The monkeypox outbreak in Western countries is “almost entirely” driven by sexual transmission, raising the spectre of stigma and discrimination, says a leading epidemiologist and public health physician.

Professor Andrew Grulich — head of the HIV epidemiology and prevention program at the Kirby Institute, UNSW Sydney — says transmission trends to mid-August show 97-99% of monkeypox cases in the UK and the US have occurred among men who have sex with men.