A survey of the occurrence of potentially harmful amounts of selenium in the vegetabtion of the Karoo.

The presence of potentially dangerous amounts of selenium in various plants taken from the areas where geeldikkop and enzootic icterus are prevalent was noted in a preliminary report by Brown & de Wet in 1962. The element was found to occur in high concentrations in the livers and kidneys of animals suffering from enzootic icterus and in lesser, but still significant amounts, in the same tissues from typical cases of geeldikkop (Brown & de Wet, 1962). Some thoughts on the possible role of selenium in the aetiology of these two conditions, as well as in that of various ill-defined syndromes occurring in the same areas, were advanced in the same report. The symptomatology, pathology and incidence of naturally occurring selenosis throughout the world were reviewed at the same time and compared with those of various syndromes, thought to be of a similar nature, which occur in the Karoo. More information on the occurrence of potentially harmful amounts of selenium in the tissues of animals raised in the Karoo and Cape Midlands appeared in subsequent publications by the authors (Brown, 1962, 1963, 1964 ; Brown & de Wet, 1963).