HIV testing at the ICTC ICTC Team Training

The HIV Antibody Test An HIV infected person can find out their sero-status through an HIV test. Most common tests detects antibodies to HIV. The only way for an HIV infected person to find out their sero-status is through undergoing an HIV test. The most common way is to detect whether their blood contains antibodies to HIV. ICTC Team Training

Window Period HIV Antibodies usually develop 4 to 12 weeks after infection (Sometimes, 3 months after infection). Window period: the period immediately after infection when there are no antibodies. Antibodies to HIV are produced from 4 to 12 weeks after the moment of infection. The period immediately after infection when there are no antibodies is called the window period. ICTC Team Training

Meaning of HIV antibody test result: A positive antibody test result Individual’s blood contains HIV antibodies Therefore, the person has HIV. A positive result on an HIV antibody test means that the individual’s blood contains the presence of HIV antibodies. So we conclude the person has the virus. ICTC Team Training

False Negative test result Testing during the window period will always cause a negative result But person is infected Therefore false negative Testing someone during the window period will of course not detect antibodies but since the person is infected, this negative result is a false negative. ICTC Team Training

Infant’s Positive test result Testing a newly born child to a woman who is infected with HIV will always cause a positive result But these could be antibodies from the mother which have passed to the child Therefore need for additional testing Antibody testing in a new-born child may pick up antibodies that have been passed on from the mother if she is infected. So we cannot accept the positive antibody test result in a new-born infant. We need to use other tests in this situation. ICTC Team Training

Commonly used HIV tests Rapid tests ELISA Western Blot Tests to detect the virus itself : PCR NACO recommends the use of rapid tests so that the client can receive the result within 30 minutes. In the ICTCs, rapid tests are used to detect HIV antibodies. They do not need special equipment and are user-friendly. ELISA or enzyme-linked immunosorbent assay is an efficient test for testing large numbers of samples per day, as in large blood banks or for surveillance studies. But it is not recommended for ICTCs because it requires skilled technical staff, equipment maintenance and a steady power supply and, therefore, may be less suitable for smaller or more isolated clinics or laboratories. The Western Blot is also an antibody test. But it is more expensive. So it is used less frequently. It is used especially in the case of an indeterminate or unclear test result from a rapid test. Finally, there are tests to detect the virus itself such as the Polymerase Chain Reaction or the PCR. The PCR is used to check for infection in babies born to women infected with HIV/AIDS. Since maternal antibodies that are circulating in the blood of new-born infants only disappear by about 18 months of age, the direct test is necessary to detect the presence of the virus in their system. ICTC Team Training

Three-test algorithm ICTC Team Training NACO recommends a three-test algorithm. A client has a blood sample drawn once. If he/ she tests negative on one rapid test, he/ she is declared as HIV-negative. But when a client tests positive on the first kit, the same blood sample is tested a total of three times using other kits with different antigens before the person is declared to be HIV-positive or HIV-infected. A positive test result is only declared when all three tests pick up the presence of antibodies. If two kits show a positive result but the third is negative, the result is declared as indeterminate. Some patients have trouble accepting a positive test result. It is important to explain to them that their blood has been tested with 3 different test kits. For an indeterminate test result, counsel the person to get tested again after 14 to 28 days. If the sample continues to produce an indeterminate result, use a Western Blot or a PCR test or send it to a National Reference Laboratory for further testing. It is important to follow this testing algorithm carefully because we want to avoid causing unnecessary distress to a patient. ICTC Team Training

Ask trainees to turn to the Handbook pages which contain the forms related to testing. These are maintained by the Laboratory Technician. The client is identified by a Patient Identification Digit (PID) which should have been assigned by the counsellor. The Laboratory Register contains details of the number of tests that have been run on a sample and the final result. ICTC Team Training

Point to Column 10 which shows the samples that are sent for quality checking to the State Reference Laboratory. This includes 20% of all positive sample and 5% of all negative samples in the first week of every quarter (that is January, April, July and October). From the Laboratory Register, the following information can be extracted for the monthly report: HIV status of clients (positive, negative, indeterminate) Kit utilisation External quality assurance ICTC Team Training

The stock register provides information on the stock of critical test kits, drugs, and other essential consumables. The information that can be extracted from this register is: Opening stock Receipts Utilisation Closing balance Note that each kit is separately recorded. ICTC Team Training