Parasitic diseases can affect nearly every organ system, including the cardiovascular system. Cardiac involvement is often underrecognized but can lead to severe complications such as myocarditis , pericarditis , cardiomyopathy , arrhythmias , and even sudden cardiac death . Below is a comprehensive overview of key parasitic organisms known to affect the heart, their mechanisms of pathology, clinical manifestations, and relevant transmission modes.
1. Toxoplasma gondii
Disease : Toxoplasmosis
Transmission : Ingestion of oocysts (from cat feces), consumption of undercooked meat, vertical (congenital) transmission
Reservoir : Cats (definitive hosts); humans and other warm-blooded animals (intermediate hosts)
Cardiac Involvement :
- T. gondii infects myocardial cells, surviving intracellularly by avoiding lysosomal degradation.
- Forms tissue cysts in cardiac muscle, especially in immunocompromised individuals.
- Chronic infections may result in myocarditis , pericarditis , cardiac dilatation , and hypertrophy .
Clinical Features :
- Fever
- Lymphadenopathy
- Retinochoroiditis
- Myocarditis and heart failure symptoms
- Pericarditis (less common)
2. Entamoeba histolytica
Disease : Amoebiasis
Transmission : Fecal-oral route
Reservoir : Humans
Geography : Common in tropical and subtropical regions
Cardiac Involvement :
- Rare but serious complication: Amoebic pericarditis
- Often secondary to direct extension of a liver abscess (especially left lobe) into the pericardium
Clinical Syndromes :
- Acute : Cardiac tamponade (chest pain, hypotension, shock)
- Chronic : Progressive pericardial effusion with fever, dyspnea, and chest discomfort
- ECG may reveal diffuse ST-elevations or low voltage
3. Trichinella spiralis
Disease : Trichinosis
Transmission : Ingestion of undercooked meat (usually pork or wild game)
Reservoir : Carnivores and omnivores (e.g., pigs, bears)
Cardiac Involvement :
- Larvae encyst in striated muscles, but cardiac pathology is usually due to an eosinophilic myocarditis —an immune-mediated reaction rather than direct invasion.
- Resembles tropical endomyocardial fibrosis in pathogenesis
Clinical Manifestations :
- Myocarditis with arrhythmias
- Chest pain, palpitations
- ECG abnormalities
- Can progress to heart failure or sudden death in severe cases
4. Echinococcus granulosus
Disease : Cystic echinococcosis (hydatid disease)
Transmission : Ingestion of tapeworm eggs from dog feces
Reservoir : Dogs (definitive host), sheep and humans (intermediate hosts)
Cardiac Involvement :
- Rare but life-threatening
- Cysts may form in myocardium, pericardium, or endocardium
Complications :
- Arrhythmias
- Myocardial infarction (due to compression)
- Cardiac tamponade , purulent pericarditis , sudden death
5. Trypanosoma cruzi
Disease : Chagas disease (American trypanosomiasis)
Transmission : Fecal contamination by triatomine bugs (kissing bugs); also congenital, blood transfusion, and organ transplant
Geography : Endemic in Latin America
Cardiac Involvement :
- T. cruzi invades cardiac myocytes and autonomic neurons
- Causes chronic myocarditis, leading to dilated cardiomyopathy
Phases :
- Acute phase (first 2 months): Fever, lymphadenopathy, hepatosplenomegaly, sometimes myocarditis
- Chronic phase (may be asymptomatic for years):
- ~30–40% develop chronic Chagas cardiomyopathy
- Features include:
- Conduction abnormalities (RBBB, LAFB)
- Ventricular arrhythmias
- Apical aneurysm (classic finding)
- Thromboembolism
- Heart failure
Summary Table: Parasitic Infections Affecting the Heart
| Parasite | Disease | Cardiac Complications | Key Clinical Features |
|---|---|---|---|
| Toxoplasma gondii | Toxoplasmosis | Myocarditis, pericarditis | Fever, lymphadenopathy, myocarditis, ocular disease |
| Entamoeba histolytica | Amoebiasis | Amoebic pericarditis | Cardiac tamponade, pericardial effusion, hepatic abscess |
| Trichinella spiralis | Trichinosis | Eosinophilic myocarditis | Myalgia, fever, chest pain, arrhythmias |
| Echinococcus granulosus | Hydatid disease | Cardiac hydatid cysts | Arrhythmias, tamponade, sudden death |
| Trypanosoma cruzi | Chagas disease | Chronic cardiomyopathy, arrhythmias | Conduction defects, apical aneurysm, CHF |
High-Yield Clinical Pearls
- Myocarditis from parasitic infections can mimic viral etiologies; always consider parasitic causes in endemic regions.
- ECG and echocardiography are crucial for assessing complications like arrhythmias, pericardial effusion, and ventricular dysfunction.
- Serological tests (e.g., ELISA, IFA) and PCR are often required for definitive diagnosis.
- Early recognition and antiparasitic therapy (e.g., benznidazole for Chagas, albendazole for echinococcosis) can reduce morbidity.
