Circular RNAs: An Under-Recognized Part in Different Scenarios of Host–Parasite Interrelationships

Circular RNAs (circRNAs) are a special category of non-coding RNAs. The latter are known for their pivotal regulatory functions over many cellular processes. In biology, circRNAs exert regulatory functions on many physiological events, most likely through the regulation of gene expression. They are also implicated in a variety of health-related issues in medicine. Advances in molecular techniques and bioinformatics are expected to expand our knowledge of circRNAs, better characterizing their nature and functions. Remarkably, parasites elaborate their own repertoire of circRNAs to regulate different biological aspects. Meanwhile, they reshape the host circRNA landscape, allowing manipulation of different events of host-parasite interplay at molecular levels. We herein present an overview of the putative role of circRNAs in major parasitic infections of medical importance. Surprisingly, we underscore limited knowledge in this domain with many gaps and uncertainties. Scrutiny into the role of circRNAs in host-parasite dynamics could lead to the development of reliable diagnostic tools, or the discovery of novel therapeutic targets or vaccine candidates, for many parasitic infections.