Frequency of Trypanosoma cruzi parasitemia among infected blood donors with a potential association between parasite lineage and transfusion transmission

International survey of strategies to mitigate transfusion-transmitted Trypanosoma cruzi in non-endemic countries, 2016-2018

BACKGROUND AND OBJECTIVES

Chagas disease, caused by Trypanosoma cruzi, is endemic to Mexico, Central and South America. While initially limited to the Americas, emigration of infected persons triggered geographically broader blood safety challenges. To mitigate transfusion-transmitted Chagas (TTC), transfusion services implemented approaches including risk factor questions and serologic testing. We sought to understand and compare strategies in non-endemic countries.

MATERIALS AND METHODS

Transfusion services in International Society of Blood Transfusion (ISBT)-affiliated organizations and members of the ISBT Working Party on Transfusion-Transmitted Infectious Diseases were invited to complete an online survey on T. cruzi mitigation strategies. The survey queried about cases of TTC, risk factors, testing methodology, educational materials, pathogen reduction, donor/product management, donor deferral and perceived public health concerns surrounding TTC.

RESULTS

Responses were received from 27 institutions in 22 countries. Most countries (77.3%) reported no historical TTC cases, while 18.2% reported 1-5 cases and 4.5% reported 6-10 cases. Concern about Chagas among the general public and public health authorities was low, but 12 of 25 blood centres reported moderate/high concern. Overall, 17 countries mitigated for TTC: 15 used risk factor questions and 10tested for T. cruzi antibodies. Ten countries used pathogen reduction but not specifically to prevent TTC.

CONCLUSION

While Chagas is rarely cited as a public health concern, blood centres in many non-endemic countries, including those outside the Americas, implemented measures to mitigate risk. Mitigation focussed on risk factors associated with Latin American immigrants and serologic testing. Thus, despite the rarity of TTC, many non-endemic countries continue to address it as an ongoing blood safety risk.

Use of a Latent Class Analysis in the Diagnosis of Chronic Chagas Disease in the Washington Metropolitan Area

BACKGROUND

The diversity of individuals at risk for Trypanosoma cruzi infection in the United States poses challenges for diagnosis. We evaluated the diagnostic accuracy of Food and Drug Administration (FDA)-cleared tests in the Washington Metropolitan area (WMA).

METHODS

In total, 1514 individuals were evaluated (1078 from Mexico, Central and northern South America [TcI-predominant areas], and 436 from southern South America [TcII/V/VI-predominant areas]). Optical density (OD) values from the Hemagen EIA and Chagatest v.3 Wiener, and categorical results of the IgG-TESA-blot (Western blot with trypomastigote excretory-secretory antigen), and the Chagas detect plus (CDP), as well as information of area of origin were used to determine T. cruzi serostatus using latent class analysis.

RESULTS

We detected 2 latent class (LC) of seropositives with low (LC1) and high (LC2) antibody levels. A significantly lower number of seropositives were detected by the Wiener, IgG-TESA-blot, and CDP in LC1 (60.6%, P < .001, 93.1%, P = .014, and 84.9%, P = .002, respectively) as compared to LC2 (100%, 100%, and 98.2%, respectively). LC1 was the main type of seropositives in TcI-predominant areas, representing 65.0% of all seropositives as opposed to 22.8% in TcII/V/VI-predominant areas. The highest sensitivity was observed for the Hemagen (100%, 95% confidence interval [CI]: 96.2-100.0), but this test has a low specificity (90.4%, 95% CI: 88.7-91.9). The best balance between positive (90.9%, 95% CI: 83.5-95.1), and negative (99.9%, 95% CI: 99.4-99.9) predictive values was obtained with the Wiener.

CONCLUSIONS

Deficiencies in current FDA-cleared assays were observed. Low antibody levels are the main type of seropositives in individuals from TcI-predominant areas, the most frequent immigrant group in the United States.

Chagas Disease in the United States: a Public Health Approach

Trypanosoma cruzi is the etiological agent of Chagas disease, usually transmitted by triatomine vectors. An estimated 20 to 30% of infected individuals develop potentially lethal cardiac or gastrointestinal disease. Sylvatic transmission cycles exist in the southern United States, involving 11 triatomine vector species and infected mammals such as rodents, opossums, and dogs. Nevertheless, imported chronic T. cruzi infections in migrants from Latin America vastly outnumber locally acquired human cases. Benznidazole is now FDA approved, and clinical and public health efforts are under way by researchers and health departments in a number of states. Making progress will require efforts to improve awareness among providers and patients, data on diagnostic test performance and expanded availability of confirmatory testing, and evidence-based strategies to improve access to appropriate management of Chagas disease in the United States.

A systematic review of the Trypanosoma cruzi genetic heterogeneity, host immune response and genetic factors as plausible drivers of chronic chagasic cardiomyopathy

Chagas disease is a complex tropical pathology caused by the kinetoplastid Trypanosoma cruzi. This parasite displays massive genetic diversity and has been classified by international consensus in at least six Discrete Typing Units (DTUs) that are broadly distributed in the American continent. The main clinical manifestation of the disease is the chronic chagasic cardiomyopathy (CCC) that is lethal in the infected individuals. However, one intriguing feature is that only 30-40% of the infected individuals will develop CCC. Some authors have suggested that the immune response, host genetic factors, virulence factors and even the massive genetic heterogeneity of T. cruzi are responsible of this clinical pattern. To date, no conclusive data support the reason why a few percentages of the infected individuals will develop CCC. Therefore, we decided to conduct a systematic review analysing the host genetic factors, immune response, cytokine production, virulence factors and the plausible association of the parasite DTUs and CCC. The epidemiological and clinical implications are herein discussed.

Relation between acetylcholinesterase and Na+, K+-ATPase activities with impaired memory of mice experimentally infected by Trypanosoma cruzi

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi and causes severe cardiac and brain damage, leading to behavioral alterations in humans and animals. However, the mechanisms involved in memory impairment during T. cruzi infection remain unknown. It has long been recognized that the enzymatic activities of acetylcholinesterase (AChE) and Na⁺, K⁺-ATPase are linked with memory dysfunction during other trypanosomiasis. Thus, the aim of this study was to evaluate the involvement of cerebral AChE and Na⁺, K⁺-ATPase activities in the memory impairment during T. cruzi (Colombian strain) infection. A significant decrease on latency time during the inhibitory avoidance task was observed in animals infected by T. cruzi compared to uninfected animals, findings compatible to memory dysfunction. Moreover, the cerebral AChE activity increased, while the Na⁺, K⁺-ATPase decreased in T. cruzi infected compared to uninfected animals. Histopathology revealed mild to moderate multifocal gliosis in the cerebral cortex and light focal meningeal lymphoplasmacytic infiltrate, which may have contributed to memory loss. Based on these evidences, we can conclude that T. cruzi (Colombian strain) causes memory impairment in mice experimentally infected. Moreover, the changes in AChE and Na⁺, K⁺-ATPase activities may be considered a mechanism involved in disease pathogenesis.