Hepatozoon pyramidumi sp. n. (Apicomplexa: Adeleorina) from the blood of Echis pyramidum: morphology and SSU rDNA sequence / Hepatozoon pyramidumi sp. n. (Apicomplexa: Adeleorina) do sangue de Echis pyramidum: morfologia e sequência de SSU rDNA

Abstract Hepatozoon pyramidumi sp. n. is described from the blood of the Egyptian saw-scaled viper, Echis pyramidum, captured from Saudi Arabia. Five out of ten viper specimens examined (50%) were found infected with Hepatozoon pyramidumi sp. n. with parasitaemia level ranged from 20-30%. The infection was restricted only to the erythrocytes. Two morphologically different forms of intraerythrocytic stages were observed; small and mature gamonts. The small ganomt with average size of 10.7 × 3.5 μm. Mature gamont was sausage-shaped with recurved poles measuring 16.3 × 4.2 μm in average size. Infected erythrocytes were hypertrophied; their nuclei were deformed and sometimes displaced from their central position in the normal uninfected cell. Merogonic stages were observed in the lung endothelial cell and the liver parenchyma cells. Mature meront was 17.8 × 13.6 µm and contained banana-shaped merozoites with average size of ~15 × 2 µm. Phylogenetic analysis based on the SSU rDNA sequence clustered Hepatozoon pyramidumi sp. n with previously sequenced Hepatozoon spp., most of them infected reptilian hosts without geographic consideration. The morphological and molecular comparison with closely related species proved the taxonomic uniqueness and novelty of the present form.

Resumo Hepatozoon pyramidumi sp. n. é descrito a partir do sangue da víbora em escamas e quilhas serrilhadas, Echis pyramidum, capturada na Arábia Saudita. Cinco de dez espécimes de víbora examinadas (50%) foram encontradas infectadas com Hepatozoon pyramidumi sp. n. com nível de parasitemia de 20% a 30%. A infecção foi restrita apenas aos eritrócitos. Foram observadas duas formas morfologicamente diferentes de estágios intra-eritrocíticos: gamontes de tamanho pequeno e madura. As formas menores de gamontes apresentaram média de 10,7 × 3,5 μm. Os gamontes maduros apresentaram forma de salsicha, com pequenos polos recurvados, medindo 16,3 × 4,2 μm, em média. Os eritrócitos infectados estavam aumentados de tamanho; seus núcleos encontravam-se deformados e, algumas vezes, deslocados de sua posição central, quando comparados às células normais não-infectadas. Foram observados estágios merogônicos em células endoteliais pulmonares e nas células do parênquima hepático. Os merontes maduros apresentavam 17,8 × 13,6 µm e continham merozoítos em forma de banana com tamanho médio de ~ 15 × 2 µm. A análise filogenética baseada nas sequências SSU rDNA agrupou Hepatozoon pyramidumi sp. n com Hepatozoon spp. detectados em répteis de várias regiões geográficas. Por meio de análises morfológicas e moleculares com espécies intimamente relacionadas, demonstrou-se a singularidade dessa nova espécie de Hepatozoon.

Comparison of methodologies for detecting Trypanosoma cruzi parasites by microscopic observation of microhematocrit capillary tubes

Abstract INTRODUCTION: The microscopic examination of microhematocrit tubes (mHCT) has been proposed as the gold standard for acute and congenital Chagas disease diagnosis. We compared different mHCT methodologies detecting T. cruzi parasites in the blood. METHODS: The rotating method, water mount, and immersion oil methods were compared for their suitability, sensitivity, and specificity. RESULTS: The rotating method was easier, faster, and more sensitive than the others with 100% specificity. CONCLUSIONS: The rotating method is feasible for laboratory technicians with standard training in microscopic techniques and is recommended for the diagnosis of acute Chagas disease in primary health care facilities.

Benznidazole therapy for Chagas disease in asymptomatic Trypanosoma cruzi -seropositive former blood donors: evaluation of the efficacy of different treatment regimens

Abstract: INTRODUCTION: Chagas disease currently affects 5.7 million people in Latin America and is emerging in non-endemic countries. There is no consensus concerning the efficacy of trypanocidal therapy for patients with the chronic form of the disease. We evaluated cardiac function and sociodemographic, clinical, and serologic characteristics of a group of asymptomatic Trypanosoma cruzi-seropositive former blood donors, and compared the effects of benznidazole treatment applied for different lengths of time. METHODS: Blood donors who screened positive for T. cruzi between 1998 and 2002 were recruited 10 years later for follow-up (n = 244); 46 individuals had received treatment. Three subjects had terminated treatment prematurely. The remaining 43 individuals were divided into two groups: individuals who had received benznidazole therapy for 50-60 days (n = 28; BT ≤60 group) or more than 60 days (n = 15; BT >60). Serologic assays, biochemical tests, electrocardiographic, echocardiographic, and clinical examinations were performed on all participants. Parasite loads were determined by qualitative and quantitative polymerase chain reaction. RESULTS: Parasitemia was significantly reduced in the BT ≤60 and BT >60 groups compared with the untreated group. There were no differences in epidemiologic profiles or clinical, biochemical, electrocardiographic, or echocardiographic data between any of the groups. CONCLUSIONS: Despite elimination or significant reduction in parasitemia in patients with chronic Chagas disease who received benznidazole, there was no clinical difference between those who were treated for >60 days and those treated for a shorter duration. Furthermore, the adverse effects of benznidazole appear to be less severe than previous reports would suggest.

