Differential diagnosis of human Entamoeba infections: Morphological and molecular characterization of new isolates in Argentina / Diagnóstico diferencial de infecciones humanas por Entamoeba: caracterización morfológica y molecular de nuevos aislados en Argentina

Abstract Entamoeba infections occur worldwide, with higher frequency in countries of low socioeconomic status and poor public health. Since Entamoeba histolytica has long been recognized as the only pathogenic species, making a differential diagnosis of other morphologically identical Entamoeba is important. This study aimed to determine the prevalence of Entamoeba species in two populations from Argentina, make a differential diagnosis by PCR and characterize Entamoeba isolates at the SSU rRNA gene. A total of 493 serial fecal samples were obtained from individuals in the provinces of Buenos Aires (n=210) and Misiones (n=283). Samples were examined by conventional methods (formalin-ethyl acetate and Willis flotation) and specific PCRs to differentiate Entamoeba species. Entamoeba isolates were characterized by sequencing a fragment of the SSU rRNA gene. The overall prevalence of Entamoeba infection was 12.4%, being more prevalent in Buenos Aires than in Misiones (14.8% vs. 10.6%). A case of E. histolytica confirmed by PCR and sequence analysis was reported for the first time in Buenos Aires. Moreover, new genetic data on Entamoeba coli and Entamoeba dispar were recorded. The phylogenetic analysis revealed a congruence between morphological characteristics and SSU rRNA gene sequences. This study increases the amount of information on the distribution of these species in Argentina and the region of the Americas.

Resumen Las infecciones por Entamoeba se producen en todo el mundo, con mayor frecuencia en países de bajo nivel socioeconómico y salud pública deficiente. Dado que se ha reconocido a Entamoeba histolytica como la única especie patógena del género, es importante realizar un diagnóstico diferencial respecto de otras especies de Entamoeba morfológicamente idénticas. Este estudio tuvo como objetivos determinar la prevalencia de especies de Entamoeba en 2 poblaciones de Argentina, realizar su diagnóstico diferencial por PCR y caracterizar los aislados de Entamoeba secuenciando un fragmento del gen SSU ARNr. Se obtuvieron 493 muestras fecales seriadas de individuos de las provincias de Buenos Aires (n=210) y Misiones (n=283). Las muestras se examinaron por métodos convencionales (sedimentación de formalina-etil acetato y flotación de Willis) y mediante PCR específicas para diferenciar especies de Entamoeba. Los aislamientos de Entamoeba se caracterizaron por secuenciar un fragmento del gen SSU ARNr. La prevalencia general de la infección por Entamoeba fue del 12,4% y fue mayor en Buenos Aires que en Misiones (14,8 vs. 10,6%). Se informó por primera vez un caso de Entamoeba histolytica en Buenos Aires, confirmado por PCR y análisis de secuencia. Además, se registraron nuevos datos genéticos sobre Entamoeba coli y Entamoeba dispar. El análisis filogenético reveló una congruencia entre las características morfológicas y las secuencias del gen SSU ARNr. A través de este estudio, hemos sumado información acerca de la distribución de estas especies en nuestro país y en la región de las Américas.

Differential diagnosis of human Entamoeba infections: Morphological and molecular characterization of new isolates in Argentina.

Entamoeba infections occur worldwide, with higher frequency in countries of low socioeconomic status and poor public health. Since Entamoeba histolytica has long been recognized as the only pathogenic species, making a differential diagnosis of other morphologically identical Entamoeba is important. This study aimed to determine the prevalence of Entamoeba species in two populations from Argentina, make a differential diagnosis by PCR and characterize Entamoeba isolates at the SSU rRNA gene. A total of 493 serial fecal samples were obtained from individuals in the provinces of Buenos Aires (n=210) and Misiones (n=283). Samples were examined by conventional methods (formalin-ethyl acetate and Willis flotation) and specific PCRs to differentiate Entamoeba species. Entamoeba isolates were characterized by sequencing a fragment of the SSU rRNA gene. The overall prevalence of Entamoeba infection was 12.4%, being more prevalent in Buenos Aires than in Misiones (14.8% vs. 10.6%). A case of E. histolytica confirmed by PCR and sequence analysis was reported for the first time in Buenos Aires. Moreover, new genetic data on Entamoeba coli and Entamoeba dispar were recorded. The phylogenetic analysis revealed a congruence between morphological characteristics and SSU rRNA gene sequences. This study increases the amount of information on the distribution of these species in Argentina and the region of the Americas.

