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.

Intestinal parasitosis, undernutrition and socio-environmental factors in schoolchildren from Clorinda Formosa, Argentina / Parasitosis intestinal, desnutrición y factores socio-ambientales en niños escolares de Clorinda Formosa, Argentina

ABSTRACT Objective To evaluate intestinal parasitosis, undernutrition and socio-environmental factors in schoolchildren from Clorinda (Formosa, Argentina). Materials and Methods Serial fecal samples and anal swabs of 114 schoolchildren, canine feces and soil samples were analyzed. Body weight and height of 215 schoolchildren were measured and undernutrition was estimated according to the World Health Organization criteria. Socio-environmental variables were assessed by means of a semi-structured questionnaire. Results 78.1% of children were infected by at least one of the 12 species identified and 70.8% had multiple parasitic infections. Blastocystis sp., Giardia lamblia and Enterobius vermicularis were the most prevalent. Additionally, 17.5% of children were infected by at least one geohelminth (e.g. Ascarislumbricoides, Trichuris trichiura, hookworms). 64.3% of canine of canine feces were positive and six parasitic species were found; the most frequent were Ancylostoma caninum, Uncinaria stenocephala and G. lamblia. Furthermore, 37.5% of soil samples showed zoonotic parasites (i.e. Ascaris sp., Toxocara sp.). Finally, 10.0% of the children were undernourished and 85.7% of them had parasites. The risk for parasitosis was higher in children that lived in houses with inadequate solid waste disposal and whose parents were unemployed or had temporary jobs. Conclusions The lack of environmental sanitation, unstable employment of parents and the presence of zoonotic species were the most relevant factors observed. Consequently, these conditions result in an increase of parasitic infections and negatively influence the growth of children.(AU)

RESUMEN Objetivo Evaluar la parasitosis intestinal, la desnutrición y los factores socio-ambientales en escolares de Clorinda (Formosa, Argentina). Materiales y Métodos Se analizaron muestras fecales y escobillados anales seriados de 114 escolares, heces caninas y muestras de suelo. Se midió el peso corporal y la talla de 215 escolares y se evaluó la desnutrición según los criterios de la Organización Mundial de la Salud. Las variables socio-ambientales se evaluaron mediante una encuesta semiestructurada. Resultados El 78,1% de los niños estuvieron parasitados por al menos 1 de las 12 especies identificadas y el 70,8% presentó parasitosis múltiples. Blastocystis sp., Giardia lamblia y Enterobius vermicularis fueron las más prevalentes. Además, el 17,5% de los niños estaban infectados con al menos un geohelminto (e.g. Ascaris lumbricoides, Trichuris trichiura, ancylostomideos). El 64,3% de las heces caninas resultaron positivas y se encontraron seis especies parasitarias; las más frecuentes fueron Ancylostoma caninum, Uncinaria stenocephala y G. lamblia. Además, el 37,5% de las muestras de suelo mostraron parásitos zoonóticos (i.e. Ascaris sp., Toxocara sp.). Finalmente, el 10% de los niños estaban desnutridos y el 85,7% de ellos resultaron parasitados. El riesgo de parasitosis fue mayor en los niños que vivían en casas con eliminación inadecuada de desechos sólidos y cuyos padres estaban desempleados o tenían empleos temporales. Conclusiones La falta de saneamiento ambiental, el empleo inestable de los padres y la presencia de especies zoo-nóticas fueron los factores observados más relevantes. En consecuencia, estas condiciones resultan en un aumento de las infecciones parasitarias e influyen negativamente en el crecimiento de los niños.(AU)

Angiostrongylus spp. in the Americas: geographical and chronological distribution of definitive hosts versus disease reports

BACKGROUND Angiostrongyliasis is an infection caused by nematode worms of the genus Angiostrongylus. The adult worms inhabit the pulmonary arteries, heart, bronchioles of the lung, or mesenteric arteries of the caecum of definitive host. Of a total of 23 species of Angiostrongylus cited worldwide, only nine were registered in the American Continent. Two species, A. cantonensis and A. costaricensis, are considered zoonoses when the larvae accidentally parasitise man. OBJECTIVES In the present study, geographical and chronological distribution of definitive hosts of Angiostrongylus in the Americas is analysed in order to observe their relationship with disease reports. Moreover, the role of different definitive hosts as sentinels and dispersers of infective stages is discussed. METHODS The study area includes the Americas. First records of Angiostrongylus spp. in definitive or accidental hosts were compiled from the literature. Data were included in tables and figures and were matched to geographic information systems (GIS). FINDINGS Most geographical records of Angiostrongylus spp. both for definitive and accidental hosts belong to tropical areas, mainly equatorial zone. In relation to those species of human health importance, as A. cantonensis and A. costaricensis, most disease cases indicate a coincidence between the finding of definitive host and disease record. However, in some geographic site there are gaps between report of definitive host and disease record. In many areas, human populations have invaded natural environments and their socioeconomic conditions do not allow adequate medical care. MAIN CONCLUSIONS Consequently, many cases for angiostrongyliasis could have gone unreported or unrecognised throughout history and in the nowadays. Moreover, the population expansion and the climatic changes invite to make broader and more complete range of observation on the species that involve possible epidemiological risks. This paper integrates and shows the current distribution of Angiostrongylus species in America, being this information very relevant for establishing prevention, monitoring and contingency strategies in the region.

