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.

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.

Parasitic risk factors in migrant horticultural families from Bolivia settled in the rural area of La Plata, Buenos Aires, Argentina

Objective

The aims were to diagnose intestinal parasites in migrant horticultural families in the rural area of La Plata, and assess factors that increase the risk of parasitic infection.

Materials and methods

Serial stool samples and anal swabs of 350 individuals were processed using sedimentation and flotation techniques. Socio-sanitary and environmental characteristics were surveyed using a semi-structured questionnaire. A generalized linear model was used to assess the change in parasitic prevalence with different predictor variables.

Results

Of all examined individuals, 79.1% were parasitized, and 12 parasites were identified. Blastocystis sp. (58.9%), Entamoeba coli (26.3%), Enterobius vermicularis (26.0%), and Giardia lamblia (24.0%) were the most prevalent species. Risk factors were age group (<12 years), sampling site, and a basic education of parents.

Conclusion

The high prevalence of intestinal parasites in horticultural families is associated with inadequate environmental sanitation, a limited access to education, and insufficient hygienic habits. An increase in parasitological references in integrated studies (human, animal and environmental health) would result in an understanding of the parasitic etiology, and the development of effective actions for the control of intestinal parasites.

•

La Plata Horticultural area is the most important region for vegetable production in Argentina.

•

79.1% of analyzed farming population was parasitized and the species found indicate an inadequate environmental sanitation.

•

An increase in parasitological references in integrated studies could mitigate the effect of intestinal parasitoses.

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.

Morphological and molecular identification of hymenolepidid cestodes in children and synanthropic rodents from rural Mexico

Hymenolepidid cestodes of synanthropic rodents represent a risk for public health. In order to describe the occurrence of hymenolepidids in children and the role of rodents as a potential source of infection, we conducted a morphological and molecular survey on cestodes in two rural villages from Yucatan, Mexico. One hundred and thirty-five stool samples from children (64 from Paraíso and 71 from Xkalakdzonot), 233 Mus musculus (159 from Paraíso and 74 from Xkalakdzonot) and 125 Rattus rattus (7 from Paraíso and 118 from Xkalakdzonot) were analyzed for the presence of cestodes. Three hymenolepidid species were identified morphologically: Hymenolepis nana in 7.8% of children from Paraíso, Hymenolepis microstoma in 4.4% of M. musculus from Paraíso and Hymenolepis diminuta in 15.3% of R. rattus from Xkalakdzonot. The molecular characterization and phylogenetic analysis based on mitochondrial cytochrome c subunit 1 (CO1) gene and ribosomal internal transcribed spacer 1 (ITS1) region, confirmed the identity of the three cestodes isolated from Yucatan. Phylogeny of the CO1 gene identified intraspecific genetic differences within H. nana ranging from 0 to 5%, in H. microstoma from 0 to 0.4%, and in H. diminuta ranged from 0 to 6.5% which suggests, the presence of complex species within H. nana and H. diminuta infecting humans and rodents, as reported by other authors. Based on the morphological and molecular results, and the epidemiological evidence, infections with H. nana suggest a non-zoonotic transmission; however, the presence of H. microstoma and H. diminuta in synanthropic rodents serve as a possible source for human infection.

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. Ascaris lumbricoides, 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.

Nutritional status, body composition, and intestinal parasitism among the Mbyá-Guaraní communities of Misiones, Argentina

Indigenous communities in Argentina represent socially and economically neglected populations. They are living in extreme poverty and environmental degradation conditions. New information about health status and socio-environmental features is urgently needed to be applied in future sanitary policies. Present study describes the nutritional status, body composition, and intestinal parasitism among Mbyá-Guaraní children from three communities in the Misiones Province. Anthropometric parameters were analyzed for 178 individuals (aged 1-14). Data were transformed to z-scores using NHANES I and II. Stunting showed the greatest prevalence (44.9%). Children were found to have low arm circumference and low arm muscle area, although with tricipital skinfold value near to the reference. They also tend to have shorter than normal lower limbs. Fecal samples and anal brushes (for Enterobius vermicularis) were collected in 45 children (aged 1-13). Ritchie's sedimentation and Willis' flotation techniques were used to determine parasitoses. Ninety five percent of children were infected with at least one species and 81.4% were polyparasitized. The higher prevalences corresponded to Blastocystis hominis, hookworms (Ancylostoma duodenale/Necator americanus), and Entamoeba coli. Associations occurred between hookworms with B. hominis/E. coli and B. hominis with nonpathogenic amoebas. Thirty nine percent of the children with stunting presented B. hominis, Strongyloides, and hookworms. Our results indicate that this indigenous population is subjected to extreme poverty conditions and is one of the most marginalized in this country. Severe growth stunting and parasitic infection are still quite common among Mbyá children affecting about half of them along with significant changes in body composition and proportions.