Hallucinations as the Primary Presenting Feature in "Folie à Famille": A Case Report.

Shared psychotic disorder (SPD) is a rare phenomenon. This case report describes a 60-year-old man (primary subject) who first developed visual hallucinations, which he claimed to see small, white insects, thread-like, about half a centimeter, emerging from the folds of his wife's skin near the elbow crease, wriggling, and then vanishing. Following his persistent suggestions, his wife (secondary subject) and later their son also developed similar hallucinations. Subsequently, delusion of parasitosis developed secondary to hallucinations in all of them. The family lives in a sparsely populated locality in close association with each other, and mostly stay indoors. The family holds strong traditional health beliefs. On detailed evaluation, no history of prior mental disorders was noted. Physical examination revealed no signs of infestation at the reported sites, and investigations did not indicate any underlying medical condition. The symptoms subsided significantly after treating them with risperidone (up to 6 mg) and trihexyphenidyl (2 mg) over a period of four weeks. This case highlights the occurrence of hallucinations as the primary symptom in folie à famille, followed by the development of delusions of parasitosis. The existing literature on folie à famille is limited, and this case report will encourage further research to clarify the exact phenomenology of this rare presentation.