Comparison of optical microscopy and quantitative polymerase chain reaction for estimating parasitaemia in patients with kala-azar and modelling infectiousness to the vector Lutzomyia longipalpis

Currently, the only method for identifying infective hosts with Leishmania infantum to the vector Lutzomyia longipalpis is xenodiagnosis. More recently, quantitative polymerase chain reaction (qPCR) has been used to model human reservoir competence by assuming that detection of parasite DNA indicates the presence of viable parasites for infecting vectors. Since this assumption has not been proven, this study aimed to verify this hypothesis. The concentration of amastigotes in the peripheral blood of 30 patients with kala-azar was microscopically verified by leukoconcentration and was compared to qPCR estimates. Parasites were identified in 4.8 mL of peripheral blood from 67% of the patients, at a very low concentration (average 0.3 parasites/mL). However, qPCR showed 93% sensitivity and the estimated parasitaemia was over a thousand times greater, both in blood and plasma, with higher levels in plasma than in blood. Furthermore, the microscopic count of circulating parasites and the qPCR parasitaemia estimates were not mathematically compatible with the published proportions of infected sandflies in xenodiagnostic studies. These findings suggest that qPCR does not measure the concentration of circulating parasites, but rather measures DNA from other sites, and that blood might not be the main source of infection for vectors.

Evaluation of clinical signs, parasitemia, hematologic and biochemical changes in cattle experimentally infected with Trypanosoma vivax / Avaliação dos sinais clínicos, parasitemia e alterações hematológicas e bioquímicas de bovinos experimentalmente infectados peloTrypanosoma vivax

Abstract Infections by Trypanosoma vivax cause great losses to livestock in Africa and Central and South Americas. Outbreaks due this parasite have been occurred with increasing frequency in Brazil. Knowledge of changes caused byT. vivax during the course of this disease can be of great diagnostic value. Thus, clinical signs, parasitemia, hematologic and biochemical changes of cattle experimentally infected by this hemoparasite were evaluated. Two distinct phases were verified during the infection – an acute phase where circulating parasites were seen and then a chronic phase where fluctuations in parasitemia were detected including aparasitemic periods. A constant reduction in erythrocytes, hemoglobin and packed cell volume (PVC) were observed. White blood cells (WBC) showed pronounced changes such as severe neutropenia and lymphopenia during the acute phase of the illness. Decreases in cholesterol, albumin, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and increases in glucose, globulin, protein, and alkaline phosphatase (ALP) were observed. The “Lins” isolate of T. vivax showed pathogenicity for cattle, and intense parasitemia was detected in the early stages of infection. Circulating parasites were detected for about two months. The most evident laboratory abnormalities were found in WBC parameters, including thrombocytopenia.

Resumo Infecções pelo Trypanosoma vivax causam grandes prejuízos à pecuária na África e Américas Central e do Sul. Surtos devido a este protozoário têm ocorrido com frequência cada vez maior no Brasil. O conhecimento das alterações provocadas pelo T. vivax durante a evolução desta enfermidade podem ser de grande valia para o auxílio no diagnóstico. Para tanto foram estudados os sinais clínicos, parasitemia, alterações hematológicas e bioquímicas em bovinos experimentalmente infectados por este hemoparasito. Foram verificadas duas fases distintas durante a infecção, uma aguda onde parasitos circulantes foram vistos durante todo o período, e posteriormente uma crônica, onde foram detectadas flutuações na parasitemia, com períodos aparasitêmicos. Foi verificada constante diminuição da contagem global de eritrócitos, teor de hemoglobina e volume globular (VG). O leucograma revelou leucopenia por neutropenia e linfopenia durante a fase aguda da enfermidade. Foram observados diminuição do colesterol, albumina, aspartato aminotransferase (AST), lactato desidrogenase (LDH) e aumento da glicose, globulinas, proteínas e fosfatase alcalina (FA). O isolado “Lins” de T. vivax apresentou patogenicidade para bovinos, verificando-se parasitemia intensa nos estágios iniciais da infecção, sendo detectados parasitas circulantes por aproximadamente dois meses. As alterações laboratoriais mais evidentes foram encontradas nos parâmetros do leucograma, ainda destacando-se um quadro de trombocitopenia.

Trypanosoma cruzi -infected Triatoma gerstaeckeri (Hemiptera: Reduviidae) from Nuevo León, México, and pathogenicity of the regional strain / Triatoma gerstaeckeri (Hemiptera: Reduviidae) infectada con Trypanosoma cruzi en Nuevo León, México, y capacidad patógena de la cepa regional

Introduction: Four species of triatomines have been reported in Nuevo León, northeast (NE) México, but Triatoma gerstaeckeri has only been recorded from a peridomestic dwelling. Objectives: To assess the natural infection index (NII) of Trypanosoma cruzi in triatomines and the infestation index (II) of T. gerstaeckeri collected in a suburban locality, and to collect histopathological data to understand tissue tropism of the regional T. cruzi strain (strain NE) obtained from the vectors collected after an experimental inoculation in Mus musculus . Materials and methods: Triatomines were collected from 85 houses and peridomiciles in Allende, Nuevo León. Stool samples were obtained to determine the T. cruzi NII and were used in an experimental mice infection. Results: A total of 118 T . gerstaeckeri were captured, and 46 (adults and nymphs) were collected inside the same house (II=1.17%). Thirty-seven reduvids were infected with T. cruzi (NII=31.3%). Tissue tropism of the T. cruzi NE strain was progressive in skeletal muscle, myocardial, and adipose tissues and was characterized by the presence of intracellular amastigotes and destruction of cardiac myocells. Conclusions: The presence of naturally infected domiciliary vectors is an important risk factor for public health in the region considering that these vectors are the principal transmission mechanism of the parasite. The T. cruzi NE strain has similar virulence to that of other Mexican and Texan strains and caused chagasic infections in 11 of 12 mice.

