Blastocystis hominis infection inducing gut microbiome dysbiosis and aggravating Parkinson's disease symptoms: a case report.

An 86-year-old male with Parkinson's disease presented with severe watery diarrhea caused by Blastocystis hominis infection.

• The patient experienced up to six episodes of watery diarrhea per day for 1 month duration.
• Diarrhea was nonbloody and nonmucoid, with no fever, nausea, vomiting, abdominal pain, bloating, loss of appetite, or anal itching.
• Stool sample was examined microscopically using normal saline, revealing Blastocystis hominis cysts; the burden was not quantified.
• A rare white blood cell count was noted in the stool sample.
• Alternative infectious etiologies including Clostridioides difficile and other common infectious pathogens were ruled out.

Treatment with intravenous ciprofloxacin and metronidazole resulted in resolution of diarrhea symptoms within 4 days.

• The patient was started on intravenous ciprofloxacin and metronidazole.
• Improvement in diarrhea consistency and frequency was observed during treatment.
• Complete resolution of diarrhea symptoms occurred within 4 days of initiating intravenous therapy.

The patient reported mild improvement in Parkinson's disease symptoms by the end of hospitalization following treatment.

• The patient self-reported mild improvement in Parkinson's disease symptoms by end of hospitalization.
• Objective neurologic post-treatment scoring, such as the Unified Parkinson's Disease Rating Scale (UPDRS), was not performed.
• The authors note that the reported neurological improvement remains subjective and unverified by standardized assessment tools.

The authors hypothesize that B. hominis infection may transiently worsen Parkinson's disease symptoms through inflammatory or microbiota-mediated pathways, but acknowledge this is speculative.

• No microbiome sequencing was performed, making any microbiota-mediated mechanism speculative.
• The paper states: 'we hypothesize that B. hominis infection may transiently worsen Parkinson's disease symptoms through inflammatory or microbiota-mediated pathways, this remains speculative in the absence of microbiome sequencing or objective neurologic evaluation.'
• The authors call for further studies integrating clinical, microbiological, and microbiome analyses.

The case highlights the need to consider parasitic infections such as B. hominis in Parkinson's disease patients presenting with chronic diarrhea.

• The stool concentration method used was acetylacetate and ether.
• The authors suggest that gut microbiome dysbiosis induced by B. hominis may aggravate Parkinson's disease symptoms.
• Targeted interventions to restore gut microbial balance are proposed as potentially able to 'mitigate disease progression and improve patient outcomes.'