Preclinical Studies and Drug Combination of Low-Cost Molecules for Chagas Disease.

Chagas disease is caused by the protozoan Trypanosoma cruzi (T. cruzi). It remains the major parasitic disease in Latin America and is spreading worldwide, affecting over 10 million people. Hundreds of new compounds with trypanosomicidal action have been identified from different sources such as synthetic or natural molecules, but they have been deficient in several stages of drug development (toxicology, scaling-up, and pharmacokinetics). Previously, we described a series of compounds with simple structures, low cost, and environmentally friendly production with potent trypanosomicidal activity in vitro and in vivo. These molecules are from three different families: thiazolidenehydrazines, diarylideneketones, and steroids. From this collection, we explored their capacity to inhibit the triosephosphate isomerase and cruzipain of T. cruzi. Then, the mechanism of action was explored using NMR metabolomics and computational molecular dynamics. Moreover, the mechanism of death was studied by flow cytometry. Consequently, five compounds, 314, 793, 1018, 1019, and 1260, were pre-clinically studied and their pharmacologic profiles indicated low unspecific toxicity. Interestingly, synergetic effects of diarylideneketones 793 plus 1018 and 793 plus 1019 were evidenced in vitro and in vivo. In vivo, the combination of compounds 793 plus 1018 induced a reduction of more than 90% of the peak of parasitemia in the acute murine model of Chagas disease.

Detection and characterization of Plasmodium spp. by semi-nested multiplex PCR both in mosquito vectors and in humans residing in historically endemic areas of Paraguay.

In Paraguay, no cases of Malaria have been recorded since 2011. Microscopy and the SnM-PCR technique were implemented to detect and characterize Plasmodium spp. both in mosquitoes and in humans residing in historically endemic areas of Paraguay, to evaluate the possibility of finding asymptomatic cases and/or Plasmodium parasites circulating in anophelines. Between 2013 and 2015, 361 human blood samples were collected on filter paper, and between 2016 and 2017, 938 female Anopheles mosquitoes were captured in 15 Paraguayan localities. All the diagnostic techniques showed negative results. We observed no asymptomatic case or Plasmodium circulating in vectors.

Evaluación de primers reportados para detección de KDR en especies de Anopheles colectadas en los departamentos de Caaguazú y Alto Paraná en Paraguay / Evaluation of primers reported for KDR detection in Anopheles species collected in the departments of Caaguazú and Alto Paraná in Paraguay

Las mutaciones KDR en el gen del canal del sodio (VGSC) han sido ya detectadas en al menos 13 especies de mosquitos Anopheles en su mayoría especies de África, pero aún resta por determinar los cebadores específicos para la detección en especies de Latinoamérica. En nuestro país la especie Anopheles darlingi es el vector principal de la malaria, y el A. albitarsis, el vector secundario. Se emplearon muestras de mosquitos Anoheles de las especies A. strodei, A. albitarsis, A. fluminensis, A. evansae, A. nuneztovari, A. nyssorhynchela lutzi y A. oswaldoi capturadas en los departamentos de Caaguazú y Alto Paraná en Paraguay. Para la amplificación y secuenciación se usaron cebadores reportados para el gen VGSC de A. albimanus en Guatemala, que resultaron ser específicos solo para la especie A. strodei. La secuencia revela el codón TTA que codifica para una Leucina como la secuencia TTG, reportada para la versión susceptible en la posición L1014. El fragmento amplificado es de aproximadamente 225 pares de bases. A nuestro entender, esta es la primera caracterización del gen VGSC en mosquitos Anopheles del Paraguay y para la especie A. strodei

KDR mutations in the sodium channel gene (VGSC) have already been detected in at least 13 species of Anopheles mosquitoes, mostly African species, but the molecular techniques for detection in Latin American species have yet to be determined. In our country, Anopheles darlingi species is the main vector of Malaria, and A. albitarsis, the secondary vector. We used samples of Anoheles from the species A. strodei, A. albitarsis, A. fluminensis, A. evansae, A. nuneztovari, A. nyssorhynchela lutzi and A. oswaldoi collected at the departments of Caaguazú and Alto Paraná in Paraguay. For the amplification and sequentiation, primers reported for the VGSC gen of A. strodei in Guatemala were used and were specific only for A. strode in this case. The sequence revealed the TTA codon that codifies for a leucine as the TTG sequence, reported for the susceptible version at position L1014. The amplified fragment is approximately 225 base pairs. To our knowledge, this is the first characterization of the VGSC gene in Anopheles mosquitoes in Paraguay and for the species A. strodei

A Nature-Inspired Design Yields a New Class of Steroids Against Trypanosomatids.

