The complex connection between some infectious illnesses and some psychiatric disorders is an important area of study, with infections known to cause a diverse range of psychiatric symptoms. This association poses significant challenges for physicians in differentiating between mental illnesses induced by infections and those stemming from underlying psychiatric conditions. This study systematically synthesizes literature from various databases that explain the relationship between certain infectious diseases and specific psychiatric disorders. The systematic review explores mechanisms such as neuroinflammation, direct central nervous system (CNS) infection, and the interaction between the immune system and psychiatric conditions. The study examines various infectious pathogens, including viruses, bacteria, parasites, prion diseases, and fungi. An analysis of these findings is presented in the study's discussion section, along with a review of therapeutic methods such as drug use and psychological treatment. The review emphasizes the need for multidisciplinary teamwork and thorough clinical examinations in managing psychiatric symptoms caused by infections. It also highlights the significant role of public health measures in mitigating the impact of psychiatric diseases related to infectious illnesses. The study finds that current therapeutic methods include pharmacological and psychological treatments, which can effectively manage these conditions. The study has concluded that psychiatric manifestations are prevalent across various infectious diseases, including those caused by viruses, bacteria, parasites, and fungi. Key mechanisms identified include neuroinflammation, direct infection of the CNS, and the immuno-psychiatric interface, all of which contribute to the development of psychiatric symptoms. The future of managing these complex conditions lies in a comprehensive approach that combines clinical, therapeutic, and public health strategies.