IntroductionCoccidian protozoa and microsporidian fungi are opportunistic pathogens increasingly implicated in infections in immunosuppressed individuals. These parasites typically infect the intestinal epithelium, resulting in secretory diarrhea and malabsorption. The disease burden and timeline are both greater and longer among immunosuppressed patients. Therapeutic options for immunocompromised individuals are limited. As a result, we wanted to better characterize the disease course and treatment efficacy of these parasitic gastrointestinal infections.MethodsWe performed a single-center, retrospective MedMined (BD Healthsight Analytics, Birmingham, AL, USA) chart review of patients between January 2012 and June 2022 diagnosed with coccidian or microsporidian infections. Relevant data were collected from Cerner’s PowerChart (Oracle Cerner, Austin, TX, USA). Descriptive analysis was performed with IBM SPSS Statistics (IBM Corp., Armonk, NY, USA), and Microsoft Excel (Microsoft, Redmond, WA, USA) was used to generate graphs and tables.ResultsIn these 10 years, there were 17 patients withCryptosporidiuminfections, four withCyclosporainfections, and no positive cultures forCystoisospora bellior microsporidian infections. In both infections, the majority of patients experienced diarrhea, fatigue, and nausea, with vomiting, abdominal pain, appetite loss, weight loss, and fever occurring to a lesser degree. Nitazoxanide was the most common treatment forCryptosporidium, while trimethoprim-sulfamethoxazole or ciprofloxacin were the treatments of choice forCyclospora. Of theCryptosporidiuminfections, three received combination therapy with azithromycin, immunoreconstitution, or IV immunoglobulins. Among the fourCyclospora-infected patients, one received combination therapy of ciprofloxacin and trimethoprim-sulfamethoxazole. Treatment lasted around two weeks, and 88% ofCryptosporidiumpatients and 75% ofCyclosporapatients had a resolution of symptoms.ConclusionThe most detected coccidian infection wasCryptosporidium,followed byCyclospora, with the lack ofCystoisosporaor microsporidian infections likely due to diagnostic limitations and prevalence.CryptosporidiumandCyclosporalikely caused their associated symptoms in most cases, with other possible etiologies, including graft-versus-host disease, medications, and feeding tubes. The small number of patients receiving combination therapy prohibited a comparison with monotherapy. In our patient population, though, there was a clinical response to treatment despite immunosuppression. While promising, additional randomized control experiments are required to fully understand the efficacy of parasitic treatments.