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Chagas disease (CD), caused by the protozoan Trypanosoma cruzi (T. cruzi), affects millions of people worldwide. Polymerase Chain Reaction (PCR) and real-time quantitative PCR (qPCR) have been used as tools to monitor parasitic levels in the bloodstream of individuals exposed to infection, thus enabling the monitoring of relapses and the effectiveness of therapy, for example. The aim of this study was to evaluate the TcSAT-IAM system, developed by our research group, on samples from patients with suspected Chagas disease infection. Initially, primer systems were developed for the detection of the nuclear DNA (SAT-DNA) from T. cruzi (TcSAT-IAM). The Cruzi system, predicted in the literature, and TcSAT-IAM were then evaluated in relation to their analytical sensitivity, specificity and efficiency. Afterwards, the applicability of the qPCR technique using both systems (separately) for the diagnosis of acute CD was evaluated in samples from 77 individuals exposed to the outbreak that occurred in Pernambuco-Brazil, relating the results obtained to those of the classical diagnostic methods recommended for this stage of the infection. TcSAT-IAM and Cruzi had a detection limit of 1 fg of target DNA (0,003 parasites). Thirty-eight cases were recorded, 28 by laboratory criteria and 10 by clinical and epidemiological criteria. Blood samples from 77 subjects were submitted to qPCR by both systems, reaching an agreement of 89.61% between them. After analyzes between systems and diagnostic criteria, the TcSAT-IAM showed sensitivity and specificity of 52.36% (CI 37.26-67.52) and 92.31% (CI 79.68-97.35), respectively, accuracy of 72.73% and moderate agreement. The TcSAT-IAM showed an accuracy of 72.58% and 75% in relation to parasitological and serological tests (IgM anti-T. cruzi), respectively. Therefore, quantitative PCR should be incorporated into the diagnosis of suspected acute cases of Chagas disease., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Inc.)

Visceral leishmaniasis (VL) is one of the leading infectious diseases affecting developing countries. Colloidal gold-based diagnostic tests are rapid tools to detect blood/serum antibodies for VL diagnosis. Lack of uniformity in the performance of these tests in different endemic regions is a hurdle in early disease diagnosis. This study is designed to validate a serum-based dipstick test in eight centres of six countries, India, Nepal, Sri Lanka, Brazil, Ethiopia and Spain with archived and fresh sera from 1003 subjects. The dipstick detects antibodies against Leishmania donovani membrane antigens (LAg). The overall sensitivity and specificity of the test with 95% confidence intervals were found to be 97.10% and 93.44%, respectively. The test showed good sensitivity and specificity in the Indian subcontinent (>95%). In Brazil, Ethiopia, and Spain the sensitivity and specificity of the dipstick test (83.78-100% and 79.06-100%) were better as compared to the earlier reports of the performance of rK39 rapid test in these regions. Interestingly, less cross-reactivity was found with the cutaneous form of the disease in Spain, Brazil, and Sri Lanka demonstrating 91.58% specificity. This dipstick test can therefore be a useful tool for diagnosing VL from other symptomatically similar diseases and against cutaneous form of leishmaniasis.

In the present communication we analyzed the levels of IgG1, IgG2, IgG3, IgG4 and IgE isotypes to soluble egg antigen of Schistosoma mansoni by ELISA in individuals from an endemic area for schistosomiasis in Northeast Brazil. The analysis was performed before and after treatment to evaluate the age-dependent pattern, and to identify differences in the reactivities to antigens. Our results suggest that schistosomiasis treatment would not interfere with this sort of immune response.