An occasional false positive wouldn’t come as any great surprise so to

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Published: July 27, 2010

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“An occasional false positive wouldn’t come as any great surprise, so to get the correlation of the sort we got did surprise me,” he said.With Mr Bailey and Dr Williams, he quickly submitted the results of the research to the Lancet, which published them as a short letter on 7 July, 1990 The resulting international publicity was huge. Kidney, bone marrow, spleen and throat tissue all had HIV present. Tissue from Carr’s brain and liver were negative, as were all the tissue samples from the “negative control”.The results surprised Dr Corbitt because they were better than he ever expected. It was left to Dr Corbitt to phone over the results to Dr Williams, who had the code to hand.Dr Corbitt read the results through “one by one” and was told that the four positives all came from David Carr. Dr Williams said he also washed the knives in alcohol to make absolutely sure there was no cross-contamination.Mr Bailey repeated the PCR experiment twice and got the same results each time: four of the tissues were positive for HIV, eight were negative. As an added precaution, half a dozen different rooms where used for each stage of the experiment and the scientists wore disposable gloves, gowns and hats while working with the samples in an air-filtered hood.They had even asked Dr Williams to slice sections off the stored tissue blocks using different laboratory knives.

Mr Bailey, who did much of the bench work, performed the PCR test on each of the 12 tissue samples. He and Dr Corbitt went to extraordinary lengths to avoid contamination because they knew how sensitive the PCR test can be.The work was done in a laboratory where, as far as they know, researchers had never handled HIV. Neither Dr Corbitt nor Mr Bailey knew which sample came from which patient because only Dr Williams had access to the code describing what each tube contained. Dr Williams said he kept the code in a locked drawer and no one but himself had seen it. “When I say no one, I mean no one,” he told the Independent.The blind experiment went ahead. Six came from David Carr and six from a man of a similar age who had died in a traffic accident in the same year. He was well aware that the PCR test was so sensitive that it could quite easily amplify any stray molecules of HIV that may contaminate the samples, so he asked Dr Williams to send him some more tissue, but this time in a proper “blind” trial.Dr Williams therefore sent Dr Corbitt 12 tissue samples in separate tubes.

Together with his research assistant, Andrew Bailey, Dr Corbitt applied the PCR test to the tissue and had a positive result: they found that HIV had infiltrated the DNA.Dr Corbitt, however, wanted to be absolutely sure that this was not a “false positive” result. The polymerase chain reaction (PCR) test had revolutionised forensic science and was now about to be employed on the mortal remains of David Carr.Dr Williams sent some samples to Gerald Corbitt, in the hospital’s virology unit. (The HIV antibody test was designed to work primarily on blood serum).Then, towards the end of the 1980s, scientists had developed a new technique for amplifying minute quantities of DNA – the genetic blueprint – from all manner of tissue fragments. Unfortunately, there was no test for HIV at the time that was sophisticated enough to use in such dried-out material. “When I was looking for the tissues for this patient, I came across blocks from patients just after the last war,” he said.Dr Williams said he located the tissue samples taken from Mr Carr in 1987. Dr Williams said that there are “thousands” of stored tissue samples in the pathology department of Manchester University.

Although it was standard practice to store such samples, the unusual nature of death led Dr Williams to take more tissue pieces than usual.He sliced small portions of tissues from just about every organ in Mr Carr’s body. Dr Williams said he preserved more than 40 samples and embedded them in paraffin blocks.Each set of tissues was given a unique number which could be used to cross-reference the samples with the post-mortem examination records of each case in question. Aids researchers took a keen interest in the case and this encouraged Dr Williams to locate the tissue samples he took in 1959 from the corpse. “He was not married and we know nothing of his sexual orientation,” the doctors wrote. The implication was that the man could have been homosexual and might have picked up the Aids virus whilst overseas.

In 1983 they wrote to the Lancet posing the question: Did our patient have Aids?They pointed out that the man – who was not then named – had been in the Navy between 1955 and 1957 when they supposed he had travelled abroad. From then on, his health deteriorated radically and dramatically.
Scaly brownish lesions had appeared on his skin. He developed a fever and a painful anal ulcer appeared in February 1959, followed by another ulcer between his nostril and upper lip. “He was wasted, febrile and ill,” his doctors wrote.Mr Carr was admitted to the Royal Infirmary on 8 April but nothing the doctors did seemed to help him. The breathlessness and wasting became severe and he died officially of pneumonia caused by Pneumocystis carinii, an “opportunistic” infection that takes advantage of a weakened immune system, and cytomegalic inclusion disease, a viral infection causing the cells of the lungs to become enlarged and damaged.The case of David Carr was so unusual that the two doctors and the hospital pathologist studying him decided to describe it to the medical community by writing a detailed description in the Lancet. It was published on 29 October 1960.Trevor Stretton, medical registrar, John Leonard, senior registrar, and George Williams, the pathologist who carried out the autopsy on Mr Carr, had no idea what was responsible for their patient’s fatal fall into ill- health. Judging by the complete lack of response to their Lancet paper, neither did anyone else.David Carr remained a medical enigma until the early 1980s when it dawned on the three doctors that their patient had symptoms similar to those beginning to appear in medical literature due to a mysterious new illness: Aids.


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