Treatments for primary delusional infestation

People with delusional infestation (DI) believe themselves to be infested with an unknown pathogen (may be described as worms, mites or insects), manifesting as itch or crawling sensations. Through repeated self-examination, cleansing routines, or attempts to capture the agent, patients will cause skin lesions, perpetuating the belief of ongoing infestation. People with DI will seek the advice of general practitioners or specialist physicians (e.g. dermatologists and microbiologists) but tend to avoid seeking psychiatric advice.

DI has two main forms: primary (a disorder characterised by delusions and abnormal tactile sensations); and secondary (symptoms caused by another defined organic or pre-existing psychiatric disorder, or substance abuse). This review is concerned with primary DI. There is no definite cause of primary DI and no current licensed treatment options. Treatments that have been reported in the literature include pharmacological (e.g. antipsychotic medication) and non-pharmacological (e.g. talking therapy) options.

The aim of this review was to evaluate the effectiveness of treatments for primary DI compared with placebo. In March 2019 we ran a search of Cochrane Schizophrenia's register of trials for relevant studies, but found none. The review authors could not, therefore, comment about the effects of current treatments for primary DI. The authors call for more well-conducted randomised trials in this area.

Authors' conclusions: 

Currently there is no evidence from RCTs available to compare treatment of primary DI with placebo. We cannot, therefore, make any conclusions regarding the effects of treatments (pharmacological or non-pharmacological) for primary DI. This lack of evidence for treatment of primary DI has implications for research and practice. Robust randomised trials are indicated.

Read the full abstract...
Background: 

Primary delusional infestation (DI) is a primary psychiatric disorder characterised by delusions and abnormal tactile sensations. The pathophysiology is undecided and treatment includes both pharmacological and non-pharmacological options. There is currently no Cochrane Review of the treatments used. Primary DI is a diagnosis often encountered by both dermatologists and psychiatrists, with a large associated disease burden.

Objectives: 

To evaluate the effectiveness of different treatments in primary delusional infestation (DI).

Search strategy: 

On 24 December 2014 and 19 March 2019, we searched the Cochrane Schizophrenia Group’s Study-Based Register of Trials including registries of clinical trials.

Selection criteria: 

Randomised controlled trials involving the treatment of adults with primary DI.

Data collection and analysis: 

Two review authors independently screened and assessed studies for inclusion using pre-specified inclusion criteria.

Main results: 

We did not identify any studies for inclusion.

Share/Save