New host, geographic records, and histopathologic studies ofAngiostrongylus spp (Nematoda: Angiostrongylidae) in rodents from Argentina with updated summary of records from rodent hosts and host specificity assessment

To date, 21 species of the genus Angiostrongylus (Nematoda: Angiostrongylidae) have been reported around the world, 15 of which are parasites of rodents. In this study, new host, geographic records, and histopathologic studies of Angiostrongylus spp in sigmodontine rodents from Argentina, with an updated summary of records from rodent hosts and host specificity assessment, are provided. Records of Angiostrongylus costaricensis from Akodon montensis andAngiostrongylus morerai from six new hosts and geographical localities in Argentina are reported. The gross and histopathologic changes in the lungs of the host species due to angiostrongylosis are described. Published records of the genus Angiostrongylus from rodents and patterns of host specificity are presented. Individual Angiostrongylusspecies parasitise between one-19 different host species. The most frequent values of the specificity index (STD) were between 1-5.97. The elevated number of host species (n = 7) of A. morerai with a STD = 1.86 is a reflection of multiple systematic studies of parasites from sigmodontine rodents in the area of Cuenca del Plata, Argentina, showing that an increase in sampling effort can result in new findings. The combination of low host specificity and a wide geographic distribution of Angiostrongylus spp indicates a troubling epidemiological scenario although, as yet, no human cases have been reported.

Distribución espacial de las parasitosis intestinales en la ciudad de La Plata, Argentina

El análisis de las parasitosis a diferentes escalas (regional, local) se facilita por el Geographic Information System (GIS), que permite identificar áreas con distinto grado de vulnerabilidad. El objetivo del trabajo fue analizar la distribución espacial de las parasitosis intestinales en el partido de La Plata, estableciendo su relación con las condiciones socio-ambientales para identificar áreas con diferente riesgo epidemiológico. Se completó una encuesta epidemiológica y se tomaron muestras seriadas de materia fecal, analizadas por la técnica de Ritchie. Se calcularon niveles de precariedad y vulnerabilidad (Iv), y se compararon con los resultados parasitológicos. Se analizaron parasitológica y ambientalmente 653 personas, de las cuales 585 (89.6%) eran niños y 68 (10.4%) adultos. El análisis indicó que los más vulnerables (Iv = 3-4) estaban en el sector con menor acceso a servicios de infraestructura urbana. El índice se encontró fuertemente asociado a la prevalencia total de parasitosis intestinales y a las 4 especies patógenas asociadas a la contaminación fecal del ambiente: Trichuris trichiura, Ascaris lumbricoides, Hymenolepis nana y Giardia lamblia (p < 0.01). Enterobius vermicularis, parásito no vinculado a la condición sanitaria de sus hospedadores, no se asoció al Iv. Hubo asociación estadística entre precariedad y parasitosis y se halló que a mayor Iv mayor frecuencia de parasitosis (p < 0.01). El uso de GIS permitió zonificar las variables socioambientales en un gradiente creciente de condiciones desfavorables y su relación con la presencia de especies patógenas. La continuidad de estos estudios en diferentes regiones de Argentina contribuye a la determinación de áreas en riesgo sanitario.

