Umuthi wenyongo: these ideas about pollution and purging of the gut are very old in southern Africa, and yet have also been changing rapidly over the last 150 years, in response to colonialism and conquest. These curative commodities, while similar in form over the last century in response to the demands of colonial systems of migrant labour to mines and cities, became hugely controversial in the 2000s in the era of “AIDS denialism” led by the former President Thabo Mbeki.