Agricultural practices and intestinal parasites: A study of socio-environmental risk factors associated with leafy vegetable production in La Plata horticultural area, Argentina.

Foodborne diseases now represent one of the most important public health problems. The objectives were to analyze the leafy vegetables and crop soil to detect parasitic species and evaluate the factors that increase the risk of parasitic contamination in the productive units in La Plata horticultural area. The study included 261 leafy vegetable and 87 crop soil samples that were processed using washing, sedimentation, and flotation techniques. Socio-environmental characteristics and agricultural practices were surveyed, and a generalized linear model was used to assess the change in parasitic prevalence with different predictor variable. The 58.6% of leafy vegetable and 31.0% of crop soil samples contained parasitic species, the most prevalent being Blastocystis sp. and oocysts of Cryptosporidium spp. Risk factors were the limited access to health, dirt roads, children and dogs circulating in crops, field cultivation, furrow irrigation and lettuce cultivation. The high prevalence of intestinal parasites in the vegetable crops was mainly associated with the conditions of structural precariousness in the production units. These results elaborated with the participation of the population, provide valuable knowledge for the planning of epidemiological programs that include environmental health as a fundamental nexus in health campaigns.

Phylogenetic relationship between Contracaecum spp. (Nematoda, Anisakidae) parasitizing cormorants (Aves, Phalacrocoracidae) in Argentina.

Species of the genus Contracaecum (Family Anisakidae) exhibit a broad host and geographical distribution, parasitizing aquatic organisms such as piscivorous birds and mammals as their definitive hosts. Several Contracaecum species have been reported parasitizing cormorants (Family: Phalacrocoracidae) in South America. The objective of this study was to highlight phylogenetic relationships between Contracaecum species parasitizing cormorants based on both molecular analyses and the papillae arrangement on the male tail. Some Contracaecum species parasitizing Red-legged cormorants from the Ría Deseado (RD), and other nematodes parasitizing eight Neotropic cormorants from San Miguel del Monte lagoon (SMML), Argentina, were collected and analyzed. Both morphological and phylogenetic analyses allowed us to recognize two species: Contracaecum chubutensis parasitizing Phalacrocorax gaimardi, and Contracaecum australe parasitic in Phalacrocorax brasilianus. According to the obtained sequences (mtDNA cox2, ITS1, ITS2, and SSrRNA), Contracaecum sp. parasitizing P. gaimardi exhibited concordance with the previously reported C. chubutensis parasitizing P. atriceps from Bahía Bustamante, Chubut province. Likewise, Contracaecum sp. isolates parasitizing P. brasilianus showed concordance with C. australe from Chile. Besides, the papillae arrangement on the male tail allowed us to understand the interspecific and genetic relationships between the Contracaecum species. The analyses confirm that C. chubutensis specimens parasitizing P. gaimardi from RD present a new host record for the species, whereas, those C. australe specimens parasitizing P. brasilianus from SMML provide a new geographical record for the species and the extension of its distribution range. Present results also confirm the inland and marine distribution of C. australe and C. chubutensis, respectively.

The genus Contracaecum Raillet & Henry (Nematoda: Anisakidae): host and geographical distribution on Neotropical and Antarctic species.

