Folie a Famille: Delusional parasitosis affecting all the members of a family

INTRODUCTION

Delusions of parasitosis (DP) or Ekbom syndrome is a psychiatric disorder in which the patient has a fixed, false belief that he or she is infested by parasites. These patients generally reject psychiatric referral or treatment and often present to a dermatologist because they are convinced of having a dermatological problem.[1],[2]

DP can manifest as a shared psychotic disorder,[3] a type of ′folie a deux′. This is a rare condition where members living with the patient also share the false belief. The essential feature of this condition is a delusion that develops in an individual who is involved in a close relationship with another person termed as the "inducer" or "primary case". The relationship is usually a prolonged one, often unhealthy and the affected members live in relative social isolation.[4] Folie a famille, where all the members of a family share the delusion, is an especially rare disorder.[5]

We present here a family with folie a famille who consulted a dermatologist for pruritic skin lesions. The report is made for the rarity of this interesting psychodermatologic disorder.

CASE REPORT

A 44-year-old man presented to the dermatologist with a six-year history of itchiness over the arms, abdomen and back. He had consulted a number of physicians but experienced temporary relief with anti-scabies treatment and steroids. Examination revealed itchy erythematous papules over the trunk and limbs. No primary dermatological diagnosis was made. Investigation revealed no infection or infestation.

The patient revealed that his wife as well as his two daughters aged 18 and 16 years also suffered from similar complaints for many years. All the family members had skin lesions similar to the index case. The skin complaint started first in the wife after she developed a delusion of persecution that certain people (her neighbors and relatives) were out to harm her and the family. She believed that her "persecutors" inflicted a worm infestation on her and the other members of the family that resulted in their skin lesions. The husband and the two daughters also subscribed to this delusion.

The psychiatrist diagnosed paranoid disorder in the wife and shared psychotic disorder in the other members of the family. The wife was described as the dominant partner who decided all the activities of the family members as well as influenced their attitudes. The daughters shared a symbiotic relationship with the mother and an unhealthy bonding with the father. There was growing social isolation of the family from the social network of neighbors and relatives. The father, along with his children, did not support the wife′s beliefs initially but later shared her delusional thinking. The mother had refused all treatment right from the outset and the family also joined her in refusing to take any psychiatric treatment. Concerted efforts by the dermatologist and the psychiatric team to get the family to understand the need for medication or even counseling were futile.

DISCUSSION

DP can present as the sole psychiatric symptom or it may be associated with an underlying psychiatric disorder.[6] It occurred as a part of a paranoid disorder in the primary case here. There have been a number of reports from India on DP.[7] The occurrence of this disorder as a shared psychotic disorder is an uncommon phenomenon. Only about 5 to 15% of such cases were found in an analysis of 1223 case reports.[8] We did not find any earlier report on this phenomenon involving all the family members.

The abnormal emotional bonding and interaction observed among the affected members of this family was described.[5] In our case, the primary case was the wife, the dominating member of the family. The husband and children were submissive, socially and culturally isolated and were drawn into sharing the delusion of the primary patient. The refusal to take any psychiatric treatment was often reported among patients with DP.[2] In our case this went further as the "primary" case influenced the refusal of treatment by other members of the family as well.

The occurrence of pruritic skin lesions simultaneously in all members of a family is common. But the absence of any specific dermatological disorder and history of failure with dermatological treatments should arouse the suspicion of some rare psychogenic disorder, as we experienced with this family.