Delusional Infestation: State of the Art.

Patients with a delusional infestation (DI) have an overwhelming conviction that they are being infested with (non) pathogens without any medical proof. The patients need a systematic psychiatric and dermatological evaluation to assess any possible underlying cause that could be treated. Because they avoid psychiatrists, a close collaboration of dermatologists and psychiatrists, who examine the patient together, seems to be a promising solution. It helps to start a trustful doctor-patient relationship and motivates the patient for psychiatric treatment. We here review diagnostic criteria, classification of symptoms, pathophysiology and treatment options of DI. Antipsychotic medication is the treatment of choice when any other underlying cause or disorder is excluded. Further research is needed to assess the pathophysiology, and other treatment options for patients with DI.

Patients labeled with delusions of parasitosis compose a heterogenous group: a retrospective study from a referral center.

BACKGROUND: There are few diagnostic tools available to the dermatologist to help in the diagnosis of patients with delusions of parasitosis (DOP). OBJECTIVE: We sought to find differences in presentation and clinical course between patients who received a final diagnosis of DOP and those who received a final diagnosis of a primary medical condition or other psychiatric disorder. METHODS: We performed a retrospective chart review of patients referred with a diagnosis of DOP. Each patient received a final consensus diagnosis. RESULTS: In all, 47 patients were included in the study. Patients reporting bugs were more likely to be given a final diagnosis of delusional disorder or found to have a medical diagnosis, whereas patients noting fibers were more likely to have a somatoform disorder. A review of systems can be helpful in making a final diagnosis. Patients referred to the clinic for DOP were 300 times more likely to require a physician to contact the hospital's legal counsel compared with other patients in the practice. LIMITATIONS: The retrospective nature of the study resulted in limited laboratory testing and psychiatric evaluation in some patients. Many of the patients may have been inappropriately referred to the DOP clinic because of other psychiatric comorbidities. CONCLUSION: Patients referred to this practice as "delusional" had a heterogeneous final diagnosis. The chief symptom of the patient was predictive of the patient's final diagnosis. The use of written questionnaires may be helpful. These patients have a greatly increased risk of requiring the physician to seek legal counsel.

Delusional infestation and the specimen sign: a European multicentre study in 148 consecutive cases.

BACKGROUND: Systematic studies of delusional infestation (DI), also known as delusional parasitosis, are scarce. They lack either dermatological or psychiatric detail. Little is known about the specimens that patients provide to prove their infestation. There is no study on the current presentation of DI in Europe. OBJECTIVES: To determine the number of true infestations, to assess with which pathogens patients believe themselves to be infested, and to gather details about the frequency and nature of the specimens and the containers used to store them, based on European study centres. METHODS: Retrospective study of consecutive cases with suspected DI from six centres (Dermatology, Psychiatry, Tropical Medicine) in four European countries (U.K., Germany, Italy, France). RESULTS: In total, 148 consecutive cases of suspected DI were included, i.e. the largest cohort reported. None of the patients had evidence of a genuine infestation, as shown by examinations by dermatologists and/or infectious disease specialists. Only 35% believed themselves to be infested by parasites; the majority reported a large number of other living or inanimate (17%) pathogens. Seventy-one patients (48%) presented with what they believed was proof of their infestation. These specimens were mostly skin particles or hair, and rarely insects (only very few of which were human pathogenic or anthropophilic, and none of these could be correlated with the clinical presentation), and only 4% were stored in matchboxes (three of 71). CONCLUSIONS: This first multicentre study of DI in Europe confirms that the term 'delusional infestation' better reflects current and future variations of this entity than 'delusional parasitosis'. The presentation of proofs of infestation, commonly referred to as 'the matchbox sign', is typical but not obligatory in DI and might better be called 'the specimen sign'.

Delusions of parasitosis of the eyelids.