Chagas disease and Leishmaniasis are neglected endemic protozoan diseases recognized as public health problems by the World Health Organization. These diseases affect millions of people around the world however, efficient and low-cost treatments are not available. Different steroid molecules with antimicrobial and antiparasitic activity were isolated from diverse organisms (ticks, plants, fungi). These molecules have complex structures that make de novo synthesis extremely difficult. In this work, we designed new and simpler compounds with antiparasitic potential inspired in natural steroids and synthesized a series of nineteen steroidal arylideneketones and thiazolidenehydrazines. We explored their biological activity against Leishmania infantum, Leishmania amazonensis, and Trypanosoma cruzi in vitro and in vivo. We also assayed their genotoxicity and acute toxicity in vitro and in mice. The best compound, a steroidal thiosemicarbazone compound 8 (ID_1260) was active in vitro (IC50 200 nM) and in vivo (60% infection reduction at 50 mg/kg) in Leishmania and T. cruzi. It also has low toxicity in vitro and in vivo (LD50 >2000 mg/kg) and no genotoxic effects, being a promising compound for anti-trypanosomatid drug development.

Helietta apiculata: a tropical weapon against Chagas disease.

The present study pretends to evaluate the in vivo efficacy of the crude chloroform bark extract of Helietta apiculata, then the activity will be compared with the reference drug, benznidazole, in acute Trypanosoma cruzi infected mice when administered by oral route. The chloroformic extract of Helieta apiculata was administered by oral route at 5, 10 and 50 mg/kg daily for two weeks. This study has shown a moderate efficacy of the H. apiculata bark extract in reducing T. cruzi parasitaemia in 42 to 54% after a monitoring of 60 days post-infection and when compared with control groups. Concerning mice mortality, only two only two mice died, one from the control group and the other one from the group threated with 10 mg of the chlorofom extract of H. apiculata, suggesting the potential of H. apiculta extracts as a safe and inexpensive treatment of Chagas disease.

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

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.

Development of bis-thiazoles as inhibitors of triosephosphate isomerase from Trypanosoma cruzi. Identification of new non-mutagenic agents that are active in vivo.

The neglected disease American trypanosomiasis is one of the major health problems in Latin America. Triosephosphate isomerase from Trypanosoma cruzi (TcTIM), the etiologic agent of this disease, has been proposed as a druggable target. Some bis-benzothiazoles have been described as irreversible inhibitors of this enzyme. On the other hand, new bioactive furane-containing thiazoles have been described as excellent in vivo anti-T. cruzi agents. This encouraged us to design and develop new bis-thiazoles with potential use as drugs for American trypanosomiasis. The bis-thiazol 5, 3,3'-allyl-2,2'-bis[3-(2-furyl)-2-propenylidenehydrazono]-2,2',3,3'-tetrahydro-4,4'-bisthiazole, showed the best in vitro anti-T. cruzi profile with a higher selectivity index than the reference drugs Nifurtimox and Benznidazole against amastigote form of the parasite. This derivative displayed marginal activity against TcTIM however the bis-thiazol 14, 3-allyl-2-[3-(2-furyl)-2-propenylidenehydrazono]-3'-phenyl-2'-(3-phenyl-2-propenylidenehydrazono]-2,2',3,3'-tetrahydro-4,4'-bisthiazole, was an excellent inhibitor of the enzyme of the parasite. The absence of both in vitro mutagenic and in vivo toxicity effects, together with the activity of bis-thiazol 5in vivo, suggests that this compound is a promising anti-T. cruzi agent surpassing the "hit-to-lead" stage in the drug development process.