Nematodes of the genus Contracaecum Raillet & Henry, 1912 (Anisakidae, Contracaecinae) have a worldwide distribution. The taxonomy of the genus Contracaecum is well-known nowadays due to several morphometric studies, scanning electron microscopy, and molecular biology. The aim of this work was to review, clarify, and summarize the valid species of the genus Contracaecum parasitizing piscivorous sea birds and mammals from both the Neotropical and Antarctic regions reviewing all scientific available papers and electronic searching data up to date. A checklist on Neotropical and Antarctic Contracaecum spp. was organized through a revision of scientific papers and original descriptions. The systematic online search and the most updated papers were obtained through SCOPUS, Google Scholar, PubMed, Medline, World Register of Marine Species, etc. We provide information about hosts, Neotropical and Antarctic localities where worms were collected, references, molecular markers, and Genbank accession numbers. Twenty-five Neotropical and Antarctic Contracaecum species have been recorded up to date and checked out as valid ones according to the most updated data. Twenty-one species parasitize exclusively fish-eating birds, two species were reported only on marine mammals, and the other two parasitize both sea birds and mammals. A total of 20 Contracaecum species are exclusively reported for the Neotropical region, three only for Antarctic hosts, and two species were reported parasitizing both Neotropical and Antarctic hosts. Several Contracaecum species (10) have been corroborated by molecular analysis of different genetic markers. After reviewing all morphological descriptions of the Contracaecum species, and despite most of them have been characterized only by morphometric methods, we are convinced that all species listed in this work correspond to good and valid Contracaecum Neotropical and Antarctic species. Present results indicate that more taxonomic and molecular studies are needed to advance the understanding of the distribution and host specificity of the Contracaecum species.

Monoecocestus (Cestoda: Anoplocephalidae) diversity in Sigmodontinae rodents characterized by morphology and molecular methods.

This paper provides new morphological and molecular data for identifying Monoecocestus species from rodents: a) morphological update of Monoecocestus spp., b) morphological data on Anoplocephalidae taxa from Sigmodontinae rodents, c) analyses of the genetic distances between the specimens studied and other Anoplocephalidae from rodents available in GenBank, and phylogenetic inferences. A total of 25 specimens of Holochilus spp. were examined from four provinces of Argentina. Cestodes specimens were removed from the rodents small intestines. Conventional studies were used for the morphological and molecular analysis. Four taxa of Monoecocestus were identified. Monoecocestus threlkeldi was identified as first record in Holochilus chacarius and from Argentina. Molecular and morphological aspects of Monoecocestus sp.1, Monoecocestus sp.2 and Monoecocestus sp.3 were described. Specimens belonging to the genus Monoecocestus may represent closely related species, demonstrating the importance of using integrative taxonomic approaches to understand biological diversity. The continuity of the studies on Anoplocephalidae will allows to advance in investigation of molecular analyses and ecological aspects that determine parasite-host-environment relationship.

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.

Update of Dicrocoeliidae (Digenea) parasitizing rodents from the Americas with a description of a new Platynosomoides species from Argentina.

Digeneans are common parasites of small mammals. Dicrocoeliidae is a family with a cosmopolitan distribution, with 18 genera previously recorded from mammals in the Americas, six of them parasitizing rodents in Argentina. In this study, an updated compilation is provided of Dicrocoeliidae from rodents in the Americas. Also, a new Platynosomoides species is described parasitizing the cricetid rodent Akodon montensis of the Atlantic Forest in Argentina. Digital repositories were used to search for Dicrocoeliidae from rodents in the Americas. Rodents were collected in four localities of the Atlantic Forest, Argentina. Digeneans were removed from the rodent's bile duct, and conventional studies were used for the morphological description. A total of 15 Dicrocoeliidae species were found parasitizing 18 rodent species from eight countries in the Americas. The new species of Platynosomoides from Akodon montensis differs from the other two species of genus by the size of body, testes, ovary, cecum length and position and length of the vitelline bands. Dicrocoeliidae show growing diversity, and the compilation of species in a rodent host base allows a clearer comparison and identification of new taxa in the future.

Prevalence of Human Intestinal Entamoeba spp. in the Americas: A Systematic Review and Meta-Analysis, 1990-2022.

