Frequency and Subtypes of Blastocystis in Patients with Diarrhea in Van, Türkiye

Abstract

Background: This study aimed to investigate the prevalence of Blastocystis in patients with diarrhea in the Van region of Türkiye and identify the predominant Blastocystis subtypes in these individuals.

Methods: A total of 200 volunteers, including 100 diarrheal patients (patient group) and 100 healthy individuals (control group), were enrolled in the study. Samples were evaluated microscopically (native-Lugol) and via polymerase chain reaction (PCR). Sequence analysis was performed on PCR amplicons of the positive samples to identify the subtypes.

Results: Blastocystis spp. was detected in 20% (20/100) of the patient group and 16% (16/100) of the control group (p = 0.461). The prevalence of Blastocystis spp. was higher in women in the patient group (21.6%) and in men in the control group (20.7%). The highest positivity rates were observed in individuals aged 11–18 years, with 40% in the patient group and 21.4% in the control group. However, no statistically significant differences were found between the patient and control groups regarding age and sex. A significant difference in Blastocystis spp. positivity was observed between the 0–18 (23%) and 19+ (10.3%) age groups (p = 0.013). There was no statistically significant relationship between gastrointestinal symptoms, such as abdominal pain, fever, nausea, and vomiting, and Blastocystis spp. positivity. Analysis of the diarrheal patients revealed the presence of subtype 1 (ST1) (71.4%) and ST2 (28.6%) genotypes.

Conclusion: No statistically significant relationship was found between Blastocystis spp. positivity and gastrointestinal symptoms, despite the pathogenicity and pathogen-subtype relationship of Blastocystis spp. remaining controversial. Among the subtypes typically associated with symptoms in previous studies, ST1 was dominant in the diarrheal patients herein. Considering these findings, the dominance of ST1 in diarrheal patients supports the subtype-pathogenicity relationship; however, further studies involving a large number of symptomatic and asymptomatic individuals are needed to clarify this issue.