Anuran amphibian Hemoparasites over the Last Century: Advances, Challenges, and Future Prospects: A Systematic Review

Hemoparasites are intracellular organisms that affect groups of vertebrates, including amphibians, yet their diversity, distribution, and ecological effects remain partially understood. This systematic review analyzed advances over the past one hundred years in the study of hemoparasites in anurans, emphasizing: (1) the geographical distribution of studies, (2) the diagnostic techniques employed, and (3) the diversity of parasites and hosts involved. To this end, 83 scientific articles published between 1924 and 2024 were reviewed, following PRISMA guidelines and within an adapted PICO framework. The results reveal a notable increase in publications since the 2000s, with a concentration in North and South America. Morphological studies predominated (69.9%), while only 22.9% combined morphological and molecular techniques and 9.6% used only molecular techniques. Protozoan genera such as Hepatozoon and Trypanosoma, as well as nematodes (microfilariae) of the family Filaroidea, were frequently reported (69.7%); on the host side, the most studied anuran families were Ranidae (34.6%), Hylidae (6.9%), and Bufonidae (21.5%). Important methodological gaps were evident, particularly biodiverse tropical regions such as Central Africa, Southeast Asia, the Andean-Amazon, and Central America. These findings underscore the need to strengthen local research capacities, expand sampling efforts, and standardize diagnostic protocols to advance knowledge of hemoparasite diversity, ecology, and their role in ecosystem health.