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Besnoitia spp. are cyst-forming coccidian parasites with a broad host range, infecting various wild and domestic animal species. Northamerican opossums (Didelphis virginiana) are severely affected by the infection with B. darlingi. This study presents a case of infection with Besnoitia in a road-killed female southern black-eared opossum (Didelphis aurita) in Misiones, Argentina. Many 0.5-1 mm cysts were observed in several muscles and visceral organs and were microscopically identified in skeletal muscles, tongue, and heart. Histological analysis disclosed multiple spherical cysts with a myriad of bradyzoites like-cells and a well-defined cyst wall. A small number of degenerate and ruptured cysts, surrounded by mild to moderate inflammation were observed. Genomic DNA from an individual cyst and muscle was extracted and ITS1 marker and 18S rRNA gene fragments from sarcocystid protozoa were successfully amplified by PCR and sequenced. The 18S sequence exhibited 100% identity with sequences of B. darlingi and B. oryctofelisi. Comparison of the complete ITS1 sequence (259 bp) revealed an identity of 99.2% with B. oryctofelisi and 97.7% with B. darlingi. This result together with the phylogeny positioning, suggest that the Besnoitia sp. in the present case differ from B. darlingi, being closely related with B. oryctofelisi.

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Toxoplasma gondii and Neospora caninum infections are important causes of abortion in ruminants. The objective of this study was to determine the seroprevalence and frequency of T. gondii and N. caninum titers in goats raised by family farmers in the Luracatao Valley of Salta province, Argentina. A total of 259 serum samples were collected from adult goats in 42 family farms in nine communities and tested for indirect fluorescent antibody test (IFAT, cut-off 1:100). Seroprevalences were 34.36% (89/259) for T. gondii and 64.09% (166/259) for N. caninum. Co-infection was found in 25.86% (67/259) of the goats tested. The most frequent IFAT titer of T. gondii found was 100 (23.93%; 62/259), and only 2% (5/259) of the goats presented titer 800. For N. caninum, the most frequent titers were 100 (25.86%; 67/259), and titers 200 (20.46%; 53/259) and 400 (14.61%, 38/259). The titers found for T. gondii could suggest a chronic infection in goats, being of importance for the region due to meat consumption and cheese production. The elevated seroprevalence of N. caninum identified in this study may be attributed to the community-specific dog population and the close interaction between dogs and goats, despite the absence of a statistically significant association. Subsequent research is warranted to assess the productive implications of T. gondii and N. caninum.

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This study aimed to determine the nPCR-RFLP genotypes of newly obtained T. gondii isolates from human congenital toxoplasmosis cases in Argentina and to determine their allelic profiles for virulence genes ROP18/ROP5. In addition, the ROP18/ROP5 profiles were also determined for previously characterized T. gondii samples. Isolation from congenital toxoplasmosis cases was carried out in mouse bioassay from two placentas (P1 and P2). Genotyping for the new human isolates was performed by nPCR-RFLP using 10 markers. The samples analyzed for ROP18/ROP5 included the two newly obtained isolates (from the congenital toxoplasmosis cases) and nine previously genotyped T. gondii DNA samples from humans and chickens. The results for P1 and P2 named as TgHm18-02Arg and TgHm19-01Arg showed ToxoDB genotypes #14 (non-archetypal) and #2 (clonal type III), respectively. Non-archetypal #14 has been isolated from human cases before in Argentina. However, this is the first report of T. gondii clonal type III in a human case in the country. The ROP18/ROP5 combination was detected in nine samples: 3/3 (n = 1), 4/3 (n = 4), 4/4 (n = 3), and 3-4/4 (n = 1). Notably, the 4/4 profile was identified for the first time and exclusively in T. gondii samples from Misiones province (which borders southern Brazil). Further studies are required to corroborate the regionalization of the ROP18/ROP5 profiles in Argentina.

