Delusional parasitosis: A case series

Abstract

Delusional parasitosis (DP) is an infrequent psychotic illness, where the patient has a false but firm belief that his body is infested with parasites. It can be primary or secondary. Usually, these patients consult nonpsychiatric specialties from where they are referred to psychiatry. The presentation of DP varies among patients, although it typically manifests as a crawling and pinpricking sensation. Hallucinations are commonly seen. Antipsychotics show good remission of symptoms. A series of seven cases of DP have been described, and the condition is briefly discussed.

Delusional parasitosis (DP) (Ekbom syndrome) is a psychotic illness characterized by the delusional belief that the patient has been infested by insects, parasites, bugs, worms, and the like. It has a prevalence of less than 3 per 1000 psychiatric inpatients or 40 per million in the general population. DP can be primary or secondary. The primary type, comprising 40% of the cases, consists of a monosymptomatic hypochondriacal psychosis, in the absence of any underlying psychiatric or medical illness. The secondary type occurs secondary to psychiatric or medical illness, such as schizophrenia, dementia, depression, diabetes, neuropathies, cardiovascular accidents, human immunodeficiency virus (HIV), allergies, and menopausal states.[1,2,3] Symptoms of DP vary among sufferers, though it typically manifests as a crawling and pinpricking sensation that is most commonly described as involving perceived parasites crawling upon or burrowing into the skin, sometimes accompanied by an actual physical sensation. Sufferers may injure themselves in attempts to be rid of the “parasites.”[1,4] Nearly any marking on the skin, or small object or particle found on the person or his clothing, can be interpreted as evidence for the parasitic infestation, and sufferers commonly compulsively gather such “evidence” and then present it to medical professionals when seeking help. This presentation of “evidence” is known as “the matchbox sign” because the “evidence” is frequently presented in a small container, such as a matchbox.[5,6] Treatment primarily involves the use of antipsychotics, along with the management of underlying psychiatric or medical conditions in cases of secondary DP.[7,8] We report seven cases of this uncommon disorder.

CASE SERIES

Case 1

A 72-year-old housewife, educated up to the 7^th standard, on tablet amlodipine for hypertension for the last 8 years, was brought by her son with complaints of sensation of bugs or insects crawling on her scalp for the past 2 years. The insects would crawl downward to the forehead and ears, which she also demonstrated by gestures of the hand. From there, she felt the insects gradually spread to the rest of the body. She experienced itching over the scalp and face, down to her hands. Therefore, she would constantly scratch all over her body and predominantly her head. The patient claimed she could see these insects and even showed them to the examiner by “plucking them out” from her eyebrow. She said she viewed the insects as multiple, white rice-like grains, which were moving all over her body. The family members did not report any such insects or bugs, but she was convinced about the same. For the past 6 months, the patient felt that the infestation may spread to all the other family members. She refused to play with her grandchildren and refrained from using the same bedding, towels, and other items that could spread the infection. The patient used various oils, rose water, and cream to soothe the itching, but to no avail. Treatment by a general physician and a dermatologist did not give relief. There was no past or family history of psychiatric illness. On mental status examination (MSE), she was kempt, with anxious affect, the delusion of parasitosis, tactile hallucination, and impaired insight. All relevant investigations were normal. The dermatological disorder was ruled out by a dermatologist. With a diagnosis of delusional disorder, she was started on tablets trifluoperazine (5 mg) and trihexyphenidyl (2 mg) twice daily and showed gradual amelioration of symptoms.

Case 2

A 57-year-old uneducated housewife, from a lower socioeconomic class, was referred for psychiatric evaluation by the urologist with complaints of insects crawling inside her bladder for the last 2 years. She was asymptomatic 2 years ago when 1 day in the morning she started feeling a tingling sensation inside her bladder and believed that insects were there inside her bladder. Initially, she felt as if there were a few insects inside her body, but in the last 3 months their number had increased, and they were coming out of her body every day while urinating. Her son took her to a urologist, where, after a urine routine and microscopic investigation, she was referred to the psychiatry outpatient department (OPD). A MSE revealed a well-groomed middle-aged female, distressed about insects crawling inside her body but denied suicidal ideation. She had delusions of parasitosis. There were no perceptual abnormalities. Her insight and judgment were impaired. With a diagnosis of delusional disorder, she was started on tablet risperidone 4 mg per day with gradual amelioration.

