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.

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.

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.

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.

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.

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.

Malnutrition and body composition in urban and rural schoolchildren: A cross-sectional study in San Rafael, Mendoza (Argentina).

OBJECTIVES: The aim of the present study was to analyze the nutritional status and body composition of children from San Rafael, Mendoza, avoiding urban and rural categorization by generating subpopulations as a function of their socio-environmental characteristics. METHODS: A cross-sectional study was performed in 3,596 schoolchildren from 4.0 to 13.9 years of age. Body weight, height, upper arm circumference, and triceps skinfold were measured. Body mass index, total muscle, and fat areas of the arm were calculated. To estimate nutritional status and body composition, the NHANES III reference was used. The socio-environmental variables were surveyed using a structured questionnaire. These variables were processed by categorical principal-component analysis (catPCA). RESULTS: The catPCA allowed the differentiation of four groups, three with urban characteristics (high urban, medium urban, impoverished urban), and a rural group. Stunting occurred at a higher rate in the impoverished urban group, and the occurrence of underweight children was higher in the rural group. The prevalence of excess weight varied in the range of 20-26%. The latter value corresponded to children of the high urban group, who also did not show reduced muscle mass. CONCLUSION: Children from San Rafael presented differences in nutritional condition and body composition associated with pronounced socio-environmental heterogeneity. Thus, we could observe a gradient from the "high urban" group, with better social, economic, and sanitation conditions and at the same time a more obesogenic environment to the "impoverished urban" and "rural" groups, whose vulnerability reflected a higher prevalence of child undernutrition and the association with excess weight and reduced muscle mass. Am. J. Hum. Biol. 28:796-803, 2016. © 2016Wiley Periodicals, Inc.

New host, geographic records, and histopathologic studies of Angiostrongylus 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 and Angiostrongylus 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 Angiostrongylus species 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.

Socio-environmental variables associated with malnutrition and intestinal parasitoses in the child population of Misiones, Argentina.

OBJECTIVES: The aim was to analyze the socio-environmental variables associated with malnutrition and intestinal parasitoses in children from Aristóbulo del Valle, Province of Misiones (Argentina). METHODS: A cross-sectional study was performed in 2,291 schoolchildren (age, 4-14 years). Body weight and height were measured and body mass index was calculated. NHANES III reference was used to estimate the nutritional status-underweight, stunting, wasting, overweight, and obesity. The parasitological analysis was performed by fecal and anal brush samples. The socio-environmental variables were surveyed using a semi-structured questionnaire. These variables were processed by categorical principal component analysis (cat-PCA). RESULTS: The two first axes defined four subgroups of schoolchildren: three of these were associated with urban characteristics (high, middle, and periurban), whereas the remaining subgroup was considered rural. Stunting and parasitic infections occurred mainly in the periurban group, that is the group of higher socio-environmental vulnerability. On the other hand, the highest prevalence of overweight and obesity and the lowest parasitism was observed in the high urban group. CONCLUSIONS: The similarity between rural and middle urban groups in stunting prevalence reveals that cities are not healthier than rural environments. On the contrary, the fact that the rural group presents the lowest prevalence of overweight reaffirms that poverty and malnutrition are progressively moving from rural to urban areas, and that rural children have still more diverse and healthy diets favored by the consumption of homemade products (i.e., orchards, animal husbandry, etc.), placing them at an earlier stage of the nutrition transition.

[Spatial distribution of intestinal parasites in the City of La Plata, Argentina]. / Distribución espacial de las parasitosis intestinales en la Ciudad de La Plata, Argentina.

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.

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.

Nutritional vulnerability in Mbyá-Guaraní adolescents and adults from Misiones, Argentina.

OBJECTIVES: The aim of this study was to evaluate the nutritional status and body composition in Mbyá-Guaraní adolescents and adults from three communities in the Province of Misiones, in northern Argentina. METHODS: Anthropometric parameters were analyzed in 45 individuals (aged 14-60). Data were transformed to z-scores using NHANES I and II. RESULTS: Ninety-three percent of the sample showed some kind of malnutrition (undernutrition and/or excess of weight). Stunting and overweight reached the highest prevalences (85.0 and 10.0%, respectively). The most Mbyá people were found to have low arm muscle and fat areas. They also tended to have shorter than normal lower limbs. Centralized obesity was evident in both sexes and in all the age intervals. CONCLUSIONS: Extreme poverty, together with changes in life habits and diet composition, resulted in decrease of body size and changes in body proportions and composition. Although these changes could be considered as an adaptive response to the chronic exposure of these populations to adverse environmental conditions, they would favor the co-occurrence of malnutrition and overweight in a single scenario, and consequently increase the risk of infectious and nontransmissible diseases.

Litomosoides pardinasi n. sp. (Nematoda, Onchocercidae) from two species of cricetid rodents in northern Patagonia, Argentina.

Seventy-seven cricetid rodents, corresponding to six different species, deposited at the Mammal Collection at Centro Nacional Patagónico, Puerto Madryn, Chubut, were examined for parasites. Litomosoides pardinasi n. sp. is described parasitizing the pleural and abdominal cavities of Phyllotis xanthopygus (Phyllotini) and the abdominal cavity of Oligoryzomys longicaudatus (Oryzomynii) in the northern Patagonia, Argentina. The new species is included in the carinii group, characterized by the presence of a right spicule with a dorsal heel and a terminal cap well cuticularized; left spicule composed with a handle longer or as long as the blade, and the blade constituted by a cuticularized distal filament. Litomosoides pardinasi n. sp. possesses a buccal capsule tubular with an anterior enlargement, and a smooth cavity; four labial and two dorsal cephalic papillae; vulva posterior to the esophagus-intestinal junction; male tail with three to five pairs of symmetric postcloacal papillae; female tail slender; vagina globular and small. This is the first record for a filarioid in a Phyllotini rodent and the southernmost record of any filarioid species worldwide.