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Sarcocystis spp. are intracellular protozoan parasites with an obligatory heteroxenous life cycle. The objective of this study was to identify Sarcocystis spp. in pig muscles from Argentina, by light and transmission electron microscopy (TEM), and molecular studies. Muscles samples from 561 pigs (Sus scrofa domestica) were classified according to the breeding system in: intensive farming (IF, n = 295; animals kept in confinement during most of their productive cycle), or semi-extensive farming (SEF, n = 266; animals bred outdoors, generally family or backyard production). Results showed that 24.8% (139/561) were positive by light microscopy, with a significantly higher prevalence in the SEF (34.6%; 92/266) than the IF pigs (15.9%; 47/295) (p < 0.05). Of the 202 samples analyzed by PCR, 96 were positive (47.5%) for the 18S rRNA (18S ribosomal RNA) fragment. All samples analyzed by the S. suihominis specific coxI (mitochondrial cytochrome c oxidase subunit I) PCR (n = 235; 96 positives by 18S rRNA PCR and 139 positives by light microscopy) were negative. Fourteen individual cysts were positive for the 18S rRNA PCR and sequenced. Consensus sequences obtained from the 18S rRNA fragment PCR ranged from 613 to 880 bp and showed 100% of identity between them and with previously reported S. miescheriana sequences. In all the pig samples analyzed by TEM, cyst wall ultrastructure was compatible with S. miescheriana. This is the first study that provides infection rates and describes and identifies morphological and molecular features of Sarcocystis spp. cysts in pigs from Argentina.

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Sarcocystis is a genus of intracellular parasitic protozoa that infects various species of mammals, birds, and reptiles worldwide. At least 46 Sarcocystis species naturally infect rodents as intermediate hosts producing tissue cysts. This study aimed to provide the first report and molecular characterisation of Sarcocystis spp. in muscles from plains viscacha (Lagostomus maximus) in Argentina. Muscle samples of 53 plains viscachas from three provinces of Argentina were processed by homogenisation and optical microscopy to detect tissue cysts. Positive samples were analysed by PCR-sequencing, using the following markers: 18S rRNA, ITS1, and coxI. The 18S rRNA and coxI consensus sequences were aligned with other sequences from Sarcocystis spp., and phylogenetic trees were constructed. Of all animals processed, 13.2% (7/53) harboured Sarcocystis sp. cysts. 18S rRNA consensus sequences were obtained from four muscle samples and one individual cyst, and they showed 99.88-100% similarity, except for the cyst sequence, which showed 97.11% homology. Similarities of only 96-97% were recorded in the 18S rRNA fragment with other Sarcocystis spp. whose sequences are available in the GenBank. The five coxI fragment sequences obtained were 100% identical and showed an identity of 99.41-99.48% with S. canis. For ITS1 only short and low-quality sequences were obtained. In the phylogenetic trees, all the sequences from plains viscachas were positioned together in a branch separated from other Sarcocystis spp. These results could be related to new Sarcocystis spp. producing sarcocysts in plains viscachas. Besides, comprehensive cyst morphological analysis using TEM from the new Sarcocystis species will allow a description of the cyst wall ultrastructure. In this sense, further studies are needed to deepen these findings and elucidate other potential intermediate and possible definitive hosts.

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The marsh deer (Blastocerus dichotomus) is the largest South American native deer species and is listed as "Vulnerable" by IUCN due to the population reduction. As part of a conservation and disease surveillance program, muscle samples from 14 marsh deer found dead in 2016 and 2017 in northeast Argentina were obtained at necropsy. Samples from each animal were processed as pooled muscles (heart, diaphragm, tongue and hindlimb) by homogenization and direct microscopical observation to detect intracellular Sarcocystis spp. cysts. Sarcocysts were observed in six samples, and several cysts recovered from two samples were processed by transmission electron microscopy. The cysts were thin-walled and showed a cyst-wall ultrastructure with ribbon-like protrusions similar to other species using cervids as intermediate host and canids as definitive hosts. Genomic DNA from individual sarcocysts from three marsh deer were successfully amplified by PCR of 18S rRNA and COI gene fragments and further sequenced. Sequence comparison revealed a 99.3-100% identity among them and only 93.7-96.6% and 88.8-89.7% identity at 18S rRNA and COI markers, respectively, with other Sarcocystis spp. Despite morphological similarities, the high sequence divergence at 18S rRNA and COI fragments allowed the assumption that Sarcocystis sp. from marsh deer is a different species from others using cervids as intermediate hosts. Therefore, we propose the name Sarcocystis blastoceris n. sp. for the species infecting marsh deer.

