African trypanosomes are parasites that cause disease in both humans and livestock throughout sub Saharan Africa, leading to death and hardship in afflicted regions. The disease is spread by tsetse flies and trypanosomes use sophisticated mechanisms to sense their environment in order to optimise their chances of transmission by blood-feeding tsetse flies. Firstly, whilst in the host bloodstream trypanosomes communicate with one another to monitor their own population density, this determining when they produce specialised transmission stages (so called ‘Stumpy’ forms). Secondly, when these stumpy forms are ingested by tsetse flies, the parasites sense their new environment and undergo extensive adaptation to allow them to successfully colonise the vector. Our research seeks to understand how trypanosomes sense other parasites and their environment in order to achieve disease transmission, this also offering new opportunities to predict parasite virulence and to develop anti-virulence or transmission blocking drugs. Also, trypanosomes are evolutionarily very ancient organisms, yet highly attuned to sensing and responding to their environment. We expect that the mechanisms through which they achieve this will provide fundamental insights in to how other pathogens are spread and even how our own cells undergo development.