Follow-up of an asymptomatic Chagas disease population of children after treatment with nifurtimox (Lampit) in a sylvatic endemic transmission area of Colombia

New insights into Trypanosoma cruzi genetic diversity, and its influence on parasite biology and clinical outcomes

Chagas disease, caused by Trypanosoma cruzi, remains a serious public health problem worldwide. The parasite was subdivided into six distinct genetic groups, called "discrete typing units" (DTUs), from TcI to TcVI. Several studies have indicated that the heterogeneity of T. cruzi species directly affects the diversity of clinical manifestations of Chagas disease, control, diagnosis performance, and susceptibility to treatment. Thus, this review aims to describe how T. cruzi genetic diversity influences the biology of the parasite and/or clinical parameters in humans. Regarding the geographic dispersion of T. cruzi, evident differences were observed in the distribution of DTUs in distinct areas. For example, TcII is the main DTU detected in Brazilian patients from the central and southeastern regions, where there are also registers of TcVI as a secondary T. cruzi DTU. An important aspect observed in previous studies is that the genetic variability of T. cruzi can impact parasite infectivity, reproduction, and differentiation in the vectors. It has been proposed that T. cruzi DTU influences the host immune response and affects disease progression. Genetic aspects of the parasite play an important role in determining which host tissues will be infected, thus heavily influencing Chagas disease's pathogenesis. Several teams have investigated the correlation between T. cruzi DTU and the reactivation of Chagas disease. In agreement with these data, it is reasonable to suppose that the immunological condition of the patient, whether or not associated with the reactivation of the T. cruzi infection and the parasite strain, may have an important role in the pathogenesis of Chagas disease. In this context, understanding the genetics of T. cruzi and its biological and clinical implications will provide new knowledge that may contribute to additional strategies in the diagnosis and clinical outcome follow-up of patients with Chagas disease, in addition to the reactivation of immunocompromised patients infected with T. cruzi.

Long-term cardiology outcomes in children after early treatment for Chagas disease, an observational study

BACKGROUND

Parasite persistence after acute infection with Trypanosoma cruzi is an important factor in the development of Chagas disease (CD) cardiomyopathy. Few studies have investigated the clinical effectiveness of CD treatment through the evaluation of cardiological events by long term follow-up of treated children. Cardiological evaluation in children is challenging since features that would be diagnosed as abnormal in an adult's ECG may be normal, age-related findings in a pediatric ECG trace. The objective was to evaluate cardiac involvement in patients with Chagas disease with a minimum follow-up of 6 years post-treatment.

METHODOLOGY

A descriptive study of a cohort of pediatric patients with CD treated with benznidazole (Bz) or nifurtimox (Nf) was conducted. Children (N = 234) with at least 6 years post CD treatment followed at the Parasitology and Chagas Service, Buenos Aires Children's Hospital (Argentina) were enrolled. By convenience sampling, children who attended a clinical visit between August 2015 and November 2019 were also invited to participate for additional cardiovascular studies like 24-hour Holter monitoring and speckle-tracking 2D echocardiogram (STE). Benznidazole was prescribed in 171 patients and nifurtimox in 63 patients. Baseline parasitemia data was available for 168/234 patients. During the follow-up period, alterations in routine ECG were observed in 11/234 (4.7%, 95% CI [2-7.4%]) patients. In only four patients, with complete right bundle branch block (cRBBB) and left anterior fascicular block (LAFB), ECG alterations were considered probably related to CD. During follow-up, 129/130 (99%) treated patients achieved persistent negative parasitemia by qPCR. Also decrease in T.cruzi antibodies titers was observed in all patients and negative seroconversion occurred in 123/234 (52%) patients.

CONCLUSIONS

A low incidence of cardiological lesions related to CD was observed in patients treated early for pediatric CD. This suggests a protective effect of parasiticidal treatment on the development of cardiological lesions and highlights the importance of early treatment of infected children.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04090489.

Platelets, Macrophages, and Thromboinflammation in Chagas Disease

Chagas disease (CD) is a major health problem in the Americas and an emerging health problem in Europe and other nonendemic countries. Several studies have documented persistence of the protozoan parasite Trypanosoma cruzi, and oxidative and inflammatory stress are major pathogenic factor. Mural and cardiac thrombi, cardiac arrhythmias, and cardiomyopathy are major clinical features of CD. During T. cruzi infection, parasite-released factors induce endothelial dysfunction along with platelet (PLT) and immune-cell activation. PLTs have a fundamental role in maintaining hemostasis and preventing bleeding after vascular injury. Excessive activation of PLTs and coagulation cascade can result in thrombosis and thromboembolic events, which are recognized to occur in seropositive individuals in early stages of CD when clinically symptomatic heart disease is not apparent. Several host and parasite factors have been identified to signal hypercoagulability and increase the risk of ischemic stroke in early phases of CD. Further, PLT interaction with immune cells and their role in host defense against pathogens and inflammatory processes have only recently been recognized and evolving. In the context of parasitic diseases, PLTs function in directly responding to T. cruzi infection, and PLT interactions with immune cells in shaping the proinflammatory or immunoregulatory function of monocytes, macrophages, and neutrophils remains elusive. How T. cruzi infection alters systemic microenvironment conditions to influence PLT and immune-cell interactions is not understood. In this review, we discuss the current literature, and extrapolate the mechanistic situations to explain how PLT and innate immune cell (especially monocytes and macrophages) interactions might be sustaining hypercoagulability and thromboinflammation in chronic CD.

Effectiveness of Nifurtimox in the Treatment of Chagas Disease: a Long-Term Retrospective Cohort Study in Children and Adults

Chagas disease (ChD), caused by Trypanosoma cruzi, has a global prevalence due to patient migration. However, despite its worldwide distribution, long-term follow-up efficacy studies with nifurtimox (NF) are scarce and have been conducted with only small numbers of patients. A retrospective study of a large cohort of ChD treated children and adults with NF. Treatment response was evaluated by clinical, parasitological, and serological after-treatment evaluation. A total of 289 patients were enrolled, of which 199 were children and 90 adults. At diagnosis, 89.6% of patients were asymptomatic. Overall, all symptomatic patients showed clinical improvement. At baseline, parasitemia was positive in 130 of 260 (50%) patients. All but one adult patient had cleared their parasitemia by the end of treatment. That patient was considered a treatment failure. Median follow-up time for children was 37.7 months, with an interquartile range of (IQR_25–75 12.2 to 85.3), and for adults was 14.2 months (IQR_25–75, 1.9 to 33.8). After treatment, a decrease of T. cruzi antibodies and seroconversion were observed in 34.6% of patients. The seroconversion profile showed that, the younger the patient, the higher the rate of seroconversion (log rank test; P value, <0.01). At least 20% seroreduction at 1 year follow-up was observed in 33.2% of patients. Nifurtimox was highly effective for ChD treatment. Patients had excellent treatment responses with fully resolved symptoms related to acute T. cruzi infection. Clearance of parasitemia and a decrease in T. cruzi antibodies were observed as markers of treatment response. This study reinforces the importance of treating patients during childhood since the treatment response was more marked in younger subjects. (This protocol was registered at ClinicalTrials.gov under registration number NCT04274101).

