Is British man the first to "recover" from HIV?

A British man has confounded doctors by testing negative for HIV antibodies several months after two positive results. This follows a report last February of a man whose test results changed following treatment, and who remained antibody negative four years later.

Feeling tired and feverish, Andrew Stimpson visited the Victoria Sexual Health Clinic for an HIV antibody test in May 2002. The initial result was negative, but he was encouraged to return for more tests because antibodies are often undetectable during the first few weeks after infection.

Mr Stimpson tested HIV antibody positive in August 2002. But he remained healthy and was not prescribed antiretroviral drugs. Tests designed to measure the amount of HIV in his blood - known as the "viral load" - found it to be "exceptionally low".

More than a year later, in October 2003, he was offered another HIV antibody test, which came back negative. Subsequent tests in December 2003 and March 2004 produced the same result.

Mr Stimpson suspected he had been misdiagnosed, and considered legal action. However an investigation by Chelsea and Westminster Healthcare NHS Trust found the clinic had not made any mistakes. The samples taken in August 2002 were retested and again found to be antibody positive. Samples from March 2004 onwards were also retested and found to be antibody negative. DNA testing confirmed that all samples belonged to Mr Stimpson.

Based on the information currently available, it is not possible to say for sure whether Mr Stimpson is currently infected with HIV or whether he has ever been infected.

A spokeswoman for the Chelsea and Westminster Healthcare NHS Trust said: "I can confirm that he has a positive and a negative test. I can't confirm that he's shaken it off, that he's been cured. We urge him, for the sake of himself and the HIV community, to come in and get tested."

This is not the first documented case of an adult reverting from HIV antibody positive to negative. In February 2005, scientists at the 12th Conference on Retroviruses & Opportunistic Infections in Boston presented the case of a man who was diagnosed HIV positive in 1995 by two separate sets of antibody tests, and who had a detectable viral load.*

Two years after diagnosis the man had a very high viral load, and he began taking antiretroviral therapy. Following three years of treatment he was again tested for HIV antibodies and the result was negative. Over the next four years, during which he took no antiretroviral drugs, the man remained antibody negative. Scientists were also unable to detect any viral load or to culture the virus from his blood or semen.

The explanation for this man's reversion is still unclear, but some experts say it may have been an effect of the therapy. Undetectable viral load is not uncommon during treatment, and the absence of antibodies is not conclusive proof that the virus has been completely eliminated.

Mr Stimpson may not be the first to revert to being HIV negative, but unlike the other man he never underwent treatment. Both cases are certainly unusual and intriguing. However it is too early to say whether they will have any implications for HIV medicine. Hopefully matters will become clearer after more tests are carried out.