Diagnostic Features of Blastocystis Life Cycle Forms in the Small Intestine in an HIV-Infected Patient

Area of Science:

• Medical Parasitology
• Gastroenterology
• Immunocompromised Host Research

Background:

• Blastocystis spp. are common intestinal parasites affecting various hosts, including humans.
• While often asymptomatic in immunocompetent individuals, Blastocystis is increasingly recognized as a cause of diarrhea in immunocompromised patients, such as those with HIV.
• At least six distinct life cycle stages of Blastocystis have been identified in stool and culture.

Purpose of the Study:

• To document the histological features of Blastocystis infection in an adult human immunodeficiency virus (HIV)-infected patient presenting with gastrointestinal symptoms.
• To correlate parasitological and molecular findings with histological observations in the duodenal tissue.

Main Methods:

• Stool samples were analyzed using standard parasitological techniques and polymerase chain reaction (PCR) for Blastocystis detection.
• Duodenal biopsy specimens were examined histologically to identify parasite forms and inflammatory responses.
• DNA sequencing was performed to determine the Blastocystis subtype.

Main Results:

• Parasitological examination of stool revealed vacuolar, granular, cyst, and multi-vacuolar forms of Blastocystis.
• PCR confirmed the presence of Blastocystis DNA, with sequencing identifying subtype ST1.
• Histological analysis of duodenal biopsies showed an inflammatory infiltrate composed of plasma cells and lymphocytes.
• Four distinct Blastocystis forms—cyst, granular, ameboid, and multi-vacuolar—were identified within the duodenal lumen and on the brush border of enterocytes.

Conclusions:

• This study presents the first reported histological evidence of four distinct Blastocystis life cycle forms (cyst, granular, ameboid, multi-vacuolar) in histological sections from the lumen and enterocyte brush border.
• The findings highlight the potential for Blastocystis to cause duodenal inflammation and tissue-level pathology in HIV-infected individuals.
• Further research is warranted to understand the clinical significance and pathogenic mechanisms of different Blastocystis subtypes in immunocompromised populations.