RÉSUMÉ
BACKGROUND: Chagas disease (CD), caused by the parasite Trypanosoma cruzi, is the most important endemic anthropozoonosis in Argentina. Since 2010, the World Health Organization has highlighted the urgent need to validate diagnostic systems that allow rapid detection of T. cruzi, infection in primary healthcare centers. Serological rapid diagnostic tests (RDTs) for T. cruzi, infection could be used to improve case management, as RDTs do not require specialized laboratories or highly trained staff to use them. We aimed to generate unbiased performance data of RDTs in Argentina, to evaluate their usefulness for improving T. cruzi, diagnosis rates. METHODS AND PRINCIPAL FINDINGS: This is a retrospective, laboratory-based, diagnostic evaluation study to estimate the clinical sensitivity/specificity of four commercially available RDTs for T. cruzi, using the Chagas disease diagnostic algorithm currently used in Argentina as the reference standard. In total, 400 serum samples were tested, 200 from individuals with chronic T. cruzi infection and 200 from individuals not infected with T. cruzi. All results were registered as the agreement of at least two operators who were blinded to the reference standard results. The sensitivity estimates ranged from 92.5-100% (95% confidence interval (CI) lower bound 87.9-98.2%); for specificity, the range was 76-96% (95% CI lower bound 69.5-92.3%). Most RDTs evaluated showed performances comparable with the reference standard method, showing almost perfect concordance (Kappa 0.76-0.92). CONCLUSIONS: Our study demonstrates that, under controlled laboratory conditions, commercially available RDTs for CD have a performance comparable to the Argentinian diagnostic algorithm, which is based on laboratory-based serological tests. For the next stage of our work, the RDTs will be evaluated in real-world settings.
Sujet(s)
Maladie de Chagas , Trypanosoma cruzi , Humains , Argentine/épidémiologie , Études rétrospectives , Population urbaine , Tests de diagnostic rapide , Maladie de Chagas/diagnostic , Maladie de Chagas/épidémiologie , Anticorps , Sensibilité et spécificité , Anticorps antiprotozoairesRÉSUMÉ
Abstract Chagas Disease is caused by Trypanosoma cruzi. This infection is endemic in the Americas region. Neurological Chagas reactivation is diagnosed through the visualization of the parasite in the cerebrospinal fluid, blood, or tissue samples. Herein, we report the visualization of trypomastigotes by direct microscopic observation of a brain biopsy specimen and its preservation fluid (PF) in a paitient infected with VIH and T. cruzi. This easy and simple diagnostic method coupled with quantitative polymerase chain reaction can be used in all tissue biopsies and PF of T. cruzi seropositive patients, suspected of Chagas disease reactivation.
Sujet(s)
Humains , Trypanosoma cruzi , Maladie de Chagas/diagnostic , Biopsie , Tests diagnostiques courantsRÉSUMÉ
Chagas Disease is caused by Trypanosoma cruzi. This infection is endemic in the Americas region. Neurological Chagas reactivation is diagnosed through the visualization of the parasite in the cerebrospinal fluid, blood, or tissue samples. Herein, we report the visualization of trypomastigotes by direct microscopic observation of a brain biopsy specimen and its preservation fluid (PF) in a paitient infected with VIH and T. cruzi. This easy and simple diagnostic method coupled with quantitative polymerase chain reaction can be used in all tissue biopsies and PF of T. cruzi seropositive patients, suspected of Chagas disease reactivation.
Sujet(s)
Maladie de Chagas , Trypanosoma cruzi , Biopsie , Maladie de Chagas/diagnostic , Tests diagnostiques courants , HumainsRÉSUMÉ
Infection by Trypanosoma cruzi (Chagas disease [ChD]) affects around 7 million people in the Americas, most of whom are unaware of their status due to lack of clinical manifestations and poor access to diagnosis. Rapid diagnostic tests (RDTs) are widely used for screening for different infections (HIV, hepatitis B, and syphilis), and their application for ChD would facilitate access to diagnosis, especially in remote areas where health services have scarce resources. We conducted a prospective intervention study in 2018 to evaluate in the field two in vitro RDTs for ChD, authorized by the National Administration of Medicaments, Aliments, and Medical Technologies of Argentina (ANMAT), in areas of endemicity and nonendemicity in Argentina. We recruited 607 volunteers older than 18 years in Salta province and the city of Buenos Aires. The RDTs Ab Standard Diagnostics SD Bioline (SD) and Check Chagas Wiener Lab (WL) were performed in situ with whole-blood samples, and confirmatory serology was done at a reference center. The rate of infection with T. cruzi was 17.8% (108/607). The SD test showed 97.2% sensitivity (95% confidence interval [CI], 93.5 to 100) and 91.7% specificity (95% CI, 96.2 to 99.2%), and the WL test showed 93.4% sensitivity (95% CI, 88.2 to 98.6%) and 99.1% specificity (95% CI, 91.9 to 100%). The sensitivity and specificity for the two RDTs tested were higher than previously reported. These results encourage the use of the tested RDTs in Salta province and for further field studies for the implementation of these RDTs in other epidemiological scenarios. This will be very important to improve access to diagnosis of Chagas and its clinical management as a neglected disease, especially in remote areas with health access barriers.