Review of pharmacological options for the treatment of Chagas disease

Chagas disease (CD) is a worldwide problem, with over 8 million people infected in both rural and urban areas. CD was first described over a century ago, but only two drugs are currently available for CD treatment: benznidazole (BZN) and nifurtimox (NF). Treating CD-infected patients, especially children and women of reproductive age, is vital in order to prevent long-term sequelae, such as heart and gastrointestinal dysfunction, but this aim is still far from being accomplished. Currently, the strongest data to support benefit-risk considerations come from trials in children. Treatment response biomarkers need further development as serology is being questioned as the best method to assess treatment response. This article is a narrative review on the pharmacology of drugs for CD, particularly BZN and NF. Data on drug biopharmaceutical characteristics, safety and efficacy of both drugs are summarized from a clinical perspective. Current data on alternative compounds under evaluation for CD treatment, and new possible treatment response biomarkers are also discussed. Early diagnosis and treatment of CD, especially in paediatric patients, is vital for an effective and safe use of the available drugs (i.e. BZN and NF). New biomarkers for CD are urgently needed for the diagnosis and evaluation of treatment efficacy, and to guide efforts from academia and pharmaceutical companies to accelerate the process of new drug development.

Assessing antibody decline after chemotherapy of early chronic Chagas disease patients

BACKGROUND

Chagas disease remains a significant public health problem in Latin America. There are only two chemotherapy drugs, nifurtimox and benznidazole, and both may have severe side effects. After complete chemotherapy of acute cases, seropositive diagnosis may revert to negative. However, there are no definitive parasitological or serological biomarkers of cure.

METHODS

Following a pilot study with seven Bolivian migrants to Spain, we tested 71 serum samples from chronic patients (mean age 12.6 years) inhabiting the Argentine Chaco region. Benznidazole chemotherapy (5-8 mg/kg day, twice daily for 60 days) was administered during 2011-2016. Subsequently, pre-and post-chemotherapy serum samples were analysed in pairs by IgG1 and IgG ELISA using two different antigens and Chagas Sero K-SeT rapid diagnostic tests (RDT). Molecular diagnosis by kDNA-PCR was applied to post-treatment samples.

RESULTS

Pilot data demonstrated IgG1 antibody decline in three of seven patients from Bolivia 1 year post-treatment. All Argentine patients in 2017 (averaging 5 years post-treatment), except one, were positive by conventional serology. All were kDNA-PCR-negative. Most (91.5%) pre-treatment samples were positive by the Chagas Sero K-SeT RDT, confirming the predominance of TcII/V/VI. IgG1 and IgG of Argentine patients showed significant decline in antibody titres post-chemotherapy, with either lysate (IgG, P = 0.0001, IgG1, P = 0.0001) or TcII/V/VI peptide antigen (IgG, P = 0.0001, IgG1, P = 0.0001). IgG1 decline was more discriminative than IgG. Antibody decline after treatment was also detected by the RDT. Incomplete treatment was associated with high IgG1 post-treatment titres against lysate (P = 0.013), as were IgG post-treatment titres to TcII/V/VI peptide (P = 0.0001). High pre-treatment IgG1 with lysate was associated with Qom ethnicity (P = 0.045). No associations were found between gender, age, body mass index and pre- or post-treatment antibody titres.

CONCLUSIONS

We show that following chemotherapy of early chronic Chagas disease, significant decline in IgG1 antibody suggests cure, whereas sustained or increased IgG1 is a potential indicator of treatment failure. Due to restricted sensitivity, IgG1 should not be used as a diagnostic marker but has promise, with further development, as a biomarker of cure. We show that following chemotherapy of early chronic Chagas disease, a significant decline in IgG1 antibody suggests cure, whereas sustained or increased IgG1 is a potential indicator of treatment failure. Due to restricted sensitivity, IgG1 should not be used as a diagnostic marker but has promise, with further development, as a biomarker of cure.

Trypanocidal therapy among children infected by Trypanosoma cruzi. Serological and electrocardiographic changes over a mean twenty-five-years follow-up period

This study compared the serological and electrocardiographic evolution among patients with chronic T. cruzi infection treated during childhood or left untreated. A retrospective cohort study was conducted during a mean follow-up period of 25 years in 82 patients: half of them underwent treatment (nifurtimox 8, benznidazole 33) before being 15 years old, whereas the other half remained untreated. During the follow-up, negative seroconversion occurred in 92.7% of the treated children, while all the untreated ones remained positive for conventional serology. At baseline, 2 patients from each group had electrocardiographic abnormalities. During the study period, 4/41 (9.75%) and 9/41 (21.95%) of treated and untreated patients displayed an altered electrocardiogram, respectively. In multivariate analyses, the probability of developing electrocardiographic abnormalities was significantly reduced among treated patients (OR = 0.18, 95% CI = 0.04-0.79; p = 0.023). Electrocardiographic abnormalities attributable to Chagas cardiomyopathy were seen in 3 patients from the untreated group (complete right bundle branch block + left anterior fascicular block, frequent ventricular extrasystole, and left anterior fascicular block). The remarkable seronegativization seen in Benznidazole and Nifurtimox recipients underlines the parasiticidal effect of both compounds. Such demonstration along with the fact that CCC-related alterations were only present in the untreated group, reinforces the view of trypanocidal treatment in chronically T. cruzi-infected children as decreasing the risk for cardiomyopathy development.

Clinical and Epidemiological Characterization of Acute Chagas Disease in Casanare, Eastern Colombia, 2012-2020

Background: Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is considered a public health problem in Latin America. In Colombia, it affects more than 437,000 inhabitants, mainly in Casanare, an endemic region with eco-epidemiological characteristics that favor its transmission. The objective of this study was to describe the clinical and epidemiological characteristics of the cases of acute CD in Casanare, eastern Colombia, in the period 2012–2020.

Methods: In the present study, 103 medical records of confirmed cases of acute CD were reviewed. The departmental/national incidence and fatality were compared by year; the climatological data of mean temperature, relative humidity, and precipitation per year were reviewed and plotted at IDEAM (Colombian Meteorology Institute) concerning the number of cases of acute CD per month, and it was compared with the frequency of triatomines collected in infested houses by community surveillance. Univariate, bivariate, and multivariate analyses were performed, comparing symptoms and signs according to transmission routes, complications, and age groups.

Results: The incidence was 3.16 cases per 100,000 inhabitants, and the fatality rate was 20% in the study period. The most frequent symptoms included: fever 98.1%, myalgia 62.1%, arthralgia 60.2%, and headache 49.5%. There were significant differences in the frequency of myalgia, abdominal pain, and periorbital edema in oral transmission. The main complications were pericardial effusion, myocarditis, and heart failure in the group over 18 years of age. In Casanare, TcI Discrete Typing Unit (DTU) has mainly been identified in humans, triatomines, and reservoirs such as opossums and dogs and TcBat in bats. An increase in the number of acute CD cases was evidenced in March, a period when precipitation increases due to the beginning of the rainy season.

Conclusions: The results corroborate the symptomatic heterogeneity of the acute phase of CD, which delays treatment, triggering possible clinical complications. In endemic regions, clinical suspicion, diagnostic capacity, detection, and surveillance programs should be strengthened, including intersectoral public health policies for their prevention and control.