Harvesting canthinones: identification of the optimal seasonal point of harvest of Zanthoxylum chiloperone leaves as a source of 5-methoxycanthin-6-one.

This article is focused on the seasonal variation in the contents of 5-methoxycanthin-6-one from the leaves of Zanthoxylum chiloperone (Rutaceae). Based on the pharmacological interest presented by 5-methoxycanthin-6-one, its seasonal variation in Z. chiloperone leaves was analysed in order to determine the best time for harvesting, optimising the 5-methoxycanthin-6-one content. The seasonal dynamics of canthinone alkaloids can be the key to improve the isolation from natural sustainable sources, such as leaves. Complementarily, this study describes the phytochemistry of leaf from this Ruraceae species.

Identification of a new amide-containing thiazole as a drug candidate for treatment of Chagas' disease.

Although the parasitic infection Chagas' disease was described over 100 years ago, even now there are not suitable drugs. The available drugs nifurtimox and benznidazole have limited efficacies and tolerances, with proven mutagenic effects. Attempting to find appropriate drugs to deal with this problem, here we report on the development and pharmacological characterization of new amide-containing thiazoles. In the present study, we evaluated the in vitro and in vivo effects of new candidates against Trypanosoma cruzi, the etiological agent of Chagas' disease. The lead amide-containing thiazole derivative had potent in vitro activity, an absence of both in vitro mutagenic and in vivo clastogenic effects, and excellent in vitro selectivity and in vivo tolerance. The compound suppressed parasitemia in mice, modifying the anti-T. cruzi antibodies like the reference drug, benznidazole, and displayed the lowest mortality among the tested drugs. The present evidence suggests that this compound is a promising anti-T. cruzi agent surpassing the lead optimization stage in drug development and leading to a candidate for preclinical study.

Optimization of antitrypanosomatid agents: identification of nonmutagenic drug candidates with in vivo activity.

Chagas disease, caused by Trypanosoma cruzi parasite, was described thousands of years ago. Currently, it affects millions of people, mostly in Latin America, and there are not suitable drugs for treating it. As an attempt to find appropriate drugs to deal with this problem, we report here on the design, synthesis, and characterization of 82 new compounds. Trypanosomicidal behavior in vitro showed more than 20 outstanding derivatives with anti-Trypanosoma cruzi activity. Furthermore, we studied the nonspecific toxicity against mammalian cells determining their selectivity and also performed mutagenicity studies. Proof of concept, in vivo studies, was conducted with two of the most promising derivatives (77 and 80). They were identified as candidates because they have (i) very simple and cost-effective syntheses; (ii) activity against different stages and strains of the parasite showing excellent in vivo behavior during the acute phase of Chagas disease; and (iii) neither nonspecific toxicity nor mutagenic activity.

Experiencias en el tratamiento para la enfermedad de Chagas en niños en edad escolar de Paraguay / Experiences in the treatment of Chagas disease in school-aged children of Paraguay

Las referencias de trabajos sobre tratamiento en pacientes con la enfermedad de Chagas en nuestro país son escasas, y en especial en el grupo etario de niños de 6 a 12 años infectados con T. cruzi. El Instituto de Investigaciones en Ciencias de la Salud (IICS) llevó a cabo dos estudios de evaluación del tratamiento en niños en edad escolar tanto de zonas marginales de Asunción, como de zonas rurales. En ambos, se incluyó la evaluación basal, el tratamiento y la evaluación post-tratamiento en los niños que resultaron con serología positiva para anticuerpos anti-T. cruzi por IFI y ELISA a fin de cumplir con el criterio de infección. El tratamiento fue con benznidazol bajo estricta supervisión médica. Aunque no se presentó la negativización serológica en el 100% de las muestras, el panorama post-tratamiento que se obtuvo en estos niños en etapa crónica reciente de la enfermedad de Chagas fue la disminución significativa en la concentración de anticuerpos anti-T. cruzi y en otros, seroconversiones negativas. En el examen parasitológico se obtuvo negativización en ambos grupos y tolerancia a la medicación. Es importante destacar que con este tratamiento, se brinda la oportunidad de disminuir la aparición de lesiones cardíacas y digestivas en la edad adulta. A su vez se deben llevar a cabo acciones sostenidas de salud pública desde el nacimiento hasta la adolescencia, ya que en estas edades, se observa la mejor respuesta a los parasiticidas.