Introducción. En Nuevo León, localizado en el noreste de México, existen cuatro especies de triatominos, de las cuales Triatoma gerstaeckeri ha sido la única reportada en peridomicilios. Objetivos. Evaluar el índice de infección natural de Trypanosoma cruzi en los triatominos y el índice de infestación de T. gerstaeckeri en una localidad suburbana, y obtener datos histopatológicos para comprender el tropismo tisular de la cepa regional (cepa NE) de T. cruzi obtenida de los vectores recolectados después de la infección experimental en Mus musculus. Materiales y métodos. La recolección de triatominos se llevó a cabo en 85 casas y peridomicilios de Allende, Nuevo León, México. Se obtuvieron muestras de las deyecciones para conocer el índice de infección natural por T. cruzi y, con estas, se hicieron inoculaciones experimentales en ratones. Resultados. Se capturaron 118 especímenes de T. gerstaeckeri , 46 (adultos y ninfas) en el mismo domicilio (índice de infestación=1,17 %). Treinta y siete redúvidos estaban infectados con T. cruzi (índice de infección natural, 31,3). El tropismo tisular de la cepa NE de T. cruzi fue progresivo en músculo esquelético, miocardio y tejido adiposo, y se caracterizó por la presencia de amastigotes intracelulares con destrucción de células cardiacas. Conclusiones. La presencia de vectores domiciliarios naturalmente infectados con T. cruzi , es un factor de riesgo importante para la salud pública de la región, considerando que este es el principal mecanismo de la transmisión del parásito y que la cepa NE de T. cruzi tiene una virulencia similar a la de otras cepas mexicanas y texanas, y causó infección chagásica en 11 de los 12 ratones inoculados.

Study of the antimalarial properties of hydroxyethylamine derivatives using green fluorescent protein transformed Plasmodium berghei

A rapid decrease in parasitaemia remains the major goal for new antimalarial drugs and thus, in vivo models must provide precise results concerning parasitaemia modulation. Hydroxyethylamine comprise an important group of alkanolamine compounds that exhibit pharmacological properties as proteases inhibitors that has already been proposed as a new class of antimalarial drugs. Herein, it was tested the antimalarial property of new nine different hydroxyethylamine derivatives using the green fluorescent protein (GFP)-expressing Plasmodium berghei strain. By comparing flow cytometry and microscopic analysis to evaluate parasitaemia recrudescence, it was observed that flow cytometry was a more sensitive methodology. The nine hydroxyethylamine derivatives were obtained by inserting one of the following radical in the para position: H, 4Cl, 4-Br, 4-F, 4-CH3, 4-OCH3, 4-NO2, 4-NH2 and 3-Br. The antimalarial test showed that the compound that received the methyl group (4-CH3) inhibited 70% of parasite growth. Our results suggest that GFP-transfected P. berghei is a useful tool to study the recrudescence of novel antimalarial drugs through parasitaemia examination by flow cytometry. Furthermore, it was demonstrated that the insertion of a methyl group at the para position of the sulfonamide ring appears to be critical for the antimalarial activity of this class of compounds.

Transmisión oral de Trypanosoma cruzi: una nueva situación epidemiológica de la enfermedad de Chagas en Colombia y otros países suramericanos / Oral transmission of Trypanosoma cruzi : a new epidemiological scenario for Chagas´ disease in Colombia and other South American countries

Durante la última década se han reportado numerosos casos de infección por Trypanosoma cruzi por vía oral, debidos a la contaminación de alimentos con heces de triatominos silvestres o con secreciones de reservorios en áreas donde los vectores domiciliados han sido controlados o no hay antecedentes de domiciliación. Con base en criterios epidemiológicos, clínicos y socioeconómicos, la Organización de las Naciones Unidas para la Agricultura y la Alimentación (FAO) y la Organización Mundial de la Salud (OMS) establecieron una clasificación de los parásitos transmitidos por contaminación de alimentos en diferentes regiones del mundo, en la cual T. cruzi ocupó el décimo lugar de importancia en un grupo de 24 parásitos. Los cambios ambientales, como la deforestación y el calentamiento global, han afectado los ecotopos y el comportamiento de los vectores y de los reservorios de T. cruzi , de manera que estos se han desplazado a nuevas zonas, generando una nueva forma de transmisión por contaminación de alimentos que requiere su evaluación en el país. La presente revisión aborda la transmisión oral de la enfermedad de Chagas con énfasis en los estudios orientados a identificar los factores de riesgo, las especies de triatominos involucrados, la fisiopatología de la infección oral y los genotipos del parásito que están implicados en esta forma de transmisión en Colombia y en otras regiones de América Latina, así como la necesidad de adoptar políticas para su control y vigilancia epidemiológica.