Sensitivity and Specificity of two rapid tests for the diagnosis of infection by Trypanosoma cruzi in a Colombian population

Objective

To evaluate diagnostic precision of two rapid diagnostic tests (RDT’s) on patients with chronic Chagas disease.

Methodology

Prospective study with the following inclusion criteria: subjects older than 3 years, signed informed consent. Exclusion criterion: subjects could not have previously received treatment for infection with T. cruzi. The study population were participants in a screening process undertaken in rural and urban zones of the department Boyacá, Colombia. Two RDT’s were performed to all participants: the Chagas Detect Plus InBios (CDP) and the Chagas Stat-Pak (CSP) and as a reference standard the ELISA Chagas III GrupoBios and the Chagas ELISA IgG+IgM I Vircell tests were used. In the case of discordant results between the two ELISA tests, an indirect immunofluorescence was done.

Results

Three hundred-five (305) subjects were included in the study (38 patients with leishmaniasis), of which 215 tested negative for T cruzi and 90 tested positive according to the reference standard. The sensitivity of the RDT’s were 100% (CI 95% 95.9–100), and the specificity of the CDP was 99.1% (CI 95% 96.6–99.8) and for CSP was 100% (CI 95% 98.3–100). The agreement of CDP was 99.5% and for CSP was 100% with Kappa values of (k = 99.1; CI 95% 92.6–99.8%) and (k = 100; CI 95% 94.3–100), respectively. RDT’s did not present cross-reactions with samples from patients who were positive for leishmaniasis.

Conclusions

The findings demonstrate excellent results from the RDT’s in terms of validity, safety, and reproducibility. The results obtained provide evidence for the recommendation for using these tests in a Colombian epidemiological context principally in endemic areas in which laboratory installations necessary to perform conventional tests are not available, or they are scarce and to help in diagnosing chronic Chagas disease in order to provide access to treatment as soon as possible.

Chagas is a disease caused by the parasite Trypanosoma cruzi, and is one of the most important public health concerns affecting the population of Latin America. This disease presents an acute phase that generally goes undiagnosed and a chronic phase with cardiac manifests principally, is diagnosed through serological tests that are not available in the majority of regions endemic for Chagas disease (CD), the results may take weeks to be returned due to logistical and operational reasons that comprise the main obstacles in initiating treatment of the disease. In the present article, quality indices of two RDT’s were evaluated during a field study in the department of Boyacá Colombia, these tests are easy to administer, require only minimal quantities of sample, provide rapid results and do not require electrical equipment or refrigeration. The sensitivity of the two RDT’s was 100% and the specificity of CDP was 99.1% and for CSP was 100% according to reference tests. The results obtained support the recommendation of using RDT’s in order to help diagnose chronic Chagas disease and thus to improve access to treatment for the populations studied as soon as possible.

Characterization and Follow-Up of Trypanosoma cruzi Natural Populations Refractory to Etiological Chemotherapy in Oral Chagas Disease Patients

We aimed to characterize the genetic constitution of natural T. cruzi populations involved in an Oral Chagas Disease (OCD) outbreak at a rural school of the community of Chichiriviche de la Costa, Venezuela, which affected patients did not respond to the etiological treatment. Peripheral blood samples and/or hemocultures were obtained from twenty-nine OCD patients at time of diagnosis or along nine years of Post-treatment (Tx) follow-up. The IgG serology, T. cruzi discrete typing units (DTU), satellite DNA-qPCR parasitic loads, and minicircle signatures were determined at Pre-Tx and after Tx. The serological titles and parasitic loads changed after treatment, with a significant decrease of IgG titers (Spearman’s r value= -0.961) and median parasite loads from 2.869 [IQR = 2.113 to 3.720] to 0.105 [IQR = -1.147 to 1.761] log10 par eq. /mL at Pre-Tx and Post-Tx, respectively, suggesting infection evolution from acute to chronic phase, without seroconversion or parasitological eradication, which was indicative of treatment failure. All patients were infected with T. cruzi DTU I populations. At Pre-Tx their median Jaccard genetic distances were 0.775 [IQR = 0.708 to 0.882], decreasing in genetic variability towards the end of follow-up (Mann-Whitney U test p= 0.0031). Interestingly, no Post-Tx minicircle signature was identical to its Pre-Tx counterpart population in a same patient, revealing selection of parasite subpopulations between the primary infection and Post-Tx. The parasitic populations isolated from hemocultures showed a lower number of bands in the minicircle signatures with respect to the signatures obtained directly from the patients’ blood samples, demonstrating a process of parasitic selection and reduction of the population variability that initially infected the patients. Decrease of parasitic loads after treatment as well as Pre- and Post-Tx intra-TcI diversity might be a consequence of both, natural evolution of the acute infection to the chronic phase and persistence of refractory populations due to Tx selection.

Virtual Screening Based on QSAR and Molecular Docking of Possible Inhibitors Targeting Chagas CYP51

Chagas is a neglected tropical disease caused by the parasite Trypanosoma cruzi with no effective treatment in all its forms. There is a need to find more effective therapeutic alternatives with reduced toxicity. In this contribution, multiple linear regression models were used to identify the molecular descriptors that best describe the inhibitory activity of 52 fenarimol analogues against Trypanosoma cruzi. The topological, physicochemical, thermodynamic, electronic, and charge descriptors were evaluated to cover a wide range of properties that frequently encode biological activity. A model with high predictive value was obtained based on geometrical descriptors and descriptors encoding hydrophobicity and London dispersion forces as necessary for the inhibition of Trypanosoma cruzi-CYP51. Docking methodology was implemented to evaluate molecular interactions in silico. The virtual screening results in this study can be used for rational design of new analogues with improved activity against Chagas disease.

Adverse Events Associated with Nifurtimox Treatment for Chagas Disease in Children and Adults

Nifurtimox (NF) is one of the only two drugs currently available for Chagas disease (ChD) treatment. However, data on NF safety are scarce, and many physicians defer or refuse NF treatment because of concerns about drug tolerance. In a retrospective study of adverse drug reactions (ADRs) associated with NF treatment of ChD, children received NF doses of 10 to 15 mg/kg/day for 60 to 90 days, and adults received 8 to 10 mg/kg/day for 30 days. A total of 215 children (median age, 2.6 years; range, 0 to 17 years) and 105 adults (median age, 34 years; range, 18 to 57 years) were enrolled. Overall, 127/320 (39.7%) patients developed ADRs, with an incidence of 64/105 adults and 63/215 children (odds ratio [OR] = 3.7; 95% confidence interval [CI], 2.2 to 6.3). We observed 215 ADRs, 131 in adults (median, 2 events/patient; interquartile range for the 25th to 75th percentiles [IQR_25-75], 1 to 3) and 84 in children (median, 1 event/patient; IQR_25-75 = 1 to 1.5) (P _adjusted < 0.001). ADRs were mainly mild and moderate. Severe ADRs were infrequent (1.2% in children and 0.9% in adults). Nutritional, central nervous, and digestive systems were the most frequently affected, without differences between groups. Treatment was discontinued in 31/320 (9.7%) patients without differences between groups. However, ADR-related discontinuations occurred more frequently in adults than in children (OR = 5.5, 95% CI = 1.5 to 24). Our study supports the safety of NF for ChD treatment. Delaying NF treatment due to safety concerns does not seem to be supported by the evidence. (This study has been registered in ClinicalTrials.gov under identifier NCT04274101.).

