Comparación de pruebas moleculares para el diagnóstico de Leishmania spp. en lesiones cutáneas con baja carga parasitaria

Introducción: La leishmaniasis cutánea (LC) es un problema grave de salud pública en Panamá. El diagnóstico de esta parasitosis ha sido siempre desafiante, no sólo debido a su similitud con otras infecciones dérmicas, sino también a características particulares de las lesiones, como cargas parasitarias bajas. ​Materiales y Métodos: En este estudio, se evaluaron mediante cuatro métodos moleculares, 235 muestras de ADN procedentes de lesiones con frotis negativos por LC obtenidas durante el período 2015-2019. Resultados: Los resultados señalan que las sensibilidades encontradas fueron de 75.6% (IC 0.6234-0.8709) para la PCR kDNA-Género específico, de 66.7% (IC 0.5359-0.776) para la PCR Hsp70-Género específico y de 77.6% (IC 0.645-0.8949) para la qPCR 18S ribosomal. Todas las pruebas obtuvieron un valor predictivo positivo de 100%, mientras que el valor predictivo negativo más alto fue con la qPCR (80.58%) y el más bajo con el PCR Hsp70-Género específico (73.2%). En cuanto a la precisión de diagnóstico se obtuvo un rango mayor del 82% en todas las pruebas evaluadas. Conclusión: Este estudio confirma la buena sensibilidad de la PCR kDNA-Viannia para el análisis de lesiones de LC con baja carga parasitaria. Esta metodología es relativamente fácil de estandarizar, por lo que se recomienda su uso en laboratorios clínicos regionales de Panamá. Aun cuando la qPCR 18S ribosomal presentó una sensibilidad relativamente menor, el uso de esta metodología debe ser también considerada por su facilidad de uso, menor tiempo de ejecución y capacidad de cuantificación. (provisto por Infomedic International)

Introduction: Cutaneous leishmaniasis (CL) is a serious public health problem in Panama. The diagnosis of this parasitosis has always been challenging, not only because of its similarity to other dermal infections, but also because of characteristics of the lesions, such as low parasite loads. Materials and Methods: In this study, 235 DNA samples from smear-negative lesions by LC obtained during the period 2015-2019 were evaluated by four molecular methods. Results: The results indicate that the sensitivities found were 75.6% (CI 0.6234-0.8709) for kDNA-Gene-specific PCR, 66.7% (CI 0.5359-0.776) for Hsp70-Gene-specific PCR and 77.6% (CI 0.645-0.8949) for 18S ribosomal qPCR. All tests obtained a positive predictive value of 100%, while the highest negative predictive value was with qPCR (80.58%) and the lowest with Hsp70-Gene-specific PCR (73.2%). In terms of diagnostic accuracy, a range greater than 82% was obtained in all the tests evaluated. Conclusion: This study confirms the good sensitivity of kDNA-Viannia PCR for the analysis of LC lesions with low parasite load. This methodology is relatively easy to standardize, so it is recommended for use in regional clinical laboratories in Panama. Although 18S ribosomal qPCR showed a relatively lower sensitivity, the use of this methodology should also be considered because of its ease of use, shorter execution time and quantification capacity. (provided by Infomedic International)

In vitro and in vivo experimental models for drug screening and development for Chagas disease

Chagas disease, a neglected illness, affects nearly 12-14 million people in endemic areas of Latin America. Although the occurrence of acute cases sharply has declined due to Southern Cone Initiative efforts to control vector transmission, there still remain serious challenges, including the maintenance of sustainable public policies for Chagas disease control and the urgent need for better drugs to treat chagasic patients. Since the introduction of benznidazole and nifurtimox approximately 40 years ago, many natural and synthetic compounds have been assayed against Trypanosoma cruzi, yet only a few compounds have advanced to clinical trials. This reflects, at least in part, the lack of consensus regarding appropriate in vitro and in vivo screening protocols as well as the lack of biomarkers for treating parasitaemia. The development of more effective drugs requires (i) the identification and validation of parasite targets, (ii) compounds to be screened against the targets or the whole parasite and (iii) a panel of minimum standardised procedures to advance leading compounds to clinical trials. This third aim was the topic of the workshop entitled Experimental Models in Drug Screening and Development for Chagas Disease, held in Rio de Janeiro, Brazil, on the 25th and 26th of November 2008 by the Fiocruz Program for Research and Technological Development on Chagas Disease and Drugs for Neglected Diseases Initiative. During the meeting, the minimum steps, requirements and decision gates for the determination of the efficacy of novel drugs for T. cruzi control were evaluated by interdisciplinary experts and an in vitro and in vivo flowchart was designed to serve as a general and standardised protocol for screening potential drugs for the treatment of Chagas disease.