Many cases of infection caused by the oral transmission of Trypanosoma cruzi have been reported during the last decade. These have been due to the contamination of food by faeces from sylvatic triatomines or by leakage from reservoirs in areas where domiciliated vectors have been controlled or where there has been no prior background of domiciliation. The United Nations Food and Agriculture Organization (FAO) and the World Health Organization (WHO) have used epidemiological, clinical and socioeconomic criteria for ranking parasites transmitted by the contamination of food in different areas of the world; T. cruzi was placed tenth in importance amongst a group of 24 parasites in such ranking. Environmental changes such as deforestation and global warming have affected ecotopes and the behaviour of T. cruzi vectors and reservoirs so that these have become displaced to new areas, thereby leading to such new transmission scenario caused by the contamination of food, which requires evaluation in Colombia. The current review deals with the oral transmission of Chagas´ disease, emphasising studies aimed at identifying the pertinent risk factors, the triatomine species involved, the physiopathology of oral infection, the parasite´s genotypes implicated in this type of transmission in Colombia and other Latin American regions, as well as the need for ongoing epidemiological surveillance and control policies.

Slow clearance of Plasmodium vivax with chloroquine amongst children younger than six months of age in the Brazilian Amazon

Plasmodium vivax is the most widespread parasite causing malaria, being especially prevalent in the Americas and Southeast Asia. Children are one of the most affected populations, especially in highly endemic areas. However, there are few studies evaluating the therapeutic response of infants with vivax malaria. This study retrospectively evaluated the parasitaemia clearance in children diagnosed with vivax malaria during the first five days of exclusive treatment with chloroquine (CQ). Infants aged less than six months old had a significantly slower parasitaemia clearance time compared to the group of infants and children between six months and 12 years old (Kaplan-Meier survival analysis; Wilcoxon test; p = 0.004). The impaired clearance of parasitaemia in younger children with vivax malaria is shown for the first time in Latin America. It is speculated that CQ pharmacokinetics in young children with vivax malaria is distinct, but this specific population may also allow the detection of CQ-resistant parasites during follow-up, due to the lack of previous immunity. .

Low transformation growth factor-β1 production and collagen synthesis correlate with the lack of hepatic periportal fibrosis development in undernourished mice infected with Schistosoma mansoni

Undernourished mice infected (UI) submitted to low and long-lasting infections by Schistosoma mansoni are unable to develop the hepatic periportal fibrosis that is equivalent to Symmers’ fibrosis in humans. In this report, the effects of the host’s nutritional status on parasite (worm load, egg viability and maturation) and host (growth curves, biology, collagen synthesis and characteristics of the immunological response) were studied and these are considered as interdependent factors influencing the amount and distribution of fibrous tissue in hepatic periovular granulomas and portal spaces. The nutritional status of the host influenced the low body weight and low parasite burden detected in UI mice as well as the number, viability and maturation of released eggs. The reduced oviposition and increased number of degenerated or dead eggs were associated with low protein synthesis detected in deficient hosts, which likely induced the observed decrease in transformation growth factor (TGF)-β1 and liver collagen. Despite the reduced number of mature eggs in UI mice, the activation of TGF-β1 and hepatic stellate cells occurred regardless of the unviability of most miracidia, due to stimulation by fibrogenic proteins and eggshell glycoproteins. However, changes in the repair mechanisms influenced by the nutritional status in deficient animals may account for the decreased liver collagen detected in the present study.

Submicroscopic malaria parasite carriage: how reproducible are polymerase chain reaction-based methods?

The polymerase chain reaction (PCR)-based methods for the diagnosis of malaria infection are expected to accurately identify submicroscopic parasite carriers. Although a significant number of PCR protocols have been described, few studies have addressed the performance of PCR amplification in cases of field samples with submicroscopic malaria infection. Here, the reproducibility of two well-established PCR protocols (nested-PCR and real-time PCR for the Plasmodium 18 small subunit rRNA gene) were evaluated in a panel of 34 blood field samples from individuals that are potential reservoirs of malaria infection, but were negative for malaria by optical microscopy. Regardless of the PCR protocol, a large variation between the PCR replicates was observed, leading to alternating positive and negative results in 38% (13 out of 34) of the samples. These findings were quite different from those obtained from the microscopy-positive patients or the unexposed individuals; the diagnosis of these individuals could be confirmed based on the high reproducibility and specificity of the PCR-based protocols. The limitation of PCR amplification was restricted to the field samples with very low levels of parasitaemia because titrations of the DNA templates were able to detect < 3 parasites/µL in the blood. In conclusion, conventional PCR protocols require careful interpretation in cases of submicroscopic malaria infection, as inconsistent and false-negative results can occur.

