Infectious Causes of Tropical Fever with Myocarditis
Dengue fever is the most important tropical infection causing myocarditis, affecting 12-50% of hospitalized patients with significant mortality risk, followed by chikungunya, yellow fever, and less commonly malaria, toxoplasmosis, and other protozoan infections. 1, 2
Primary Arboviral Causes
Dengue (Most Common)
Dengue represents the leading cause of myocarditis among tropical fevers, with cardiac involvement occurring in 12.4% of all dengue cases and up to 50% of hospitalized patients 2. The myocarditis can:
- Mimic acute myocardial infarction clinically
- Trigger intracoronary thrombosis, coronary dissection, and intramural hematoma in rare cases
- Present with arrhythmias, pericarditis, and LV dysfunction 1
Critical risk stratification: Men face higher risk of cardiac complications with greater rates of LV systolic dysfunction compared to women. Pediatric populations show higher prevalence of severe disease (52.4%), though adults have higher mortality (34.8%) 2. Any echocardiographic abnormality in dengue patients associates with adverse outcomes 1.
The mortality from dengue myocarditis is 26.44%, with severity risk increased 2.44-fold and mortality risk increased 19.41-fold compared to dengue without myocarditis 2, 3.
Chikungunya
Chikungunya causes myocarditis as one of the most frequent systemic manifestations, often presenting with hypotension 1. Cardiovascular phenotypes include:
- Myocarditis (most common)
- Acute coronary syndrome
- Pericarditis and pericardial effusion
- Pulmonary congestion 1
Yellow Fever
Severe yellow fever cases frequently involve myocardial injury through direct viral damage and inflammation 1. Characteristic findings include:
- Bradycardia (pathognomonic feature)
- ECG abnormalities
- LV wall thickening with hyper-refringent myocardial texture suggesting infiltration 1
Zika Virus
Cardiac manifestations are rare but documented, including 1:
- Arrhythmias
- Pericardial effusion
- Heart failure with potential progression to dilated cardiomyopathy
- Congenital heart disease in 10-14% of congenital Zika syndrome cases
Protozoan Causes
Malaria
While traditionally not considered a major cause of cardiac morbidity, cardiovascular complications occur in 7% of adults with symptomatic malaria 1. Cardiac involvement includes:
- Impaired LV function (most common echocardiographic finding)
- Reduced global longitudinal strain that improves with antimalarial treatment
- Myocarditis in severe cases, particularly with Plasmodium falciparum 1
Important caveat: Cardiac complications are likely underdiagnosed due to under-reporting 1.
Other Protozoan Infections
Toxoplasmosis, leishmaniasis, and amoebiasis rarely affect the myocardium, typically only in severe forms through inflammatory or immune-mediated mechanisms 1, 4. Cardiac involvement is significantly underdiagnosed in these neglected diseases 1.
Bacterial Causes
Enteric Fever (Typhoid)
Toxic-infective myocarditis and pancarditis develop in severe typhoid fever cases 5. Clinical presentation may be atypical, requiring high suspicion.
Rickettsioses
Myocarditis and pericarditis are rare complications, typically associated with Rickettsia rickettsii and R. conorii 6. Even African tick-bite fever (R. africae), usually benign, can cause acute myocarditis 6.
Q Fever (Coxiella burnetii)
Cardiac involvement occurs in 28.5% of Q fever cases with 25% mortality 7. Manifestations include:
- Infective endocarditis (all chronic cases)
- Myocarditis (can progress to dilated cardiomyopathy)
- Pericarditis 7
Geographic Distribution Patterns
Africa: Malaria dominates (28-47% of febrile cases), with schistosomiasis (3-6%) and rickettsioses (1-5%) 8
Asia: Dengue (13-18%) and enteric fever (3-17%) predominate 8
Latin America: Dengue most common (8-13%), with leptospirosis also significant (10%) 8
Clinical Recognition Pitfalls
Cardiovascular complications are systematically underdiagnosed because 1:
- Non-specific symptoms overlap with primary infection
- Limited access to cardiac imaging in endemic areas
- Predominant clinical focus on neurologic or hemorrhagic manifestations
- Only small percentage of dengue patients receive cardiac evaluation in endemic regions 1
Maintain high suspicion for myocarditis in any tropical fever patient presenting with: chest pain, dyspnea, hypotension, arrhythmias, or elevated cardiac biomarkers, particularly with dengue, chikungunya, or yellow fever 1, 2.