Among the seven species of Entamoeba known to infect humans, E. histolytica is widely recognized as a pathogen. It is reported that Entamoeba infections are common in the developing world, but rare in developed countries. The best way to diagnose these protozoan parasites is to detect antigens or DNA in the stool. This study aimed to review the prevalence, distribution, and diagnosis methods of Entamoeba spp. infecting humans in the Americas between 1990 and 2022. A systematic review and meta-analysis were performed, including 227 studies on Entamoeba infections from 30 out of 35 American countries. The pooled prevalence of each species of Entamoeba was calculated using the random-effects model. The assignment of Entamoeba species was mainly performed by microscopy. The most widely distributed and prevalent species was E. coli (21.0%). Of the studies, 49% could not differentiate the species of the Entamoeba complex. The pathogenic species E. histolytica was distributed among 22 out of 30 American countries studied, with a pooled prevalence of 9%. Molecular data on Entamoeba species are still scarce. This is the first study that reviewed and summarized data on the prevalence of this protozoan genera among American countries.

Rodentolepis microstoma isolated from different species of Sigmodontinae rodents (Rodentia: Cricetidae) in the Cuenca del Plata, Argentina: Morphological aspects and molecular characterization.

The purpose of this paper was to study specimens of the genus Rodentolepis isolated from eight species of Sigmodontinae rodents (Rodentia: Cricetidae) from six provinces in the Cuenca del Plata, Argentina, based on morphological, morphometric and molecular characteristics (ITS1 rDNA and cox1 mtDNA). The genetic distances among studied specimens and other Hymenolepididae from rodents available in the GenBank were analyzed and phylogenetic inferences were provided. A total of 955 specimens of Sigmodontinae rodents were examined from seven localities of six provinces in the Cuenca del Plata region in Argentina. Tapeworms were removed from the rodents' small intestines. Conventional studies were used for the morphological and molecular analysis. Specimens of R. microstoma were identified. An amended diagnosis and detailed morphological description of this species is provided. The molecular analyses showed that the specimens studied form the same clade as that of R. microstoma previously studied from other hosts and regions. The genetic polymorphisms of R. microstoma observed corresponded to different groups of species hosts and regions. Moreover, eight species of sigmodontine rodents and 33 localities from the Cuenca del Plata region in Argentina constitute new host and geographical records. This study shows the importance of using integrative taxonomic approaches that combine morphological and molecular characters to understand biological diversity. Moreover, the discovery of R. microstoma in humans suggests the importance of further studies on this zoonotic cestode. This study provides important data on the taxonomy and distribution of R. microstoma to advance knowledge of the transmission dynamics of this parasite.

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.

Hymenolepidid cestodes: Diversity, morphological and molecular characterization of a new species, and phylogeny of parasitic species of rodents from North and South America.

Rodents are hosts of a wide diversity of cestodes. Fifteen genera included in the family Hymenolepididae parasitize rodents, and only four of these genera have been recorded from the Neotropical region. The purpose of this paper is to update species of Hymenolepididae from rodents, describe a new species of Hymenolepis based on morphological and molecular characterization (ITS1 rDNA and cox1 mtDNA), comparing the features among the species from North and South American rodents, and provide phylogenetic inferences of Hymenolepididae from rodents based on sequences available in the GenBank. Rodents were collected in the Parque Provincial Ernesto Tornquist, Buenos Aires, Argentina. Hymenolepis ivanovae n. sp. differs from other Hymenolepis species registered from North and South American rodents by body size, scolex, suckers, cirrus sac, cirrus, testes, and eggs, among others. Comparative morphometric data for Hymenolepis species from North and South American rodents is provided. Molecular analyses place H. ivanovae n. sp. within the genus Hymenolepis with strong support, and show it close to species of zoonotic importance. The new species is the first species of Hymenolepis described from Sigmodontinae rodents.