Sujet(s)
Maladie de Chagas , Trypanosoma cruzi , Argentine/épidémiologie , Maladie de Chagas/diagnostic , Maladie de Chagas/épidémiologie , Tests diagnostiques courants , Humains , Études prospectives , Sensibilité et spécificitéRÉSUMÉ
In a pilot study, we showed that the intermittent administration of benznidazole in chronic Chagas disease patients resulted in a low rate of treatment suspension and therapeutic failure, as assessed by quantitative PCR (qPCR) at the end of treatment. Here, a 3-year posttreatment follow-up study of the same cohort of patients is presented. The treatment scheme consisted of 12 doses of benznidazole at 5 mg/kg of body weight/day in two daily doses every 5 days. Parasite load, Trypanosoma cruzi-specific antibodies, and serum chemokine levels were measured prior to treatment and after a median follow-up of 36 months posttreatment by DNA minicircle kinetoplastid and nuclear DNA satellite sequence qPCR methods, conventional serological techniques, a Luminex-based assay with recombinant T. cruzi proteins, and a cytometric bead array. At the end of follow-up, 14 of 17 (82%) patients had negative qPCR findings, whereas three of 17 (18%) had detectable nonquantiï¬able findings by at least one of the qPCR techniques. A decline in parasite-specific antibodies at 12 months posttreatment was confirmed by conventional serological tests and the Luminex assays. Monocyte chemoattractant protein 1 levels increased after treatment, whereas monokine induced by gamma interferon levels decreased. New posttreatment electrocardiographic abnormalities were observed in only one patient who had cardiomyopathy prior to treatment. Together, these data strengthen our previous findings by showing that the intermittent administration of benznidazole results in a low rate of treatment suspension, with treatment efficacy comparable to that of a daily dose of 5 mg/kg for 60 days.
Sujet(s)
Maladie de Chagas , Nitroimidazoles , Trypanocides , Trypanosoma cruzi , Maladie de Chagas/traitement médicamenteux , Études de suivi , Humains , Nitroimidazoles/usage thérapeutique , Projets pilotes , Trypanocides/usage thérapeutiqueSujet(s)
Maladie de Chagas/prévention et contrôle , Infections à VIH/prévention et contrôle , Transmission verticale de maladie infectieuse/prévention et contrôle , Complications infectieuses de la grossesse/prévention et contrôle , Syphilis/prévention et contrôle , Adulte , Argentine , Bolivie , Maladie de Chagas/épidémiologie , Maladie de Chagas/transmission , Enfant , Enfant d'âge préscolaire , Femelle , Infections à VIH/épidémiologie , Infections à VIH/transmission , Hépatite B/épidémiologie , Hépatite B/prévention et contrôle , Hépatite B/transmission , Humains , Transmission verticale de maladie infectieuse/statistiques et données numériques , Mâle , Paraguay , Grossesse , Complications infectieuses de la grossesse/épidémiologie , Population rurale/statistiques et données numériques , Syphilis/épidémiologie , Syphilis/transmission , Jeune adulteRÉSUMÉ
trans-Sialidase and cruzipain are important virulence factors from Trypanosoma cruzi, the etiological agent of Chagas disease, that have highly antigenic domains in their structure and were reported as potential tools for diagnosis of the illness. The aim of the present study is to assess the possibility of using cruzipain and the catalytic domain of trans-sialidase in a Surface Plasmon Resonance-based immunosensor for the diagnosis of chronic Chagas disease. Immunoassays carried out with canine sera verified that cruzipain allows the detection of anti-Trypanosoma cruzi antibodies whereas recombinant trans-sialidase did not yield specific detections, due to the high dilutions of serum used in the immunoassays that hinder the possibility to sense the specific low titer antibodies. The developed cruzipain-based biosensor, whose price per assay is comparable to a commercial enzyme-linked immunosorbent assay (ELISA), was successfully applied for the rapid quantification of specific antibodies against Trypanosoma cruzi in fresh human sera showing an excellent agreement with ELISA.
Sujet(s)
Anticorps antiprotozoaires/sang , Maladie de Chagas/diagnostic , Maladie de Chagas/médecine vétérinaire , Test ELISA/méthodes , Trypanosoma cruzi/isolement et purification , Animaux , Maladie de Chagas/sang , Maladie de Chagas/parasitologie , Cysteine endopeptidases/analyse , Cysteine endopeptidases/génétique , Cysteine endopeptidases/immunologie , Maladies des chiens/sang , Maladies des chiens/diagnostic , Maladies des chiens/parasitologie , Chiens , Glycoprotéines/analyse , Glycoprotéines/génétique , Glycoprotéines/immunologie , Humains , Sialidase/analyse , Sialidase/génétique , Sialidase/immunologie , Protéines de protozoaire/analyse , Protéines de protozoaire/génétique , Protéines de protozoaire/immunologie , Trypanosoma cruzi/génétique , Trypanosoma cruzi/immunologie , Facteurs de virulence/sang , Facteurs de virulence/génétique , Facteurs de virulence/immunologieRÉSUMÉ
Congenital infection is currently the first cause of new cases of Chagas disease in Argentina and nonendemic areas worldwide. Its diagnosis is of utmost importance to guarantee curative treatment. To improve such diagnosis, a transfer process of PCR tests to the national laboratory network has been initiated. We performed a comparative study of four PCR assays [two end-point PCR and two duplex real-time quantitative PCR (qPCR) procedures] to detect Trypanosoma cruzi DNA in blood samples. Because satellite DNA and kinetoplastid DNA qPCR methods showed the best performance and the use of two different molecular targets for confirmatory purposes has been recommended, these methods were selected to perform the transfer process and, in consequence, subjected to an analytical verification protocol based on international guidelines. The anticipated reportable range was verified between 0.25 and 105 parasite equivalents per milliliter of blood (par. eq./mL) for both qPCR methods, and the limit of detection was estimated to be 0.87 (95% CI, 0.62-1.24) and 0.43 (95% CI, 0.32-0.59) par. eq./mL for satellite DNA and kinetoplastid DNA qPCR methods, respectively. In addition, both qPCR methods showed trueness and verified precision in the highest and the lowest concentrations tested. This work provides critical knowledge of the technology transfer process planned to cover laboratories of the regional network with known installed facilities.