Platelets and platelet disorders in Africa

Summary Blood platelets, which are known to play important roles in normal vertebrate biology, are influenced by a variety of factors, the majority of which are acquired. In this chapter, attention is drawn to the need to re-examine one of the old accepted values in haematology, the normal platelet count. In addition, effects of some environmental factors, such as malarial parasitaemia, on both platelet count and platelet function are fully discussed. Similarly, the effects of HIV on platelets, as well as on other haematological parameters, in the African environment are described briefly. The urgent need is stressed for careful evaluation of the impact of HIV on the total disease burden in the population. In addition, the effect of environmental factors on the manifestations of some clinical features, e.g. splenomegaly and anaemia, in acute idiopathic thrombocytopenic purpura are highlighted. It is suggested that in such environments, the presence of these features do not constitute contraindications to making the diagnosis when other criteria are met.