Nutritional status, intestinal parasitic infections, and socio-environmental conditions in Mbyá-guaraní children: The current situation in communities in central Misiones, Argentina.

OBJECTIVES: Our previous research in Mbyá-guaraní communities of central Misiones showed high levels of growth stunting and intestinal parasites in children, as well as associations between these variables and deficient sanitary conditions. New studies were necessary to update the present health status of the previously studied Mbyá populations after around two decades. Therefore, we evaluated the current nutritional status, intestinal parasites, and socio-environmental conditions among Mbyá-guaraní children from these communities. METHODS: Body weight and height of 102 individuals (aged 2-14) were measured and nutritional status was estimated according to the World Health Organization criteria. Serial fecal samples and anal swabs were analyzed from 75 children (aged 1-14). Socio-environmental data were obtained from questionnaires. RESULTS: The prevalence of undernutrition was 31.4% and excess of weight was 10.8%. The prevalence of stunting and of overweight reached 30.4% and 8.8%, respectively. About 85% of the children were infected with at least one of the 14 species identified, and around 44% had multiple parasite infections. The most prevalent species were Enterobius vermicularis and hookworms. Among undernourished children, 88.2% were parasitized by at least one of the potentially pathogenic species detected. Most of the families lived in overcrowded conditions in precarious houses, defecated in latrines, and consumed well water. A higher risk of parasitosis was associated with the source of drinking water. CONCLUSIONS: Although the prevalence of undernutrition and intestinal parasites decreased compared with our previous studies, we still observed the coexistence of stunting, excess weight, and parasitic infections, in a context of socio-environmental vulnerability.

Percepción social sobre roedores urbanos y riesgo sanitario en barrios del Gran La Plata, Provincia de Buenos Aires, Argentina / Social perception on urban rodents and sanitary risk in neighborhoods from Gran La Plata, Province of Buenos Aires, Argentina

NTRODUCCIÓN: Los roedores sinantrópicos, representados por el ratón doméstico (Mus musculus), la rata parda (Rattus norvegicus) y la rata negra (Rattus rattus), representan un riesgo importante para la salud. En Sudamérica, la fragmentación socioeconómica se refleja en marcadas diferencias entre centros urbanos y áreas periféricas, y se asocia a un registro heterogéneo. El objetivo fue relevar datos por encuestas a los habitantes de dos barrios del Gran La Plata con características contrastantes para explorar, describir y evaluar la percepción en relación con la presencia de roedores en domicilio, peridomicilio y barrio como vehículos de transmisión de enfermedades. MÉTODOS: A partir de un diseño descriptivo exploratorio, se confeccionaron y realizaron encuestas siguiendo la técnica de muestreo estratificado. Se consideraron las variables género y grupo, de tal manera que la muestra tuviese la misma distribución. La información se transfirió a una base de datos y se analizó a través de IBM SPSS Statistics V25. RESULTADOS: Existe una preocupación común respecto al rol de los roedores urbanos como reservorios y fuentes de infección de patologías zoonóticas. En el barrio más vulnerable, la presencia de roedores fue más frecuente que en el centro de la ciudad. DISCUSIÓN: Este estudio provee un abordaje diferente en relación con roedores y patologías asociadas, considerando la percepción social y revelando su importancia para los programas de manejo y control.

Hassalstrongylus dollfusi (Nematoda, Heligmonellidae): rediscovery in native South American rodents, six decades after its description.

