Human hookworms from Argentina: Differential diagnosis of Necator americanus and Ancylostoma duodenale in endemic populations from Buenos Aires and Misiones / Ancylostomideos humanos de Argentina: Diagnóstico diferencial de Necatoramericanus y Ancylostoma duodenale en poblaciones endémicas de Buenos Aires yMisiones

Abstract Hookworm infection is endemic in many countries throughout the world; however,the information about the prevalence of each species, Necator americanus and Ancylostomaduodenale, is inaccurate in many South American countries. We aimed to determine the preva-lence of human hookworm species by combining the results of both microscopy and PCR amongendemic populations in Argentina, represented by natives and immigrants. A total of 140 serialfecal specimens were obtained from natives in the province of Misiones and an immigrantcommunity living in the province of Buenos Aires. Samples were examined using the formalin-ethyl acetate concentration technique (FECT) and one flotation technique (screening tests)and specific PCRs for N. americanus and A. duodenale. We characterized samples containingN. americanus by sequencing a fragment of the cytochrome b gene. The observed hookwormprevalence as assessed by the screening tests and PCR were 24.3% and 32.8%, respectively. PCRpositive samples were identified as N. americanus. PCR had 100% sensitivity compared with73.9% of screening tests. A total of 12 samples from individuals with hookworm-infected house-hold members were positive only by PCR. N. americanus sequences showed 90.5% identity, beingmore similar to each other than to any of the sequences obtained from GenBank. This is thefirst study that provides molecular data and characterization of N. americanus in Argentina.The complementary use of FECT and one flotation technique to screen hookworm infections,followed by PCR to differentiate the species contribute to produce better prevalence estimates.

Resumen La infección por Ancylostomideos es endémica en muchos países del mundo, pero la información sobre la prevalencia de las especies que la causan, Necator americanus y Ancylostoma duodenale, es inexacta en América del Sur. Nuestro objetivo fue determinar la prevalencia de especies de Ancylostomideos humanos en poblaciones de Argentina nativas o provenientes de áreas endémicas, combinando los resultados de microscopía y PCR. Un total de 140 muestras fecales seriadas fueron obtenidas de individuos nacidos en la provincia de Misiones con residencia en esta y de miembros de una comunidad oriunda del Paraguay establecida en la provincia de Buenos Aires. Las muestras fueron examinadas por la técnica de formol-acetato de etilo (FAE) y una técnica de flotación como pruebas de cribado, y se efectuaron PCR específicas para N. americanus y A. duodenale. Caracterizamos muestras que contienen N. americanus secuenciando un fragmento del gen del citocromo b. La prevalencia de Ancylostomideos según las pruebas de cribado y el método PCR fueron del 24,3 y 32,8%, respectivamente. Las muestras positivas por PCR se identificaron como N. americanus. La PCR tuvo una sensibilidad del 100,0% en comparación con el 73,9% de las pruebas de detección. Hubo 12 muestras de individuos con miembros de la familia infectados con anquilostomas que solo por PCR fueron positivas. Las secuencias de N. americanus mostraron un 90,5% de identidad y fueron más similares entre sí que a cualquiera de las secuencias obtenidas de GenBank. Este es el primer estudio que proporciona datos moleculares y la caracterización de N. americanus en Argentina. El uso complementario de FAE y una técnica de flotación para detectar infecciones por anquilostomas, seguido de PCR para diferenciar las especies, contribuye a producir mejores estimaciones de prevalencia.

Human hookworms from Argentina: Differential diagnosis of Necator americanus and Ancylostoma duodenale in endemic populations from Buenos Aires and Misiones.

Hookworm infection is endemic in many countries throughout the world; however, the information about the prevalence of each species, Necatoramericanus and Ancylostomaduodenale, is inaccurate in many South American countries. We aimed to determine the prevalence of human hookworm species by combining the results of both microscopy and PCR among endemic populations in Argentina, represented by natives and immigrants. A total of 140 serial fecal specimens were obtained from natives in the province of Misiones and an immigrant community living in the province of Buenos Aires. Samples were examined using the formalin-ethyl acetate concentration technique (FECT) and one flotation technique (screening tests) and specific PCRs for N. americanus and A. duodenale. We characterized samples containing N. americanus by sequencing a fragment of the cytochrome b gene. The observed hookworm prevalence as assessed by the screening tests and PCR were 24.3% and 32.8%, respectively. PCR positive samples were identified as N. americanus. PCR had 100% sensitivity compared with 73.9% of screening tests. A total of 12 samples from individuals with hookworm-infected household members were positive only by PCR. N. americanus sequences showed 90.5% identity, being more similar to each other than to any of the sequences obtained from GenBank. This is the first study that provides molecular data and characterization of N. americanus in Argentina. The complementary use of FECT and one flotation technique to screen hookworm infections, followed by PCR to differentiate the species contribute to produce better prevalence estimates.

