In the present review, we aim to provide a general introduction to different facets of the arms race between pathogens and their hosts/environment, emphasizing its evolutionary aspects. We focus on vector-borne parasitic protozoa, which have to adapt to both invertebrate and vertebrate hosts. Using Leishmania, Trypanosoma and Plasmodium as main models, we review successively (i) the adaptations and counter-adaptations of parasites and their invertebrate host, (ii) the adaptations and counter-adaptations of parasites and their vertebrate host and (iii) the impact of human interventions (chemotherapy, vaccination, vector control and environmental changes) on these adaptations. We conclude by discussing the practical impact this knowledge can have on translational research and public health. Using a few pathogen models, the authors reviewed the different facets of the arms race between pathogens and hosts (vertebrate and invertebrate), with an emphasis on the evolutionary aspects of it. The authors discussed the impact of human interventions on these adaptations. Graphical Abstract Figure. Using a few pathogen models, the authors reviewed the different facets of the arms race between pathogens and hosts (vertebrate and invertebrate), with an emphasis on the evolutionary aspects of it. The authors discussed the impact of human interventions on these adaptations.