Molecular and biological characterization of Trypanosoma cruzi strains isolated from children from Jequitinhonha Valley, State of Minas Gerais, Brazil

Introduction The biological diversity of Trypanosoma cruzi strains plays an important role in the clinical and epidemiological features of Chagas disease. Methods Eight T. cruzi strains isolated from children living in a Chagas disease vector-controlled area of Jequitinhonha Valley, State of Minas Gerais, Brazil, were genetically and biologically characterized. Results The characterizations demonstrated that all of the strains belonged to T. cruzi II, and showed high infectivity and a variable mean maximum peak of parasitemia. Six strains displayed low parasitemia, and two displayed moderate parasitemia. Later peaks of parasitemia and a predominance of intermediate and large trypomastigotes in all T. cruzi strains were observed. The mean pre-patent period was relatively short (4.2±0.25 to 13.7±3.08 days), whereas the patent period ranged from 3.3±1.08 to 34.5±3.52 days. Mortality was observed only in animals infected with strain 806 (62.5%). Histopathological analysis of the heart showed that strains 501 and 806 caused inflammation, but fibrosis was observed only in animals infected with strain 806. Conclusions The results indicate the presence of an association between the biological behavior in mice and the genetic characteristics of the parasites. The study also confirmed general data from Brazil where T. cruzi II lineage is the most prevalent in the domiciliary cycle and generally has low virulence, with some strains capable of inducing inflammatory processes and fibrosis. .

Plasmodium vivax malaria: related factors to severity in the State of Maranhão, Brazil

INTRODUCTION: Malaria caused by Plasmodium vivax species has shown signs of severity, recorded with increasing frequency in the medical literature. This study aimed to characterize the signs of severe malaria by Plasmodium vivax in the State of Maranhão, Brazil. METHODS: A descriptive cohort study of patients assisted in the field and a historical and concurrent study of a series of cases among hospitalized patients were undertaken to identify the clinical and laboratory signs of severity. RESULTS: A total of 153 patients were included in the study, 13 of whom were hospitalized. Males made up the majority, numbering 103 (67.3%). The age of the patients ranged from 10 to 70 years, 92.2% were natives of the State of Maranhão, and 65% of the patients had had malaria before. The average time elapsed between symptom onset and diagnosis among outpatients was three days, while among hospitalized patients this average reached 15.5 days, a statistically significant difference (p=0.001). The parasitemia ranged from 500 to 10,000 parasites/µl in 92.8% of cases. The clinical and laboratory manifestations of severity were vomiting and diarrhea, jaundice, drowsiness, mental confusion, seizures, loss of consciousness, agitation, bleeding, pale skin, coughing and dyspnea, thrombocytopenia, anemia, elevation of nitrogenous compounds, and elevated transaminases and bilirubin. CONCLUSIONS: The monitoring of malaria patients with Plasmodium vivax showed the possibility of aggravation, the intensity of which varied in different circumstances, especially the interval time between falling ill and diagnostic confirmation.

Respuesta terapéutica de Plasmodium vivax a la cloroquina, en Riberalta, Guayaramerín y Yacuiba, Bolivia / Therapeutic response of Plasmodium vivax to chloroquine in Bolivia

Introducción. La determinación de la eficacia de la cloroquina contra Plasmodium vivax permite mejorar la capacidad de vigilancia de la resistencia a los antipalúdicos. Objetivo. Evaluar la eficacia terapéutica de la cloroquina como tratamiento de malaria no complicadapor P. vivax en Riberalta, Guayaramerín y Yacuiba, Bolivia. Materiales y métodos. Se llevó a cabo un estudio de la eficacia in vivo en pacientes mayores de cinco años; se suministró cloroquina (25 mg/kg en tres días) y se hizo seguimiento por 28 días, midiendo los niveles de cloroquina en sangre y desetilcloroquina, el día dos y el día de registro de reaparición de parasitemia. Para la evaluación de la incidencia acumulada de falla del tratamiento, se usó el análisis de supervivencia de Kaplan-Meier. Resultados. Se estudiaron 223 pacientes (Riberalta, 84; Guayaramerín, 80; Yacuiba, 59). Las medias de densidad parasitaria (formas asexuadas) del día 0 en Riberalta fueron de 6.147, en Guayaramerín, 4.251, y en Yacuiba, 5.214 parásitos/μl de sangre. En el mismo orden, los promedios de concentraciones sanguíneas de cloroquina-desetilcloroquina del día 2 fueron de 783, 817 y 815 ng/ml. Mientras en Yacuiba no se presentaron fracasos terapéuticos, en Riberalta ocurrieron con frecuencia de 6,2 % y en Guayaramerín de 10 %. Los valores de cloroquina y desetilcloroquina en sangre de pacientes con fracaso terapéutico fueron menores de 70 ng/ml en el día de reaparición de parasitemia. Conclusión. No se evidenció resistencia de P. vivax a la cloroquina en las tres regiones de evaluación en Bolivia. Se requieren mayores estudios de la concentración de la cloroquina en sangre.

Introduction. Knowledge of the therapeutic efficacy of chloroquine for Plasmodium vivax infections improves the capacity for surveillance of anti-malarial drug resistance. Objective. The therapeutic efficacy of chloroquine as treatment was evaluated for uncomplicated Plasmodium vivax malaria in Bolivia. Materials and methods. An in vivo efficacy study of chloroquine was undertaken in three regions of Bolivia--Riberalta, Guayaramerín and Yacuiba. Two hundred and twenty-three patients (84, 80, and 59 in the three regions, respectively) aged over 5 years old were administered with chloroquine (25 mg/kg/three days) and followed for 28 days. Blood levels of chloroquine and desethylchloroquine were measured on day 2 and on the day of reappearance of parasitemia. The cumulative incidence of treatment failure was calculated using the Kaplan and Meier survival analysis. Results. The mean parasitemias (asexual) on day 0 were 6,147 parasites/μl of blood in the Riberalta population, 4,251 in Guayaramerín and 5,214 in Yacuiba. The average blood concentrations of chloroquine-desethylchloroquine during day 2 were 783, 817, and 815 ng/ml, respectively. No treatment failures were observed in Yacuiba, whereas in Riberalta and Guayaramerín, the frequencies of treatment failures were 6.2% and 10%. Blood levels of chloroquine and desethylchloroquine in patients with treatment failure showed values below 70 ng/ml on the day of reappearance of parasitemia. Conclusion. Resistance of Plasmodium vivax to chloroquine was not demonstrated in three regions of Bolivia.

