No abstract

Blastocystis spp. is the most common protozoan detected in human stool samples. In developing countries, infection rates are higher than 20%. The presence of this parasite in the feces of several host species suggests its zoonotic potential. The clinical relevance and the pathogenic role of Blastocystis spp. in the intestinal tract remain unclear. There are several clinical reports that recognize it as the etiologic agent of several intestinal disorders such as diarrhea, inflammatory bowel disease and ulcerative colitis, although the pathogenicity of this parasite has not been proved yet. This wide range of clinical manifestations could be related to the genetic diversity exhibited by this parasite.

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.

Introduction: Intestinal parasitic infections have been reported in different regions of Argentina. Giardia intestinalis is recognized as "the national parasite". The aim of this work was to determine the prevalence of both intestinal parasites and G. intestinalis genotypes, as well as to analyze the clinical and epidemiological characteristics in schoolchildren from a suburban community. Methodology: Serial coproparasitological analysis and perianal swab method were performed in 244 schoolchildren. Demographic, sociocultural and environmental variables were registered. The presence of signs/symptoms and risk behaviours were also recorded. Stools with G. intestinalis were selected for genotyping. Results: Out of 244 schoolchildren, 179/244 (73.4%) were infected with intestinal parasites. The presence of intestinal parasitosis was associated only with house flooding. Multivariate analysis identified that use of a latrine is significantly correlated with G. intestinalis and age six to 11 years with E. vermicularis. Signs and symptoms were recorded in 62% of infected children and in 57.9% of those not infected. Genomic amplification was revealed that 65.7% (46/70) of Giardia positive samples corresponded to genotype B, 31.4% (22/70) to genotype AII, and two samples (2.8%) had mixed infection (AII + B). Conclusions: This study shows a high percentage of infected children living in a suburban community in poor sanitary conditions, and not visiting the doctor in spite of evident signs and symptoms associated a digestive pathology. This situation supports the need for continuing the development of community programs allowing the improvement of quality of life and control of parasitosis in deprived populations.

The results suggest an association between intestinal parasites and physical growth in suburban children. Rural children seem to be protected against the effects of parasitic infection.