Trypanosoma brucei, a protozoan parasite, is the causative agent of African sleeping sickness in humans (T. b. gambiense and T. b. rhodesiense) and nagana in cattle (T. b. brucei). These diseases result in much economic hardship and morbidity in Sub-Saharan Africa. The life cycle of these organisms requires an insect vector and a mammalian host. Two T. brucei parasites (blue pseudocolor) are pictured in close interaction with innate immune cells in the liver of an infected mouse. These interactions will probably result in phagocytosis of the parasite. Credit: Cell Picture Show, By Gilles Vanwalleghem, Daniel Monteyne, Etienne Pays, and David Pérez-Morga, Université Libre de Bruxelles. Image: Scanning electron microscopy of a liver slice.