Western Blot Test for HIV

Western blot test for HIV is one of the confirmatory tests. HIV ELISA/Western blot test is a group of blood tests that are used to diagnose chronic infection with human immunodeficiency virus.

How the Western blot test for HIV is performed

Blood is specifically drawn from a vein, generally from the inside of the elbow or the back of the hand. The germ-killing medicine is used for cleaning the site. The health care worker uses an elastic band and wraps it to the upper side of the hand for creating the pressure so the vein swells with blood. Furthermore, the health care worker inserts the needle into the vein. Thus, the blood is collected in the tube that is connected with the needle. The elastic band is removed after the process is done. The needle is also removed after collecting the blood and the site from where the blood was taken is covered to cease any bleeding. In children, a sharp tool that is called as a lancet may be used to puncture the skin in order to collect the blood from the vein. The blood is collected in pipette that is a small glass tube or onto a test strip or onto a slide. A bandage may be used in order to stop the blood oozing from the punctured site.

How the test will feel

Some people suffer from a moderate pain or slight feeling of being pricked or a stinging sensation. Throbbing may occur afterwards.
How to prepare for the test
No preparation is essential.
Why the test is performed

There are several reasons for being tested for HIV and those reasons are:

• Those who want to be tested
• People in high risk group i.e. commercial sex workers, injection drug users and their sexual partners, and men who have sex with men
• Screening people for certain infections and reasons i.e. Kaposi's sarcoma, Pneumocystis pneumonia
• Screening HIV women who are pregnant and do not want to pass the infection to their babies

What Normal Results (negative) mean

Normal results mean negative results of the tests. However, it should be kept in mind that if the test is performed during the acute stage of HIV infection, the result will be generally appear as negative in spite of being infected with HIV. The reason is that the antibodies (response to the HIV) are not formed by the immune system still it recognizes the existence of HIV at the primary stage or at the beginning of the HIV infection. So, retesting is suggested after six months of infection.

What Abnormal results (positive) mean

An abnormal result means positive results. However, positive result of ELISA does not essentially means that an individual is infected with HIV. There are certain conditions that may be responsible for a false positive result, for example Lyme disease, syphilis, and lupus. Though the result of ELISA test appears to be positive, it is often followed by western blot tests for confirming the existence of the HIV in the blood. It confirms the HIV infection. If the result of the Western blot test appears to be negative, it means the ELISA test results is false positive. Sometimes, the western blot test appears to be indeterminate. In such situation, some additional testing is carried out for confirming the result of this test.

It does not mean that a person is not HIV infected though his/her test results are negative. The window period that occurs between HIV infection and appearance of antibodies that are created by the immune system can be measured. If an individual is infected with primary or acute HIV infection, he/she may be in a window period, ELISA and western blot test both will not identify the existence of HIV. In such situation, additional tests will be performed.

Western blot test for HIV is performed for confirming the ELISA tests results. It confirms the results of ELISA and decides whether a person is infected with HIV or not.