Is that HIV-screened blood safe?

Women, during childbirth,
sometimes need blood transfusion.Several millions of people worldwide need blood transfusion to stay alive as a result of problems such as road traffic accident and severe malaria. However, such blood needs to be properly screened to ensure it is HIV-free under every circumstance, reports Sade Oguntola.

As Mrs Taye Akinshola will readily attest, blood transfusion helped to save her life after she had her last baby at a private hospital in Lagos. She was bleeding profusely after she had the baby and the medical doctor asked that her husband should go and collect a certified screened blood from the centrally-controlled blood transfusion service in the city. Mrs. Akinshola is one of the several millions of people worldwide that need blood transfusion to stay alive as a result of many problems such as road traffic accident, severe malaria and so on that had made them to have a low blood level.

However, not all cases end up like Mrs. Akinshola’s. One of such individuals is the baby girl that was transfused at Lagos University Teaching Hospital(LUTH), a leading hospital in Lagos. According to the hospital’s medical director, soon after Eniola’s birth, she was found to be jaundiced. An exchange blood transfusion was prescribed, and the father donated some units of blood. However, the father’s blood was found to be incompatible, so blood from the hospital’s blood bank was administered.

Before long, the baby tested positive for HIV, though both parents tested negative. According to the hospital, “the blood transfused into the body was screened and found to be HIV negative at the time it was transfused into the body.” Meanwhile, an investigation done by the government concluded that the likely source of the infection was the transfused blood.

This is but a single case of an individual that became infected with HIV, but it highlights the fact that blood transfusions are not risk-free. The fact that the blood was screened for HIV is no guarantee that it is safe. “Although HIV may not be detected by a test during the window period, HIV can be transmitted during that time. In fact, individuals are often most infectious during this time, which is shortly after they exposed to HIV,” according to the U.S Centres for Disease Control and Prevention.

It can take some time for the immune system to produce enough antibodies for the antibody test to detect and this time can vary from person to person. This period is referred to as the window period. Most people will develop detectable antibodies within two and eight weeks, an average of 25 days. Even so, there is a chance that some individuals will take longer time to develop detectable antibodies. In some very rare cases, it can take up to six months.

Experts have adduced that few of the cases missed may be due to several factors. “Carrots and tomatoes are some food items that when eaten before going for an HIV test that uses ELISA method, have the chance of giving a false HIV result,” according to A. O. Osoba, a professor and consultant of medical microbiology, during a lecture he gave at a training workshop in Ibadan.

According to him, “Some vegetables, especially carrot, tomatoes and cully flower have some constituents inside them which interfere with the indicator system for ELISA test used for HIV. The ELISA test consists of two parts, antibody and antigen reaction. The antibody is in the patient’s blood and the antigen is from the testing reagent. For the reaction taking place, you have an indicator system to tell you if a reaction has taken place. The indicator system is the one that is affected by the constituent of the vegetable and there will then be a false positive HIV result. That is one of the reasons why before you can say someone has HIV, it must be confirmed using other methods such as the Western blot test or Polymerase Chain Reaction (PCR) test.

Meanwhile, Professor Wuraola Shokunbi, a consultant haematologist at the University College Hospital (UCH), Ibadan, said that the window period is of great implication in determining those that are HIV-positive whether or not the test is to ascertain if they are fit to donate blood. “Aside the fact that all screening test programmes are highly sensitive to detect all cases, the effectiveness of the method in picking those with the virus at the window period depends on the patient’s conditions, test kits and many other factors,” she stated.

Nonetheless, Dr. Wale Egbewunmi, the South-Western National Blood Transfusion Service(NBTS) Zonal Coordinator, said that no single test for screening blood for HIV, be it for determining an individual’s HIV status or in screening those that will be able to donate blood, is 100 per cent guaranteed. “With the test kits used world over, including in USA, there is a reported chance of one in a thousand cases of transmitting HIV; one in 25,000 in South Africa and one in 380,000 in Germany and even one in 660,000 cases in the US.

“While more than 14 million units of blood and blood products are transfused yearly in the United State of America, only 29 documented AIDS cases have occurred in transfusion recipients since HIV screening began in March 1985.” He assured, however, that any risk of HIV transmission through blood, no matter how small it may be, must be avoided as much as possible, through routine screening for HIV antibodies and other measures taken to ensure improved blood safety.

He further explained that with all HIV tests that rely on detecting the HIV antibody, their effectiveness in detecting those with the virus is dependent on when such an individual takes the test and whether they have enough HIV antibodies that the HIV test could detect. He stated that, for some individuals, it might take as long as three months before the antibody for HIV starts to appear and that this is the basis for asking people to repeat the test some months after a negative result.

Dr. Egbewunmi declared that the most sensitive test that can detect HIV at the earliest time is that which is able to pick the antibody within six and eight days of contracting the infection. “The type we use in the NBTS can pick the antibody as from the 12th day. No known test or method that can offer complete assurance that HIV is absent. So also, the variability of HIV is another issue, whether the person has HIV type 1, 2 or their subtypes. This variability in HIV subtypes accounts for why you cannot be 100 per cent sure that any method is accurate.

He assured that the process of getting safe blood for use in medical care starts with the type of donors recruited. “If we look at your lifestyle and find that you are having risk behaviour with respect to HIV, you will be disqualified from donating blood. All of these are part of efforts to reduce the possibility of taking blood from people in the window period” He declared that as much as possible, voluntary blood donors are encouraged instead of paid blood donors because paid donors have higher HIV prevalence. In addition, to ensure blood safety, he said, NBTS always preaches that blood should be the last alternative for treatment in medical care.