Caracterización de la transmisión de la malaria por Plasmodium vivax en la región fronteriza de Panamá con Costa Rica en el municipio de Barú, Panamá / Characterization of Plasmodium vivax malaria transmission at the border of Panamá and Costa Rica

Introducción. Pocos estudios describen los factores asociados con la dinámica de transmisión de la malaria, o paludismo, por Plasmodium vivax en las regiones endémicas de Panamá. Objetivo. Caracterizar la dinámica de transmisión de la malaria producida por P. vivax en la región fronteriza de Panamá con Costa Rica. Materiales y métodos. Se llevó a cabo un estudio observacional, descriptivo y transversal. Se evaluaron la incidencia parasitaria anual, el índice de láminas positivas y el índice anual de exámenes de sangre. Se identificaron los anofelinos vectores, y se caracterizaron sus criaderos preferenciales, densidad larvaria e índice de picada/hombre/noche. Se hizo búsqueda pasiva y activa de casos sospechosos mediante examen de gota gruesa. Resultados. De 10.401 muestras de gota gruesa, 83 resultaron positivas para P. vivax. El 84 % de los casos provenía de zonas rurales, el 79 % constituía una población económicamente activa, la mediana de edad fue de 36 años y, la media, de 30 años. El 58,5 % de los casos fueron de sexo masculino. La incidencia parasitaria anual fue de 4,1 por 1.000 habitantes; el índice de láminas positivas fue de 0,8 % y el índice anual de exámenes de sangre fue de 51,9 %. El 65,0 % de los casos diagnosticados registró entre 100 y 2.000 parásitos/μl de sangre. Se identificaron los mosquitos vectores Anopheles albimanus y An. punctimacula. Conclusión. Es necesario el seguimiento de estudios entomológicos, el fortalecimiento de la vigilancia epidemiológica, la consideración de los factores de riesgo y la realización de un trabajo en coordinación con las autoridades de salud de Costa Rica, para controlar la malaria en esta región.

Introduction. Few studies have described the factors associated with Plasmodium vivax transmission dynamics in endemic regions from Panamá. Objective. Malaria transmission dynamics produced by P. vivax were characterized at the border between Panamá and Costa Rica. Materials and methods. In the municipality of Barú, an observational, descriptive and cross-sectional study was undertaken to measure the annual parasite index (API), slide positivity index (SPR), and the annual blood examination rate (ABER). The most frequent symptoms and signs in malaria patients were recorded. The anopheline species were identified in the area and the preferred larval habitats, the density of larval populations in the larval habitats and the bites/human/night were characterized. Results. Of a total of 10,401 thick smear blood samples, 83 were positive for P. vivax. Of these, 84% came from rural areas and 79% were from economically active individuals. The median and average ages were 36 and 30 years, respectively, and 58.5% of the malaria cases were male. API was 4.1/1,000 inhabitants; SPR was 0.8% and ABER was 51.9%. Of the diagnosed cases, 54% showed blood parasitemias ranging between 100-2,000 parasites/μl. The majority of the cases were observed in May and June. Two mosquito vector species were identified-- Anopheles albimanus and An. punctimacula. Conclusion. These observations indicate the advisibility of continued entomological studies, strengthening of epidemiological surveillance, consideration of additional risk factors and evaluation of work performance in the border region. This will require coordination with health authorities of both countries to control malaria in this region.

Aporte de la técnica de PCR en el diagnóstico de Mansonella ozzardi en zonas endémicas de la Argentina / Contribution of the PCR assay to the diagnosis of Mansonella ozzardi in endemic areas of Argentina

Mansonella ozzardi es un nematode parásito tisular, agente etiológico de mansonellosis en casi la totalidad de los países latinoamericanos. En Argentina la mansonellosis ha sido descrita a lo largo de la región de las yungas. Su diagnóstico microscópico puede dar resultados falsos negativos en microfilaremias bajas. El objetivo del presente estudio fue optimizar su diagnóstico molecular y comparar los resultados con los obtenidos mediante las pruebas microscópicas de Knott, de gota gruesa y de extendido hemático fino, en 92 muestras de sangre de pacientes de zona endémica. La técnica de PCR seguida de la secuenciación del producto amplificado presentó una sensibilidad del 100 % frente al método de Knott, considerado como referencia, e incluso permitió identificar 7 casos más de la parasitosis.

Mansonella ozzardi is a tissue-dwelling parasitic nematode, the causative agent of mansonelliasis in almost all Latin American countries. It has been described along the Argentine Yungas region. The microscopic diagnosis can yield false-negative test results at low microfilaremia levels. The aim of this study was to optimize the molecular diagnostic technique and compare it with the Knott's method and standard blood smear procedures (thin blood films and thick smears) in 92 blood samples of individuals from an endemic area. The PCR technique followed by the sequencing of the amplified product yielded 100 % sensitivity compared to the Knott's test, which is considered a reference method. Seven more cases of this parasitosis could only be identified with the molecular technique.