American trypanosomiasis (Chagas disease) in solid organ transplantation.

This review addresses relevant aspects of Chagas disease in the solid organ transplantation setting. This trypanosomiasis was geographically restricted to America, but migration has turned Chagas disease into a global public health concern. Parasite persistence in chronically infected individuals entails the potential of transmission with organ donation and the potential for reactivation under immunosuppression. Prospective monitoring with real-time PCR or direct methods for detection of parasitemia and treatment of documented episodes of transmission/ reactivation (rather than prophylactic treatment) is the recommended approach for managing patients at risk. Chagas disease is an important cause of terminal cardiomyopathy. Clinical results demonstrate that with adequate monitoring and treatment, patients with Chagas cardiomyopathy benefit from heart transplantation, with long-term results even better than patients who underwent heart transplantation due to other conditions. Kidney and liver (and possibly other solid organs) transplantation can be safely performed in chronically infected patients with adequate management. Chronically infected patients are also suitable for organ donation (with the exception of the heart and intestines). Although reactivations and transmissions are observed, serious clinical disease is rare, and they are usually successfully managed with benznidazole or nifurtimox.

Strongyloidiasis Outside Endemic Areas: Long-term Parasitological and Clinical Follow-up After Ivermectin Treatment.

Background: Strongyloides stercoralis affects 30-100 million people worldwide. The first-line therapy is ivermectin. Cure is defined as the absence of larvae by parasitological methods 1 year after treatment. To date, no longitudinal parasitological studies for longer periods of time have been conducted to confirm its cure. Here, we evaluated treatment response in long-term follow-up patients with chronic infection using parasitological and molecular methods for larvae or DNA detection. Methods: A prospective, descriptive, observational study was conducted between January 2009 and September 2015 in Buenos Aires, Argentina. Twenty-one patients with S. stercoralis diagnosis were evaluated 30, 60, and 90 days as well as 1, 2, 3, and/or 4 years after treatment by conventional methods (fresh stool, Ritchie method, agar plate culture), S. stercoralis-specific polymerase chain reaction (PCR) in stool DNA, and eosinophil values. Results: During follow-up, larvae were detected by conventional methods in 14 of 21 patients. This parasitological reactivation was observed starting 30 days posttreatment (dpt) and then at different times since 90 dpt. Eosinophil values decreased (P = .001) 30 days after treatment, but their levels were neither associated with nor predicted these reactivations. However, S. stercoralis DNA was detected by PCR in all patients, both in their first and subsequent stool samples, thus reflecting the poor efficacy of ivermectin at eradicating parasite from host tissues. Asymptomatic eosinophilia was the most frequent clinical form among chronically infected patients. Conclusions: These results suggest that the parasitological cure is unlikely. Strongyloidiasis must be considered a chronic infection and ivermectin administration schedules should be reevaluated.

Comparison between PCR and larvae visualization methods for diagnosis of Strongyloides stercoralis out of endemic area: A proposed algorithm.

Underdiagnosis of chronic infection with the nematode Strongyloides stercoralis may lead to severe disease in the immunosuppressed. Thus, we have set-up a specific and highly sensitive molecular diagnosis in stool samples. Here, we compared the accuracy of our polymerase chain reaction (PCR)-based method with that of conventional diagnostic methods for chronic infection. We also analyzed clinical and epidemiological predictors of infection to propose an algorithm for the diagnosis of strongyloidiasis useful for the clinician. Molecular and gold standard methods were performed to evaluate a cohort of 237 individuals recruited in Buenos Aires, Argentina. Subjects were assigned according to their immunological status, eosinophilia and/or history of residence in endemic areas. Diagnosis of strongyloidiasis by PCR on the first stool sample was achieved in 71/237 (29.9%) individuals whereas only 35/237(27.4%) were positive by conventional methods, requiring up to four serial stool samples at weekly intervals. Eosinophilia and history of residence in endemic areas have been revealed as independent factors as they increase the likelihood of detecting the parasite according to our study population. Our results underscore the usefulness of robust molecular tools aimed to diagnose chronic S. stercoralis infection. Evidence also highlights the need to survey patients with eosinophilia even when history of an endemic area is absent.

Internal travel and risk of dengue transmission in Colombia.

