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Trypanosoma cruzi

T. cruzi infection causes acute Chagas’ disease, with fever, inflammation, subcutaneous edema, lymphadenopathy, hepatosplenomegaly, myocarditis, and in rare cases, meningoencephalitis that typically resolves within 4 to 8 weeks. Chronic Chagas’ disease develops in 30 to 40% of patients with T. cruzi infection and typically has cardiac manifestations (arrhythmias and conduction abnormalities, heart failure, apical aneurysms, and sudden death) or gastrointestinal manifestations (megaesophagus and megacolon). Patients with cardiac manifestations of chronic Chagas’ disease almost always have evidence of myocarditis and fibrosis on histopathological examination of heart tissue; most have noncaseating granulomas (62%) and giant cells (38%). Intracellular amastigotes are identified in only a minority of patients (15%).

Transplant recipients who have Chagas’ disease due to reactivation of latent T. cruzi infection, which can be either transmitted from the donor or already present in the recipient, classically present with fever, inflammatory panniculitis, and skin nodules. Less commonly, these patients have meningoencephalitis or myocarditis that can rapidly progress to allograft rejection and congestive heart failure if it is not treated.

In South America, reactivation of latent T. cruzi infection occurs in 20 to 90% of transplant recipients who have a known history of Chagas’ disease, with reactivation mostly occurring 11 to 23 weeks after transplantation. Among transplant recipients, risk factors for reactivation of latent T. cruzi infection include rejection of the transplant (hazard ratio for reactivation with vs. without risk factor, 1.31); the development of post-transplantation cancer (hazard ratio, 5.07), particularly post-transplantation lymphoproliferative disorder; and the use of mycophenolate for immunosuppression (hazard ratio, 3.14).

In the United States, it is recommended that patients who have a known history of Chagas’ disease or have received an organ from a donor with Chagas’ disease be monitored by means of polymerase-chain-reaction (PCR) testing for the development of parasitemia. Testing begins within 2 weeks after transplantation and is performed weekly for the first 2 months, then every 2 weeks or monthly until month 6; it is typically performed by the Centers for Disease Control and Prevention

Serologic studies are preferred for chronic Chagas’ disease because the disease is often associated with a low parasite burden that may not be detectable by PCR testing or microscopic examination of blood preparations. There is no standard serologic assay; therefore, the diagnosis of chronic Chagas’ disease requires two positive tests that differ with regard to technique or antigen. Currently, there are only two approved medications for the management of Chagas’ disease: nifurtimox and benznidazole. Benznidazole is the preferred agent because it has a better safety profile.

References

Case 20-2019: A 52-Year-Old Woman with Fever and Rash after Heart Transplantation M.G. Ison and Others. N Engl J Med 2019;380:2564-2573

Bern C. Chagas’ disease. N Engl J Med 2015;373:456-66.

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