3-Trifluoromethylquinoxaline N,N'-dioxides as anti-trypanosomatid agents. Identification of optimal anti-T. cruzi agents and mechanism of action studies.

For a fourth approach of quinoxaline N,N'-dioxides as anti-trypanosomatid agents against T. cruzi and Leishmania, we found extremely active derivatives. The present study allows us to state the correct requirements for obtaining optimal in vitro anti-T. cruzi activity. Derivatives possessing electron-withdrawing substituents in the 2-, 3-, 6-, and 7-positions were the most active compounds. With regard to these features and taking into account their mammal cytotoxicity, some trifluoromethylquinoxaline N,N'-dioxides have been proposed as candidates for further clinical studies. Consequently, mutagenicity and in vivo analyses were performed with the most promising derivatives. In addition, with regard to the mechanism of action studies, it was demonstrated that mitochondrial dehydrogenases are involved in the anti-T. cruzi activity of the most active derivatives.

Zanthoxylum chiloperone leaves extract: first sustainable Chagas disease treatment.

ETHNOPHARMACOLOGICAL RELEVANCE: Zanthoxylum chiloperone var. angustifolium Engl. (Rutaceae) stem bark is used traditionally in Paraguay for its antiparasitic properties. Canthin-6-one is main compound isolated from Zanthoxylum chiloperone var angustifolium with broad spectrum antifungal, leishmanicidal and trypanocidal activities. AIM OF THE STUDY: The qualitative and quantitative characterization and the isolation of main alkaloidal components of different organs of Zanthoxylum chiloperone are investigated by HPLC-UV-MS. The in vitro biological activity of each extract against trypomastigote and amastigote forms of Trypanosoma cruzi parasites were evaluated, then comparison the in vivo efficacy of the ethanolic leaves extract of Zanthoxylum chiloperone with reference drug, benznidazole, in acute Trypanosoma cruzi infected mice when administered by oral route. We have also evaluated the mutagenic and cytotoxic activity of the main component of Zanthoxylum chiloperone, i.e. canthin-6-one, by mouse bone marrow micronucleus test. MATERIALS AND METHODS: The compositions of the ethanol extracts obtained after the maceration process were studied by HPLC-UV-MS methods. The quantitation analysis was performed by external standard method, using a calibration curve constructed utilizing solutions containing different concentrations of the reference samples. The anti-trypomastigote activity was evaluated by the lysis effect on mouse blood trypomastigotes (Y strain Trypanosoma cruzi). The anti-amastigote Trypanosoma cruzi activity was evaluated by a modified colorimetric method with chlorophenol red-ß-d-galactopyranoside (CPRG). The cytotoxicity of extracts and compounds was performed on NCTC 929 cells. The in vivo efficacy of the ethanolic leaves extract of Zanthoxylum chiloperone and benznidazole, in acute Trypanosoma cruzi (two different strains) was evaluated in Trypanosoma cruzi infected mice; the drugs were administered by oral route. The mortality rates were recorded and parasitaemias in control and treated mice were determined once weekly for 70 days. The mutagenic and cytotoxic activity of the main component of Zanthoxylum chiloperone, canthin-6-one, by mouse bone marrow micronucleus test. RESULTS: Canthin-6-one was the main compound of stem and root bark and 5-methoxy-canthin-6-one in leaves and fruits. The ethanolic leaves extract, canthin-6-one and benznidazole presented, approximately, the same level of in vitro activity against trypomastigote and amastigote forms of Trypanosoma cruzi. We have also evaluated the mutagenic and cytotoxic effects of canthin-6-one by micronucleus test in mice. This test showed any mutagenic and cytotoxic damages. The effects of oral or subcutaneous treatments at 10 mg/kg daily for 2 weeks with the ethanolic extract of leaves of Zanthoxylum chiloperone were examined in Balb/c mice infected acutely with Trypanosoma cruzi (CL or Y strain) and compared with benznidazole at 50 mg/kg for 2 weeks. In these experiments, 70 days after infection, parasitaemia and serological response were significantly reduced with the oral ethanolic extract treatment compared with reference drug. CONCLUSIONS: This study have shown the efficacy of the leaves extract of Zanthoxylum chiloperone in reducing Trypanosoma cruzi parasitaemia in vivo assays and could be welcomed by scientific and rural communities of Paraguay because it could help them towards the use of local resources to treat an endemic infection, Chagas disease, affecting 20% of the population of this country.

