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.

[Reproducibility of serological tests for the diagnosis of Trypanosoma cruzi infection in pregnant women in an endemic area of Santander, Colombia]

INTRODUCTION

The diagnosis of chronic Trypanosoma cruzi infection is supported by serological tests whose reproducibility has not been well documented.

OBJECTIVE

To evaluate the reproducibility of the serological tests ELISA, IFAT and IHAT for the diagnosis of T. cruzi infection in pregnant women in an endemic zone in Santander.

MATERIALS AND METHODS

Through an evaluation study of diagnostic technologies, the reproducibility of the serological tests ELISA, IFAT and IHAT was determined in serum and eluted blood from pregnant women living in an endemic area for Chagas' disease in Santander. The samples were selected by cross sectional sampling. The software Stata ™ version 10.0 was used for statistical analysis. By means of the comparison of the highest kappa coefficient of each technique, the test with the best reproducibility was determined.

RESULTS

A total of 777 samples were tested. In serum, ELISA (cutoff point: 0.3), IFAT (cutoff point: 1/32) and IHAT (cutoff point: 1/16) had kappa coefficients greater than 0.8 (0.98, 95% CI: 0.93-1.00; 0.98, 95% CI: 0.92-1.00 and 0.88, 95% CI: 0.74-0.97, respectively); no statistically significant differences among the three tests were found (p> 0.05). For the blood eluates, kappa coefficients were below 0.8 (highest kappa: 0.55, 95% CI: 0.41-0.68).

CONCLUSIONS

For the three serological tests using serum, the reproducibility determined by the kappa coefficient was perfect. Selecting any of them is useful for the diagnosis of T. cruzi infection. Given its simplicity and cost, the ELISA test is recommended for screening for this infection.

First report of human Trypanosoma cruzi infection attributed to TcBat genotype

Chagas disease is an endemic disease of the American continent caused by Trypanosoma cruzi and divided into six discrete typing units (TcI - TcVI). Nearly 10 million people harbour the infection representing a serious issue in public health. Epidemiological surveillance allowed us to detect a bat-related T. cruzi genotype (henceforth named TcBat) in a 5-year-old female living in a forest area in northwestern Colombia. Molecular tools determined a mixed infection of T. cruzi I and TcBat genotypes. This represents the first report of TcBat infection in humans; the epidemiological consequences of this finding are discussed herein.

[Characterization of the national malaria diagnostic network, Colombia, 2006-2010]

INTRODUCTION

The implementation and development of activities of the quality assurance system of malaria diagnosis, allows the adequate operation of the national diagnostic network, needed to strengthen prevention and control actions of this important public health problem.

OBJECTIVE

To characterize the malaria diagnosis network in Colombia between 2006 and 2010.

MATERIALS AND METHODS

A retrospective study was made by reviewing the annual reports of malaria diagnosis network activities that were sent by the Public Health Laboratories (PHL) between 2006 and 2010. The study included analysis of diagnostic coverage in population at risk and an evaluation of activities and training to the people responsible for malaria diagnosis.

RESULTS

Malaria diagnostic coverage has increased in Colombia, from 53% of municipalities covered in 2006 to 80% in 2010. The number of places that perform diagnosis increased by 31% with a significant increase, for the same period, of the number of microscopists (56%) and laboratories (30%), to 1,195 and 1,780 respectively, registered in 2010. During the period of study, the percentage of PHL that carried out at least 3 of the activities of the quality assurance system for the diagnostic network at local level was 67%.

CONCLUSIONS

It is necessary to continue strengthening the malaria diagnosis network to provide timely and adequate diagnosis in order to reduce the morbidity and mortality by malaria.

Correlation between malaria incidence and prevalence of soil-transmitted helminths in Colombia: an ecologic evaluation

INTRODUCTION

Recent studies have suggested an association between the soil-transmitted helminth infections and malaria incidence. However, published evidence is still insufficient and diverging. Since 1977, new ecologic studies have not been carried out to explore this association. Ecologic studies could explore this correlation on a population level, assessing its potential importance on public health.

OBJECTIVES

The aim of this evaluation is to explore the association between soil-transmitted helminths prevalence and malaria incidence, at an ecologic level in Colombia.

