Introduction

A delusion of parasitosis is defined as the fixed, false belief of infestation by invisible organisms or fibrous material of unknown origin. The differential diagnosis is true infection, substance use disorder, dementia or other neuropsychiatric disease.

Objectives

Our goal was to characterize delusions of parasitosis, classically named Ekbom syndrome, among individuals attending our emergency department (ED).

Methods

Over a four-year period (2017-2020), we carried out a retrospective case-register study of patients with DSM-5 Ekbom syndrome attending an ED that provides mental health services to an area of nearly 450.000 inhabitants in Sabadell (Barcelona, Spain).

Results

There were 13 eligible patients: 7 were diagnosed for the first time and 6 had multiple episodes. Female-to-male ratio was 1.6:1; average age was 56.9. The most common diagnosis was delusional disorder (n=5;8.5%), followed by schizophrenia (n=3;23.1%) and organic disorders (n=2;15.4%). Origin: Africa (n=5;38.5%), South-America (n=4;30.8%) and Spain (n=4;30.8%). Fifty percent showed poor treatment compliance. Antipsychotics used: risperidone (n=8;61.54%), olanzapine (n=4;30.8%). Five patients received antidepressants. Most patients had previously been seen by other medical specialties (internal medicine, dermatology and hematology). ''Match box sign'': 7 patients (53.8%). Cerebral atrophy was present on brain scan in 4 patients. After discharge: acute psychiatric unit (n=7), outpatient appointments (n=4), day hospital (n=1) and 1 to a psychogeriatric unit.

Conclusions

Delusions of parasitosis are rare in our emergency department. The typical patient is a postmenopausal woman, a visitor or immigrant to Spain. Effective treatment requires a focus on cultural, gender, and age aspects, with close cooperation between psychiatry and other relevant specialties.

Introduction

Treatment response in schizophrenia can be influenced by cultural and ethno-biological factors. However, in delusional disorder (DD), these potential influences have been poorly investigated.

Objectives

This review aims to synthesize what is known about the influence that cultural and biological factors may have on treatment response in DD.

Methods

A systematic review was performed on PubMed from inception to 2020 in keeping with PRISMA directives. Search terms:[(cultural OR ethnic* OR ethno*) AND (treatment OR therap* OR antipsychotic response) AND (delusional disorder)]. We included all studies whose objective was to explore ethno-psychopharmacological aspects of treatment response in DD.

Results

A total of 182 papers were retrieved. Four studies tested ethno-biological factors and 10 reported cultural aspects of treatment response in DD.

1.Cultural hypothesis: 3 studies reported cultural differences in diagnostic practices; in 2 studies, culturally-determined long durations of untreated psychosis (DUP) and comorbidity with mood disorders was associated with response to both antipsychotics (AP) and antidepressants (AD); 3 studies reported that response and AP dose were similar among cultures and that culturally-sensitive psychotherapy improved adherence; 2 studies showed that, where women had poor access to health care, mortality rates were high.

2.Ethno-biological hypothesis: 1 study reviewed moderators and mediators of ethno-specific treatment response; 1 study presented a culture-bound syndrome (Taijin kyofusho) for which AD were found effective; 2 studies in diverse populations found that DD and schizophrenia were both significantly linked to HLA genes.

Conclusions

The sociodemographic profile of DD is consistent across various cultures and, when treated appropriately, responds, but in an ethno-culturally-specific manner.