Journal of Postgraduate Medicine
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Year : 1994  |  Volume : 40  |  Issue : 4  |  Page : 222-4  

Delusional parasitosis--study of 3 cases.

K Hanumantha, PV Pradhan, B Suvarna 
 Dept. of Psychiatry, KEM Hospital, Parel, Bombay, Maharashtra.

Correspondence Address:
K Hanumantha
Dept. of Psychiatry, KEM Hospital, Parel, Bombay, Maharashtra.


Delusional disorder-somatic (parasitosis) type is a rare psychiatric disorder which poses a challenge to diagnostic and therapeutic skills. Pimozide, a highly specific dopamine blocker has shown promising results in the 3 cases illustrated here. These cases were seen over a period of 3 years. All the three patients believed that an insect has entered through the ear and is burrowing tracts/laying multiple eggs. They approached the ENT surgeons or neurosurgeon with a fear that their brain will be invaded. On psychiatric evaluation, no past or present history of major psychiatric illness was found. Premorbid personalities were well adjusted. Only for two patients, acute moderate stressors were detected. Delusions disappeared by the end of 2 wks but therapy was continued for 5 months.

How to cite this article:
Hanumantha K, Pradhan P V, Suvarna B. Delusional parasitosis--study of 3 cases. J Postgrad Med 1994;40:222-4

How to cite this URL:
Hanumantha K, Pradhan P V, Suvarna B. Delusional parasitosis--study of 3 cases. J Postgrad Med [serial online] 1994 [cited 2023 Oct 1 ];40:222-4
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  ::   IntroductionTop

Delusion is defined as a false personal belief based on incorrect inference about external reality and firmly sustained in spite of what almost everyone else believes and in spite of what constitutes incontrovertible and obvious proof or evidence to the contrary[1].

Delusional disorder constitutes 1% to 4% of all psychiatric admissions. Delusional disorder is predominantly an illness of middle to late adult life, usually occurring in persons who are married. Delusional disorder occurs more frequently in lower socioeconomic classes[2],[3].

Delusional parasitosis tends to be under-diagnosed as they present to dermatologist and surgeons more readily than to psychiatrists[4]. A careful history taking will lead to early detection and referral of such cases. Delusional disorder has to be differentiated from major depression and schizophrenia since delusions can be part of the latter disorders. Psychiatric evaluation in doubtful cases avoid unnecessary investigations, invasive procedures and financial burden.

We present here 3 case reports of delusional parasitosis, which responded well to pimozide. These patients were seen over a period of 3 years.

  ::   Case reportsTop

Case 1: Mr. X, 42 yr. male, married, illiterate mill worker presented to the ENT Surgeon with the complaint of insect in right ear. ENT Examination did not reveal any evidence of insect in the right ear. When the patient was told so, he tried to convince the surgeon that the insect has already made tracks and sat hidden. The patient was referred for psychiatric evaluation. On enquiry, patient gave history that 2 months ago he suddenly got up from his sleep when he felt a insect entering his right ear. He tried removing it but failed.

Gradually the patient felt that the insect was making multiple tracks. Sometimes he could hear the noises made by the insect. (He described the insect to be about 23 inches long, blackish in colour having multiple legs, something like a centipede). The patient believed that the insect was growing in size.

Patient religiously followed the advice given by his colleagues to get the insect out such as eating a particular food which was felt to be toxic to insect, pouring warm water into the ear, sleeping in a particular posture and keeping various eatables near the right ear so that he could pull out the insect when it came out to eat. Eight days prior to hospitalization, the patient was convinced that the insect would lay eggs, which would hatch out at any time and invade the whole of his brain. This would mean the end of his life. This thought worried him so much that he hardly slept 12 hours/day, had stopped going to work and refused to eat. The patient would lie in bed with sweetmeats beside his right ear. This was the time he was brought to the ENT surgeon for removal of the insect.