Parasitosis analysis at regional levels is simplified by the use of the Geographic Information System (GIS), which enables the identification of areas with different degrees of vulnerability. We analyzed the spatial distribution of intestinal parasites in La Plata district and their relationship with socio-environmental conditions in order to identify areas with different degrees of epidemiological risk. An epidemiological survey was completed; stool samples were collected and analyzed by Ritchie's method. Levels of precariousness and vulnerability (Iv rate) were calculated and compared to the parasitological results. Parasitological and environmental analysis were carried out on a total of 653 individuals, of whom 585 (89.6%) were children and 68 (10.4%) adults. The analysis indicated that the most vulnerable (Iv = 3-4) were those located in areas with less access to urban infrastructure services. The Iv was strongly associated with the overall prevalence of intestinal parasitosis and the 4 pathogenic species related to the fecal contamination of the environment: Trichuris trichiura, Ascaris lumbricoides, Hymenolepis nana and Giardia lamblia (p < 0.01). On the other hand, Enterobius vermicularis, a parasite not related to the sanitary condition of its host, was not associated with the Iv. Statistical association between poverty and parasitosis was noted; the greater the Iv, higher the incidence of parasites (p < 0.01). GIS allowed zoning socio-environmental variables in an increasing gradient of unfavorable conditions and their relationship to the presence of pathogenic species. The continuity of these studies in different regions of Argentina contributes to the determination of health risk areas.

La prevalencia de geohelmintiasis se relaciona con las condiciones socioambientales / The prevalence of geohelminthiasis is related to socio-environmental conditions

Se realizó un estudio socioambiental y parasitológico en niños de áreas urbanas, periurbanas y rurales de las provincias de Buenos Aires y Misiones. Se completó una encuesta epidemiológica y se tomaron muestras fecales seriadas, las cuales se analizaron mediante técnicas de flotación y sedimentación. Del total de muestras fecales (1893), 5.5% fueron positivas en Buenos Aires y 25.6% en Misiones. El área periurbana de Misiones presentó la mayor prevalencia de parasitosis total (34.1%) y de biparasitados y poliparasitados (45.4%). Las especies más prevalentes fueron Strongyloides stercoralis (22.1%) en el sector periurbano y Ancylostomideos (21.6%) en el área rural de Misiones. Hymenolepis nana y Ascarislumbricoides mantuvieron bajas frecuencias en ambas provincias y Trichuris trichiura sólo se encontró en el periurbano de Buenos Aires. La prevalencia de geohelmintos aumentó con la edad (p < 0.05) y se asoció en el área periurbana de ambas provincias y rural de Misiones con las condiciones socioambientales: vivienda precaria, piso de tierra, eliminación de excretas en letrinas o a cielo abierto, sin recolección domiciliaria de residuos, madre sin actividad laboral, padres sin instrucción primaria (p < 0.05). Las características biogeográficas y las condiciones socioambientales de la provincia de Misiones favorecen la persistencia de las formas parasitarias en el ambiente.

Estudio comparativo de recuperación de formas parasitarias por tres diferentes métodos de enriquecimiento coproparasitológico / Comparative study of parasitic forms recuperation using three different coproparasitoscopic methods

Se analizaron 165 muestras fecales seriadas, utilizando dos métodos de sedimentación: Ritchie (R) y Carles Barthelemy (CB) y uno de flotación: Willis (W), con el fin de optimizar el diagnóstico de los parásitos intestinales y determinar la eficacia de las técnicas. Se hallaron parásitos en 119 (72,1 por ciento) de los analizados. Hubo diferencias significativas en la recuperación de protozoos (p < 0,001), observándose 81,4 por ciento (R), 77,4 por ciento (CB), y 57,8 por ciento (W). Blastocystis hominis, G.lamblia, Ascaris lumbricoides y Trichuris trichiura se recuperaron con mayor frecuencia mediante sedimentación, resultando más efectivo el método de Ritchie (p < 0,05).

A total of 165 fecal samples were analyzed, using two sedimentation methods: Ritchie (R), Carles Barthelemy (CB), and one of flotation: Willis (W), in order to optimize intestinal parasites diagnosis and to determine the techniques effectiveness. Parasites were found in 119 (72,12%) of those analyzed. Significant differences were in protozoa recovery (p < 0,001), being observed 81.4% (R), 77.4% (CB), and 57.8% (W). Blastocystis hominis, Giardia lamblia, Ascaris lumbricoides and Trichuris trichiura were recovered more frequency by means of sedimentation, being Ritchie´s method the most effective one (p < 0.05).

Neohilgertia venusti Gen. N. SP. N. (Nematoda: Oxyuridae)from Thylamys venustus cinderellus (Thomas) Reig, Kirsch & Marshall, 1985 (Marsupialia: Didelphidae) in Burruyacu, Tucuman, Argentina - Systematic position and possible evolution

Neohilgertia gen. n. proposed for Oxyuridae nematodes from Thylamys venustus cinderellus (Marsupialia: Didelphidae) is described. The hypothesis about the possibility of a secondary parasitism for marsupials and the origin of the genus in the African Sciuridae parasite ancestors is discussed