Prospective, historically controlled study to evaluate the efficacy and safety of a new paediatric formulation of nifurtimox in children aged 0 to 17 years with Chagas disease one year after treatment (CHICO)

Nifurtimox is a recommended treatment for Chagas disease, but data from treated children are limited. We investigated the efficacy, safety and tolerability of nifurtimox administered as divisible, dispersible 30 mg and 120 mg tablets in children with Chagas disease. In this blinded, controlled study conducted January 2016-July 2018, 330 patients aged <18 years from 25 medical centres across three South American countries were randomised 2:1 to nifurtimox 10-20 mg/kg/day (aged <12 years) or 8-10 mg/kg/day (aged ≥12 years) for 60 days (n = 219), or for 30 days plus placebo for 30 days (n = 111) (ClinicalTrials.gov NCT02625974). The primary outcome was anti-Trypanosoma cruzi serological response (negative seroconversion or seroreduction ≥20% in mean optical density from baseline determined by two conventional enzyme-linked immunosorbent assays) at 12 months in the 60-day treatment group versus historical placebo controls. Nifurtimox for 60 days achieved negative seroconversion (n = 10) and seroreduction (n = 62) in 72 patients (serological response 32.9%; 95% confidence interval [CI] 26.4%, 39.3%, of all treated patients), confirming superiority relative to the upper 95% CI of 16% for controls. In patients aged <8 months, 10/12 treated for 60 days (83.3%) and 5/7 treated for 30 days (71.4%) achieved negative seroconversion. Overall serological response was lower for 30-day than for 60-day nifurtimox (between-treatment difference 14.0% [95% CI 3.7%, 24.2%]). The frequency of T. cruzi-positive quantitative polymerase chain reactions decreased substantially from baseline levels (60-day regimen 53.4% versus 1.4%; 30-day regimen 51.4% versus 4.5%). Study drug-related treatment-emergent adverse events (TEAEs), which were observed in 62 patients (28.3%) treated for 60 days and 29 patients (26.1%) treated for 30 days, were generally mild or moderate and resolved without sequelae; 4.2% of all TEAEs led to nifurtimox discontinuation. Age- and weight-adjusted nifurtimox for 60 days achieved a serological response at 12 months post-treatment that was superior to historical placebo, was well tolerated and had a favourable safety profile in children with Chagas disease. Although, at 1 year serological follow-up, efficacy of the shorter nifurtimox treatment was not comparable to the 60-day treatment regimen for the overall study population, further long-term follow-up of the patients will provide important information about the progress of serological conversion in children treated with nifurtimox, as well as the potential efficacy difference between the two regimens over time.

The Clinical and Parasitologic Follow-up of Trypanosoma cruzi-infected Children in a Nonendemic Country

BACKGROUND

Chagas disease has become a global health problem, with the pediatric population being especially vulnerable. Our aim was to describe the clinical-epidemiologic aspects of disease in this population, as well as tolerance and adherence to treatment and the subsequent evolution of the disease.

METHODS

A prospective study involving 949 children 0-14 years of age screened from 2007 to 2018. Diagnosis was performed by polymerase chain reaction and/or microhematocrit in <1-year-old children or serology in those ≥1 year of age. After diagnosis, children were examined for the clinical manifestation of Chagas disease and were treated with benznidazole. Treatment response was monitored by polymerase chain reaction and serology.

RESULTS

Forty children were infected (4.2% of the population screened). Twelve children were diagnosed during the acute phase (≤1-year-old), 3 of whom were symptomatic, and 28 (4- to 14-year-olds) were in the chronic phase: 18 in the indeterminate phase and 10 presented cardiac and/or digestive involvement. Regarding treatment, 10 (25.6%) children had side effects (6 mild, 2 moderate and 2 severe reactions), leading to treatment interruption in 3 of them. No side effects were detected in ≤1-year-old children (P < 0.05). Cure was confirmed in 29.4% of the children during follow-up, and the age of the children at treatment (≤1 year) was clearly associated with the effectiveness of treatment (P < 0.05).

CONCLUSIONS

Effectiveness and safety of treatment were optimum in ≤1-year-old children. Increased side effects, cardiac and/or digestive disorder incidence and lower treatment effectiveness were detected in older children, highlighting the need for early screening.

Epidemiology and pathogenesis of maternal-fetal transmission of Trypanosoma cruzi and a case for vaccine development against congenital Chagas disease

Trypanos o ma cruzi (T. cruzi or Tc) is the causative agent of Chagas disease (CD). It is common for patients to suffer from non-specific symptoms or be clinically asymptomatic with acute and chronic conditions acquired through various routes of transmission. The expecting women and their fetuses are vulnerable to congenital transmission of Tc. Pregnant women face formidable health challenges because the frontline antiparasitic drugs, benznidazole and nifurtimox, are contraindicated during pregnancy. However, it is worthwhile to highlight that newborns can be cured if they are diagnosed and given treatment in a timely manner. In this review, we discuss the pathogenesis of maternal-fetal transmission of Tc and provide a justification for the investment in the development of vaccines against congenital CD.

Complementary Paths to Chagas Disease Elimination: The Impact of Combining Vector Control With Etiological Treatment

Background

The World Health Organization’s 2020 goals for Chagas disease are (1) interrupting vector-borne intradomiciliary transmission and (2) having all infected people under care in endemic countries. Insecticide spraying has proved efficacious for reaching the first goal, but active transmission remains in several regions. For the second, treatment has mostly been restricted to recently infected patients, who comprise only a small proportion of all infected individuals.

Methods

We extended our previous dynamic transmission model to simulate a domestic Chagas disease transmission cycle and examined the effects of both vector control and etiological treatment on achieving the operational criterion proposed by the Pan American Health Organization for intradomiciliary, vectorial transmission interruption (ie, <2% seroprevalence in children <5 years of age).

Results

Depending on endemicity, an antivectorial intervention that decreases vector density by 90% annually would achieve the transmission interruption criterion in 2–3 years (low endemicity) to >30 years (high endemicity). When this strategy is combined with annual etiological treatment in 10% of the infected human population, the seroprevalence criterion would be achieved, respectively, in 1 and 11 years.

Conclusions

Combining highly effective vector control with etiological (trypanocidal) treatment in humans would substantially reduce time to transmission interruption as well as infection incidence and prevalence. However, the success of vector control may depend on prevailing vector species. It will be crucial to improve the coverage of screening programs, the performance of diagnostic tests, the proportion of people treated, and the efficacy of trypanocidal drugs. While screening and access can be incremented as part of strengthening the health systems response, improving diagnostics performance and drug efficacy will require further research.

Longitudinal follow up of serological response in children treated for Chagas disease

Background

Evaluation of therapeutic response in chronic Chagas disease is a major challenge, due to prolonged persistence of Trypanosoma cruzi-specific antibodies, lack of sensitivity of parasitological tests, and need for long-term follow-up to observe negative seroconversion of conventional serological tests (CS). The objective of this study was to evaluate F2/3-ELISA serology, a promising early biomarker of therapeutic response, and T.cruzi Polymerase chain reaction (PCR) for T. cruzi Deoxyribonucleic acid (DNA), for neonatal diagnosis and evaluation of parasitemia after treatment.

