Background Intestinal bacterial dysbiosis and increased gut permeability are associated with higher risk of developing type 1 diabetes (T1D) or celiac disease (CD). There is a lack of information on parasitism involved in gut disturbance of predisposed children. We evaluated the effect of enteropathogenic parasites ( Cryptosporidium spp., Cyclospora spp. G. lamblia , and Blastocystis spp.) on the bacterial structure of feces from children with autoantibodies for T1D or CD. Participants included 37 children under 18 years of age, from whom stools were analyzed for enteric parasites by qPCR and 22/37 for bacterial profile by sequencing the V3–V4 region of the 16s rRNA gene. Dietary, clinical, and socioeconomic data was recorded. Results Pathogens parasitized 28/37 participants, Cryptosporidium spp. was the most prevalent (62.2%), followed by both Cyclospora cayetanensis and Blastocystis spp (37.8%). There were no dietary differences ( p > 0.05) attributable to parasitism. Co-infected participants with Cryptosporidium and Cyclospora did not differ (p = 0.064) from non-infected participants in bacterial alpha phylogenetic diversity. The same parasites’ co-infection was associated with a decreased abundance of the Ruminococaceae (p = 0.04) and Verrucomicrobioceae families, of the Akkermansia genus (p = 0.009). There was a lower Firmicutes/Bacteroidetes ratio (p = 0.02) in infected than in uninfected participants. Conclusions Cryptosporidium and Cyclospora affected the bacterial structure at family and genus levels, decreasing the ratio between Firmicutes and Bacteroidetes in children with auto-antibodies for T1D or CD, which could increase the risk of illness onset.

Introduction: Entamoeba histolytica, E. dispar, and E. moshkovskii are morphologically identical, but intestinal amebiasis is caused only by E. histolytica. Mexico is among the countries with high amebae infection rates, although the contribution of pathogenic amoeba to the total detected cases remains unknown, especially in the northwestern dry region. Therefore, the aim of this study was to identify the actual prevalence of E. histolytica using real-time polymerase chain reaction (PCR) in schoolchildren of northwestern Mexico. Methodology: Participants were children from five public elementary schools in the low-socioeconomic-level suburban areas of Hermosillo, Sonora, Mexico. One stool sample was collected from each child and analyzed by the Faust technique for Entamoeba spp. and by real-time PCR for E. histolytica. Results: Analysis of stool samples from 273 children (9.0 ± 1.5 years of age) resulted in 25 (9.2%) positive for E. histolytica/E. dispar/E. moshkovskii by the Faust technique; of these, 3 were positive for E. histolytica by real-time PCR. In addition, 2 samples that were negative for E. histolytica/E. dispar/E. moshkovskii by the Faust technique were positive by real-time PCR. Conclusions: The actual prevalence of E. histolytica in our study population was 1.8%, which is lower than those reported in previous studies in other Mexican regions.