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Friday,August 07,2020 20:35 PM

How reliable is an HIV test?

By Vision Reporter

Added 7th November 2006 03:00 AM


It started last year in August. David Senyonga, 33, would get on and off fevers coupled with persistent heavy cough.


It started last year in August. David Senyonga, 33, would get on and off fevers coupled with persistent heavy cough.

By Elvis Basudde

It started last year in August. David Senyonga, 33, would get on and off fevers coupled with persistent heavy cough. The doctor said he had pneumonia and gave him 12 injections. But the cough persisted, forcing Senyonga to go to Entebbe Grade B where he was diagnosed with Tuberculosis (TB) and was referred to the TB department for treatment. He opted for herbal medicine instead.
He was advised by a friend to go for an HIV test and on August 5, he tested HIV positive at a prominent hospital. Senyonga was told he could not access antiretroviral drugs (ARVs) until he did a CD4 count test. When his elder brother consulted me, I took him to Mulago Hospital for a CD4 count test to see if he was eligible to start on ARVs.
Three weeks later. August 28, Senyonga’s HIV test results read negative. He has never been the same again. He has since started getting TB treatment from Mulago Hospital.

How is this possible?
Can a positive HIV test, done from a credible and registered hospital turn negative in another after three weeks?
According to Dr Emmanuel Luyirika, Director of Clinical Services at The Mildmay Centre, there is no known recorded scientific data of a person reverting a sero status from positive to negative. It is therefore possible that there could have been a problem with the tests.
Dr. Stephen Watiti, an HIV activist says while an HIV test remains a reliable tool to determine one’s HIV status, in medicine you never say ‘Never’.
“You can never completely rule out human error in a laboratory. There can also be cross-reactions with different viruses, which might be similar to HIV.”
He advised Senyonga to go back for another test in three months’ time.
According to doctor and author, Christine Maggiore, most tests we have (the ELISA and Western Blot tests), detect only antibodies specific to HIV. In her book, What If Everything You Thought You Knew About AIDS Was Wrong, she says, “since the antibody production generated by a number of common viral infections can continue for years after the immune system has defeated the virus, people never exposed to HIV can have consistent false positive reactions on HIV tests for years or for their entire lives.”
Dr Victor Musiime of Joint Clinical Research Centre said there are tests that actually look for the HIV and in Uganda, the common ones are RNA and DNA-PCR.
“RNA is the viral load test which actually counts the number of virus copies per unit of blood.”
“DNA-PCR looks for real bits of the HIV to declare a sample positive and negative. It is what we use in children because when the mother is HIV positive, a child will inherit the antibodies from the mother and test positive to other tests even when it is actually negative,” he said.
At JCRC, it is free for children below one and a half years. Others who want it as a confirmatory test have to pay $30 (sh55,500). The test is also available at Entebbe Virus Research Institute.

How can you ensure accurate results?
Watiti advises that you go to a centre with a credible laboratory that has competent and well-trained workers who are registered and also licensed to work there.
Take your time and follow all the procedures.
“Senyonga could have been in a hurry and probably skipped a set up procedure at the first hospital,” Watiti said.
But Senyonga said during his first test, the doctor just took his blood for an HIV test without counselling him and told him to take a CD4 count test if he wanted to start on ARVs.
The doctor confirmed he tested Senyonga but refused to take an interview.
Senyonga’s laboratory certificate reads: “Serology test for HIV antibodies — Positive capillus.”
Watiti says this screening test is very sensitive but not specific.
“It can detect any antibodies even when it is not HIV.
“If Senyonga had gone for counselling, he would have been told that this kind of test requires another confirmatory test,” he said.
Watiti explains that different health centres have different types of tests.
When a capillus." test posts positive results, it has to be followed by another confirmatory test before anybody can be pronounced as HIV positive.
All testing centres must offer pre-test counselling to prepare the person for the results.
Also, before giving out the results, post-test counselling should be done.
Dr. Watiti advises that Senyonga should take a confirmatory DNA-PCR test.
Ends

How reliable is an HIV test?

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