Actividad tripanocida in vitro e in vivo de extractos etanólicos de algunas plantas medicinales bolivianas / In vitro and in vivo trypanocidal activity, of ethanolic extracts from some bolivian medicinal plants

A 100 años del descubrimiento de la enfermedad de Chagas, aun no existen drogas que satisfagan completamente. Los extractos de plantas medicinales son una posibilidad de obtener nuevos compuestos que sean activos contra Trypanosoma cruzi. Se evaluó la actividad tripanocida in vitro sobre las formas tripomastigotes de ocho extractos etanólicos provenientes de 4 plantas medicinales bolivianas. El extracto etanólico de la corteza de Anacardium occidentale fue el más activo in vitro (CI50= 200 µg/ml), seguido de las hojas de Bowdichia virgilioides (350 µg/ml). A. occidentale, B. virgilioides y Senna reticulata, no son eficaces en la fase aguda de la enfermedad de Chagas en el modelo murino. (AU)

In vitro and in vivo antitrypanosomatid activity of 5-nitroindazoles.

Previously, we have identified a series of 5-nitroindazoles with good antiprotozoal activities, against Trypanosoma cruzi epimastigotes and Trichomonas vaginalis. Most of them have shown very low unspecific toxicity on macrophage cell lines. In the present work, we assayed these compounds on T. cruzi bloodstream trypomastigotes and Leishmania promastigotes (Leishmania amazonensis, Leishmania braziliensis and Leishmania infantum). Derivatives 1, 2, 7 and 8 displayed remarkable trypanocidal activity (>80% lysis) equivalent to gentian violet. Derivatives 2 and 10, as Pentamidine, caused the complete lysis of promastigotes of Leishmania. An oxidative stress-mediated mechanism of action was confirmed for derivatives 1, 10 and 12 on T. cruzi epimastigotes. Supported by the in vitro activities, derivatives 1 and 2 were submitted to in vivo assays using an acute model of Chagas' disease and a short-term treatment. None of the animals treated with derivatives 1 and 2 died, unlike the untreated control and Benznidazole groups.

Investigaciones sobre la enfermedad de Chagas en el Departamento de Medicina Tropical del Instituto de Investigaciones en Ciencias de la Salud: año 1982-2009: a 100 años del descubrimiento de la Enfermedad de Chagas / Research on Chagas disease in the Department of Tropical Medicine from the Instituto de Investigaciones en Ciencias de la Salud: years 1982-2009: 100 years after the discovery of Chagas disease

El Departamento de Medicina Tropical del Instituto de Investigaciones en Ciencias de la Salud se dedicó desde sus inicios (1982) a la investigación de la Enfermedad de Chagas realizando estudios serológicos, búsqueda de un modelo animal y control de la enfermedad a través del mejoramiento de la vivienda. Tiene una colonia de primates, un bioterio de ratones destinado al mantenimiento de cepas de referencia de Trypanosoma cruzi, y un vinchucario. Se han incluido líneas de investigación como la búsqueda de productos naturales con actividad sobre T. cruzi y Leishmania sp. En el área de vectores, se realizaron trabajos sobre ecología y dinámica de distribución de vectores y ensayos en campo para la búsqueda de atractantes eficaces para la detección temprana de reinfestación. En 1995, se aislaron parásitos del primer caso humano de Leishmaniasis visceral, iniciándose luego estudios diagnósticos de Leishmaniasis visceral canina con otros departamentos de la institución alertando sobre la urbanización de esta enfermedad en el Gran Asunción. Cuenta con un banco de cepas, único en Paraguay y mantiene cepas usadas en el diagnostico serológico de la Enfermedad de Chagas y la Leishmaniasis. También ofrece servicios de asistencia para consulta clínica, serológica, radiológica y cardiológica para pacientes chagásicos. El departamento continua trabajando en estas patologías consideradas actualmente como desatendidas, aunando esfuerzos con organismos nacionales e internacionales para identificar compuestos líderes para el tratamiento, contribuir al conocimiento de las mismas, y especialmente con el compromiso de dar una respuesta al siempre relegado paciente chagásico.

