Blastocystis in Swiss children: a practical approach

Area of Science:

• Medical Parasitology
• Pediatric Gastroenterology
• Clinical Microbiology

Background:

• Blastocystis is a globally prevalent protozoan parasite with unclear pathogenesis and clinical significance.
• Previous studies highlight the worldwide distribution of Blastocystis but lack consensus on its role in pediatric symptoms.
• The pleomorphic nature of Blastocystis complicates diagnosis and understanding of its clinical impact.

Purpose of the Study:

• To investigate the clinical characteristics of pediatric patients with Blastocystis in northern Switzerland.
• To establish recommendations for clinicians regarding the testing of children for Blastocystis.
• To clarify the association between Blastocystis and specific symptoms in the pediatric population.

Main Methods:

• Retrospective analysis of pediatric patient stool samples tested over a 10-year period in northern Switzerland.
• Analysis of 4047 stool samples from 1887 patients; 240 samples (160 patients) were positive for Blastocystis.
• Correlation analysis between Blastocystis and symptoms such as abdominal pain, diarrhea, and nausea/vomiting, considering chronicity.

Main Results:

• Blastocystis was detected in 160 pediatric patients, with abdominal pain being the leading symptom in 63% of cases.
• A significant correlation was found between Blastocystis and chronic abdominal pain (p < 0.0001), but not with diarrhea or other symptoms.
• Co-infection with other parasites, primarily Endolimax nana, occurred in 26.3% of Blastocystis-positive patients.

Conclusions:

• Blastocystis carriage is frequent, and testing should be reserved for children at risk of symptomatic infection, particularly those with chronic abdominal pain.
• Children with persistent abdominal symptoms (over 4 weeks) should undergo analysis of two distinct stool samples.
• Screening for Blastocystis after travel or immigration is not recommended due to its common carriage and unclear pathogenicity.