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.

Redescription of Ingliseria cirrohamata (Linstow, 1888) (Nematoda: Acuariidae), including new hosts and geographical records.

Inglisera cirrohamata (Linstow, 1888) (Nematoda: Acuariidae) is redescribed based on specimens collected from the type host, Phalacrocorax verrucosus (Aves: Phalacrocoracidae), and the type locality, Kerguelen Island, in the southern Indian Ocean. Three new hosts and 2 new localities were recorded, i.e., Phalacrocorax [atriceps] albiventer and P. brasilianus from Puerto Madryn, Argentina and P. magellanicus from Puerto Williams, Chile. The structure of the cephalic ornamentations was observed and fully described. The presence of 6 pairs of postcloacal papillae is confirmed, a description of the tip of left spicule is given, and the presence of post-deirids is reported for the first time. This constitutes the first record of this nematode in South America and provides the first study of the genus by scanning electron microscopy.

A new species of Litomosoides Chandler, 1931 (Nematoda: Filarioidea) from the long-nosed hocicudo Oxymycterus nasutus Waterhouse (Rodentia: Cricetidae) in Uruguay.

A new species of Litomosoides Chandler, 1931 was collected from the abdominal cavity of Oxymycterus nasutus Waterhouse (Rodentia: Cricetidae) in the grassland of the Departamento Rocha, Uruguay. Litomosoides nasuti n. sp. belongs to the 'sigmodontis group', and is characterised by: salient amphids; two ventral and one dorsal labial papillae, but no cephalic papillae; a buccal capsule with a transparent anterior segment and an annular asymmetrical thickening; a muscular oesophagus; a bottle-shaped buccal cavity; the male with symmetrically situated cloacal papillae (one pair ad-cloacal and three pairs post-cloacal); phasmids displaced laterally to the longitudinal axis; and microfilariae without terminal nuclei in the tail tip. It resembles five known species; three of which have been recovered from Oxymycterus spp. in neighbouring countries. However, the new species can be differentiated from L. sigmodontis Chandler, 1931 by the shape and size of the buccal capsule; from L. navonae Notarnicola, 2005 by the muscular oesophagus; from L. legerae Bain, Petit & Berteaux, 1980 by the length of the oesophagus and the cephalic papillae; from L. anguyai Notarnicola, Bain & Navone, 2002 by the absence of lappets in the female tail; and from L. oxymycteri Notarnicola, Bain & Navone, 2000 by absence of pre-cloacal papillae. L. legerae from O. quaestor and L. sigmodontis from Sigmodon hispidus in North America are closely related species, as indicated by Brant & Gardner's phylogenetic tree based on morphological characters. However, a new analysis is needed to include the recently described Argentinean species for a better understanding of the diversification of this genus.

Species of Contracaecum Parasitizing the Magellanic Penguin Spheniscus magellanicus (Spheniscidae) from the Argentinean Coast.

Anisakid nematodes have a worldwide distribution and are associated with fishes, birds, and marine mammals from freshwater, brackish, and marine systems. The aims of this work are to report for the first time Contracaecum mirounga parasitizing the Magellanic penguin Spheniscus magellanicus, to report another Contracaecum species in the same host species, and to discuss the validity of Contracaeceum spheniscus. Several dead chicks, juveniles, and adults of S. magellanicus were collected along the Argentinean coast from 2002 to 2009. Nematodes were removed from digestive tracts and studied using both light and scanning electron microscopy. Nematode prevalences were 2.38% for C. mirounga and 12.5% for Contracaecum sp. Contracaecum mirounga was found in 1 penguin from Península Valdés, Chubut. This species is known as a specific parasite of marine mammals such as Pinnipedia, thereby suggesting that this nematode is not as specific as believed. Another species of Contracaecum sp. was found parasitizing 1 penguin from the Río de la Plata coast. It possessed an unusual interlabial morphology and arrangement of male caudal papillae. Despite the low prevalence, the distinct morphological features are convincing and support the presence of a new Contracaecum species. However, a formal description is not presented because sufficient male specimens are lacking. Finally, C. spheniscus is considered a junior synonym of Contracaecum pelagicum. Future molecular studies might be helpful to determine the real diversity of Contracaecum species parasitizing S. magellanicus considering the number of sibling species recognized among the anisakids.

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.

Intestinal parasitosis, undernutrition and socio-environmental factors in schoolchildren from Clorinda Formosa, Argentina.

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.

A new species of Liniscus (Nematoda: Trichuridae) from Oxymycterus rufus and Akodon azarae (Cricetidae: Sigmodontinae) in Buenos Aires Province, Argentina.

Liniscus diazae n. sp. (Nematoda: Trichuridae) is described from the urinary bladder of Oxymycterus rufus and Akodon azarae (Cricetidae: Sigmodontinae) from Buenos Aires Province, Argentina. Liniscus diazae can be differentiated from its congeners by having a much longer spicule and without an elevated vulva. In addition, L. diazae can be distinguished from L. incrassatus and L. himizu by having a longer body length. Males are similar in posterior width to L. papillosus and L. himizu, but thinner than L. incrassatus and L. maseri. This is the second record of a capillarid from mammals in Argentina. An updated list of capillarid species of rodents and insectivores from North America, with their synonyms, hosts, sites of infection, and geographic distribution, is provided.