The Department of Tropical Medicine of the Instituto de Investigaciones en Ciencias de la Salud has worked since the beginning (1982) in the research of Chagas disease performing serological studies, search of an animal model and control of Chagas disease via housing improvement. The department has an animal care facility, including primatesand mice, the latter used in the maintenance of Trypanosoma cruzi reference strains, as well as a colony of triatomine bugs. New research lines have been included such as thesearch of natural products with activity against T. cruzi and Leishmania sp. In the vectors area, studies about vectors ecology and distribution dynamics have been performed as well as field assays for the search of attractants efficient for the early detection of reinfestation. In 1995, parasites were isolated in the first human case of visceral leishmaniasis in Paraguay since 1903, starting then diagnosis studies of canine visceral leishmaniasis with other departments of the institute giving the alert about the urbanization of the disease in the Great Asunción. The department has a strain bank, unique in Paraguay, and maintains strains for the serological diagnosis of Chagas disease and leishmaniasis. It also offers clinical, serological, radiological and cardiologic care services for chagasic patients. The department continues working in these pathologies currently considered as neglected diseases, joining efforts with national and international institutions to identify leader compounds for the treatment, contribute to the knowledgeof these diseases and mainly answer to the commitment of providing assistance to the always relegated chagasic patient.

2H-benzimidazole 1,3-dioxide derivatives: a new family of water-soluble anti-trypanosomatid agents.

Three series of benzimidazole N-oxide derivatives were developed and were examined for their activity against trypanosomatid parasites (Trypanosoma cruzi and Leishmania spp.). 2H-benzimidazole 1,3-dioxides displayed remarkable in vitro activities against both parasites, with derivatives 28, 29, and 32 being the most potent (IC50 < 5 microM) against the epimastigote form of T. cruzi and 28, 33, and 35 the most potent against the promastigote form of Leishmania spp. Unspecific cytotoxicity was evaluated using murine macrophages, and derivative 33 was not toxic at a concentration 30 times that of its IC50 against T. cruzi that was completely toxic for Leishmania spp., implying that the series of 2H-benzimidazole 1,3-dioxides is selective toward both trypanosomatid parasites. Derivatives 33 and 35 were submitted to an in vivo assay using an acute model of Chagas' disease and a short-term treatment (30 mg/kg/day orally administrated as aqueous solution, during 10 days). While in the control (untreated) and Benznidazole (50 mg/kg/day) groups survival fraction was 60.0% and 87.5%, respectively, none of the animals treated with derivatives 33 and 35 died. From the preliminary structure-activity relationship studies reduction potential and electrophilicity were found relevant to anti-T. cruzi activity. Active compounds are better electrophiles and more easily reduced than inactive ones.

Evaluación de metodos de diagnóstico de parasitosis intestinales utilizados en el Laboratorio de Análisis Clinicos / Annual reports 1997 / Evaluation of diagnostic methods for intestinal parasites used in the Laboratory of Clinical Chemistry

Este estudio ha tenido como finalidad actualizar los datos de parasitosis intestinal, estudiando 227 muestras de heces de niños de 1 a 12 años de comunidades rurales y urbanas. Se han empleado cuatro métodos: directo, de flotación o Willis, de concentración o MGL y Harada-Mori, éstos dos últimos diferentes a los rutinariamente empleados. En las zonas estudiadas se encontró que 166 niños (72, 8 por ciento) estaban parasitados, observándose protozoarios con mayor frecuencia que vermes.El método directo fue el más sensible, dando un porcentaje de positividad del 68.9 por ciento (n=157), le siguen el MGL 44 por ciento (n=100), Willis 36 por ciento (n=81) y cultivo 22.4 por ciento (n=51). Los paásitos más frecuentemente observados fueron: G. lamblia (23,7 por ciento), B. hominis (21,9 por ciento), A. lumbricoides (16,7 por ciento), N. Americanus (15,4 por ciento)