Feeding sources and trypanosome infection index of Rhodnius pallescens in a Chagas disease endemic area of Amador County, Panama

The sylvatic triatomine Rhodnius pallescens is considered to be the most important and widespread vector of Trypanosoma cruzi and Trypanosoma rangeli in Panama. However, its behavior and biological characteristics have only been partially investigated. Thus, to achieve sustainable and efficient control over Chagas disease in Panama, a better understanding of the ecology and biology of R. pallescens is essential. In this study we evaluated R. pallescens host feeding sources using a dot-blot assay, and the trypanosome infection index by PCR analysis in a Chagas disease endemic area of central Panama. It was found that in peridomestic palm trees, 20.3 percent of the examined bugs had fed on opossums (Didelphis marsupialis). However, we observed an increased anthropophagy (25.4 percent) for those bugs collected inside houses. Considering the domestic and peridomestic habitats as a whole, the proportion of collected R. pallescens infected with trypanosomes was 87.4 percent. In the two habitats the predominant infection was with T. cruzi (80-90 percent). Between 47-51 percent of the analyzed triatomines were infected with T. rangeli. Mixed infections (40-51 percent) were also detected. These findings provide a better basis for the implementation of a rational control and surveillance program for Chagas disease in regions where R. pallescens is endemic.

O triatomíneo silvestre Rhodnius pallescens é considerado o mais importante vetor do Trypanosoma cruzi e Trypanosoma rangeli no Panamá. Entretanto, seu comportamento e características biológicas são pouco estudados. Para controlar a doença de Chagas no Panamá é necessário melhorar a compreensão dos aspectos eco-biológicos do R. pallescens. Neste estudo, investigaram-se as fontes de alimentação de R. pallescens usando dot-blot e o índice de infecção por Trypanosoma por metodologia molecular, em área endêmica da doença de Chagas na região central do Panamá. Foi observado que 20,3 por cento dos barbeiros coletados em palmeiras peridomésticas se alimentavam de gambás (Didelphis marsupialis). Contudo, barbeiros coletados dentro das residências apresentaram antropofagia aumentada (25,4 por cento). Considerando o ambiente doméstico e peridoméstico juntos, o percentual de R. pallescens infectados com Trypanosoma foi de 87,4 por cento. Nos ambientes doméstico e peridoméstico, a infecção por T. cruzi foi de 80,4 por cento e 90 por cento; a infecção por T. rangeli foi de 47 por cento e 51 por cento, respectivamente. Observou-se infecção mista em 43 por cento dos triatomíneos coletados em ambiente doméstico e em 51 por cento dos triatomíneos peridomésticos. Estes achados fornecem embasamento para a implementação de um controle adequado e um programa de vigilância para a doença de Chagas em regiões onde o R. pallescens é endêmico.

Protozoarios enteropatógenos asociados con diarrea en niños menores de cinco años, provincia de Panamá, 2006-2007 / Protoza enteropathogen associated with diarrhea in children less than five years, province of Panama, 2006-2007

La diarrea infantil continúa siendo un grave problema de salud a nivel mundial principalmente en países en vías de desarrollo como Panamá. Sin embargo, los parásitos y otros agentes asociados a los episodios de diarrea en niños menores de cinco años han sido poco estudiados en nuestro medio. En este sentido se propuso realizar la presente investigación a fin de determinar la frecuencia de la infección con protozoarios enteropatógenos en heces diarreicas de niños menores de cinco años de la provincia de Panamá. La metodología utilizada consistió en análisis microscópico (directo y tinción de kinyoun) y detección de coproantígenos (ELISA). Se encontró que el 37.3% (132/354) de las muestras de diarrea evaluadas presentaron infecciones con protozoarios. El 65.9% (87/132) de las muestras positivas provienen de niños menores de dos años de edad. La infección con Cryptosporidium spp.estuvo frecuentemente asociada (24.6%) a los casos de diarrea infantil provenientes del distrito de la Chorrera. Se estima que el 77.6% de los casos de giardiasis y el 100% de los casos de criptospidiosis no estan siendo identificados en los laboratorios investigados. La baja frecuencia de los casos de Entamoeba sp.(>5%) sugiere una relación de menor importancia para los casos de diarreas estudiados.Por otro lado los resultados obtenidos con una prueba de aglutinación demostraron una frecuencia relativamente baja (13%,46/354) para la infección con rotavirus. Los resultados obtenidos en este estudio deben alertar a los directores y trabajadores de la salud en la provincia de Panamá.