Psychological interventions in the treatment of delusional parasitosis: a brief review

This review synthesized evidence on the most up-to-date treatment outcomes in patients with delusional parasitosis and examined the impact of incorporating psychological interventions in conjunction with psychiatric treatment. The reporting of this review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. PubMed and Google Scholar were searched between 2013 and 2023. Nine studies were included in this review. Partial remission was observed across all cases, irrespective of the treatment approach employed. Complete remission was limited to only three studies. No correlation was observed between the incorporation of psychological intervention in conjunction with psychotropic medication and an enhanced remission outcome. The findings underscore the importance of psychotropic medication as a fundamental component in the treatment of delusional parasitosis. The results highlight that although first- and second-generation psychotropic medications are the mainstay treatment options, they nevertheless play a limited role because of the patients' steadfast delusions of infestations.

A case series of shared delusional infestation: folie à deux revisited

Delusional infestation describes the unshakeable belief that one's skin is infected or infested with an external organism or inanimate material, in the absence of supportive medical evidence. It is one of the most challenging psychodermatological conditions to manage, given the rigidity of patients' physically focused health beliefs, and the competing need to introduce antipsychotic therapy to bring about resolution. This is rendered exponentially more complex when partners or family members are similarly afflicted. This situation is known as shared delusional infestation, shared psychotic disorder (SPD), or folie à deux. We present a series of three couples with SPD who were referred to our tertiary psychodermatology service during the same year. On examining the literature we were intrigued to discover that subtly different subtypes of SPD have been recognized since the late 1800s. These include folie simultanée, imposée, communiquée and induite. Our cases neatly demonstrate three of these variants, and highlight the difficulties in facilitating effective treatment.

Longer Duration of Untreated Psychosis is Associated with Poorer Outcomes for Patients with Delusional Infestation

We examined the association between the duration of untreated psychosis and outcome for patients with delusional infestation. This multi-centre international study included 211 consecutive patients. Illness severity was evaluated at first presentation and outcome was measured with the Clinical Global Impression scale (CGI) at baseline and follow-up. A regression analysis showed a clear clinical and statistically significant association between shorter duration of untreated psychosis and better outcome at follow-up. Patients with a duration of untreated psychosis of less than one year showed a CGI-S change from 5.37 to 2.07; those with a duration of untreated psychosis of 1-5 years a change from 5.48 to 2.59, and those with a duration of untreated psychosis of >5 years a change from 5.59 to 3.37. This difference of 1.1 CGI points between the groups resembles a clinically relevant difference in patient outcome. Our results suggest that longer duration of untreated psychosis in patients with delusional infestation is associated with significantly less favour-able clinical outcomes.

Delusional Infestation: Perspectives from Scottish Dermatologists and a 10-year Case Series from a Single Centre

Perceptions of the clinical management of delusional infestation (DI) were compared with clinical outcomes in this 10-year case series from a single centre in Dundee, UK. An online questionnaire (survey-monkey, a TM brand of online survey available for free for basic use) was sent to Scottish Dermatologists to gauge their opinions and confidence in the management of DI. Also, a retrospective review of medical case notes of patients seen by dermatologists in one institution was undertaken and clinical outcomes were reported by patients' general practitioners (GP). The survey showed that 61% of responding dermatologists encountered 1-5 cases of DI per year. Twenty-four percent respondees were 'confident' in managing patients with DI, 54% were 'somewhat confident'. Forty-seven patients (62% female, 70% single) were seen over the 10 years; 43% brought a self-collected specimen to clinic, 68% of patients had a psychiatric comorbidity, 23% of patients had primary DI and 11/47 (23%) were seen by a psychiatrist. Clinical outcomes as rated by patients' GPs were reasonable or good in 2/3 patients. A poor outcome was seen in 12 patients and associated with chronic pain in 50% (p < 0.01) and psychiatric comorbidity in 100% (p < 0.01). We conclude that good outcomes can be achieved in some patients with DI without psychiatric input and without psychoactive treatment.

[Nosographic considerations on delusional parasitosis based on three clinical observations]

Ekbom syndrome or delusional parasitosis is a rare disease characterized by the unwavering conviction of having cutaneous infestation of insects or parasites. This is a monothematic delusion of hallucinatory origin that typically affects older women. We report the case of three patients with delusional parasitosis in different clinical settings. The first patient suffered from isolated delusional parasitosis corresponding to the condition described by Karl Ekbom. The second case suffered from secondary delusional parasitosis, occurring in the setting of leukoencephalopathy (CADASIL). Lastly, the third patient appeared in a state which was evocative of a depressive episode with psychotic symptom integrating delusional parasitosis. These three clinical vignettes perfectly illustrate the trans-nosographic dimension of this syndrome and the difficulties in treating these patients, both in terms of therapeutic alliance and of choice of pharmacological treatment.

Delusional Infestation and Chronic Pruritus: A Review

The literature on chronic pruritus, paresthesia and delusional infestation indicates that a wide variety of conditions ranging from AIDS to vitamin deficiencies may cause these symptoms. In many, or perhaps most of these cases, activation of itch pathways seems to be the underlying cause of the skin sensations and perhaps even the visual hallucinations characteristic of delusional infestation. The principle difference between diagnoses of chronic pruritus and delusional infestation appears to lie in the patient's interpretation of the cause of the symptoms, rather than underlying physiological differences. Delusional infestation, paresthesia and chronic pruritus must be considered symptoms of underlying conditions.