Tratamiento con benznidazol en niños de seis a doce años infectados con T. cruzi / Annual reports 1995 / Treatment with benznidazole in six-twelve aged children infected with T. cruzi

Este estudio se realizò en el marco del Programa Nacional de Control de la Enfermedad de Chagas se desarrollò a fin de evaluar el èxito terapèutico del benznidazol en niños de 6 a 12 años de edad infectados con T. cruzi y establecer las mejores tècnicas para determinar la cura parasitològica y serològica de las personas tratadas. Para ello, 20 niños en edad escolar procedentes de dos compañias del Departamento de Paraguarì (àrea endèmica para la enfermedad de Chagas), cuya infecciòn con T. cruzi fue determinada mediante un tamizaje serològico (ELISA), fueron tratados con benznidazol (5-7mg/kg de peso por 60 dìas). Antes del inicio del tratamiento, los niños fueron sometidos a un examen clìnico de control, hemocultivo, xenodiagnòstico, parasitemia directa, reacciòn en cadena de la polimerasa (PCR) y confirmaciòn serològica (ELISA, IFI). Ademàs, se realizaron determinaciones basales y a los 20 dìas del tratamiento de hemograma, GOT, bilirrubina total, directa e indirecta para controlar la apariciòn de efectos colaterales del tratamiento. No se observaron variaciones entre las determinaciones hematològicas y quìmicas basales y las realizadas a los 20 dìas. En el estudio basal, el 15 por ciento (3/20) de las muestras tuvo parasitemia directa positiva, el 5 por ciento (1/20) tuvo hemocultivo positivo, el 55 por ciento (11/20) de los xenodiagnòsticos fue positivo y el 85 por ciento (17/20) tuvo PCR positivo. En cuanto a la serologìa, el 100 por ciento de las muestras fueron positivas tanto por ELISA como por IFI. A los seis meses de finalizado el tratamiento, se realizò la primera evaluaciòn serològica y parasitològica detectàndose en el 100 por ciento de las muestras parasitemia negativa. La serologìa para T. cruzi siguiò siendo positiva en todos los casos por ambos mètodos (ELISA e IFI) pero se observò una disminuciòn de los tìtulos que fue estadìsticamente significativa tanto por ELISA (p<0,0001) como por IFI (p<0,05). A los seis meses del tratamiento, si bien todas las muestras fueron negativas por todos los mètodos parasitològicos incluyendo al PCR, tècnica altamente sensible en la fase crònica de la enfermedad de Chagas y al xenodiagnòstico, no se puede hablar aùn de cura en forma concluyente debido a la positividad de los mètodos serològicos que puede indicar presencia del paràsito o una memoria inmunològica remanente. Sin embargo, se debe resaltar la disminuciòn, estadìsticamente significativa, de los tìtulos serològicos por los dos mètodos utilizados

Prevalencia de la enfermedad de Chagas en niños en edad escolar de las zonas marginales de Asunciòn / Annual reports 1995 / Prevalence of chagas disease in school aged children of marginal zones of Asunciòn

La enfermedad de chagas es un problema de salud pública en América Latina debida a su amplia distribución, elevada prevalencia y por la magnitud del daño que produce y las dificultades para lograr su control. En Paraguay la enfermedad se encuentra distribuìda principalmente en los departamento de Paraguarí, Cordillera y Central. La prevalencia en zonas marginales, donde las migraciones de poblaciones rurales y de áreas endémicas hacen posible la urbanización de la enfermedad, no ha sido estudiada aún. Este es un estudio descriptivo con muestreo de corte transversal y reclutamiento por sistemas probabilísticos, llevado a cabo en niños en edad escolar en zonas marginales de Asunción para determinar la prevalencia de la enfermadad de Chagas. Métodos serológicos, aislamiento de parásitos y cuestionarios fueron utilizados para alcanzar los objetivos. Novecientos cincuenta y tres niños fueron estudiados para determinar la prevalencia de la enfermedad de chagas en zonas marginales dando como resultado el 1.4 por ciento.