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 Table of Contents    
Year : 2018  |  Volume : 60  |  Issue : 2  |  Page : 254-255
A case of delusional parasitosis responded to blonanserin

Department of Psychiatry, University College of Medical Sciences and G.T.B. Hospital, Delhi, India

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Date of Web Publication17-Aug-2018

How to cite this article:
Rathi A, Bhatia M S. A case of delusional parasitosis responded to blonanserin. Indian J Psychiatry 2018;60:254-5

How to cite this URL:
Rathi A, Bhatia M S. A case of delusional parasitosis responded to blonanserin. Indian J Psychiatry [serial online] 2018 [cited 2022 Dec 2];60:254-5. Available from:


Delusional parasitosis is characterized by delusion of being infested by pathogens without any medical or microbiological evidence.[1] It has variously been described as entomophobia, parasitophobia, dermatozoenwahn, Ekbom's syndrome, parasitophobic neurodermatitis, and delusional parasitosis.[1],[2] It can occur secondary to dementia, psychosis, or medical conditions such as Vitamin B12 deficiency, pellagra, severe renal disease, diabetes mellitus, multiple sclerosis, hepatitis, cerebrovascular disease, temporal lobe epilepsy, and leprosy.[3],[4] We report the case of a patient of delusional parasitosis of leg who responded to blonanserin, a new atypical antipsychotic.

A 34-year-old, Hindu, high school passed, married male, working in an electronic shop, belonging to middle socioeconomic background, was referred from dermatology department with a 1-year history of feeling of an insect crawling across his both legs during the night, which he attributed to infestation of bedding by insects. He had washed all the beddings of the house numerous times, resorted to sleeping only in undergarments, and used insecticides and mosquito repellent creams for removing insects, but felt no relief. On examination, he was found to have intertrigo (candidal infection) of the axilla and groin but no evidence of any parasitic infestation. He was prescribed 1% clotrimazole cream for topical application, tablet fluconazole 150 mg weekly, and tablet cetirizine 10 mg at bedtime for intertrigo. After 2 weeks of treatment, his intertrigo resolved, but this complaint of crawling of insect across his lower limbs persisted, for which he was referred to the department of psychiatry.

Detailed assessment revealed preoccupation with the complaint that there is an insect which crawls over his lower limb. There had been no change in the symptoms since the onset. He said that he was unaware of the source of infestation but believed that it might be present in the bedding, but was not sure as his wife did not have similar complaints. Due to this infestation, he had developed anxiety and sleeplessness and was unable to do his job efficiently. He did not believe the suggestion of his friends and wife that there is no such infestation with insects and was firm in his belief that there are indeed insects which crawl over his lower limbs.

Detailed systemic examination including neurological examination did not reveal any abnormality. His relevant investigations were normal. There was no history of chronic physical disease or drug abuse. There was no family history of any psychiatric illness.

Mental state examination revealed no perceptual abnormality. He was anxious. Thinking revealed the presence of delusions of insect repeatedly crawling over his lower limbs. No other psychopathology was detected. Higher mental functions were normal.

The patient was explained the treatment options available. He was also told that an antipsychotic pimozide was the most accepted treatment for this disorder but was explained the need for regular cardiac monitoring to which he refused. He was given options of using atypical antipsychotics, most of which have shown efficacy in this condition. The patient was started on 2 mg of risperidone but could not tolerate it because of excessive sedation. The patient reported features of akathisia on 10 mg of aripiprazole. He conveyed an inability to afford amisulpride. Due to all these issues, after discussion, he was started on tablet blonanserin 4 mg/day (in divided doses), which was increased to 8 mg/day after 2 weeks and tablet lorazepam 2 mg at night for sleep (on SOS basis). There was partial improvement after 4 weeks of treatment. The dose was further increased to 12 mg/day after 4 weeks. There was complete remission of the patient's delusion at 6 weeks of treatment. On following him up at 3 months, he did not develop the delusion again.

The exact mechanism of this disorder is not known. One hypothesis is that these patients suffer a profound breakdown in their ability to discriminate between normal and abnormal somatic perceptions and the delusion may be mediated by a pathological overactivity of the dopaminergic system. There are reports mentioning the usefulness of second-generation antipsychotics in the treatment of delusional parasitosis.[2],[4],[5] Blonanserin is used for the treatment of schizophrenia and has not been tried in the treatment of delusional infestation. The present case responded completely to blonanserin.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

   References Top

Freudenmann RW, Lepping P. Delusional infestation. Clin Microbiol Rev 2009;22:690-732.  Back to cited text no. 1
Bhatia MS, Jagawat T, Choudhary S. Delusional parasitosis: A clinical profile. Int J Psychiatry Med 2000;30:83-91.  Back to cited text no. 2
Bhatia MS, Jhanjee A, Srivastava S. Delusional infestation: A clinical profile. Asian J Psychiatr 2013;6:124-7.  Back to cited text no. 3
Shome S, Chadda R, Ramam M, Bhatia MS, Gautam RK. Delusional parasitosis in leprosy. Indian J Psychiatry 1993;35:225.  Back to cited text no. 4
Lepping P, Russell I, Freudenmann RW. Antipsychotic treatment of primary delusional parasitosis: Systematic review. Br J Psychiatry 2007;191:198-205.  Back to cited text no. 5

Correspondence Address:
Anubhav Rathi
Department of Psychiatry, University College of Medical Sciences and G.T.B. Hospital, Delhi
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/psychiatry.IndianJPsychiatry_287_13

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