Acute hepatitis B infection usually refers to the first 6 months after someone is exposed to the hepatitis B virus. Once infected, some are able to fight the viral infection while in some others the infection leads to a “chronic state,” or lifelong illness. In such individuals the infection over a period of time can cause serious life threatening problem. Hence, screening and early diagnosis of the condition is important so that due precautions and treatment if necessary can be undertaken.


Which people should be screened for hepatitis B and why?

Spread of Hepatitis B occurs through blood products, sexually as well as from mother to fetus. Screening is recommended for persons at high risk for contracting the disease. These include:-

Hemodialysis patients

Pregnant women

Infants born mothers who are HBsAg-positive

Persons known or suspected of having been exposed to HBV - donors of blood, organs, and tissues

People born in areas where HBsAg (Hepatitis B surface antigen) prevalence is found to be equal to or more than 2%

Men who have had sex with men

Drug addicts using injectable drugs

HIV positive individuals

Patients likely to take immunosuppressive treatment or cancer chemotherapy

Patients with increase in liver enzymes of undetermined cause

What tests are used for screening hepatitis B?

The following tests are used for HBV screening:-

Hepatitis B surface antigen:- A blood test to detect the presence of hepatitis B surface antigen (HBsAg) is used to screen people for hepatitis B. Persons who test positive can spread the infection to others. The test turns positive around 3 to 5 weeks after a person has been exposed to the virus. It persists in individuals who are chronically infected, but disappears once the infection has resolved. In brief it indicates:-

Hepatitis B surface antigen (HBsAg)

Active HBV

Screening Test for HBV infection. Sometimes may be falsely negative in some patients with active HBV. Positive person can spread infection. Persistence after 6 months indicates chronic infection.

Anti-HBs:

This test detects the presence of antibodies to the hepatitis B surface antigen i.e. if the person has been previously exposed to hepatitis B. It tests positive in persons who are immune to hepatitis B or have recovered from hepatitis B infection. It indicates that the person has protective immunity against hepatitis B and will not pass the infection to others.

Hepatitis B surface antibody (HBsAb)

Positive test indicates patient is immune to HBV (through past exposure or vaccination)

Negative test indicates that the patient is not immune; if active HBV disease is not present, consider vaccination

Total anti-HBc: This test detects the presence of antibodies to hepatitis B core antigen. It is positive in acute as well as in chronic infection and in those recovered from hepatitis B. There are two types of anti-HBc antibodies. The presence of the IgM subtype is indicates acute infection or reactivation of infection, whereas the IgG subtype indicates chronic infection. In brief:-

Hepatitis B core antibody (HBcAb), IgG Ig M

Positive test indicates past exposure to HBV and does not indicate whether patient has active infection or has cleared infection (check HBsAg and HBsAb) Indicates Chronic infection Indicates acute infection or reactivation of infection

Negative test indicates that the person has probably has not been infected with HBV