Folie à Trois: Itching for an Answer: 1828

The patient is a 24 year-old woman with no remarkable medical history who had first contacted her primary care provider in December 2016 with concerns for possible infection after learning of her sister's diagnosis of pinworms having had shared sleeping quarters with her in November 2016. Her sister had been diagnosed with pinworms via a tape test and approximately 2 weeks after diagnosis the patient began to complain of rectal and vaginal itching. The patient had taken pyrantel as well as her first dose of albendazole prior to referral to Gastroenterology (GI) - at which time her symptoms persisted day and night and the patient reported pinworms passed in her stool. Upon first meeting with GI, she noted her mother also had an infection with pinworms. Later in mid-December, the patient received a second dose of albendazole and vaginal exam demonstrated no pinworms with culture/Gram stain showing moderate Gardnerella and clue cells indicative of bacterial vaginosis (BV). For persistent symptoms, she underwent a colonoscopy in January 2017 with ileal and colonic biopsies negative for organisms. After, she had seen a number of other physicians who could not confirm pinworms. She received another dose of mebendazole and began treatment for BV with metronidazole which provided no relief. Upon presentation in February, the patient's symptoms grew worse and her twin sister as well as mother reported recurrent perianal/vaginal symptoms. Despite a negative work-up, all three women were convinced they were suffering from parasitic infection. An infection with pinworms, Enterobius vermicularis, has classically been diagnosed via the “scotch tape test” or measures akin to this including assessment with an adhesive paddle to visualize pinworm eggs. Once diagnosed, treatment is pursued with pyrantel pamoate, albendazole, or mebendazole. Delusional infestation (DI) is considerably rare and often presents with sensations of formication. Patients have been noted to bring in specimens to consultation (“specimen sign”) and in approximately 8-12% of cases, patients have been observed to induce their belief onto a family member or close contact (folie a famille/folie a deux). DI can be challenging for both patients and care providers given the symptoms can be distressing enough to impact quality of life while making their healthcare difficult to navigate. Treatment for DI can be successful and is typically achieved with antipsychotics.