Biological behavior of Trypanosoma cruzi stocks obtained from the state of Amazonas, Western Brazilian Amazon, in mice / Comportamento biológico de isolados de Trypanosoma cruzi obtidos no estado do Amazonas, Amazônia Ocidental Brasileira, em camundongos

INTRODUCTION: The biological diversity of circulating Trypanosoma cruzi stocks in the Amazon region most likely plays an important role in the peculiar clinic-epidemiological features of Chagas disease in this area. METHODS: Seven stocks of T. cruzi were recently isolated in the State of Amazonas, Brazil, from humans, wild mammals, and triatomines. They belonged to the TcI and Z3 genotypes and were biologically characterized in Swiss mice. Parasitological and histopathological parameters were determined. RESULTS: Four stocks did not promote patent parasitemia in mice. Three stocks produced low parasitemia, long pre-patent periods, and a patent period of 1 day or oscillating parasitemia. Maximum parasitemia ranged from 1,400 to 2,800 trypomastigotes/0.1mL blood. Mice inoculated with the T. cruzi stocks studied showed low positivity during fresh blood examinations, ranging from 0% to 28.6%. In hemoculture, positivity ranged from 0% to 100%. Heart tissue parasitism was observed in mice inoculated with stocks AM49 and AM61. Stock AM49 triggered a moderate inflammatory process in heart tissue. A mild inflammatory process was observed in heart tissue for stocks AM28, AM38, AM61, and AM69. An inflammatory process was frequently observed in skeletal muscle. Examinations of brain tissue revealed inflammatory foci and gliosis in mice inoculated with stock AM49. CONCLUSIONS: Biological and histopathological characterization allowed us to demonstrate the low infectivity and virulence of T. cruzi stocks isolated from the State of Amazonas.

INTRODUÇÃO: A diversidade biológica dos estoques Trypanosoma cruzi circulantes na Região Amazônica pode desempenhar importante papel nas características clínico-epidemiológicas peculiares da doença de Chagas nesta área. MÉTODOS: Sete isolados de T. cruzi do Estado do Amazonas provenientes de humanos, mamíferos silvestres e triatomíneos, pertencentes aos genótipos TcI e Z3, foram biologicamente caracterizados em camundongos Swiss. Foram avaliados parâmetros parasitológicos e histopatológicos. RESULTADOS: Quatro isolados não produziram parasitemia patente em camundongos. Três isolados promoveram baixa parasitemia com longos períodos pré-patentes, período patente de um dia ou parasitemia oscilante. A parasitemia máxima variou de 1.400 a 2.800 tripomastigotas/0,1mL de sangue. Os camundongos inoculados com os isolados estudados mostraram baixa positividade no exame a fresco, variando de 0 a 28,6%. Para a hemocultura, a positividade variou de 0 a 100%. Parasitismo cardíaco foi observado em camundongos inoculados com os isolados AM49 e AM61. O isolado AM49 produziu inflamação moderada no tecido cardíaco. Processo inflamatório discreto foi observado no tecido cardíaco de camundongos inoculados com os isolados AM28, AM38, AM61 e AM69. Processo inflamatório em músculo esquelético foi muito frequente. O exame do tecido cerebral revelou focos inflamatórios e gliose em camundongos inoculados com o isolado AM49. CONCLUSÕES: A caracterização biológica e histopatológica demonstrou baixa infecciosidade e virulência dos estoques de T. cruzi isolados no Estado do Amazonas.

Blood parasites in passerine birds from the Brazilian Atlantic Forest / Hemoparasitos em passeriformes da Mata Atlântica Brasileira

Parasites may lead bird species to extinction, affect host temporal and spatial population dynamics, alter community structure and alter individuals’ social status. We evaluated blood parasite prevalence and intensity according to bird families and species, among 925 birds that were caught in 2000 and 2001, in the Atlantic Forest in the State of Minas Gerais, Brazil. We applied Giemsa staining to thin blood smears, to detect blood parasites. The birds (n = 15.8%) in 11 families, were infected by at least one parasite genus, especially Muscicapidae (28.3%) and Conopophagidae (25%). Among the 146 infected birds, Plasmodium was detected in all bird families and had the highest prevalence (54.8%). Trypanosoma, Haemoproteus and microfilaria had lower prevalence rates (23.3, 23.3 and 2.1%, respectively). Birds caught during the rainy season were more infected than birds caught during the dry season. The overall low prevalence of blood parasites in birds is similar to the patterns found elsewhere in the Neotropical region.

Parasitos podem levar espécies de aves à extinção, afetar as dinâmicas temporais e espaciais dos hospedeiros, alterar a estrutura de comunidades e o status social de indivíduos. Avaliou-se a prevalência e a intensidade de parasitos em famílias e espécies de 925 aves capturadas, entre 2000 e 2001, na Mata Atlântica de Minas Gerais. Foram coradas com Giemsa extensões de sangue para detectar parasitos hematozoários. As aves (n= 15,8%) 11 famílias estavam infectadas por pelo menos um gênero de parasito, especialmente Muscicapidae (28,3%) e Conopophagidae (25%). Entre as 146 aves infectadas, Plasmodium foi detectado em todas as famílias e possuiu a maior prevalência (54,8%). Trypanosoma,Haemoproteus e microfilaria possuíram baixas prevalências (23,3, 23,3 e 2,1%, respectivamente). Aves capturadasdurante a estação chuvosa estavam mais infectadas do que aves capturadas durante a estação seca. A baixa prevalência geral de parasitos do sangue das aves é semelhante aos padrões encontrados em outras localidades da região Neotropical.

