Xenodiagnóstico na doença de Chagas crônica: I- Sensibilidade de Panstrongylus megistus e Triatoma infestans

Borges-Pereira, José; Junqueira, Angela C. V.; Santos, Laura Cristina; Castro, Jose; Araújo, Izeneide Barros de; Coura, José Rodrigues

doi:10.1590/s0037-86821996000400005

Cited by 12 publications

(6 citation statements)

References 14 publications

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“…3,4 The chagasic patients living in this region had high parasitemia levels based on positive xenodiagnosis results compared with individuals from other endemic areas. 17 This phenomenon could explain the PCR results observed in patients from Virgem da Lapa. Compared with conventional serologic tests, we found a higher PCR sensitivity than those reported by Britto and others 6 and Junqueira and others 7 (45% and 60%, respectively), who used the protocol reported by Wincker and others.…”

Section: Resultsmentioning

confidence: 85%

Chagas' disease diagnosis: comparative analysis of parasitologic, molecular, and serologic methods.

Gomes

Galvao²,

Macedo³

et al. 1999

The American Journal of Tropical Medicine and Hygiene

126

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Abstract. During the course of chronic chagasic infection, low parasitemia levels prevent parasite detection by current techniques such as hemoculture and xenodiagnosis. Since serologic tests have sensitivity but lack specificity, molecular assays based on the polymerase chain reaction (PCR) have been proposed as alternative tools for parasite detection in individuals with chronic Chagas' disease. A variable degree of PCR efficiency has been reported in the literature and illustrates the need for further evaluation of large numbers of chagasic patients. In this study, we compared an optimized PCR technique with hemoculture and complement-mediated lysis (CoML) in 113 individuals from or living in endemic areas of Brazil who had conventional serologic results that were either positive, negative, or inconclusive. The PCR amplification yielded positive results in 83.5% (66 of 79) of individuals with positive serology, 47.6% (10 of 21) with negative serology, and 46.2% (6 of 13) with inconclusive serology. Of 10 patients with negative serology and positive PCR result, eight (80%) had positive CoML, indicating that they could have been chagasic but were not mounting immune responses. The PCR results were also positive for all individuals who had positive hemoculture, for 37 individuals with negative hemoculture and positive serology, and for two of six individuals with inconclusive serology and negative hemoculture. Thirteen individuals living in nonendemic areas who had negative serology were used as a negative control group: 100% had negative PCR results. Our results show that the optimized PCR protocol used here was very sensitive in detecting the presence of Trypanosoma cruzi in chronic chagasic patients. The PCR and CoML results were well correlated in all of the groups studied, which suggests that our PCR protocol may be effective in the evaluation of cure in patients who receive anti-parasite treatment.Different approaches have been used in the diagnosis of chronic Chagas' disease. Serologic tests are used to detect antibodies against Trypanosoma cruzi and not the presence of the parasite itself. These tests have high sensitivity but lack specificity because of antigenic cross-reactivity with parasites such as Leishmania sp. and T. rangeli.1,2 Parasitologic tests such as hemoculture or xenodiagnosis have proven to be highly specific, but the sensitivity of these techniques is low. Recently, molecular assays such as the polymerase chain reaction (PCR), which amplify certain repetitive sequences of trypanosome kinetoplast DNA (kDNA) have been proposed as a good alternative tools for detection of T. cruzi in human blood.3-5 The ഠ330-basepair (bp) fragment of the kinetoplast minicircles is normally used as a target for amplification.The PCR assay has shown a variable degree of efficiency. Initial sensitivity reports ranged from 96% to 100% compared with serologic diagnosis.3,4 A lower sensitivity level was observed by Britto and others 6 and Junqueira and others. 7 These inconsistencies illustrate the need for addi...

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Section: Resultsmentioning

confidence: 85%

Chagas' disease diagnosis: comparative analysis of parasitologic, molecular, and serologic methods.

Gomes

Galvao²,

Macedo³

et al. 1999

The American Journal of Tropical Medicine and Hygiene

126

View full text Add to dashboard Cite

show abstract

“…This can be explained by parasitemia levels in infected individuals living in different endemic areas and may be related to the complexity of the T. cruzi life cycle. Patients living in Virgem da Lapa, Minas Gerais showed high levels of parasitemia based on positive xenodiagnosis when compared with individuals from other areas 51 . The presence of T. cruzi in the peripheral circulation at any given time of blood collection depends on the parasite's life cycle, the immune balance between parasite and host 52 , and the time between the blood collection and sample processing 4,21 .…”

Section: Discussionmentioning

confidence: 90%

Combined parasitological and molecular-based diagnostic tools improve the detection of Trypanosoma cruzi in single peripheral blood samples from patients with Chagas disease

Volpato

Sousa

D’Ávila

et al. 2017

Rev. Soc. Bras. Med. Trop.