Case 2: Mr. Y, 53 yr old male, widower, businessman, studied up to the 10th standard, referred from the ENT department for psychiatry evaluation of the complaint that a cockroach had entered his brain.

On enquiry, the patient narrated that 6 weeks back he was sleeping on a railway platform waiting for a train. He woke up with a foreign body sensation in his right ear. He also saw many cockroaches moving around in the vicinity and believed that the foreign body sensation was due to the entry of a cockroach into his right ear. He tried to remove the cockroach from the ear but failed. After a day or two, he started experiencing peculiar sensations in the head, which he believed to be due to movement of the cockroach. He believed that the cockroach was growing in size and would not be able to come out through the small ear orifice through which it had entered.

He got worried and approached people for help. As days passed by, he believed that the cockroaches had increased in number and were moving all around his brain, particularly when he combed his hair. When confronted during the interview, the patient showed the secretions in the inner can thus of the eyes to be the excreta of the cockroaches, as a supportive proof of his belief system.

Case 3: Mrs. Z, 35 yr old married, uneducated female was referred by the neurosurgery department. The patient had compelled the general practitioner for a neurosurgery referral to get rid of the eggs laid inside the brain by the fly when she was working in the fields.

The patient consented to surgery even it meant death on the table because she was very scared that the eggs would hatch out. She also wanted to disprove the general practitioner and the neurosurgeon who did not agree to her complaint that the fly entered her ear, laid eggs in the brain and flew off.

In all the above 3 cases there was not past or present history of major psychiatric illness. There was no history suggestive of substance abuse, head injury, epilepsy or other major medical illness. Premorbid personality was well adjusted.

In Cases 1 and 2, there were acute moderate stressors antedating the symptoms. One of the daughters of Mr x had developed a mental illness and had to be hospitalised while there was a sudden unexplained death of Mr y's father. Routine blood and urine investigations and skull Xray did not reveal any abnormality.

Case no. 1 was hospitalised and cases 2 and 3 were treated on OPD basis. They were started on pimozide 4 mg once daily and stepped upto 1216 mg/ day over a week. The delusions were shakeable by early second week and had disappeared by the end of 2nd week. Case no 1 and 2 developed extrapyramidal reactions and were given trihexyphenidyl 6 mg/day. The 2 patients were maintained on 68 mg/day of pimozide for the next three months, which was gradually tapered over two months. Long-term followup was, not possible.

  ::   DiscussionTop

Delusional (paranoid) disorder previously known as mono-symptomatic hypochondriacal psychosis is characterised by single delusional system, which is fixed, unarguable and impaired reality.

Subtypes of delusional disorder with which the patient can present are somatic type, jealousy, poverty, reference, persecutory, erotomania, nihilistic, grandiose, of being controlled[5]. Somatic type can be of following types body odour (halitosis) infestations, mis-shappeness (dysmorphic), tumour, blockade of intestines[6].

Whatever the name given to this disorder and its subtypes, it should be emphasised that these illnesses are real, may not be rare and present a challenge to our diagnostic and therapeutic skills[7].

There are reports where psychotropic drugs like tricyclic antidepressants[8] and amoxapine[9] are found to be useful in treating delusional disorder patients.

Pimozide, a specific dopamine blocker, appears to give dramatic results in the doses of 412 mg/day[10]. In the above mentioned case similar encouraging results with pimozide in the dose of 416 mg/day were obtained.

Most patients, who were considered untreatable in the past, tend to be benefited by pimozide. Perhaps, half the cases with delusional disorders may remit, but relapse and chronicity are common. Supportive psychotherapy is a good adjunct to somatic treatment as these patients lack insight into illness, which is an insurmountable barrier to initiating treatment and their sensitivity to all side effects may constitute an additional frustrating factor in their care[11].

Most patients of delusional disorder can be treated effectively in out patient settings. Hospitalisation may be necessary in the face of potentially dangerous behaviour or unmanageable aggressiveness.


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