Amazonian toxoplasmosis complicated by severe hypoxemic pneumonia and myopericarditis in an immunocompetent adult

Amazonian toxoplasmosis (AT) is a severe form of acute toxoplasmosis occurring in the Guiana Shield and characterized by a high frequency of multivisceral involvement, even in immunocompetent individuals. Pulmonary, ocular, hepatic, and lymphatic manifestations are well documented, but cardiac involvement remains exceptionally rare and likely underdiagnosed. The diagnosis is challenging because the early symptoms are nonspecific and cardiac abnormalities may be clinically silent. We present a case of severe AT with documented myopericarditis in a previously healthy young adult (one of the few such cases reported in the literature), highlighting the diagnostic challenges and the importance of early recognition.

A 25-year-old immunocompetent male soldier deployed in the Amazonian Forest of French Guiana developed high-grade fever, headache with retro-orbital pain, myalgia, rash, and gastrointestinal symptoms (diarrhea). After an initial emergency department visit suggesting dengue fever, his condition deteriorated with respiratory distress, hepatosplenomegaly, hepatic cytolysis, hyponatremia, and radiologic evidence of bilateral pneumonia. Twelve days later, he progressed to septic shock requiring vasopressor support and high-flow oxygen therapy. Extensive infectious workup was negative except for positive serology and polymerase chain reaction for Toxoplasma gondii, supporting a diagnosis of acute toxoplasmosis. These findings were consistent with severe acute toxoplasmosis in the reported clinical context. During follow-up, cardiac troponin value progressively increased. Transthoracic echocardiography revealed a circumferential pericardial effusion, and cardiac magnetic resonance imaging confirmed recent myopericarditis. Colchicine and ramipril were introduced. The patient completed a 6-week course of antiparasitic therapy (trimethoprim–sulfamethoxazole) and was considered cured at the 4-months follow-up after symptom onset.

This case illustrates that AT may lead to severe complications, including myopericarditis, even in previously healthy individuals, a presentation that is very rarely reported in the literature. The diagnosis is challenging due to nonspecific early symptoms, overlap with other tropical infections, and limited access to advanced imaging in remote areas. Clinicians practicing in endemic regions should consider toxoplasmosis in the differential diagnosis of unexplained pneumonia, pericarditis or myocarditis.