Advancing protozoan vaccine research: A review of promising candidates and emerging technologies

Protozoan parasites, a diverse group of unicellular eukaryotic organisms, represent a significant challenge to global human and animal health, particularly in regions with constrained healthcare resources. These pathogens are etiological agents of most severe and often fatal diseases, collectively accounting for millions of infections and deaths annually. Despite the profound impact on public health, vaccine development for protozoan diseases has been markedly slower than the advancements in combating other infectious agents. However, recent strides in understanding parasite biology and host-pathogen interactions, coupled with advancements in immunological research, have provided renewed prospects for effective vaccine design. This systematic review critically examines the progress in vaccine development targeting six major protozoan pathogens: Plasmodium falciparum, Toxoplasma gondii, Leishmania donovani, Trypanosoma cruzi, Theileria annulata, Theileria parva, and Babesia bovis. This literature explores potential antigenic targets and emerging vaccine delivery technologies. This comprehensive review of the existing literature aims to delineate key gaps, prioritize research directions, and facilitate the translation of scientific insights into effective strategies. Furthermore, this review contributes to the expanding knowledge repository, serving as a foundational resource for advancing protozoan vaccine research and development.