Evidence of Trypanosoma cruzi infection (Chagas' disease) among patients undergoing cardiac surgery.

BACKGROUND: Trypanosoma cruzi, the agent of Chagas' heart disease, is transmitted by triatomine insects and by blood transfusion. The emigration of several million people from T cruzi-endemic countries to the United States has raised concerns regarding a possible increase in cases of Chagas' heart disease here, as well as an increased risk of transfusion-transmitted T cruzi. To investigate these 2 possible outcomes, we tested a repository of blood specimens from multiply transfused cardiac surgery patients for antibodies to T cruzi. METHODS AND RESULTS: Postoperative blood specimens from 11 430 cardiac surgery patients were tested by enzyme immunoassay, and if repeat-reactive, were confirmed by radioimmunoprecipitation. Six postoperative specimens (0.05%) were confirmed positive. Corresponding preoperative specimens, available for 4 of these patients, were also positive. The other 2 patients had undergone heart transplantations. Tissue samples from their excised hearts were tested for T cruzi by polymerase chain reaction and were positive. Despite the fact that several of these 6 patients had histories and clinical findings suggestive of Chagas' disease, none of them were diagnosed with or tested for it. Patient demographics showed that 5 of 6 positive patients were Hispanic, and overall, 2. 7% of Hispanic patients in the repository were positive. CONCLUSIONS: No evidence for transfusion-transmitted T cruzi was found. All 6 seropositive patients apparently were infected with T cruzi before surgery; however, a diagnosis of Chagas' disease was not known or even considered in any of these patients. Indeed, Chagas' disease may be an underdiagnosed cause of cardiac disease in the United States, particularly among patients born in countries in which T cruzi is endemic.

Trypanosoma cruzi in a low- to moderate-risk blood donor population: seroprevalence and possible congenital transmission.

BACKGROUND: Several recent studies documented the seroprevalence of Trypanosoma cruzi in blood donors at high risk for infection, but little information is available regarding donors with lower levels of risk. Thus, the present study was designed to measure the seroprevalence of T. cruzi in a donor population with a low to moderate risk for infection. STUDY DESIGN AND METHODS: During a 10-month period, donations from all allogeneic blood donors in the American Red Cross Southwest Region were tested for T. cruzi antibodies by enzyme immunoassay, and results were confirmed by radioimmunoprecipitation. Confirmed-seropositive donors were counseled and lookback investigations were initiated for those who were repeat donors. RESULTS: A total of 100,089 donations were tested: 150 were repeatably reactive, and 3 (0.003%) were confirmed as positive for T. cruziantibodies. All three seropositive donors were from the Waco, TX, area, where the estimated seroprevalence rate was 1 in 7700. Two of these three donors reported no risk factors; both were born in the United States and had not traveled to an endemic area. Both had extensive familial histories of cardiac disease and complications. CONCLUSION: Blood donors seropositive for T. cruzi are present in populations with low to moderate risk, albeit at lower rates. The presence of seropositive blood donors without the usual identifiable risk factors argues against the use of a geographic screening question and also suggests that other routes of transmission, including the congenital route, should be considered in efforts to increase blood safety.

Seroepidemiology of Trypanosoma cruzi, etiologic agent of Chagas' disease, in US blood donors.

A comprehensive seroepidemiologic study was conducted in two Red Cross regions (Los Angeles and Miami) to determine the prevalence of Trypanosoma cruzi antibodies in at-risk blood donors, to identify additional risk factors, and to assess the likelihood of transmitting T. cruzi by transfusion. At-risk and control donors were stratified by a broad risk question, tested for T. cruzi antibodies, and if confirmed as seropositive, enrolled in case-control and lookback investigations. A total of 299,398 donors were queried; 23,978 at-risk and 25,587 control donations were tested, and T. cruzi antibodies were confirmed in 34 donors (33 and 1, respectively). Seropositive donors shared one risk factor; birth/extensive time in a T. cruzi-endemic area. Lookback studies identified 11 recipients, all negative for T. cruzi antibodies. Screening strategies that use a question are unlikely to identify all seropositive donors. The lack of definitive data on the risk of transmission by transfusion indicates additional studies of donors and recipients are needed.