Case 3

A 45-year-old known case of paranoid schizophrenia for 22 years presented to the psychiatry OPD alone with the belief that there are two worms inside both his auditory canals. He was convinced that his neighbors had implanted those two worms when he was asleep, because of jealousy against him for the fame and prosperity he had. He used to hear the voices of some of those neighbors taunting him, and he would get agitated and abusive at that. When his family members tried to pacify him, he would get even more irritated and would accuse them of siding with the neighbors. The symptoms developed 8 months ago. An organic cause was ruled out by the otorhinolaryngologist. The patient had three prior episodes of paranoid schizophrenia. For the first two, he had received inpatient treatment, and for the third, he had received outpatient treatment. Remission would occur within 6–7 months of treatment initiation. However, he would keep dropping out of treatment within a few months and would maintain well for a few years before landing in another episode. On MSE, the patient had delusions of parasitosis, persecutory delusions, somatic delusion, and second-person auditory hallucinations. He had poor insight, and his judgment was lacking. As he was a known case of type 2 diabetes mellitus, he was started on first-generation antipsychotics. After 6 months of regular treatment, he reported improvement, after which he was lost to follow-up.

Case 4

A 35-year-old lady was brought by her husband to the psychiatry OPD due to complaints of a belief that insects were crawling on her scalp giving rise to irresistible urges of wanting to scratch her scalp. She was also plucking her hair strands entirely. This symptom was a 3-month duration superimposition on her previous symptoms of suspecting the neighbors of wanting to abduct her child and hearing their voices discussing their plans for the same, for the last 11–12 months. The patient had bald patchy areas on the scalp with sparing growth and scabs. MSE revealed delusion of parasitosis, persecutory delusions, tactile hallucinations, obsessions and compulsions, and third-person auditory hallucinations. With a diagnosis of paranoid schizophrenia and obsessive–compulsive disorder, she was started on 6 mg of risperidone, 60 mg of fluoxetine, and 2 mg of trihexyphenidyl. After 15 months, she was maintaining well on regular treatment and follow-up.

Case 5

A 65-year-old married male farmer from a lower socioeconomic class with education till 2^nd standard, with no past or family history of psychiatric illness, came to the psychiatry OPD with wife and son with complaints of feeling of small black and white-colored insects crawling and creeping across his skin with itching on his whole body, especially on his scalp and both arms, with the belief that insects are flying around him and picking his skin, with the belief that the insects change shape, color, and fly away once he scratches them. The duration of the illness was 2 years. The course of illness was insidious and progressive. He would collect those insects by picking and scratching his skin, keep it folded in a piece of paper, and show it to the doctors as proof that he was not lying. His general physical and systemic examination was within normal limits. A MSE revealed a sad mood, distressed effect, DP, visual and tactile hallucinations, lack of insight, and impaired judgment. A dermatological reference ruled out a skin disorder. Routine blood investigations revealed hemoglobin A1C (HBA1C) levels of 7 for which he was started on metformin 500 mg. He was started on risperidone 6 mg with trihexyphenidyl 2 mg. On follow-up, after 2 months he was symptom-free.

Case 6

A 37-year-old woman, Master of Business Administration (MBA) graduate, homemaker, living with her husband and two children, and belonging to a lower socioeconomic status, was referred from dermatology OPD with complaints of insects crawling on her hands, legs, and upper trunk when she washes clothes of her husband, apprehension with palpitation, irritability, worrying thoughts related to husband, and sleep and appetite reduced, for 4 months. Those insects only came from her husband's clothes and so she had to wash her hands and body after washing his clothes, but still, those insects remained on her body. Her husband said that she gets irritable on asks her not to wash clothes multiple times. After a few days, she started asking her husband not to come close to her and even to sleep in a different room as she would get insects on her body from his clothes and his room if she stayed around him. Her sleep and appetite were reduced. Due to severe itching, she got multiple scratches on her body. Initially, the dermatologist prescribed medicated cream for her eczema. Her scratching reduced, but her thoughts of insects crawling on her body did not reduce. This led to her psychiatric referral. MSE revealed anxious affect, the delusion of parasitosis, tactile hallucinations, and a lack of insight. Relevant investigations were within normal limits. She was treated with risperidone 4 mg, trihexyphenidyl 2 mg, and fluoxetine 20 mg. Her worrying thoughts reduced in a week, and her delusion changed to ideas in subsequent follow-ups.