The authors describe preseptal cellulitis and corneal ulceration due to secondary infection of self- inflicted wounds in a patient with delusions of parasitosis. A 42-year-old man presented with a 3-day history of progressive painful, purulent, periocular erythema. He reported that "little black bugs and whitish eggs" had infiltrated his body including the left eye and eyelids. On examination, he was agitated with superficial wounds covering the majority of his body. Ophthalmic evaluation was notable for markedly erythematous and mildly edematous eyelids resulting in complete blepharoptosis. Excoriations with yellow-brown serous crusting carpeted the periocular region. A 1-mm pericentral corneal ulcer was also noted. No objective evidence of parasites was found and his infection resolved with antibacterial therapy (intravenous ceftriaxone and vancomycin, and topical vancomycin and ceftazidime). Delusions of parasitosis may result in self-mutilation with secondary infection. Appropriate psychiatric care is needed to prevent ongoing destructive behavior.

Delusional parasitosis: a new pathway for diagnosis and treatment.

Delusional parasitosis is an uncommon disorder that presents particular challenges to the dermatologist. Patients often resist psychiatric referral. Evidence of efficacy of treatment options is generally weak, but some studies exist. By identifying whether the disorder is primary or secondary to another illness, by attempting to involve the liaison psychiatry team if possible and by treating the patient with a modern antipsychotic, remission is achievable. A pathway for diagnostics and therapy is presented. Treatments of choice are 'atypical' or second-generation antipsychotics such as amisulpride, risperidone or olanzapine in age-appropriate doses. Pimozide is no longer the treatment of choice, owing to a higher risk of adverse drug reactions and lower concordance. In some cases, depot antipsychotics can be considered. For diagnostics and treatment, close collaboration of dermatologists and psychiatrists is recommended.

Delusional parasitosis [abstract]

Delusional parasitosis is a rare psychiatric syndrome in which the patient believes that he/she is infested with parasites despite clear evidence to the contrary. It was first described in the literature about 100 years ago when it was referred to as psychogenic parasitosis. It can occur in the form of a delusional disorder of the somatic type (DSM IV) but it has also been reported in schizophrenia, affective or organic psychosis or induced psychosis. Patients with delusional parasitosis generally think that mites, lice or other insects have invaded their skin and most frequently seek treatment from dermatologists or family practitioners. It is a chronic disorder that may occur at any age but is more common in the elderly, particularly in females. The patient may try to pick the parasites out of the skin causing cutaneous lesions. Treatment is based on antipsychotic agents, psychotherapy and cooperation between dermatologist and psychiatrist. A case of delusional disorder of the somatic type (DSM IV) in a 55-year-old male is described. The patient sought medical attention because he strongly believed that his skin was infested with mites for three years. He tried to pick mites out of the skin of his face, neck, abdomen and back and this caused severe keloid formation. He was first seen by a dermatologist whose clinical and laboratory investigations for parasitic infestations were negative. After investigation, the patient was referred to the psychiatrist. Haloperidol was prescribed and there was good response to antipsychotic treatment. The delusional symptoms improved over the first three months and then a full recovery was observed. The patient maintained the recovery at one-year follow-up. (AU)

Suspected intestinal myiasis due to Dryomyza formosa in a Japanese schizophrenic patient with symptoms of delusional parasitosis.

A third-stage larva of Dryomyza formosa (Wiedemann) (Diptera: Dryomyzidae) was found in the fresh stool of a 27-year-old Japanese woman resident of Shiobara, 150 km north of Tokyo, on 16 November 1998. This is the first record of myiasis due to Dryomyza. Detection of this maggot (2cm long) by the patient herself was associated with her longstanding delusion of abdominal parasitosis as a symptom of chronic schizophrenia. Circumstantial evidence agreed with this being a genuine case of intestinal myiasis, apparently due to accidental ingestion of the insect, with no signs that the patient had contrived the report, nor that the maggot had invaded the stool post-defaecation. This case draws attention to the likelihood that some personality states are predisposed to noticing and reporting myiasis, when it occurs. We review other conditions (mental and physical) that are more prone to myiasis.