Hepatitis B: Causes, Symptoms, Treatment & Prevention
Hepatitis B virus belongs to hepadnaviruses family. This family of viruses includes duck hepatitis B virus (DHBV), ground squirrel hepatitis virus (GSHV), and woodchuck hepatitis virus (WHV). The virion of hepatitis B virus is a 42nm particle that is surrounded by an envelope. Enclosed in an envelope is a nucleocapsid that contains a small DNA genome. The core antigen is named as HBcAg and anti-HBc is its antibody.
The genome of hepatitis B virus is a circular, partially double stranded DNA of almost 3200 base pairs. The genomic DNA encodes four overlapping coding regions. The surface gene codes for HBsAg which is a surface protein. The surface gene(S) long with preS1 and preS2 code for large and middle surface proteins that help in recognition of virus by receptors that are present in liver cells and these receptors are called hepatocyte receptors.HBV produces surplus of genome-free subviral spheres and filaments of about 22nm. Envelope proteins are exposed on the Dane particles and the small surface proteins are present in subviral particles.
Epidemiology of Hepatitis B
The developed countries have less chance of HBV chronic infection due to migration of carriers from endemic areas. In most endemic areas, the major mode of transmission is perinatal transmission but in African countries horizontal spread during the first 2 years of life is predominant mode of transmission. In low prevelance areas, unprotected sexual intercourse and the drug injection are the major mode of transmission of chronic HBV infection.
How Hepatitis B can be transmitted?
- Sexual transmission- In low prevelance areas, unprotected intercourse is the major mode of transmission of HBV infection. 40% of infections in UN are transmitted via heterosexual intercourse an approximately 25% among homosexuals men. Use of contraceptive methods during sexual intercourse can greatly reduce the infection rate.
- Percutaneous Innoculation- It is also an effective mode of transmission of HBV infection. The common route is sharing of syringes and needles in intravenous drug users. Public health awareness about the use of disposable syringes, needles or equipments is important in preventing this mode of HBV transmission.
- Perinatal transmission- It is the transmission of virus from HBeAg-positive mother to her infant that may occur in uterus. The infection can be high as 90% so, neonatal vaccination is highly effective. It can be prevented by testing of HBsAg in all women at the first prenatal visit. Newborns from HBV-positive mothers can be effectively protected by active-passive immunization.
- Horizontal transmission- HBV infection can be transmitted through horizontal transmission via minor breaks in the mucous membrane and skin. It can also be transmitted through bodily contact with other persons. There is no valid evidence of HBV transmission through body fluids except blood.
- Transfusion- Blood transfusion can transmit HBV infection from donor to the recipient if the donor is HBV positive. For preventing that type of transmission, screening of blood should be done before every small transfusion.
- Nsoscomial infection- It can occur from patient to patient and from patient to health care worker. HBeAg- negative persons are not infected but HBeAg-positive persons are infected and should perform protective measures such as wearing double gloves.
- Organ transplantation- HBV infection can be seen in patients after the transplantation of extrahepatic organs from HBSAG- positive donors such as kidney. For the prevention of such transmission, donors should be screened properly.
Sign and Symptoms of Hepatitis B
- Slight fever during acute Hepatitis B infection
- Mild gastrointestinal upset
- Visible jaundice
- Darkening of urine
- Pale colored stools
- Hepatomegaly is present
- Macular rash
- Urticarial lesions
- Arthritis antedates
- Glomerulonephritis
- Nephrotic syndrome
- Liver injury
- HBsAg and anti-HBcIgM are the only tests needed for the diagnosis of acute hepatitis B.
- Liver functioning tests are similar to that of LFTs of hepatitis A.
- Liver histology of HBV is also similar to HAV.
- Renal involvement can be found on the basis of urinary findings.
How Hepatitis B can be treated?
Hepatitis B on early stage can be treated by taking supportive measures such as bed rest and nutritious diet. For treatment of chronic hepatitis B, a-interferon that inhibits viral infections normalize ALT levels
, and it also leads to the appearance of HBe and disappearance of HBeAg. However in severe conditions liver transplantation should be performed.
How to prevent HBV infection?
- By careful screening of blood donors and pregnant women.
- Use of properly sterilized syringes, needles and other surgical equipments.
- Safe sexual intercourse and avoid sexual contact with carriers.
- Vaccination should be made necessary for all the persons including infants and adults.
- Risk of vertical transmission of HBV infection can be greatly reduced with the postpartum vaccination and immunoprophylaxis.
