Blastocystis Genetic diversity in animal and human samples from different departments of Colombia using complete sequencing of the 18S rRNA gene (SSU rRNA) by Oxford Nanopore

Blastocystis is a common protozoan present in gut microbiota of both animals and humans, exhibiting a global distribution. This protist has raised attention due to its association with gastrointestinal symptoms in humans and pertinent public health implications. This study explores Blastocystis frequency, distribution, and subtype diversity in distinct hosts across specific areas of Colombia. The investigation involved collecting 111 human stool and 277 animal fecal samples, followed by DNA extraction and PCR-based detection. Subsequently, full-length 18S SSU rRNA Next-Generation Sequencing (NGS) was performed. Results showed widespread Blastocystis distribution, with 48.1% in humans and 31.4% detection in animals. Dogs, cats, sheep, pigs, and zoo animals tested positive, aligning with global prevalence patterns. Although, subtype distribution varied between hosts and regions. Subtypes ST1 to ST3 appeared in both human and animal hosts. Their presence in animals like pigs and zoo animals emphasizes zoonotic transmission concerns. ST2 was identified just in humans samples in Bolivar, indicating host-specific preferences regions. Distinct subtypes (ST5, ST10, ST14, ST15, ST21, ST24, ST25, ST26) were exclusive to animals, suggesting host-specific reservoirs. Mixed infections, where multiple subtypes coexist, occurred in animals and humans, revealing genetic diversity could be influenced by gut microbiota, immune responses, and environment factors. In conclusion, this study elucidates Blastocystis prevalence and subtype diversity in Colombia. Findings highlight zoonotic transmission potential, diverse subtype coexistence, and regional subtype preferences. Further research is essential for understanding transmission dynamics, health consequences, and intervention strategies for Blastocystis infections in animals and humans.