The use of zidovudine (AZT) to combat AIDS and HIV may be causing mutations of the HIV virus which are resistant to the drug. Researchers at the Saint-Pierre University Hospital in Brussels describe four patients whose HIV viruses were mutations and all resistant to treatment from AZT. “This problem is probably more frequent than was previously thought, and these findings have implications for the design of clinical trials,” the doctors wrote. In the same issue of the New England Journal of Medicine (7 October 1993), researchers from the Universitaire de Bordeaux in France describe an infant infected with AZT resistant HIV. The child’s HIV infected mother had been treated with zidovudine for 23 months. Meanwhile, French biologists claim to have identified a second element in human cells needed for HIV infection. Work in mice showed that only cells with both molecules termed “CD4” and “CD26” on their surface could be infected with HIV (The Lancet, 30 October 1993). These findings come at a time when there is increasing concern about potential contamination of blood products and inaccurate HIV tests. Two German firms, Haemoplas in the western city of Osterode, and UB Plasma, based in Koblenz, were recently found to have sold HIV contaminated blood products. The products were bought by Germany and other countries in Europe, including Britain, Austria, Italy, Switzerland, Sweden, Greece and France. The British Department of Health has withdrawn two products marketed in the UK which were based on these products. Meanwhile, the British Public Health Laboratory Service has discovered a number of laboratories which are erroneously diagnosing healthy patients as HIV positive.