Summary of Myocarditis: Etiology, Diagnosis, and Therapy

## Introduction Parasitic infections are a group of diseases caused by single-celled parasites or helminths, which can affect various organs, including the heart and digestive tract. This material focuses on the clinical manifestations, diagnosis, and treatment of selected parasitic infections: Chagas disease, African trypanosomiasis, toxoplasmosis, and trichinellosis. > Definition: A parasitic infection is a condition in which a host organism is colonized by a parasite that utilizes the host for nutrition, reproduction, or to complete its life cycle. ## Chagas Disease (Trypanosoma cruzi) ### Disease Progression - **Acute Phase:** often unrecognized; manifests in <5% of patients several weeks post-infection with non-specific symptoms or, rarely, with acute myocarditis and meningoencephalitis. - **Silent (Latent) Phase:** without antiparasitic treatment, can persist for >10–30 years. - **Chronic Phase:** in approximately half of patients, manifestations gradually develop primarily in the cardiovascular and gastrointestinal systems. ### Typical Cardiac Manifestations - Conduction abnormalities: sinus node, AV node, often right bundle branch block - Arrhythmias: atrial fibrillation, ventricular tachyarrhythmias - Small apical ventricular aneurysms - Increased risk of thromboembolism from dilated ventricles > Definition: An aneurysm is a pathological outpouching of a heart chamber wall, which can be a source of thrombi. ### Diagnosis - Direct parasite detection (xenodiagnosis) is rarely used - Serological tests for specific IgG antibodies: due to limitations in sensitivity and specificity, at least two positive independent tests are required to confirm the diagnosis. ### Treatment - **Antiparasitic treatments:** benznidazole, nifurtimox — effective in children with chronic infection; however, in adults with established cardiomyopathy, their efficacy in halting disease progression is not conclusive. - **Symptomatic and supportive treatment for chronic cardiac disease:** heart failure medications, implantable cardioverter-defibrillators, anticoagulants for thromboembolism risk - Patients with advanced disease: transplantation followed by monitoring and repeat antiparasitic treatment to suppress reactivation. Fun fact: Chagas Disease is named after the Brazilian physician Carlos Chagas, who discovered the causative agent of the disease and described its entire life cycle. ## African Trypanosomiasis (Sleeping Sickness) ### Causative Agent and Transmission - Transmission: by the bite of the tsetse fly - Two main types: **Trypanosoma brucei gambiense** (West African form, slow progression) and **Trypanosoma brucei rhodesiense** (East African form, rapid progression) ### Clinical Presentation and Diagnosis - Gambiense: slow, progresses over years with continuous spread - Rhodesiense: rapid progression, perivascular infiltration, myocarditis, heart failure, frequent arrhythmias - Diagnosis: identification of trypanosomes in blood, lymph nodes, or other affected sites ### Treatment - Antiparasitic therapy depends on the species and stage of infection; effectiveness may be limited Did you know that travelers to endemic areas can be infected even during a short stay, making prevention and prompt medical attention important if infection is suspected? ## Toxoplasmosis (Toxoplasma gondii) ### Transmission and Risk Groups - Transmission: undercooked meat (beef, pork), contaminated cat feces, organ transplants, transfusions, maternal-fetal transmission - Risk of reactivation especially in immunocompromised patients (e.g., AIDS) ### Clinical Manifestations - In immunocompetent individuals: often asymptomatic; if active infection, initially positive IgM, later IgG - In immunocompromised individuals: encephalitis, chorioretinitis; in the heart, myocarditis, pericardial effusion, constrictive pericarditis, heart failure ### Diagnosis - Immunocompetent individuals: positive IgM followed by IgG - Immunocompromised individuals: positive Ig