Introduction:
Blastocystis is a genetically diverse unicellular parasite that colonizes the intestines of humans and a wide range of animals. The organism’s basic biology is poorly understood, and controversy surrounds its taxonomy and pathogenicity. Although just three morphological forms—vacuolar, granular, and ameboid—have been identified, recent research has discovered more forms—cyst, avacuolar, and multivacuolar [1].
The organism is categorized as a stramenopile based on molecular evidence, similar to diatoms, chrysophytes, water molds, and slime nets [2].
It is customary to refer to Blastocystis organisms isolated from humans as B. hominis. However, due to low host specificity and significant genetic variation, the name Blastocystis species is thought to be more suitable. The subtype (ST), if genetic typing is performed, should also be recorded. Among the nine STs identified in humans, the four most common are ST1, ST2, ST3, and ST4. Several other STs might be connected to zoonotic transmission [2].
Infections occur worldwide in both immunocompetent and immunodeficient individuals. Blastocystis may be transmitted through food, water, or contact with human or animal feces. It is more common among people who live in or travel to developing countries and those who work with animals. B. hominis infection typically causes non-specific symptoms such as watery diarrhea, nausea, abdominal pain, bloating, excessive gas, loss of appetite, weight loss, anal itching, and fatigue. Metronidazole is advised as the antibiotic of choice if therapy seems necessary, despite reports of its inability to completely eradicate the organism [1].
Case reports have suggested a pathogenic role of B. hominis in causing intestinal inflammation and linking it to irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) [3].
This case report explores the relationship between Blastocystis hominis and its potential exacerbation of Parkinson’s disease symptoms through gut microbiota dysbiosis. By examining the case of an elderly male with Parkinson’s disease who developed severe gastrointestinal symptoms alongside worsening motor function, we aim to shed light on how microbial disturbances in the gut may influence neurological conditions, offering insights into potential therapeutic avenues.