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Sarcocystis spp. are intracellular protozoan parasites with an obligatory heteroxenous life cycle. The objective of this study is to identify Sarcocystis spp. in wild boar muscles from Argentina by light and transmission electron microscopy and molecular characterization. Muscle samples from diaphragm, tongue, masseter, intercostals, heart, and forelimbs of 240 wild boars were analyzed. Of the animals, 48.3% (116/240) were positive for sarcocysts by light microscopy, whereas 45.8% (110/240) were positive for Sarcocystis spp. by PCR targeting 18S rRNA fragment. These samples were subjected to a specific PCR for S. suihominis coxI gene, 3.6% (4/110) of which were weak positives. Unfortunately, sequence analysis was inconclusive. This could be related to a potentially low S. suihominis cyst load in the samples, or to an incomplete primer matching with the South American S. suihominis sequences. Seventeen individual sarcocysts were positive by PCR for the 18S rRNA fragment, whose sequences showed 99.75-100% identity with each other and with previously reported S. miescheriana sequences. A total of 21 cysts collected from 11 muscle samples and analyzed by TEM presented a cyst wall type compatible with S. miescheriana, and one cyst presented an ultrastructure compatible with S. suihominis. The latter came from a sample that also contained S. miescheriana cysts, indicating that the animal was co-infected. This is the first study that provides infection rates and describes and identifies morphological and molecular features of Sarcocystis spp. cysts in wild boars from South America.

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INTRODUCTION: Intestinal parasites have the greatest impact on child populations as they can, in the long term, lead to stunted growth with advances in cognitive development. The transmission of these parasites is favored by environments of social vulnerability. METHODS: In a cross-sectional study carried out in the District of Hurlingham, in the suburbs of Buenos Aires, the prevalence of intestinal parasitoses and its associated risk factors in a child population attending Primary Health Care Centers was estimated. Coproparasitological survey, Graham test and a socio-environmental and labor survey were performed. RESULTS: A total of 130 children, 50.8% women and 49.2% men (0-12 years) were analyzed; 89.1% of those over 4 years of age were in school. In 28.5% of households, the mother or father had a formal job and 63.8% received the Universal Child Allowance. Conditions of social vulnerability were observed in the analyzed population: poor access to network water and sewage and environmental sanitation. The parasitological diagnosis revealed that 75 children [57.7% (95% CI: 48.7-66.3)] were parasitized. Protists were more frequent than helminths and the most prevalent species were Blastocystis spp, Enterobius vermicularis, Giardia lamblia and Cryptosporidium sp. The parasites in children were associated with schooling (p <0.01) and age (p <0.05). DISCUSSION: This work constitutes the first survey on intestinal parasitoses in the District of Hurlingham and the socioeconomic and environmental context where it is developed.

Introducción: Los parásitos intestinales tienen mayor impacto en las poblaciones infantiles ya que pueden, a largo plazo, conducir a un retraso en el crecimiento con alteración del desarrollo cognitivo. Sumado a esto, los entornos de vulnerabilidad social favorecen la transmisión y permanencia de estos parásitos en el ambiente. Métodos: En un estudio transversal realizado en el Municipio de Hurlingham (conurbano bonaerense) se estimó la prevalencia de enteroparasitosis y sus factores de riesgo asociados en una población infantil concurrente a Centros de Atención Primaria para la Salud locales mediante un análisis coproparasitológico, un test de Graham y una encuesta socioambiental y laboral. Resultados: Un total de 66 niñas (50.8%) y 64 niños (49.2%) entre 0 a 12 años fueron analizados. El 89.1% de los mayores de 4 años estaban escolarizados. En el 28.5% de los hogares la madre o el padre tenía trabajo formal y el 63.8% percibía la asignación universal por hijo (AUH). Se observaron condiciones de vulnerabilidad social en la población analizada, tales como: falta de acceso al agua de red y cloacas y un saneamiento ambiental deficiente. El diagnóstico parasitológico reveló un total de 75 casos [57.7% (IC 95%: 48.7-66.3)] de parasitosis. Los protistas fueron los parásitos más frecuentes y las especies más prevalentes: Blastocystis spp, Enterobius vermicularis, Giardia lamblia y Cryptosporidium sp. La presencia de parásitos estuvo asociada a la escolarización (p <0.01) y a la edad del niño (p <0.05). Discusión: Este fue el primer relevamiento sobre las enteroparasitosis en el municipio de Hurlingham y el contexto socioeconómico y ambiental donde se desarrollan.