Methods

Prospective cohort study, with three-year clinical, serological and parasitological follow-up of pediatric Chagas disease patients treated with benznidazole. Serology was evaluated by Enzyme-Linked ImmunoSorbent Assay (ELISA), Indirect hemagglutination (IHA) and F2/3-ELISA; Parasitemia by microhematocrit (MH) and PCR.

Results

A cohort of 107 pediatric patients treated with benznidazole was enrolled in the study. ELISA and IHA were initially reactive in 100% of patients, F2/3-ELISA serology was reactive in 80% (86/107) and 91% (97/107) had detectable parasitemia. Seventy-six (71%) patients completed at least 36 months of serological follow up after treatment. Although a similar decreasing linear trend was observed for all serological tests, F2/3-ELISA presented earlier, age dependent, negative seroconversion compared to CS. All patients reaching undetectable CS titers had previously seroreverted by F2/3-ELISA. All patients with persistently decreasing antibody titers had negative PCRs throughout the follow up period. No new cardiological lesions were observed during the 3 years follow-up period.

Conclusions

The data reported here, using CS, F2/3 ELISA and PCR provide support for the efficacy of benznidazole in congenital Chagas diseases. These results provide support for scaling up of screening, diagnosis and access to benznidazole treatment.

Trial registration

ClinicalTrials.gov 0028/04 in the Research Council, Secretary of Health Buenos Aires city Goberment.

Evaluation of therapeutic response in chronic Chagas disease is a major challenge, particularly in the early post-treatment phase, due to prolonged persistence of Trypanosoma cruzi-specific antibodies and lack of sensitivity of available parasitological tests. The main limitation in evaluating Chagas disease treatment response stems from the need for long-term follow-up to observe negative seroconversion of conventional serological tests. New biomarkers of cure are needed. We evaluated F2/3-ELISA, a promising early serological marker of therapeutic response, and T.cruzi PCR for T.cruzi DNA, for neonatal diagnosis and evaluation of parasitemia after treatment. F2/3-ELISA and PCR proved to be excellent early markers of treatment response that correlate with ELISA and IHA but can identify treatment response or failure at much earlier timepoints. This information can help design future paediatric clinical trials in Chagas disease.

Negligible exposure to nifurtimox through breast milk during maternal treatment for Chagas Disease

BACKGROUND

Treatment with nifurtimox (NF) for Chagas disease is discouraged during breast-feeding because no information on NF transfer into breast milk is available. NF is safe and effective for paediatric and adult Chagas disease. We evaluated the degree of NF transfer into breast milk in lactating women with Chagas disease.

PATIENTS AND METHODS

Prospective study of a cohort of lactating women with Chagas disease. Patients were treated with NF for 1 month. NF was measured in plasma and milk by high performance liquid chromatography (HPLC). Breastfed infants were evaluated at admission, 7th and 30th day of treatment (and monthly thereafter, for 6 months).

RESULTS

Lactating women with chronic Chagas disease (N = 10) were enrolled (median age 28 years, range 17-36). Median NF dose was 9.75 mg/kg/day three times a day (TID). Six mothers had mild adverse drug reactions (ADRs), but no ADRs were observed in any of the breastfed infants. No interruption of breastfeeding was observed. Median NF concentrations were 2.15 mg/L (Inter quartil range (IQR) 1.32-4.55) in milk and 0.30 mg/L (IQR 0.20-0.95) in plasma. Median NF milk/plasma ratio was 16 (range 8.75-30.25). Median relative infant NF dose (assuming a daily breastmilk intake of 150 mL/kg/day) was 6.7% of the maternal dose/kg/day (IQR 2.35-7.19%).

CONCLUSIONS

The low concentrations of NF in breast milk and the normal clinical evaluation of the breastfed babies imply that maternal NF treatment for Chagas disease during breastfeeding is unlikely to lead to clinically relevant exposures in the breastfed infants.

TRIAL REGISTRATION

Clinical trial registry name and registration number: ClinicalTrials.gov NCT01744405.

Nifurtimox versus benznidazole or placebo for asymptomatic Trypanosoma cruzi infection (Equivalence of Usual Interventions for Trypanosomiasis - EQUITY): study protocol for a randomised controlled trial

Background

Either benznidazole (BZN) or nifurtimox (NFX) is recommended as equivalent to treat Trypanosoma cruzi infection. Nonetheless, supportive data from randomised trials is limited to individuals treated with BZN in southern cone countries of Latin America.

Methods

The goal of this randomised, concealed, blind, parallel-group trial is to inform the trypanocidal efficacy and safety of NFX and its equivalence to BZN among individuals with T. cruzi positive serology (TC+). Eligible individuals are TC+, 20–65 years old, with no apparent symptoms/signs or uncontrolled risk factors for cardiomyopathy and at negligible risk of re-infection. Consenting individuals (adherent to a 10-day placebo run-in phase) receive a 120-day BID blinded treatment with NFX, BZN or matching placebo (2:2:1 ratio). The four active medication arms include (1) a randomly allocated sequence of 60-day, conventional-dose (60CD) regimes (BZN 300 mg/day or NFX 480 mg/day, ratio 1:1), followed or preceded by a 60-day placebo treatment, or (2) 120-day half-dose (120HD) regimes (BZN 150 mg/day or NFX 240 mg/day, ratio 1:1). The primary efficacy outcome is the proportion of participants testing positive at least once for up to three polymerase chain reaction (PCR) assays (1 + PCR) 12–18 months after randomisation. A composite safety outcome includes moderate to severe adverse reactions, consistent blood marker abnormalities or treatment abandons. The trial outside Colombia (expected to recruit at least 60% of participants) is pragmatic; it may be open-label and not include all treatment groups, but it must adhere to the randomisation and data administration system and guarantee a blinded efficacy outcome evaluation. Our main comparisons include NFX groups with placebo (for superiority), NFX versus BZN groups and 60CD versus 120HD groups (for non-inferiority) and testing for the agent-dose and group-region interactions. Assuming a 1 + PCR ≥ 75% in the placebo group, up to 25% among BZN-treated and an absolute difference of up to ≥ 25% with NFX to claim its trypanocidal effect, 60–80 participants per group (at least 300 from Colombia) are needed to test our hypotheses (80–90% power; one-sided alpha level 1%).

Discussion

The EQUITY trial will inform the trypanocidal effect and equivalence of nitroderivative agents NFX and BZN, particularly outside southern cone countries. Its results may challenge current recommendations and inform choices for these agents.

Trial registration

ClinicalTrials.gov, NCT02369978. Registered on 24 February 2015.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3423-3) contains supplementary material, which is available to authorized users.

Prevalence of Chagas disease in Colombia: A systematic review and meta-analysis

Background

Despite the adoption of campaigns to interrupt the main vector and to detect Trypanosoma cruzi in blood banks, millions of people are still chronically infected; however, the prevalence data are limited, and the epidemiology of Chagas disease has not been systematically evaluated. This study aimed to estimate the prevalence of Chagas disease in Colombia.

Methods

A systematic literature review and meta-analysis was conducted to select all observational studies reporting the prevalence of Chagas disease in Colombia, based on serological diagnosis in participants of any age and published between January 2007 and November 2017. Pooled estimates and 95% confidence intervals (95% CIs) were calculated using random-effects models. In addition, the I² statistic was calculated.

