Molecular Detection and Subtype Characterization of Blastocystis spp. in Symptomatic Children Using PCR and Sequencing.

BACKGROUND: Blastocystis spp. is a globally distributed intestinal protozoan that infects humans and various animals. This protozoan is a common pathogen among humans and animals and can be transmitted from animal species to humans. Therefore, the present study aimed to identify and characterize Blastocystis sub-types in children with gastrointestinal symptoms using PCR and sequencing. METHODS: Overall, 150 stool samples were collected from children referred to academic hospitals in Mashhad, Iran over a period of seven months in 2020. Participants were divided into two groups: symptomatic cases (n = 50) and asymptomatic controls (n = 100). DNA was extracted from Blastocystis-positive samples and analyzed by PCR followed by sequencing for subtype identification. RESULTS: Blastocystis spp. was found in 6 (12%) of the symptomatic children and 7 (7%) of the asymptomatic group. All isolates from symptomatic cases belonged to subtype ST1, whereas isolates from the control group included ST1, ST2, ST3, and ST7. ST1 was the most frequently detected subtype overall. Among symptomatic children, abdominal pain was the most frequent symptom. CONCLUSION: ST1 was the predominant subtype in both symptomatic and asymptomatic children, though it was the only subtype observed in symptomatic cases. These findings suggest a potential link between ST1 and gastrointestinal symptoms. Further studies with larger populations and in diverse geographic regions are warranted to investigate the clinical significance and distribution patterns of Blastocystis subtypes.