Molecular characterization of Trypanosoma cruzi Mexican strains and their behavior in the mouse experimental model / Caracterização molecular de cepas mexicanas de Trypanosoma cruzi e seu comportamento no modelo experimental do camundongo

INTRODUCTION: For a long time, the importance of Chagas disease in Mexico, where many regarded it as an exotic malady, was questioned. Considering the great genetic diversity among isolates of Trypanosoma cruzi, the importance of this biological characterization, and the paucity of information on the clinical and biological aspects of Chagas disease in Mexico, this study aimed to identify the molecular and biological characterization of Trypanosoma cruzi isolates from different endemic areas of this country, especially of the State of Jalisco. METHODS: Eight Mexican Trypanosoma cruzi strains were biologically and genetically characterized (PCR specific for Trypanosoma cruzi, multiplex-PCR, amplification of space no transcript of the genes of the mini-exon, amplification of polymorphic regions of the mini-exon, classification by amplification of intergenic regions of the spliced leader genes, RAPD - (random amplified polymorphic DNA). RESULTS: Two profiles of parasitaemia were observed, patent (peak parasitaemia of 4.6×10(6) to 10(7) parasites/mL) and subpatent. In addition, all isolates were able to infect 100 percent of the animals. The isolates mainly displayed tropism for striated (cardiac and skeletal) muscle. PCR amplification of the mini-exon gene classified the eight strains as TcI. The RAPD technique revealed intraspecies variation among isolates, distinguishing strains isolated from humans and triatomines and according to geographic origin. CONCLUSIONS: The Mexican T. cruzi strains are myotrophic and belong to group TcI.

INTRODUÇÃO: Durante muito tempo, foi questionada a importância da doença de Chagas no México onde muitos a consideravam um padecimento exótico. Considerando a grande diversidade genética existente, entre os isolados de Trypanosoma cruzi, a importância da caracterização biológica desses e o escasso número de informações sobre os aspectos clínicos e biológicos da doença de Chagas no México, o objetivo deste trabalho foi realizar a caracterização biológica e molecular de isolados de Trypanosoma cruzi originários de diferentes áreas endêmicas deste país, principalmente do Estado de Jalisco. MÉTODOS: Oito cepas mexicanas de Trypanosoma cruzi foram caracterizadas biologicamente e geneticamente (PCR específica para Trypanosoma cruzi, PCR-multiplex, amplificação do espaço não transcrito dos genes do mini-exon, amplificação das regiões polimórficas do gene do mini-exon, classificação pela amplificação de regiões intergênicas dos genes do spliced leader, RAPD - random amplified polymorphic DNA). RESULTADOS: Foram observados dois tipos de parasitemia: patente com picos máximos de parasitemia entre 4,6x10(6) e 10(7) parasitas/mL e subpatente. Além disso, todos os isolados foram capazes de infectar 100 por cento dos animais. Observou-se tropismo predominante pelo músculo estriado (cardíaco e esquelético). As técnicas de PCR do gene do mini-éxon classificaram as oito cepas como TcI e a técnica de RAPD mostrou variação intra-especifica das mesmas, separando as cepas isoladas de humanos daquelas de triatomíneos e por origem geográfica. CONCLUSÕES: As cepas mexicanas de Trypanosoma cruzi são miotrópicas e correspondem ao TcI.

Plasmodium falciparum gametocyte carriage, sex ratios and asexual parasite rates in Nigerian children before and after a treatment protocol policy change instituting the use of artemisinin-based combination therapies

The effects of artemisinin-based combination therapies (ACTs) on transmission of Plasmodium falciparum were evaluated after a policy change instituting the use of ACTs in an endemic area. P. falciparum gametocyte carriage, sex ratios and inbreeding rates were examined in 2,585 children at presentation with acute falciparum malaria during a 10-year period from 2001-2010. Asexual parasite rates were also evaluated from 2003-2010 in 10,615 children before and after the policy change. Gametocyte carriage declined significantly from 12.4 percent in 2001 to 3.6 percent in 2010 (@@χ2 for trend = 44.3, p < 0.0001), but sex ratios and inbreeding rates remained unchanged. Additionally, overall parasite rates remained unchanged before and after the policy change (47.2 percent vs. 45.4 percent), but these rates declined significantly from 2003-2010 (@@χ2 for trend 35.4, p < 0.0001). Chloroquine (CQ) and artemether-lumefantrine (AL) were used as prototype drugs before and after the policy change, respectively. AL significantly shortened the duration of male gametocyte carriage in individual patients after treatment began compared with CQ (log rank statistic = 7.92, p = 0.005). ACTs reduced the rate of gametocyte carriage in children with acute falciparum infections at presentation and shortened the duration of male gametocyte carriage after treatment. However, parasite population sex ratios, inbreeding rates and overall parasite rate were unaffected.