Results

The literature search yielded a total of 1,510 studies; sixteen articles with relevant prevalence data were included in the systematic review. Of these, only 12 articles were included for entry in the meta-analysis. The pooled prevalence of Chagas disease across studies was 2.0% (95% CI: 1.0–4.0). A high degree of heterogeneity was found among studies (I² > 75%; p < 0.001). The publication bias was not statistically significant (Egger’s test, p = 0.078). The highest pooled prevalences were found in the adult population (3.0%, 95% CI: 1.0–4.0), pregnant women (3.0%, 95% CI: 3.0–4.0) and the Orinoco region (7.0%, 95% CI: 2.2–12.6).

Conclusions

The results indicate that the T. cruzi-infected population is aging, the adult population, pregnant women and that the Orinoco region (department of Casanare) have the highest prevalences. These results highlight the need to maintain screening and surveillance programs to identify people with chronic T. cruzi infections.

Distinct Treatment Outcomes of Antiparasitic Therapy in Trypanosoma cruzi-Infected Children Is Associated With Early Changes in Cytokines, Chemokines, and T-Cell Phenotypes

Background: In contrast to adults, Trypanosoma cruzi-infected children have more broadly functional Trypanosoma cruzi-specific T cells, and the total T-cell compartment exhibits fewer signs of immune exhaustion. However, not much is known about the link between immunocompetence and the treatment efficacy for human Chagas disease.

Methods: Using cytokine enzyme-linked immunosorbent spot (ELISPOT) polychromatic flow cytometry, cytometric bead assay, multiplex serological assays and quantitative PCR, we evaluated T. cruzi-specific T-cell and antibody immune responses, T-cell phenotypes and parasitemia in children in the early chronic phase of Chagas disease undergoing anti-Trypanosoma cruzi treatment.

Results: Treatment with benznidazole or nifurtimox induced a decline in T. cruzi-specific IFN-γ- and IL-2-producing cells and proinflammatory cytokines and chemokines. T-cell responses became detectable after therapy in children bearing T-cell responses under background levels prior to treatment. The total frequencies of effector, activated and antigen-experienced T cells also decreased following anti-T. cruzi therapy, along with an increase in T cells expressing the receptor of the homeostatic cytokine IL-7. Posttreatment changes in several of these markers distinguished children with a declining serologic response suggestive of successful treatment from those with sustained serological responses in a 5-year follow-up study. A multivariate analysis demonstrated that lower frequency of CD4⁺CD45RA⁻CCR7⁻CD62L⁻ T cells prior to drug therapy was an independent indicator of successful treatment.

Conclusions: These findings further validate the usefulness of alternative metrics to monitor treatment outcomes. Distinct qualitative and quantitative characteristics of T cells prior to drug therapy may be linked to treatment efficacy.

Molecular diagnosis of Trypanosoma cruzi

Chagas disease, caused by the kinetoplastid protozoan Trypanosoma cruzi, affects millions of people, most of them neglected populations. The different phases of the disease, the transmission mode and the high genetic variability of the parasite determine that molecular detection methods display different degree of success. Molecular diagnostic tests may be employed during epidemiological surveys of transmission, for early diagnosis of congenital transmission and acute infections due to oral transmission, transfusion or transplantation routes, reactivation due to immunosuppression and monitoring of treatment response in chronically infected patients receiving trypanocidal chemotherapy. This manuscript summarizes the most widely used molecular tools to detect T. cruzi infection in different epidemiological and clinical scenarios.

Trypanosoma cruzi genetic diversity: Something new for something known about Chagas disease manifestations, serodiagnosis and drug sensitivity

The genetic diversity of Trypanosoma cruzi, the protozoan agent of Chagas disease, is widely recognized. At present, T. cruzi is partitioned into seven discrete typing units (DTUs), TcI-TcVI and Tcbat. This article reviews the present knowledge on the parasite population structure, the evolutionary relationships among DTUs and their distinct, but not exclusive ecological and epidemiological associations. Different models for the origin of hybrid DTUs are examined, which agree that genetic exchange among T. cruzi populations is frequent and has contributed to the present parasite population structure. The geographic distribution of the prevalent DTUs in humans from the southern United States to Argentina is here presented and the circumstantial evidence of a possible association between T. cruzi genotype and Chagas disease manifestations is discussed. The available information suggests that parasite strains detected in patients, regardless of the clinical presentation, reflect the principal DTU circulating in the domestic transmission cycles of a particular region. In contrast, in several orally transmitted outbreaks, sylvatic strains are implicated. As a consequence of the genotypic and phenotypic differences of T. cruzi strains and the differential geographic distribution of DTUs in humans, regional variations in the sensitivity of the serological tests are verified. The natural resistance to benznidazole and nifurtimox, verified in vivo and in vitro for some parasite stocks, is not associated with any particular DTU, and does not explain the marked difference in the anti-parasitic efficacy of both drugs in the acute and chronic phases of Chagas disease. Throughout this review, it is emphasized that the interplay between parasite and host genetics should have an important role in the definition of Chagas disease pathogenesis, anti-T. cruzi immune response and chemotherapy outcome and should be considered in future investigations.

Treatment of Chagas Disease in the United States

PURPOSE OF REVIEW

Chagas disease (CD) is endemic to much of Latin America, but also present in the United States (U.S.). Following a lengthy asymptomatic period, CD produces serious cardiac or gastrointestinal complications in 30-40% of people. Less than 1% of the estimated six million cases in the Americas, including 326,000-347,000 in the U.S., are diagnosed. Infected persons are typically unaware and the bulk of clinicians are unfamiliar with current treatment guidelines. This review provides U.S. and other clinicians with the latest knowledge of CD treatment.

RECENT FINDINGS

Chagas cardiomyopathy (CCM) causes severe fibrosis and autonomic damage in the myocardium. Eliminating the parasite through antitrypanosomal therapy with benznidazole, a nitroimidazole derivative or nifurtimox, a nitrofuran compound, potentially prevents heart failure and other sequelae of advanced CCM. Benznidazole, recently approved by the U.S. Food and Drug Administration (FDA) for children 2-12 years old, is the first-line therapy; optimal dosages are currently being studied. Antitrypanosomal therapy prevents congenital transmission; produces high cure rates for acute, congenital, and early chronic cases; and improves clinical outcomes in adult chronic indeterminate cases. However, this benefit was not observed in a large clinical trial that included patients with advanced CCM.

SUMMARY

Treatment with antitrypanosomal drugs can cure CD in acute, congenital, and early chronic cases and provides improved clinical outcomes for chronic indeterminate cases. This treatment should be offered as early as possible, before advanced CCM develops.

Course of serological tests in treated subjects with chronic Trypanosoma cruzi infection: A systematic review and meta-analysis of individual participant data

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This is the first meta-analysis of individual data in chronic Trypanosoma cruzi infection after treatment.

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The probability of seroreversion is variable along the course of follow-up.

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An interaction was found between age at treatment and country setting.

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The course of parasitological/molecular tests after treatment needs to be assessed.

Objective

To determine the course of serological tests in subjects with chronic Trypanosoma cruzi infection treated with anti-trypanosomal drugs.

Methods

A systematic review and meta-analysis was conducted using individual participant data. Survival analysis and the Cox proportional hazards regression model with random effects to adjust for covariates were applied. The protocol was registered in the PROSPERO database (http://www.crd.york.ac.uk/PROSPERO; CRD42012002162).

