Background: Blastocystis is a common protist detected in fecal samples of humans and a wide range of animals. The parasite exhibits extensive genetic diversity with seventeen distinct subtypes (STs) identified collectively from humans, other mammals and birds. Shared STs between animal and human hosts were considered to be potentially zoonotic. However, Blastocystis infection among non-human hosts, in Egypt has not been investigated so far.Objective: To determine the occurrence and ST distribution of Blastocystis species isolated from domestic mammals, poultry and their in-contact humans.Material and Methods: A total of 416 fecal samples from domestic animals (mammals and poultry) as well as their in-contact humans were screened by inoculation into Jones' media. Positive samples were subtyped using seven pairs of ST-specific sequence-tagged-site (STS) primers.Results: The occurrence of Blastocystis spp. infection was 69.8% in poultry, 17.7% in domestic mammals and 35.7% in humans. Among the studied animal species ST1-ST7 were identified with varying percentages; however, only four STs (ST1-ST4) were identified in humans. A minority of human subjects examined (16/56, 28.5%) were carrying the same ST detected in their domestic animals.Conclusion: The detection of all the tested STs among the infected animal species examined highlights the broad genetic diversity observed among Blastocystis spp. isolated from animals. However, the detection of only four STs among humans suggests that these STs can easily infect humans and the animals carrying the same STs could be possible reservoirs. Surprisingly, direct handling of animals was not found to be a major contributor to human blastocystosis in Egypt, denoting the role of anthroponotic transmission and the possibility of fecal cross-contamination from other potential reservoir animals in the surrounding environment.

Achillea fragrantissima (Forssk.) Sch. Bip. (known as Qaysoom), Echinops spinosus L. (known as Shoak Elgamal) and Artemisia judaica L. (known Shih Baladi) are members of the Asteraceae family known for their traditional medical use in Egypt. The ethanol extracts of these plants were evaluated for their efficacy against a protozoan parasite (Blastocystis). Two different molecular subtypes of Blastocystis were used (ST1 and ST3). Significant growth inhibition of Blastocystis was observed when exposed to both A. judaica (99.3%) and A. fragrantissima (95.6%) with minimal inhibitory concentration (MIC₉₀) at 2000 µg/mL. Under the effect of the extracts, changes in Blastocystis morphology were noted, with the complete destruction of Blastocystis forms after 72 h with the dose of 4000 µg/mL. Different subtypes displayed different responses to the herbal extracts tested. ST1 exhibited significantly different responses to the herbal extracts compared to ST3. A. judaica was selected as the herb of choice considering all of its variables and because of its effective action against Blastocystis. It was then exposed to further fractionation and observation of its effect on ST1 and ST3. Solvent portioned fractions (dichloromethane (DCM), ethyl acetate (EtOAc) and n-hexane) in A. judaica were found to be the potent active fractions against both of the Blastocystis subtypes used.

Dientamoebafragilis (D. fragilis) is a protozoan parasite whose pathogenic potential is still disputable. The aim of this study was to illustrate the pathogenicity of D. fragilis infection and to determine the infective dose for experimental mice infection. Three groups of mice (8/each) were orally inoculated with in vitro cultured D. fragilis. The infected groups (G1- G3) received 103, 105 and 4 × 106D. fragilis/0.5 ml culture, respectively. A control group (G4) only received parasite-free culture. Two weeks post-inoculation all mice were euthanized for histopathological examination. All mice of G3 (100%) and three mice of G2 (37.5%) were infected, and the results were confirmed by PCR and different staining methods. On the other hand, all mice from group G1 showed a completely negative result. Histopathological examination of the colon and caecum of the highly infected group G3 showed active colitis, with infiltration of mixed inflammatory cells such as eosinophils, neutrophils and lymphocytes within the lamina propria of the intestinal wall. The parasite was not invading the colonic mucosa. This study revealed that infection with D. fragilis is dose-dependent. Moreover, a dose of 105D. fragilis/mouse or higher is necessary to infect mice through the oral route. In addition, this route of infection, although non-invasive, can induce severe inflammatory changes to the colonic and caecal mucosa in experimentally infected mice.