. Chronic infection and carriage is confirmed by testing for HBsAg (Hepatitis B Surface Antigen).
2. Liver Function Tests: Acute infection shows elevated liver enzymes (ALT, AST) in the range of thousands. The values are usually normal or elevated to a more modest level in chronic infection
3. Blood clotting tests: During acute infection or acute flares and while the liver function deteriorates, the blood clotting may get affected due to altered production of clotting factors
4. Abdominal Ultrasound: This is done in chronic infections to evaluate for liver cirrhosis and to look for liver cancer.

Treatment of HBV Infection

The treatment is supportive in acute infection, with the goal of stabilising the patient. Adequate hydration, high calorie nutrition and rest is recommended for recovery. There is no specific medication during this period

Chronic HBV infection now has many different options medications for treatment. It is best to consult with a specialist to decide of the right treatment regimen. The following options are available

• Antiviral medications :These keep the viral replication to a minimum delaying progress of the disease and reduce risk of transmission. Some drugs available are tenofovir, lamivudine, entecavir etc.
• Interferon injections: Interferons are substances naturally produced by virus infected cells to protect adjacent cells. These interferons are given through injections into the body to protect the liver cells from infection.
• Liver transplant: in severe end stage liver failure, or in the case of massive tumors, transplanting the liver may be the only option for survival.

Prevention of HBV Infection

The HBV vaccine contains the HBsAG subunit of the virus and it is recommended that everyone gets vaccinated. The WHO recommends vaccinating all new-borns within 24 hours of birth as this would control the mother to child transmission of the virus. Other individuals at high risk of HBV such as health care workers, immunocompromised individuals, patients who receive multiple blood transfusion, IV drug abusers and household contacts of chronic HBV carriers ought to be vaccinated with the thee dose series.

If a person is exposed to HBV either through contact with blood or through sexual contact with an infected person, they must be tested immediately for immunity by checking antibody titres to HBsAG. If they are not immune, they should receive Hepatitis B Immune globulins and be given vaccination. Immune individuals should receive a booster dose of the vaccine.

References

1. Hepatitis B [Internet]. World Health Organization. [cited 2018 Jul 28]
2. Hepatitis B | NIDDK [Internet]. National Institute of Diabetes and Digestive and Kidney Diseases. [cited 2018 Jul 28].
3. Appendix B: Postexposure Prophylaxis to Prevent Hepatitis B Virus Infection [Internet]. [cited 2018 Jul 28]