Results

A total of 27 studies (1296 subjects) conducted in eight countries were included. The risk of bias was low for all domains in 17 studies (63.0%). Nine hundred and thirteen subjects were assessed (149 seroreversion events, 83.7% censored data) for enzyme-linked immunosorbent assay (ELISA), 670 subjects (134 events, 80.0% censored) for indirect immunofluorescence assay (IIF), and 548 subjects (99 events, 82.0% censored) for indirect hemagglutination assay (IHA). A higher probability of seroreversion was observed within a shorter time span in subjects aged 1–19 years compared to adults. The chance of seroreversion also varied according to the country where the infection might have been acquired. For instance, the pooled adjusted hazard ratio between children/adolescents and adults for the IIF test was 1.54 (95% confidence interval 0.64–3.71) for certain countries of South America (Argentina, Bolivia, Chile, and Paraguay) and 9.37 (95% confidence interval 3.44–25.50) for Brazil.

Conclusions

The disappearance of anti-T. cruzi antibodies was demonstrated along the course of follow-up. An interaction between age at treatment and country setting was found.

Comparison of parasite loads in serum and blood samples from patients in acute and chronic phases of Chagas disease

Molecular methods have been developed for the detection and quantification ofTrypanosoma cruziDNA in blood samples from patients with Chagas disease. However, aspects of sample processing necessary for quantitative real-time PCR (qPCR), such as the addition of guanidine hydrochloride to whole blood samples, may limit timely access to molecular diagnosis. We analysed 169 samples from serum and guanidine-EDTA blood (GEB) obtained from patients in acute and chronic phases of Chagas disease. We applied qPCR targeted to the satellite DNA region. Finally, we compared the parasite loads and cycle of threshold values of the qPCR. The results confirmed the usefulness of serum samples for the detection and quantification of parasite DNA in patients with Chagas disease, especially in the acute phase. However, the parasite loads detected in serum samples from patients in the chronic phase were lower than those detected in GEB samples. The epidemiological implications of the findings are herein discussed.

Long-term comparative pharmacovigilance of orally transmitted Chagas disease: first report

BACKGROUND

Two old drugs are the only choice against Trypanosoma cruzi and little is known about their secondary effects in the acute stage of oral-transmitted Chagas disease (ChD).

METHODS

A cross-sectional analytical surveillance study was conducted in a sizable cohort of patients seen during the largest acute foodborne ChD microepidemic registered so far. Individuals were treated with benznidazole (BNZ) or nifurtimox (NFX). 'Common Terminology Criteria for Adverse Events' was assessed to categorize side effects according to severity.

RESULTS

Out of 176 treatments applied, 79% had one or more adverse effects, which predominated in adults (97.8%) as compared to children (75.5%). Risk of side effects with NFX was significantly higher than BNZ. Four adults and a child treated with NFX had severe side effects (pulmonary infarction, facial paralysis, neutropenia, blurred vision, bone marrow hypoplasia) warranting hospitalization, and drug suspension. Adverse effects frequently reported with NFX were abdominal pain, hyporexia, weight loss, headache, nausea and lymphocytosis, whereas skin rash, neurosensory effects, hyporexia, fatigue, pyrosis, abdominal pain and eosinophilia were observed with BNZ.

CONCLUSIONS

Frequency and severity of side effects during treatment of acute oral infection by T. cruzi demand direct supervision and close follow-up, even in those asymptomatic, to prevent life-threatening situations.

Improving access to Chagas disease diagnosis and etiologic treatment in remote rural communities of the Argentine Chaco through strengthened primary health care and broad social participation

BACKGROUND

Rural populations in the Gran Chaco region have large prevalence rates of Trypanosoma cruzi infection and very limited access to diagnosis and treatment. We implemented an innovative strategy to bridge these gaps in 13 rural villages of Pampa del Indio held under sustained vector surveillance and control.

METHODOLOGY

The non-randomized treatment program included participatory workshops, capacity strengthening of local health personnel, serodiagnosis, qualitative and quantitative PCRs, a 60-day treatment course with benznidazole and follow-up. Parents and healthcare agents were instructed on drug administration and early detection and notification of adverse drug-related reactions (ADR). Healthcare agents monitored medication adherence and ADRs at village level.

PRINCIPAL FINDINGS

The seroprevalence of T. cruzi infection was 24.1% among 395 residents up to 18 years of age examined. Serodiagnostic (70%) and treatment coverage (82%) largely exceeded local historical levels. Sixty-six (85%) of 78 eligible patients completed treatment with 97% medication adherence. ADRs occurred in 32% of patients, but most were mild and manageable. Four patients showing severe or moderate ADRs required treatment withdrawal. T. cruzi DNA was detected by qPCR in 47 (76%) patients before treatment, and persistently occurred in only one patient over 20-180 days posttreatment.

CONCLUSIONS AND SIGNIFICANCE

Our results demonstrate that diagnosis and treatment of T. cruzi infection in remote, impoverished rural areas can be effectively addressed through strengthened primary healthcare attention and broad social participation with adequate external support. This strategy secured high treatment coverage and adherence; effectively managed ADRs, and provided early evidence of positive therapeutic responses.

Safety Profile of Nifurtimox for Treatment of Chagas Disease in the United States

BACKGROUND

Nifurtimox is 1 of only 2 medications available for treating Chagas disease (CD) and currently the only drug available in the United States, but its safety and tolerance have not been extensively studied. This is the first study to evaluate tolerance of nifurtimox in US patients with CD.

METHODS

This investigation assessed side effects in a sample of 53 patients with CD, all Latin American immigrants, who underwent treatment with nifurtimox (8-10 mg/kg in 3 daily doses for 12 weeks) from March 2008 to July 2012. The frequency and severity of adverse events (AEs) was recorded.

RESULTS

A total of 435 AEs were recorded; 93.8% were mild, 3.0% moderate, and 3.2% severe. Patients experienced a mean of 8.2 AEs; the most frequent were anorexia (79.2%), nausea (75.5%), headache (60.4%), amnesia (58.5%), and >5% weight loss (52.8%). Eleven patients (20.8%) were unable to complete treatment. Experiencing a moderate or severe AE (odds ratio [OR], 3.82; P < .05) and Mexican nationality (OR, 2.29; P < .05) were significant predictors of treatment discontinuation, but sex and cardiac progression at baseline were not. Patients who did not complete treatment experienced nearly 3 times more AEs per 30-day period (P = .05).

CONCLUSIONS

Nifurtimox produces frequent side effects, but the majority are mild and can be managed with dose reduction and/or temporary suspension of medication. The high frequency of gastrointestinal symptoms and weight loss mirrors results from prior investigations. Special attention should be paid during the early stages of treatment to potentially severe symptoms including depression, rash, and anxiety.

Molecular Diagnosis of Chagas Disease in Colombia: Parasitic Loads and Discrete Typing Units in Patients from Acute and Chronic Phases

BACKGROUND

The diagnosis of Chagas disease is complex due to the dynamics of parasitemia in the clinical phases of the disease. The molecular tests have been considered promissory because they detect the parasite in all clinical phases. Trypanosoma cruzi presents significant genetic variability and is classified into six Discrete Typing Units TcI-TcVI (DTUs) with the emergence of foreseen genotypes within TcI as TcIDom and TcI Sylvatic. The objective of this study was to determine the operating characteristics of molecular tests (conventional and Real Time PCR) for the detection of T. cruzi DNA, parasitic loads and DTUs in a large cohort of Colombian patients from acute and chronic phases.

