“Nobody can test HIV-negative after a positive credible test has been done,” says Dr Francis Ssali, a physician at Joint Clinic Research Centre (JCRC). But 16-year-old, Ruth Nakalembe, seems to be exceptional.
After testing positive five different times, Nakalembe recently tested negative after two confirmatory tests at Mbuya Parish Outreach Clinic. Two initial tests were done at Mulago Hospital and the third at Mbuya Parish Outreach Clinic.
Nakalembe finds it hard to believe. She said the doctor, who carried out the second confirmatory test told her to believe the results. “I still don’t believe it. I always think there was a mistake made,” she said.
“After the death of my husband, I tested HIV-positive,” says her mother, a teacher at Crane High School, where Nakalembe studies. “The doctor advised me to test all my children and Nakalembe tested positive in January 2003 at the age of 12. Her confirmatory test in July 2003, also posted positive.”
It has not been easy for Nakalembe. She suffered depression and stigma, failed to get antiretroviral drugs and her mother resorted to buying local herbs for her.
Three other tests in 2004 and 2005 at Mbuya Outreach Clinic, were positive. In 2006, she went for a routine test and tested negative. The counsellor advised her to take a confirmatory test. Two months later, Nakalembe’s confirmatory test posted negative.
Ssali, who is also the research coordinator at JCRC, says no test can be 100% water tight. This could arise from the reagents used, storage problems, human error, or such variables. Nakalembe used the confirmatory rapid kit. “There are scenarios we get where somebody can turn a false positive,” he said.
“So, when you test positive to a rapid test kit and the confirmatory test posts negative, a third test has to be done. It is called a tie-breaker kit — it resolves the uncertainty. If it turns out negative, then we know that person is negative.”
Ssali said when the rapid tests had just been introduced, the algorithm (a set of rules for solving a problem in a finite number of steps) for how to use them had not been worked out. Nakalembe took the three rapid tests.
“We found the same people posting false positives and negatives. Most likely, that is when Nakalembe did the tests and could have been posting false positives. So, the Ministry of Health came up with an approved algorithm that makes rapid tests more accurate. Now we have kits that are used as screening kits.
“If the screening kit is positive, then we do another test with another kit, which is a confirmatory kit. If the two different kits agree that you are positive, we consider that as the true result. If they differ, we use a tie-breaker. When the individual is still not satisfied, we advise them to use DNA and Western blot tests to confirm.
“A DNA test is very specific and at the moment, we use it to diagnose very early HIV infections, which may not be picked with the antibody test (the Elisa and the Rapid tests),” Ssali says.
Dr Stephen Watiti, who works at The Mildmay Centre with people living with HIV, says tests can be affected by many things including the standards of laboratories used. “That is why it is important to have these tests done in a credible laboratory and specimens saved for further tests if needed.”
He advised Nakalembe to keep going for confirmatory tests until her doubts are allayed. “In medicine, we never say never. If she was positive and has turned negative, we may not be able to confirm that scientifically.
“Miracles by definition are those occurrences, which we cannot explain using scientific means. I believe that the HIV test is still the only credible way we can test for HIV infections and if Nakalembe tests negative, and is healthy, most likely she is HIV negative. It is one of the miracles!” Watiti says.
Betty Tibaleka, a journalist who hosted Nakalembe on her Untold Story programme on UBC Television recently, says she has had many stories like Nakalembe’s.
Tibaleka says her (Tibaleka’s) relative even had a Western blot and DNA confirmatory tests, but tested negative. “People should know that this is a dynamic disease, which is undergoing research. There are still many mysteries about this disease,” she says.