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Resumen Introducción: Los parásitos intestinales tienen mayor impacto en las poblaciones infantiles ya que pueden, a largo plazo, conducir a un retraso en el crecimiento con alteración del desarrollo cognitivo. Sumado a esto, los entornos de vulnerabilidad social favorecen la transmisión y permanencia de estos parásitos en el ambiente. Métodos: En un estudio transversal realizado en el Municipio de Hurlingham (conurbano bonae rense) se estimó la prevalencia de enteroparasitosis y sus factores de riesgo asociados en una población infantil concurrente a Centros de Atención Primaria para la Salud locales mediante un análisis coproparasitológico, un test de Graham y una encuesta socioambiental y laboral. Resultados: Un total de 66 niñas (50.8%) y 64 niños (49.2%) entre 0 a 12 años fueron analizados. El 89.1% de los mayores de 4 años estaban escolarizados. En el 28.5% de los hogares la madre o el padre tenía trabajo formal y el 63.8% percibía la asignación universal por hijo (AUH). Se observaron condiciones de vulnerabilidad social en la población analizada, tales como: falta de acceso al agua de red y cloacas y un saneamiento ambiental deficiente. El diagnóstico parasitológico reveló un total de 75 casos [57.7% (IC 95%: 48.7-66.3)] de parasitosis. Los protistas fueron los parásitos más frecuentes y las especies más prevalentes: Blastocystis spp, Enterobius vermicularis, Giardia lamblia y Cryptosporidium sp. La presencia de parásitos estuvo asociada a la escolarización (p<0.01) y a la edad del niño (p<0.05). Dis cusión: Este fue el primer relevamiento sobre las enteroparasitosis en el municipio de Hurlingham y el contexto socioeconómico y ambiental donde se desarrollan.

Abstract Introduction: Intestinal parasites have the greatest impact on child populations as they can, in the long term, lead to stunted growth with advances in cognitive development. The transmission of these parasites is favored by environments of social vulnerability. Methods: In a cross-sectional study carried out in the District of Hurlingham, in the suburbs of Buenos Aires, the prevalence of intestinal parasitoses and its associated risk factors in a child population attending Primary Health Care Centers was estimated. Coproparasitological survey, Graham test and a socio-environmental and labor survey were performed. Results: A total of 130 children, 50.8% women and 49.2% men (0-12 years) were analyzed; 89.1% of those over 4 years of age were in school. In 28.5% of households, the mother or father had a formal job and 63.8% received the Universal Child Allowance. Conditions of social vulnerability were observed in the analyzed population: poor access to network water and sewage and environmental sanitation. The parasitological diagnosis revealed that 75 children [57.7% (95% CI: 48.7-66.3)] were parasitized. Protists were more frequent than helminths and the most prevalent species were Blastocystis spp, Enterobius vermicularis, Giardia lamblia and Cryptosporidium sp. The parasites in children were associated with schooling (p<0.01) and age (p<0.05). Discussion: This work constitutes the first survey on intestinal parasitoses in the District of Hurlingham and the socioeconomic and environmental context where it is developed.

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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.

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Sarcocystis spp. are intracellular protozoan parasites with heteroxenous life cycles. This study described Sarcocystis spp. infection in adult South American native deer huemul (Hippocamelus bisulcus) and pudu (Pudu puda). Heart, diaphragm, tongue, and skeletal muscle samples were collected from 5 huemuls and 2 pudus, found dead in National Parks. Direct microscopic examination, transmission electron microscopy, PCR, and sequencing were performed. Sarcocystis spp. microscopic thin-walled cysts were identified in 3 huemuls and 1 pudu. Several cysts from 1 huemul and 1 pudu were observed by TEM; ultrastructure was similar to previously reported as cyst wall type 17 and types 2 and 8, respectively. Fragments of the 18S rRNA and cytochrome c oxidase subunit I (cox1) genes were amplified and sequenced from 3 individual cysts from 2 huemuls and 2 cysts from the pudu. The sequences from huemuls showed a high identity among them (> 99%) at both amplified targets. The highest identities were > 99.7% at 18S rRNA and 93% at cox1 with S. tarandivulpes sequences. The 18S rRNA gene sequences from pudus showed an identity > 99.7% with Sarcocystis sp., S. taeniata, and S. linearis sequences, while the cox1 sequences were different, one showing 99.42% identity with S. venatoria and the other 98.22% with S. linearis. A single species, similar to S. tarandivulpes, was identified in all huemul samples while 2 molecularly different Sarcocystis spp. were found in 1 pudu with high similarities to either S. venatoria or to S. linearis, S. taeniata-like, and S. morae. Based on the cox1 sequence identities, at least the Sarcocystis sp. in huemuls might represent a new species, primarily occurring in this host. Additional sarcocyst isolates from both hosts need to be examined molecularly in order to firmly establish whether these species are indeed native to huemuls and/or pudus or are derived from introduced deer species.

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