Detection and molecular identification of Blastocystis isolates from humans and cattle in northern Egypt.

Blastocystis is one of the less well-understood waterborne protozoa of medical and veterinary importance. The present study aimed to detect, identify, and subtype Blastocystis in cattle and humans in northern Egypt and to investigate the potential for zoonotic transmission. Fecal samples were collected from 136 humans (68 in contact with animals and 68 no animal contact) and 190 cattle from a rural area in Kafr El-Sheikh Province, Egypt. All samples were microscopically examined by direct wet mount technique and cultured in Jones' medium. Genomic DNA was extracted from positive cultures. A region of the Blastocystis small subunit ribosomal ribonucleic acid (SSU rRNA) gene was amplified using PCR. Blastocystis subtypes were identified by sequencing of the amplified SSU rRNA gene. The relatedness of sequence types obtained in this study and others submitted in GenBank was compared according to their genetic relatedness. Out of 136 human and 190 cattle samples, Blastocystis was detected in 53 (38.9%) and 37 (19.4%), respectively using either culture or direct wet mount. Blastocystis SSU rRNA gene was amplified in 55 samples (32 humans and 23 animals). Six subtypes were identified (STs 1-3 in humans and ST4, ST10 and ST14 in cattle) and were distinguishable with inter (up to 0.075) and intra (up to 0.024) subtype variations. A close phylogenetic relationship between human and animal isolated STs 1-4 was demonstrated. To the best of our knowledge, this is the first study to investigate the the potentiality for zoonotic transmission of certain Blastocystis subtypes in northern Egypt. © Indian Society for Parasitology 2021.