Hassalstrongylus dollfusi (Díaz-Ungría, 1963) Durette-Desset, 1971 was described in a wild house mouse, Mus musculus, from Venezuela and, since then, has never been reported again in the type host or in any other host. In this work, specimens assignable to H. dollfusi were found at 10 localities in Northeast Argentina, in five species of sigmodontine rodents. The nematodes were attributed to H. dollfusi based on diagnostic characters such as: synlophe with 22-31 subequal ridges; in males, hypertrophy of right ray 4 of the male bursa, thickening of the dorsal ray and bases of rays 8, distal tip of the spicules bent and spoon shaped; and, in females, presence of subventral postvulvar alae supported by hypertrophied struts. The new host recorded are: Oligoryzomys fornesi, O. flavescens, O. nigripes, Holochilus chacarius and Akodon azarae. The parasite showed a strong preference for host species of Oligoryzomys, which appear to act as primary hosts. The parasite could be present, parasitizing different species of Oligoryzomys, in a geographic area from the type locality in Venezuela southward to north Corrientes in Argentina. It has not been reported from populations of Oligoryzomys spp. of the Argentinean and Brazilian Atlantic Forest, nor south of 28° S, which may be explained by constraints in the environmental conditions required by the free-living stages of the parasite. This study provides the first identification and redescription of H. dollfusi in southern South America, from autochthonous hosts, six decades after its description.

TITLE: Hassalstrongylus dollfusi (Nematoda, Heligmonellidae) : redécouverte chez des rongeurs autochtones d'Amérique du Sud, six décennies après sa description. ABSTRACT: Hassalstrongylus dollfusi (Díaz-Ungría, 1963) Durette-Desset, 1971 a été décrit chez une souris grise sauvage, Mus musculus, au Venezuela et, depuis lors, n'a plus jamais été signalé chez l'hôte-type ni chez aucun autre hôte. Dans ce travail, des spécimens attribuables à H. dollfusi ont été trouvés dans dix localités du nord-est de l'Argentine, chez cinq espèces de rongeurs Sigmodontinae. Les nématodes ont été attribués à H. dollfusi sur la base de caractères diagnostiques tels que : synlophe avec 22­31 crêtes subégales; chez le mâle, hypertrophie de la côte 4 droite de la bourse, épaississement de la côte dorsale et des bases des côtes 8, extrémité distale des spicules recourbée et en forme de cuillère; et, chez les femelles, présence d'ailes postvulvaires subventrales à fort support cuticulaire. Les nouveaux hôtes signalés sont : Oligoryzomys fornesi, O. flavescens, O. nigripes, Holochilus chacarius et Akodon azarae. Le parasite a montré une forte préférence pour les espèces hôtes du genre Oligoryzomys, qui semblent agir comme hôtes primaires. Le parasite pourrait être présent, parasitant différentes espèces d'Oligoryzomys, dans une zone géographique allant de la localité-type au Vénézuéla vers le sud jusqu'au nord de Corrientes en Argentine. Il n'a pas été signalé dans les populations d'Oligoryzomys spp. de la Forêt Atlantique argentine et brésilienne, ni au sud de 28° S, ce qui peut s'expliquer par des contraintes dans les conditions environnementales requises par les stades libres du parasite. Cette étude fournit la première identification et redescription d'H. dollfusi dans le sud de l'Amérique du Sud, à partir d'hôtes autochtones, six décennies après sa description.

Intestinal parasites in child and youth populations of Argentina: Environmental factors determining geographic distribution.

The transmission of intestinal parasites is generally considered to be "mediated by the environment" which suggests that they are particularly sensitive to the changes that occur in it. The aim of the present study was to evaluate the environmental variables that act as risk factors for intestinal parasitosis in children and youths in Argentina. The association between environmental variables related to temperature, precipitation and soil and parasitosis found in children and youths from different provinces was evaluated, including land use/cover classes obtained from satellite images. Of the total population analyzed, 66.9% of the participants were parasitized. The total number of identified parasite species was 17 and the most prevalent were Blastocystis sp. (42.2%), Enterobius vermicularis (33.6%) and Giardia lamblia (17.0%). Infection by protozoa, and by G. lamblia in particular, was greater when the mean summer temperature was higher (OR=1.2 for both). Blastocystis sp. and geohelminths were greater due to an increase in isothermality (OR=1.1 and 1.2, respectively). The risk of infection with Ascaris lumbricoides was associated with an increase in the temperature in the wettest quarter (OR=1.2). Hookworm infection was associated with an increase in the normalized difference vegetation index (OR=32.5). Most of participants infected with hookworms lived in areas with abundant arboreal-shrubby and agropastoral use vegetation. The heterogeneous distribution of enteric parasites is indicative of the wide environmental variability of Argentina.

