Ward Cates led a delicate rescue mission to Cameroon this month to salvage a pioneering clinical trial for an Aids prevention drug that has proved groundbreaking in more ways than he imagined.

The Cameroon authorities suspended the trial in early February after increasing criticism of two US government-linked research bodies Family Health International, the public health group Dr Cates works for, and the Bill & Melinda Gates Foundation. Gilead, a Californian drugs company, also came under fire.