Environmental parameters influencing the distribution of parasite species in three neighbourhoods of differing socioeconomic conditions in La Plata, Argentina were analysed. Coproparasitological screenings were performed in children up to 14 years old from a marginal zone (100), a suburban neighbourhood (101), and an urban area (91) in 1999--2000. The presence of parasite species in environmental samples (water and soil) and the degree of association among parasite communities was documented and evaluated. The prevalence of infection in each population was 73.0%, 54.4% and 35.2%, respectively. The frequencies of helminths and pathogenic protozoa were both higher in the marginal zone, where sanitary and environmental conditions were significantly inferior compared with the other zones. The high prevalence of intestinal parasites in this infantile population was related to parasitic contamination of the soil and water sources in addition to deficient sanitary and sociocultural conditions. Calculation of an equitability index revealed that the specific richness was less equitable once socioeconomic conditions and hygienic practices were improved. This study demonstrates the need to implement management practices for the control of intestinal parasitoses in accordance with the environmental and sociocultural characteristics of a given ecosystem.

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SUMMARYWe evaluate the prevalence of intestinal parasites in 504 people and the degree of association between environmental variables and parasites found in population, soil and water in a rural area of Argentina during [2002][2003]. A structured survey was used to evaluate the environmental variables and fecal-human, soil and water samples were analyzed. The prevalence of parasites was 45.4%. Most prevalent protozoa were Blastocystis hominis (27.2%) and Giardia lamblia (6.9%), while the most prevalent helminth was Ascaris lumbricoides (3.8%). The analyzed environmental variables showing association (p < 0.05) with presence of parasites in population were: cardboard-tin or wooden house, dirt floor, home or communal water pump, faucet outside the house or public faucet and cesspool or latrine. Parasite forms were found in 82.3% of the soil samples and in 84.2% of the water samples. In both samples we found parasites that were also found in people. In this study we have found deficient sanitary conditions associated with presence of parasites in population and we have evidenced that contaminated soil and water were the source of these parasites.

In a study, carried out in 2000, of the clinical and parasitological status of a Wichi Aboriginal community living in the suburbs of Tartagal, northern Salta, Argentina, 154 individuals were screened for parasitic infections. Ninety-five faecal samples were also obtained from the same population. Ninety-three percent of the subjects were positive for 1 or more of the parasites investigated by direct test and 70.5% of them had parasitic superinfection. The most frequent helminths were Strongyloides stercoralis (50.5%) and hookworm (47.4%). We found low reinfection rates and a long reinfection period after treatment and provision of safe water and sanitation. Serum reactivity of these patients was analysed by enzyme-linked immunosorbent assay and indirect immunofluorescent assay and 22.1% of them had anti-Toxocara antibodies, 16.2% were positive for a complex antigen of Leishmania braziliensis, 29.9% were positive for a complex Trypanosoma cruzi antigen, and 17.5% were positive for a specific Trypanosoma cruzi antigen, Ag 163B6/cruzipain.

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Oral treatment with a potential probiotic (Enterococcus faecalis CECT 7121) appears to reduce the parasite burden of mice infected with Toxocara canis

The protozoan parasite most frequently associated with diarrhoea worldwide is Giardia intestinalis. In 2005, a study was initiated to identify the genotypes of this parasite infecting children in the Argentinian provinces of Buenos Aires, Mendoza and Chaco, and to explore the associations between the genotype detected in a child, the characteristics of the child's household and the child's clinical presentation. Overall, 998 children (504 boys and 494 girls) aged between 2-14 years, with or without symptoms, were enrolled. The G. intestinalis in 94 of the 117 stool samples found positive for the parasite by microscopy were successfully genotyped by PCR. Seventy-seven of the children were found to be infected with genotype B only and 14 with genotype AII only, three children being found to have mixed (AII and B) infections. Only genotype B was detected in children from rural areas (P<0·05) and most Giardia detected in children from households with a piped water supply were also of this genotype (P<0·05). The other household characteristics investigated (quality of building, history of flooding, type of sanitation, level of overcrowding, and presence/absence of pet dogs) had no significant effect on the genotype distribution. Children infected with genotype AII were significantly younger than those infected with genotype B (P<0·05) and there was a significant positive association between infection with genotype B and abdominal pain (P<0·05). Diarrhoea was not, however, found to be significantly associated with genotype-AII or genotype-B infection. This is the first published report on the Giardia genotypes circulating in the provinces of Mendoza and Chaco. The results indicate the importance of asymptomatic children in the transmission of Giardia among the young.

2). Statistical analysis revealed that a male sex, flooding of the home, the use of a latrine, and an abdominal pain were correlated with the presence of these parasites, which indicate the importance of these factors in rural communities.