Bridging perception and reality: Parasitic identification in delusional parasitosis

Delusional parasitosis (DP) is a psychiatric condition in which individuals hold a fixed, false belief that they are infected with parasites. These patients frequently consult parasite clinics and submit household or biological debris, often nonparasitic in origin, for parasitological examination. Although parasitologists are not directly responsible for treating this psychiatric disorder, they play a key role in identifying or excluding parasitic infections and guiding appropriate care. Misidentification of artifacts as parasites may result in unnecessary treatment, prolonged distress, and, in some cases, delayed diagnosis of DP. Thus, this study examined specimens submitted for parasitological diagnosis with the aim of assessing diagnostic accuracy and evaluating the role of laboratory confirmation in managing suspected parasitic infections.

This retrospective study analyzed 382 clinical specimens submitted for parasitological examination to the Department of Helminthology, Faculty of Tropical Medicine, Mahidol University (June 2014-June 2022). All specimens were examined macroscopically and microscopically using standard parasitological techniques.

Parasitic infections were present in 108 (28.3%) specimens, including nematodes, cestodes, and trematodes, such as Trichuris trichiura, Enterobius vermicularis, hookworm, and Taenia spp. The remaining 274 (71.7%) specimens included negative fecal specimens and specimens comprising various artifacts, such as food residues, plant materials, synthetic fibers, skin flakes, and other debris. This study was concurrently performed using outpatient data obtained from the Parasite Excellence Clinic, Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University. Notably, 84 patients were ultimately diagnosed with DP.

Accurate parasite identification is crucial to ensure proper treatment in true parasitic infections and prevent DP misdiagnosis. This study highlights the importance of an integrated parasitology-psychiatry approach, particularly when patients present with persistent symptoms despite negative laboratory test results. These findings support the establishment of diagnostic protocols and improved interdisciplinary communication to enhance care for patients with suspected parasitic infections.