Molecular Characterization of Blastocystis from Animals and Their Caregivers at the Gdańsk Zoo (Poland) and the Assessment of Zoonotic Transmission

SIMPLE SUMMARY: Blastocystis is one of the most common microorganisms living in the intestines of humans and various animals worldwide. Although the presence of this microorganism does not cause any ailments in many people, in some others Blastocystis is a source of various gastrointestinal disorders, such as abdominal pain, nausea, diarrhea, constipation, flatulence, or lack of appetite, as well as extraintestinal complaints, such as itching and skin rash. Transmission of Blastocystis is possible by direct contact with contaminated individuals, and by consuming water or food contaminated with cysts. It has been suggested that contact between animals and humans may pose a risk of human Blastocystis infection. In our study, we compared Blastocystis isolated from zoo animals and their keepers. The detection of identical sequences of Blastocystis in three monkeys and the man who looked after them showed that transmission of this microorganism between non-human primates (NHPs) and humans is possible under favorable conditions. Our research has shown that further investigation of animals and their in-contact humans is needed to better understand the transmission of Blastocystis between animals and humans and to find out which animals pose a risk of human infection, and to what extent. ABSTRACT: Blastocystis is a highly genetically diverse gut protist commonly found in humans and various animals. The role of animals in human infection is only partly understood. The aim of this study was to determine the host specificity and possibility of zoonotic transmission of this microorganism. Subtypes of Blastocystis isolated from 201 zoo animals and their 35 caregivers were identified by sequencing of the SSU rRNA gene. Blastocystis was found in 26.86% of animal and 17.14% of human samples. Both mammalian (ST1–ST3, ST5, ST8, ST10, ST13, ST14) and non-mammalian subtypes were detected. Of the subtypes found in non-human primates (ST1, ST2, ST3, and ST13), two subtypes (ST1 and ST3) were also detected in humans. The presence of identical ST1 sequences in three monkeys and their caregiver indicates the possibility of direct transmission of Blastocystis between these animals and humans. Detection of ST5 only in wild boars and peccaries, ST8 only in Marsupial, ST10 and ST14 only in Bovidae, and non-mammalian subtypes in reptiles suggests higher host specificity for these subtypes, and indicates that their transmission between animals and humans is unlikely. Additionally, this was probably the first time that ST5 was found in peccaries, ST2 in patas monkeys, and ST8 in red kangaroos.