Things you must know before getting tested for Hepatitis B

There are several different types of Hepatitis B tests available. Depending on your prescription or choice of test, here are some important things that you should know.

Published Date : 2023-04-27T03:59:31.293Z

Updated Date : 2023-04-27T05:59:52.338Z

What is Hepatitis B

Hepatitis B is a viral infection. It is transmitted through blood or body fluids like semen, vaginal fluids. The virus infects the liver and is also known to be a reason for liver cancer.

Sexual Contact

Hepatitis B can spread to unprotected anal/oral/vaginal sex. The virus is present in almost all body fluids, and any break in the skin/cut exposed to contaminated body fluids can transmit the infection. As such even small amounts of sufficiently contaminated body fluids can transmit this infection.

Shared Needles

The most common mode of spread is by sharing needles, in case of intravenous drug users. The virus can survive inside needles for a variable period of time and can be tramsitted to the next user of the needle.

Blood Transfusion

The virus is also commonly transferred in blood transfusions. If the blood has not been properly tested for Hepatitis B

Types of Hepatitis B Tests

There are many different types of Hepatitis B Tests. Each test is positive during a different phase of the virus. Some tests are done for screening purposes while others are done to monitor the course of the infection. Also some tests may be positive in case of chronic infections while others may not.

Hepatitis B Surface Antigen

HBsAg or Hepatitis B Surface Antigen is the most commonly tested Hepatitis B Test, commonly done for screening purposes. This basically tests for the actual viral particle (its surface proteins)

When is HbsAg positive?

HbsAg starts to turn positive about 1 month after the infection, peaks at around 3 months, and stays positive for about 6 months. If the body manages to clear out the infection, this marker becomes negative, and signifies cure. If the body is not able to clear the infection, the marker persists to be positive for many months and years.

Antibodies to Hepatitis B Surface Antigen

Anti-HbsAg is an antibody that is produced by the body against the HbsAg. These antibodies only get produced if the body manages to clear the virus. They turn positive around 7 months after the infection, and coincide with the time of disappearance of the HbsAg from the blood. The presence of these antibodies is protective and it means that the body is free of the infection. These are the same antibodies that turn positive after vaccination.

Hepatitis B Envelope Antigen

This is a part of the envelope of the hepatitis B virus. This antigen follows the trend of the Hepatitis B Surface Antigen, and is detectable after 1 month, peaks at 3 months and falls around 6 months. The presence of Hb Envelope Antigen indicates increased viral replication and heightened infectivity. Similar to HbsAg this antigen is not cleared in case of persistent or chronic infection.

Hepatitis B Envelope Antibodies

In case the body clears the infection, these antibodies will appear around 6 months. And they stay elevated for several years. In case of chronic infection, the antibodies appear after several years. The presence of these antibodies can indicate whether the infection is acute or chronic, depending on the presence or absence of the Envelope Antigen

Hepatitis B Core Antibodies

These are antibodies created against the core of the Hepatitis B Virus. These antibodies are of two types. The IgM antibodies are seen earlier and indicative of acute infection, the IgG antibodies are seen later. They persist throughtout life and do not have prognostic value. They can only determine the length of the infection

IgM antibodies to Hepatitis B Core

These antibodies are seen around 3 months, and they stay elevated thereafter. Their presence indicate acute or recent infection

IgG Antibodies to Hepatitis B Core Antigen

These antibodies are seen after 6 months, their presence indicates the duration of infection

Nucleic Acid Testing

Nucleic Acid Tests look for the Hepatitis B DNA. This is the earliest and fastest positive way to check for Hepatitis B infection. these tests can be positive around 15-34 days post infection depending on the assay used, and the strain of Hepatitis B.

I had recent unprotected sex, which test should I do?

If your exposure was greater the last 90 days, HbsAg testing may be sufficient to screen for Hepatitis B. If your exposure was within the last 90 days, and you have a low risk of infection, you can still do the HbsAg test and repeat it after 3 months to be doubly sure. If you have a higher risk of infection (Eg your partner is known positive) you can go for Nucleic Acid Testing, knowing that its window period may still be 1 month. If you have been very recently exposed (within 30 days), no test can give you confirmatory results. You will have to get repeated any test that you do after 90 days.

I am frequent needle drug user, which test should i do?

Since you are a regular user, it is hard to determine your time of exposure. It may be very recent or relatively remote. In such cases, the best method is regular screening, with HbsAg, at frequent intervals in consultation with your doctor.

My HbsAg test was negative, does it mean I am free of Hepatitis B?

If you were infected in the last 90 days, the test may still be negative (Falsely). As such you need to repeat the test after 90 days. If you are confident that you had no exposure within the last 90 days and the test is negative, you can be almost certain that you do not have Hepatitis B.

I was vaccinated for Hepatitis B, which test should I do to check if the vaccine was successfull?

The anti HbsAG antibodies will be positive in case of successfull vaccination and your HbsAg test will be negative.