Host-parasite associations are driven by complex ecological interactions that can be influenced by the parasite, the host, and the climatic conditions. Knowledge about the structures of host-parasite interaction networks is still incipient and studies mainly focused on the infracommunity levels. So, we conducted a systematic review using full-text articles to understand the relation between Brazilian small mammals and protozoan infections besides identify their functional roles in the network. We identified 4527 potentially relevant references and finally included 41 papers and considered 42 species of small mammals and 13 species of the protozoan. We found non-specificity of this relationship, with a modular network that is nestedness with low specialization values with most of the parasite and hosts occupying ultraperipheral or peripheral roles. Didelphids were homogeneously distributed among all modules, reinforcing the ancient relationship between this clade and the protozoan clade to spread infections. We also identify an isolated relation between the rodent O. cleberi and T. dionisii, a common bat protozoan highlighting that the environment and features of the parasites and hosts make these relationships more complex, and understanding these relationships can help to understand the dynamics of many infectious diseases.