MATERIALS AND METHODS

Using data from the National Health Survey, which was carried out in 1980 in Colombia, we calculated Spearman correlation coefficients between the prevalence of: Ascaris lumbricoides, Trichuris trichiura and hookworm, with the 1980 malaria incidence data of the same year provided from the Colombian Malaria National Eradication Service. A robust regression analysis with least trimmed squares was performed.

RESULTS

Falciparum malaria incidence and Ascaris lumbricoides prevalence had a low correlation (R²= 0.086) but this correlation was stronger into the clusters of towns with prevalence of Ascaris lumbricoides infection above 30% were only included (R²= 0.916).

CONCLUSION

This work showed an ecologic correlation in Colombia between malaria incidence and soil-transmitted helminths prevalence. This could suggest that either there is an association between these two groups of parasites, or could be explained by the presence of common structural determinants for both diseases.

Validez de los estudios de asociación entre geohelmintos e incidencia de malaria: ¿Debería impactar las políticas de salud?

INTRODUCCIÓN: La distribución mundial de las geohelmintiasis y la malaria se encuentra ampliamente sobrepuesta. Algunos estudios sugieren una asociación entre las infecciones por geohelmintos y la incidencia de malaria. OBJETIVOS: Identificar la evidencia epidemiológica disponible y evaluar la validez de estos estudios. METODOLOGÍA: Una revisión sistemática fue realizada en bases de datos especializadas. Los estudios identificados fueron analizados críticamente y ordenados según clasificación de la U.S. Preventive Services Task Force. Se identificaron las principales limitaciones metodológicas de cada estudio. RESULTADOS: Se encontraron seis estudios publicados sobre el tema. Solo dos estudios tienen un alto nivel de evidencia (nivel I), tres de nivel II-2, y uno de nivel III-3. Existen importantes limitaciones metodológicas para aclarar la asociación entre geohelmintos e incidencia de malaria. CONCLUSIONES: Es apresurado discutir las potenciales implicaciones en salud pública de estos hallazgos dada la escasez de estudios y la validez limitada de la evidencia existente. Futuros estudios con nuevas consideraciones metodológicas podrían mejorar el conocimiento acerca de esta asociación. Sin embargo, es más importante realizar acciones sobre los determinantes estructurales para controlar y prevenir la ocurrencia de ambas enfermedades.

[Acute Chagas disease in Colombia: a rarely suspected disease. Report of 10 cases presented during the 2002-2005 period]

INTRODUCTION

In Colombia, reported cases of acute Chagas disease are sporadic.

OBJECTIVE

Ten cases were described that had been reported to the Parasitology Laboratory of the Colombian National Health Institute between December 2002 and November 2005.

MATERIALS AND METHODS

Information from clinical records, epidemiological report forms, laboratory and blood tests was collated. In addition the following data were compiled: demographic variables, clinical findings, results of laboratory tests and other exams (such as peripheral blood smears), IFAT for IgG antibodies, isolation in culture medium, inoculation in mice, polymerase chain reaction tests and isoenzyme eletrophoresis.

RESULTS

All the cases presented in known endemic areas for Chagas disease transmission in Colombia. Three cases were from Putumayo Province, two each from the provinces of Arauca, Casanare, Norte de Santander and one from Santander Province. The probable mode of transmission was vector-borne. Seven cases presented in adults aged 18 to 50, three in children aged 6 months to 2 years. Seven were male and three were female. The most frequent symptom was fever in nine cases. Signs of portal of entry were rare; only one patient presented a possible Romahia's sign. Three patients presented myocarditis, two acute cardiac failure and one cardiac tamponade. Parasitemia was evident in nine cases; five had positive IgG serological tests; five cases were confirmed through parasite isolation; isoenzyme electrophoresis showed Trypanosoma cruzi group I.

CONCLUSIONS

Clinical variability prevailed. In none of the cases was a clinical diagnosis suspected. The diagnosis was made and confirmed through laboratory tests alone. The results highlight the importance of including this disease in the differential diagnosis of febrile syndrome in endemic regions due to its good response to etiological treatment and thereby preventing its progression to the chronic phase.