Intestinal parasites in canine feces contaminating urban and recreational areas in Ushuaia (Argentina).

Wild and domestic dogs are important reservoir hosts of numerous intestinal parasites that represent potential infection sources for both humans and wild or other domestic animals. The aim of this study was to determine the presence, diversity, and contamination potential of intestinal parasites in dog feces contaminating urban and recreational areas in Ushuaia (Tierra del Fuego province, Argentina). A total of 80 canine fecal samples were collected from urban (playgrounds, streets, sidewalks, squares and coastal walks) and recreational areas (winter centers for raising and training sled dogs) in 2018. Samples were preserved in 5% formalin and processed using formalin-ethyl acetate sedimentation and FLOTAC dual Pellet techniques. Data were analyzed using the R software. At least one parasite species was recovered in 32.5% of the total samples examined. Of the seven parasite species detected, infection by protozoan species was higher than helminth infections (28.8% versus 8.8%). Sarcocystis sp. (20.0%), Giardia sp. (8.8%) and Cystoisospora spp. (7.5%) were the most frequent species, followed by Toxocara canis (5.0%), Echinococcus spp./Taenia spp. (2.5%), Trichuris vulpis and Uncinaria sp. (1.3% for both). Single infections (69.2%) were more frequent than coinfections with two (19.2%) and three parasite species (11.5%). This study provides the first description of the diversity and frequency of intestinal parasite species in dog feces from Ushuaia, the southernmost city in the world. The unfavorable environment of Ushuaia, characterized by low temperatures and winter snowfall, is likely to reduce parasite survivability, decreasing contamination potential. Some parasite species found are potentially zoonotic and represent an important risk for the human population and a source of infection to free-roaming pets. The results of this study revealed the need to strengthen the prevention, surveillance and control of these infections in pets, as well as to implement programs for public health education, control measures for the free-roaming canine population, and responsible pet ownership in the study area.

Parásitos intestinales en poblaciones infantojuveniles; ambiente y comportamiento social / Prevalence of intestinal parasites in child and youth populations; environment and social behavior

Introduction: The decreasing prevalence of parasitosis from north to south in Argentina has led the scientific community to focus the epidemiological studies on the most vulnerable areas and, consequently, neglect the populations of Patagonia (South Argentina). The objectives of the present study were (i) to determine the prevalence of intestinal parasites in children and youth of Puerto Madryn (Chubut province, Patagonia), and (ii) to evaluate the parasitic infections found concerning socio-environmental factors and hygiene practices of the population. Materials and methods: Serial stool samples were processed using modified Ritchie and FLOTAC dual pellet techniques, and samples of anal swabs were examined by sedimentation. Socio-environmental variables and hygiene practices of the participants were surveyed using a semi-structured questionnaire. Results: Of all examined participants, 39.1% (68/174) were parasitized. A total of 6 parasite species were found and the most prevalent were Blastocystis sp (19.0%), Enterobius vermicularis (17.8%), and Giardia lamblia (6.3%). The risk of parasitosis and infection for Blastocystis sp was greater in participants who lived in houses without piped water (OR = 2.9 and OR = 3.2, respectively). The risk of infection for G. lamblia was positively associated with the lack of public waste collection service (OR = 5.6). Infection for E. vermicularis was higher in participants whose parents had a basic level of education (OR = 5.0). Conclusion: The parasitic infections observed reflect the environmental conditions of Patagonia and the need to focus studies on populations from peripheral areas to urban centers that are exposed to greater socio-economic vulnerability.

