Clinical Pearls & Morning Reports
Published June 26, 2019
Between 30 and 365 days after heart transplantation, the leading cause of death is infection. One approach to reduce the frequency of recipient-origin infection is candidate screening. Most centers routinely screen for cytomegalovirus, Epstein–Barr virus, hepatitis B virus, hepatitis C virus, HIV, syphilis, toxoplasma, and tuberculosis. Guidelines recommend additional screening on the basis of risk of regionally limited disease. Read the latest Case Records of the Massachusetts General Hospital here.
Q: How common is unexpected donor-derived infection among transplant recipients in the United States?
A: Donor-derived infection is defined as any infection present in a transplant recipient that has resulted from an infection present in the donor and transmitted by the donor organ. Certain donor-derived infections are very common, and antimicrobial prophylaxis, preemptive treatment, or microbiologic monitoring is typically used to reduce the risk of clinically significant disease in the recipient. Most of the focus on donor-derived infection is on unexpected transmissions, or infections present in the recipient that had not been suspected in the donor at the time of donation. Estimates from the United States and France suggest that unexpected transmissions are uncommon, occurring in less than 0.1% of all transplant recipients, and the rate is exceptionally low when the organ is from a living donor.
Q: What characterizes the illness among transplant recipients who have Chagas’ disease due to reactivation of latent Trypanosoma cruzi infection?
A: 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.
A: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%).
A: 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.