METHODOLOGY/PRINCIPAL FINDINGS

Samples were obtained from 708 patients in all clinical phases. Standard diagnosis (direct and serological tests) and molecular tests (conventional PCR and quantitative PCR) targeting the nuclear satellite DNA region. The genotyping was performed by PCR using the intergenic region of the mini-exon gene, the 24Sa, 18S and A10 regions. The operating capabilities showed that performance of qPCR was higher compared to cPCR. Likewise, the performance of qPCR was significantly higher in acute phase compared with chronic phase. The median parasitic loads detected were 4.69 and 1.33 parasite equivalents/mL for acute and chronic phases. The main DTU identified was TcI (74.2%). TcIDom genotype was significantly more frequent in chronic phase compared to acute phase (82.1% vs 16.6%). The median parasitic load for TcIDom was significantly higher compared with TcI Sylvatic in chronic phase (2.58 vs.0.75 parasite equivalents/ml).

CONCLUSIONS/SIGNIFICANCE

The molecular tests are a precise tool to complement the standard diagnosis of Chagas disease, specifically in acute phase showing high discriminative power. However, it is necessary to improve the sensitivity of molecular tests in chronic phase. The frequency and parasitemia of TcIDom genotype in chronic patients highlight its possible relationship to the chronicity of the disease.

Serological based monitoring of a cohort of patients with chronic Chagas disease treated with benznidazole in a highly endemic area of northern Argentina

This study aimed to evaluate well-documented diagnostic antigens, named B13, 1F8 and JL7 recombinant proteins, as potential markers of seroconversion in treated chagasic patients. Prospective study, involving 203 patients treated with benznidazole, was conducted from endemic areas of northern Argentina. Follow-up was possible in 107 out of them and blood samples were taken for serology and PCR assays before and 2, 3, 6, 12, 24 and 36 months after treatment initiation. Reactivity against Trypanosoma cruzi lysate and recombinant antigens was measured by ELISA. The rate of decrease of antibody titers showed nonlinear kinetics with an abrupt drop within the first three months after initiation of treatment for all studied antigens, followed by a plateau displaying a low decay until the end of follow-up. At this point, anti-B13, anti-1F8 and anti-JL7 titers were relatively close to the cut-off line, while anti-T. cruzi antibodies still remained positive. At baseline, 60.8% (45/74) of analysed patients tested positive for parasite DNA by PCR and during the follow-up period in 34 out of 45 positive samples (75.5%) could not be detected T. cruzi DNA. Our results suggest that these antigens might be useful as early markers for monitoring antiparasitic treatment in chronic Chagas disease.

Course of Chronic Trypanosoma cruzi Infection after Treatment Based on Parasitological and Serological Tests: A Systematic Review of Follow-Up Studies

Background

Chagas disease is caused by the flagellate protozoan Trypanosoma cruzi (T. cruzi). It is endemic in Latin American countries outside the Caribbean. The current criterion for cure in the chronic phase of the disease is the negativization of at least two serological tests such as enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence assay (IIF) and indirect hemagglutination assay (IHA). The serological evolution of treated subjects with chronic T. cruzi infection is variable. Treatment failure is indicated by a positive parasitological and/or molecular test (persistence of parasitemia).

Objectives

To summarize the pattern of response to treatment of parasitological, molecular and serological tests performed during the follow-up of subjects with chronic T. cruzi infection.

Methods

Electronic searches in relevant databases and screening of citations of potentially eligible articles were accomplished. Organizations focusing on neglected infectious diseases were asked for help in identifying relevant studies.

Included studies were randomized controlled trials (RCTs), quasi-RCTs, and cohort studies involving adults and children with chronic infection who received trypanocidal treatment (benznidazole or nifurtimox) and were followed over time. The assessment of risk of bias was performed separately for each study design. The Cochrane Collaboration’s tool and the guidelines developed by Hayden et al. were used. Two reviewers extracted all data independently. A third review author was consulted in case of discordant opinion.

Additional analyses were defined in ad-hoc basis. Scatter plots for percentage of positive parasitological and molecular tests and for negative serological tests were developed by using the lowess curve technique. Heterogeneity was measured by I².

The protocol was registered in PROSPERO, an international prospective register of systematic review protocols (Registration Number CRD42012002162).

Results

Out of 2,136 citations screened, 54 studies (six RCTs and 48 cohort studies) were included. The smoothed curves for positive xenodiagnosis and positive polymerase chain reaction (PCR) were characterized by a sharp decrease at twelve month posttreatment. Afterwards, they reached 10–20% and 40% for xenodiagnosis and PCR, respectively. The smoothed curves for negative conventional serological tests increased up to 10% after 48 months of treatment. In the long-term, the rate of negativization was between 20% and 45%.

The main sources of bias identified across cohort studies were the lack of control for confounding and attrition bias. In general, RCTs were judged as low risk of bias in all domains. The level of heterogeneity across included studies was moderate to high.

Additional analysis were incomplete because of the limited availability of data. In this regard, the country of origin of study participants might affect the results of parasitological and molecular tests, while the level of risk of bias might affect serological outcomes. Subgroup analysis suggested that seronegativization occurs earlier in children compared to adults.

Conclusions

We acknowledge that there is a dynamic pattern of response based on parasitological, molecular and serological tests in subjects chronically infected with T. cruzi after treatment. Our findings suggest a trypanocidal effect in the long-term follow-up.

Further research is needed to explore potential sources of heterogeneity and to conduct reliable subgroup analysis.

Safety Profile of Nifurtimox and Treatment Interruption for Chronic Chagas Disease in Colombian Adults

Nifurtimox (NFX) is one of the approved drugs used to treat Chagas disease. Safety profile studies and models on risk factors for treatment interruption in adults are scarce in Latin America. This study evaluated retrospectively the medical records of adult Chagas disease patients treated with NFX between 2007 and 2012 in Bogotá, Colombia. An accelerated failure time model was used, and associations were expressed as time ratio (TR). In total, 76 adult patients with NFX were included: 60 (79.0%) completed 60 days of treatment, 61 (80.3%) presented adverse drug reactions (ADRs), and 16 (21.0%) required treatment interruption. The predominant symptoms were epigastric pain (23.7%), nauseas (18.4%), sleep disturbances (18.4%), loss of appetite (17.1%), and temporary loss of memory (15.2%). ADRs were classified as mild (64.5%), moderate (30.4%), and severe (5.1%). Time of treatment was significantly longer when presenting ≤ 3 ADRs (TR: 1.78; 95% CI: 1.04–3.03), presence of non-severe ADRs (TR: 6.52; 95% CI: 3.24–13.1), doses of NFX ≤ 8 mg/kg/day (TR: 1.78; 95% CI: 0.90–3.49), and age < 48 years (TR: 1.57; 95% CI: 0.90–2.74). Treatment with NFX in adults caused a high frequency of ADRs, but most of the cases were mild and did not require treatment interruption. Severity and number of ADRs were the main predictors for treatment interruption.