Case 7

A 70-year-old illiterate female, housewife, residing in a rural area was referred for psychiatric evaluation by a dermatologist. For the past 6 months, she had complained of infestation to her hair, began to pull out all her hair, and was completely bald. History revealed a gradually increasing infestation of her hair with intense itching. The movement of the insects was more at night, and she claimed she could hear the chirping of the organisms, which were not visible. There was no past or family history of psychiatric disorders. She had delusions of infestation and auditory hallucinations in clear sensorium. She lacked insight, and her judgment was impaired. Relevant investigations were normal. Along with the dermatological shampoo and lotion, she was started on tablet trifluoperazine (5 mg) and trihexyphenidyl (2 mg) twice daily. After a month, she said the itching had stopped and probably the organisms had been killed by the local medication. After 3 months, she was symptom-free and there was regrowth of hair all over her scalp.

DISCUSSION

A very obvious finding in this case series is how the patients were referred from other OPDs for a psychiatric evaluation. While patients recognize their symptoms as distressing and requiring relief, they are unwilling to consider them to be psychiatric. In cases of monosymptomatic delusions, particularly, the lack of any other psychiatric symptoms confounds doctors as well. Lack of improvement in cases motivates them to send the patients to psychiatry OPD.[1] Four of the seven cases were of primary type, and three of them were referred from nonpsychiatric OPDs. However, cases of secondary DP may require referrals to nonpsychiatric OPDs, as was seen in our cases.[2]

There is a female preponderance in this condition, as is also reflected in our series. It is also more commonly seen after the age of 50 years. Four of our cases are over the age of 50, and none had a particularly young age of onset.[3] Females are also more likely to have a longer course of illness.[4] All of the cases had an insidious onset of illness, and four of six had symptoms lasting more than 6 months, suggesting chronicity of symptoms, which is consistent with the literature. The disorder is not known to show spontaneous remission and requires pharmacotherapy for the same. Relapses are usually associated with drug discontinuation, as was reflected by one of our cases in which the patient had had three similar episodes, all of which subsided with treatment.

The most common comorbid psychiatric condition is depression, followed by substance use disorders and anxiety disorders. However, in our study, the only comorbid psychiatric condition was paranoid schizophrenia. The socio-occupational functioning is greatly disrupted due to the distressing nature of these complaints as was seen in our patients.[4]

Five of our cases had tactile, two had visual, and one had auditory hallucinations. Hallucinations in these modalities are frequently encountered in DP.[3] Visual hallucinations may also occur in 74% of patients with DP, as seen in two of our patients. Tactile hallucinations are seen in as many as 77% of cases. When accompanied by pain, it is more characteristic of paranoid schizophrenia, as was in our case where the distress of the patient was so deep that she had the urge to remove hair strands entirely.[3]

Sound remission rates have been achieved with antipsychotics, especially in the first generation.[2] Among the second-generation antipsychotics, risperidone and amisulpride are used for treatment.[1,4] We employed risperidone in four of the seven cases and first generation antipsychotic in three.

To conclude, DP is a psychiatric condition that often presents to nonpsychiatric medical professionals. After multiple treatment attempts have gone in vain, they are usually sent for assessment of a psychiatric evaluation. The cases show a good response to antipsychotics. Better awareness of such disorders by the general physician, early recognition of features, establishing a good rapport, timely referral to psychiatry, and empathic treatment are the cornerstones of management in such cases.

Declaration of patient consent

The authors declare that they have obtained consent from patients. Patients have given their consent for their images and other clinical information to be reported in the journal. Patients understand that their names will not be published and due efforts will be made to conceal their identity but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.