Geographical origin of chronic Chagas disease patients in Brazil impacts the performance of commercial tests for anti-T. cruzi IgG

BACKGROUND Chagas disease, caused by Trypanosoma cruzi, affects nearly six million people worldwide. Various serological tests have been developed for its diagnosis. OBJECTIVE Examine the performance of a set of commercial immunological assays in relation to the geographical origin of the patient sample comparing four states of Brazil: Amazonas (AM), Mato Grosso do Sul (MS), Minas Gerais (MG) and Piauí (PI). METHODS Seven immunoassays were employed to detect anti-T. cruzi IgG antibodies in 379 patient samples that had been previously diagnosed using the two-step protocol required by the Brazilian Ministry of Health. FINDINGS A significant variation in the percent reactive was calculated for the samples from AM and MS, while the PI and MG showed a significant variation in the percent non-reactive. The average reactivity index was significantly higher for samples from the states of PI and MG states than AM and MS. MAIN CONCLUSIONS All tests presented a satisfactory performance overall. Yet, variations were observed that were associated to the region of origin of the samples. Our analyses suggest that future evaluations of immunoassays should include a sampling of sera from regions where the test will be applied in addition to the available International Biological Reference Standards.

Chagas disease in Virgem da Lapa, Minas Gerais, Brazil: left ventricle aneurysm and the risk of death in the 24-year interval

BACKGROUND Left ventricular aneurysm (LVA) is indicator of high morbidity in Chagas' disease. A cross-sectional study performed identified LVA in 18.8% of the chronic chagasic patients (CCP). OBJECTIVE Determine the risk of death of patients with chronic chagasic cardiopathy (CCC) and LVA in 24-year interval. MATERIAL AND METHODS In 1995 a cohort of 298 CCP was evaluated by anamnesis, physical examination, EKG and ECHO and classified in groups: G0 = 86 without cardiopathy; G1 = 156 with cardiopathy without LVA and G2 = 56 with cardiopathy and LVA. 38 patients of G0 and G1 used benznidazole. Information about the deaths was obtained in the notary, death certificates, hospital records and family members. FINDINGS Were registered 113 deaths (37.9%): 107 (35.9%) attributed to cardiopathy and 6 (2.0%) to other causes (p < 0.05). Amongst these 107 deaths, 10 (11.6%) occurred in G0; 49 (31.4%) occurred in G1 and 48 (85.7%) occurred in G2 (p < 0.05). The risk of death was 2.7 and 7.4 times significantly higher in G2, than in G1 and G0, respectively. CONCLUSION Chronic chagasic patients with LVA and ejection fraction < 45% have a higher risk of death than those without.

Application of WHO International Biological Reference Standards to evaluate commercial serological tests for chronic Chagas disease

BACKGROUND Chagas disease, resulting from Trypanosoma cruzi infections, continues to be a health concern mainly in Latin American countries where the parasite is endemic. The laboratory diagnosis of a chronic infection is determined through serological assays for antibodies against T. cruzi and several tests are available that differ in key components, formats and methodologies. To date, no single test meets the criteria of a gold standard. The situation is further complicated by the difficulties associated with performance comparisons between different immunoassays or methodologies executed at different times and geographical areas. OBJECTIVE To improve the diagnosis of Chagas disease, the WHO coordinated the development of two International Biological Reference Standards for antibodies against anti-T. cruzi: NIBSC 09/186 and NIBSC 09/188 that respectively represent geographical regions with the highest prevalence of TcII and TcI lineages of the parasite. METHODS The principle goal of this study was to verify the behavior of these standards when assayed by several commercially available serological tests that employ different methods to capture and detect human anti-T. cruzi antibodies. FINDINGS AND MAIN CONCLUSIONS The results reinforce the recommendation that these standards be considered for performance evaluations of commercialised immunoassays and should be an integral step in the development of new test components or assay paradigms.

Human acute Chagas disease: changes in factor VII, activated protein C and hepatic enzymes from patients of oral outbreaks in Pará State (Brazilian Amazon)

Oral transmission of Chagas disease has been increasing in Latin American countries. The present study aimed to investigate changes in hepatic function, coagulation factor levels and parasite load in human acute Chagas disease (ACD) secondary to oral Trypanosoma cruzi transmission. Clinical and epidemiological findings of 102 infected individuals attended in the State of Pará from October 2013 to February 2016 were included. The most common symptoms were fever (98%), asthenia (83.3%), face and limb edema (80.4%), headache (74.5%) and myalgia (72.5%). The hepatic enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) of 30 ACD patients were higher compared with controls, and this increase was independent of the treatment with benznidazole. Moreover, ACD individuals had higher plasma levels of activated protein C and lower levels of factor VII of the coagulation cascade. Patients with the highest parasite load had also the most increased transaminase levels. Also, ALT and AST were associated moderately (r = 0.429) and strongly (r = 0.595) with parasite load respectively. In conclusion, the present study raises the possibility that a disturbance in coagulation and hepatic function may be linked to human ACD.