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Introduction:In order to detect Trypanosoma cruzi and determine the genetic profiles of the parasite during the chronic phase of Chagas disease (ChD), parasitological and molecular diagnostic methods were used to assess the blood of 91 patients without specific prior treatment. Methods: Blood samples were collected from 68 patients with cardiac ChD and 23 patients with an indeterminate form of ChD, followed by evaluation using blood culture and polymerase chain reaction. T. cruzi isolates were genotyped using three different genetic markers. Results: Blood culture was positive in 54.9% of all patients, among which 60.3% had the cardiac form of ChD, and 39.1% the indeterminate form of ChD. There were no significant differences in blood culture positivity among patients with cardiac and indeterminate forms. Additionally, patient age and clinical forms did not influence blood culture results. Polymerase chain reaction (PCR) was positive in 98.9% of patients, although comparisons between blood culture and PCR results showed that the two techniques did not agree. Forty-two T. cruzi stocks were isolated, and TcII was detected in 95.2% of isolates. Additionally, one isolate corresponded to TcIII or TcIV, and another corresponded to TcV or TcVI. Conclusions: Blood culture and PCR were both effective for identifying T. cruzi using a single blood sample, and their association did not improve parasite detection. However, we were not able to establish an association between the clinical form of ChD and the genetic profile of the parasite.

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“…In addition, parasitological outcomes cannot be considered a reliable surrogate marker for benznidazole’s therapeutic efficacy. Blood cultures and xenodiagnosis have very low sensitivity [ 58 ] and have fallen into disuse. On the other hand, PCR techniques are much more sensitive, but, for patients with visceral involvement they have not been demonstrated to be predictive of clinical response [ 21 ].…”

Section: Discussionmentioning

confidence: 99%

Use of benznidazole to treat chronic Chagas disease: An updated systematic review with a meta-analysis

et al. 2022

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Background Approximately 6 million people worldwide are affected by Chagas disease, with many in the chronic phase of the disease (CCD). It is crucial to evaluate the effectiveness of benznidazole for CCD treatment. Methods/Principal findings We updated a meta-analysis published in 2009 up to February 2021, including controlled trials (RCT) and prospective observational studies (OBS) that compared benznidazole vs placebo/no-treatment (P/nT). Main outcomes evaluated were clinical progression (CP) and seroreversion with subgroup analysis performed according to study design and participants’ age. Parasitological response and safety were also described. We identified 879 articles and selected nine for inclusion (corresponding to eight studies). After adding the nine articles from the previous meta-analysis, 17 studies were analyzed corresponding to 6640 patients. The odds ratio (OR) for seroreversion in children treated with benznidazole vs P/nT was 38.3 (95%CI: 10.7–137) and 34.9 (95%CI: 1.96–624.09) in RCT and OBS, respectively. In adults the OR for seroreversion in OBS was 17.1 (95%CI: 2.3–129.1). CP was only evaluated in adults, where benznidazole did not demonstrate a beneficial effect: OR 0.93 (95%CI: 0.8–1.1) and OR 0.49 (95%CI:0.2–1.2) for RCT and OBS, respectively. Most outcomes were deemed to have a low level of certainty, except for the beneficial effect in children and the low efficacy in adults (moderate certainty). Conclusions Benznidazole should be recommended for CCD in children, though this is only based on serological response and a moderate grade of evidence, while in adults benznidazole efficacy remains uncertain. More data on clinical efficacy of benznidazole in CCD is needed in both children and adults.

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Xenodiagnóstico na doença de Chagas crônica: I- Sensibilidade de Panstrongylus megistus e Triatoma infestans

Cited by 12 publications

References 14 publications

Chagas' disease diagnosis: comparative analysis of parasitologic, molecular, and serologic methods.

Chagas' disease diagnosis: comparative analysis of parasitologic, molecular, and serologic methods.

Combined parasitological and molecular-based diagnostic tools improve the detection of Trypanosoma cruzi in single peripheral blood samples from patients with Chagas disease

Use of benznidazole to treat chronic Chagas disease: An updated systematic review with a meta-analysis

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