Introducción: La prevalencia de parasitosis decreciente de norte a sur en la Argentina, ha llevado a la comunidad científica a enfocar sus estudios epidemiológicos hacia las zonas más vulnerables y desatender a las poblaciones de la Patagonia (sur de Argentina). Los objetivos del presente estudio fueron: determinar la prevalencia de parásitos intestinales en niños y jóvenes de Puerto Madryn (Chubut, Patagonia), y evaluar las infecciones parasitarias en relación con los factores socioambientales y las prácticas de higiene de la población. Materiales y métodos: Se procesaron muestras seriadas de materia fecal mediante las técnicas Ritchie modificada y FLOTAC dual pellet, y muestras de escobillado anal por sedimentación. Se relevaron las variables socioambientales y las prácticas de higiene de los participantes mediante cuestionarios semiestructurados. Resultados: El 39.1% (68/174) de la población analizada estuvo parasitado. Se halló un total de 6 especies parásitas, las más prevalentes de las cuales fueron Blastocystis sp (19.0%), Enterobius vermicularis (17.8%) y Giardia lamblia (6.3%). El riesgo de parasitosis y de infección por Blastocystis sp fue mayor en los participantes que no poseían agua de red (odds ratio [OR] = 2.9 y OR = 3.2, respectivamente). La infección por G. lamblia se asoció de manera positiva con la falta de recolección pública de residuos (OR = 5.6). La infección por E. vermicularis fue superior en los participantes con padres que tenían un nivel de estudios primario (OR = 5.0). Conclusión: Las infecciones parasitarias observadas reflejan las condiciones ambientales de la Patagonia y la necesidad de orientar los estudios a poblaciones periféricas de los centros urbanos, las cuales están expuestas a mayor vulnerabilidad socioeconómica

Morphological and molecular characterization of Bertiella sp. (Cestoda, Anoplocephalidae) infection in a human and howler monkeys in Argentina.

Bertiella sp. is a typical parasite in non-human primates and only a few cases of bertiellosis have been reported in humans. We present a new case study of bertiellosis in a 42-year-old woman caretaker of howler monkeys in a wild rehabilitation center in Argentina. Bertiella sp. infection was also diagnosed in the monkeys. Proglottids and feces were collected from the caretaker and monkeys; the samples were submitted for parasitological examination by morphological characterization and molecular identification using both nuclear (18S and ITS1-5.8-ITS2 rDNA) and mitochondrial (cox1) markers. Morphological and molecular data were consistent and allowed the classification of the specimen to the genus level. The analyses also showed the presence of cysts of Giardia lamblia and oocysts of Cryptosporidium spp. in howler monkeys, and cysts of Blastocystis sp. in both the caretaker and monkeys. This study recorded the fourth case of bertiellosis in a human host from Argentina and the eighth case in South America. Moreover, this is the first study that compares the morphological and molecular features of Bertiella sp. found in both a human and monkeys from the same geographical region. These results suggest that the cohabitation between humans and monkeys increases the opportunities of infection by Bertiella sp. and other potential zoonotic parasites.

Cestode Parasites of Armadillos (Mammalia: Xenarthra) from Argentina: Two New Species of Mathevotaenia (Anoplocephalidae) in Tolypeutes matacus.

A total of 20 specimens of Tolypeutes matacus (Desmarest, 1804) from the Chaco Region in Argentina were examined. This study revealed the presence of 3 species of the genus Mathevotaenia Akumyan, 1946 (Cestoda Anoplocephalidae), two of them new for science. These species are described, illustrated, and compared with related species. Mathevotaenia chamicalensis n. sp. is characterized by having a small body with 45-65 proglottids; a globose scolex, longer than wide and well delimited from strobila; a long neck; mature and gravid proglottids longer than wide; and 20-35 testes located in a single field. Mathevotaenia yepesi n. sp. is characterized by having a small body with 86-128 proglottids; a rectangular scolex, wider than long and not well delimited from strobila; neck absent; mature and gravid proglottids wider than long; and 23-50 testes located in the medial portion of the proglottid. The finding of Mathevotaenia argentinensis Campbell et al., 2003 parasitizing T. matacus represents the first record in armadillos.