As part of the South African panel's investigation, a programme of experiments is under way to satisfy any doubts over whether HIV causes AIDS.

In the first of these, blood tests for HIV from five laboratories in South Africa were retested at the US Centers for Disease Control in Atlanta, Georgia. The new tests were 99.9% consistent with the originals — indicating that HIV testing in South Africa is highly reliable.

A second experiment will investigate the claim made by some dissidents that these test results are disrupted by reactions with antibodies raised in response to other diseases, such as malaria and tuberculosis. This work is due to be complete within six to nine months.

A further experiment will use an approach based on the polymerase chain reaction to screen test samples simultaneously for several diseases (or strains thereof) while significantly reducing the risk of contamination. This work is expected to measure the number of multiple infections, and to help identify strains of both tuberculosis and HIV that are resistant to treatment.