Leishmania parasites: could we consider them as living organisms per se?

Over the last 10 years – in Microbes and Infection – the publications dealing with protozoan parasites were mainly providing insights on the pathogenic processes leading to the local or systemic damages in the mammals, these parasitic organisms exploit/subvert as hosts. As a result, many investigators introduced the objectives of their analysis by referring to “host–pathogen” interactions. Though we, as investigators, are all determined to decipher the pathogenic processes which can indeed be coupled to the parasite uncontrolled development, I think that the parasites – alike the living organisms they subvert as hosts – need to be considered as living organisms per se, instead of being considered as “pathogens”. Such a conceptual frame will promote research on the processes on which relies their perpetuation whatever the level under investigations – individual and/or population level. Only the unicellular protozoan parasites of the genus Leishmania known to be hosted by blood-feeding insects and mammals will be further considered in this brief contribution.