Delusional Parasitosis : An unusual presentation
Sagar Karia1, Mansi Somaiya2, Nilesh Shah3, Sushma Sonavane4, Avinash De Sousa5
2Professor and Head
1,2,3,4Department of Psychiatry, Lokmanya Tilak Municipal Medical College and General Hospital, Mumbai
Dr. Avinash De Sousa, Carmel, 18, St. Francis Avenue, Off S.V. Road, Santacruz West, Mumbai – 400-054.
Tel – 91-22-26460002
E-mail – firstname.lastname@example.org
Delusional parasitosis (DP) is an uncommon condition. We report a 70 year old lady who presented with a delusion of parasitosis, other delusions, tactile and visual hallucinations and secondary major depressive disorder. The DP was one delusion of the other delusions of the persistent delusional disorder. However with the presence of other hallucinations the diagnosis of schizophrenia was also considered. Organicity was ruled out. Depression was treated with antidepressants and psychotic symptoms were treated with Tiapride and olanzapine.
Delusional parasitosis is a rare condition wherein the affected individual has the unshaken belief (delusion) that they are infested by bugs, parasites, worms or other living organisms. The symptoms, beliefs and dysfunction could range from merely a feeling of being infested to a sensation of crawling of insects in the skin (formication). It was first described in Thiberge(1894) in patients who reported in (1894) and Perrin (1896) and term was coined by Willan and Jordens(1946).1
DP is more common in the old and in women.2 They usually have a long history of rashes, pruritus and abnormal sensations. They usually treat themselves by scratching or use of pesticides and often exhibit specimens of parasite in the matchbox (matchbox sign)3 & behaviors like quitting jobs, excessive cleaning, mutilation of body using pesticides and home remedies.4 They provide elaborate descriptions of the pests. It may result in emotional trauma, job loss and social isolation.1 Delusions may also be shared by another family member/ family.2
Delusional parasitosis in ICD 10 occurs as a part of Persistent delusional disorder and DSM –IV TR in Delusional disorder, Somatic type. Primary psychotic DP exits when the delusion of parasitic infection is the only manifestation of the disease and no other psychiatric or psychological disorder is present. Secondary DP can occur as a part of depression or schizophrenia. DP can also be a feature of underlying medical illness like CNS disorder, systemic infections or malignancies, substance use disorders.5
Here we report a 70 yr old lady who presented with an insidious onset of illness since a year, precipitated with an inflammatory condition of the left nostril and with continuous and progressive course. She began to have thoughts that an insect entered into her head through the nose and entered her stomach and her vagina. She claimed that the insect sucked her blood and was also crawling all over her body and scalp. She would scratch the skin and scalp as a result. She would pluck her hair in an attempt to remove the insect. She denies seeing images of the insects and on occasions experienced the insects crawling on the body. This occurred in clear consciousness. In a few days she began to voice, that there were stones and mud shedding all over from her body. She could see the stones and would feel them. She was preoccupied with the presence of them all over the body. Despite reassurances by the family members she continued to harbor this belief. She remained preoccupied with this the entire day and night. Her sleep was disturbed. She feared eating as she thought she may ingest insects and stones. She would spend hours washing the mud and stones over her body. In the meanwhile she also developed a hyperpigmentation over her face. Gradually she manifested sadness, anhedonia, crying spells, expressed a helplessness and hopelessness about her health.
On presentation to the dermatology department, the dermatologist, suggested facial hypermelanosis due to frictional dermatitis and treated her with multivitamins and antihistaminics. There was no h/o of any medical illness/focal neurologic deficit or signs of dementia. Hemogram, renal function, liver function, electrolytes, thyroid function, Serum cortisol, ACTH, sugar levels were within normal limits. CT brain suggested sub-acute infarcts. Psychometric tests did not suggest any organicity/dementia. She was treated with tiapride 100mg/d but due to partial response olanzapine 10mg/d was added for her psychotic symptoms. Depression was treated with Mirtazapine 30 mg/d and Escitalopram 20mg/d. Patient is behaviorally maintained on these medications. Delusional parasitosis resolved with significant relief in other delusions.
Pimozide was the drug of choice however due to safety issues it is not used. The condition is usually managed by second generation antipsychotics like risperidone, olanzapine, quetiapine, etc.6 In addition systemic condition in a secondary DP is treated.7 52 cases of delusional parasitosis were reported of which 54% responded completely to pharmacotherapy and 2% showed no response.8 Use of ECT was first described by Harbauer in 1949 and has also been tried in some cases also.1,9 In this patient, who presented with symptom of delusional parasitosis, delusion that stones fall from the body, visual & tactile hallucinations, the complexities can have implications in diagnosis and management. The diagnostic confusion to a clinician - DP with other delusions, visual & tactile hallucinations can be diagnosed as a case of schizophrenia but on the other hand can also be diagnosed as delusional disorder since the patient mainly presents with a set of delusions. Hallucinations may occur- as tactile and auditory (especially in elderly) but may not be persistent and may occur as a part of the syndrome. In addition, clinical management of schizophrenia has evidence based guidelines but treatment of delusional parasitosis as a part of delusional disorder is limited only to case series and reports and lacks adequate randomized controlled trials. No medication is licensed for DP. This liberalizes the treatment options. Treatment of delusional disorder consists not only of antipsychotics but also involves forming a meaningful therapeutic relationship with the patient to understand the somatic aspect of the relationship. Hence DP can occur as a part of psychotic illness, which could range from delusional disorder to schizophrenia. Treatment is challenging and comorbidity must be addressed.
2. Trabert, W. 1995. 100 years of delusional parasitosis. Psychopathology 28: 238-246.
4. Goddard, J. 1995. Analysis of 11 cases of delusions of parasitosis reported to the Mississippi Department of Health. South. Med. J. 88: 837-839.
5. Lepping P, Freudenmann RW. Delusional parasitosis: a new pathway for diagnosis and treatment. Clinical Dermatology 2007; 33:113-117.
6. Aw, D.C., Thong, J.Y. & Chan, H.L. Delusional parasitosis: case series of 8 patients and review of the literature. Ann Acad Med Singapore 2004;33:89-94.
7. Berrios GE. Delusional parasitosis and physical disease. Compr Psychiatry 1985; 26:395-403.
Conflict of interest – Nil