Human behavior plays a key role in the dynamics of dengue transmission. However, research on the relationship between human movement and dengue transmission within endemic countries is limited. From January 2008 to December 2011, the authors of this study conducted a retrospective analysis of imported dengue infections in Bogotá, Colombia. Bogotá is a vector-transmission-free city that is also the capital district and most populated municipality in Colombia. The study revealed that 1) Bogotá inhabitants acquired dengue infection in diverse localities throughout the country but the largest proportion of cases (35.6%) were contracted at popular tourist destinations in dengue-endemic areas near Bogotá (<200-km radius from city limits), and 2) the number of imported dengue cases increased after major holidays, a transmission pattern not seen in dengue-endemic areas, where disease incidence correlates with rainy periods. It is therefore recommended that physicians consider the effect of travel when diagnosing their patients' illnesses, especially outside dengue-endemic areas where diagnosis of the disease can be challenging due to its nonspecific symptoms. The study also showed that analysis of dengue cases imported to regions free of vector transmission can generate an evidence-based model for characterizing the impact of human movement on the spread of diseases like dengue in countries where they are endemic.

Internal travel and risk of dengue transmission in Colombia / Desplazamientos internos y riesgo de transmisión del dengue en Colombia

Human behavior plays a key role in the dynamics of dengue transmission. However, research on the relationship between human movement and dengue transmission within endemic countries is limited. From January 2008 to December 2011, the authors of this study conducted a retrospective analysis of imported dengue infections in Bogotá, Colombia. Bogotá is a vector-transmission-free city that is also the capital district and most populated municipality in Colombia. The study revealed that 1) Bogotá inhabitants acquired dengue infection in diverse localities throughout the country but the largest proportion of cases (35.6%) were contracted at popular tourist destinations in dengue-endemic areas near Bogotá (<200-km radius from city limits), and 2) the number of imported dengue cases increased after major holidays, a transmission pattern not seen in dengue-endemic areas, where disease incidence correlates with rainy periods. It is therefore recommended that physicians consider the effect of travel when diagnosing their patients' illnesses, especially outside dengue-endemic areas where diagnosis of the disease can be challenging due to its nonspecific symptoms. The study also showed that analysis of dengue cases imported to regions free of vector transmission can generate an evidence-based model for characterizing the impact of human movement on the spread of diseases like dengue in countries where they are endemic.

El comportamiento humano es un factor clave en la dinámica de transmisión del dengue. Sin embargo, la investigación sobre la relación entre los desplazamientos de personas y la transmisión del dengue en los países con endemicidad es escasa. Los autores realizaron un análisis retrospectivo de las infecciones por dengue importadas a Bogotá, Colombia, de enero del 2008 a diciembre del 2011. Bogotá es una ciudad libre de transmisión por vectores que además es la capital y también el municipio más poblado de Colombia. El estudio reveló que: 1) los habitantes de Bogotá contraían la infección por dengue en diferentes localidades del país, pero la mayor proporción de casos (35,6%) se había registrado en destinos turísticos populares de zonas endémicas cercanas a Bogotá (en un radio de <200 km respecto de los límites de la ciudad), y 2) el número de casos importados de dengue aumentaba después de los feriados más importantes, un patrón de transmisión que no se observaba en las zonas endémicas, en las que la incidencia de la enfermedad se correlacionaba con las épocas de lluvias. Por consiguiente, los autores recomiendan que los médicos tomen en cuenta el factor del viaje a la hora de diagnosticar a sus pacientes, especialmente fuera de las áreas endémicas, en las que el diagnóstico del dengue puede ser problemático debido a la inespecificidad de los síntomas. El estudio también indicó que el análisis de los casos de dengue importados a las regiones libres de transmisión por vectores puede ser útil para generar un modelo basado en datos probatorios que permita determinar la repercusión de los desplazamientos de personas en la propagación enfermedades como el dengue, en los países donde son endémicas.

High rate of strongyloidosis infection, out of endemic area, in patients with eosinophilia and without risk of exogenous reinfections.

Strongyloides stercoralis chronic infections are usually asymptomatic and underestimated. We used direct fresh stool examination, Ritchie's method, and agar plate culture for diagnosis in patients with eosinophilia and previous residence in endemic areas. The frequency of strongyloidosis detected among these patients was high: 21 of 42 were positive. Among them, 10 were positive only by agar plate culture. After ivermectin treatment, patients resulted negative for parasitological tests and reduced their eosinophil counts. Half of the submitted patients that were followed 4-12 months after treatment remained negative without eosinophilia, except one who showed an eosinophil ascending curve before reappearance of larvae in stools. The high frequency of strongyloidosis found in this group emphasizes the relevance of including this parasitosis among differential diagnosis in patients with eosinophilia and past risk of S. stercoralis infection to prevent disseminated infections secondary to corticoid therapy.