Letters to the Editor
Delusion of Oral Parasitosis in a Patient with Major Depressive Disorder
Dear Editor: Delusion of parasitosis is a false belief in which sufferers have a strong conviction that they are infested with small, insect-like organisms. Patients believe that these organisms live and thrive in their skin and, sometimes, in other parts of their bodies. This condition is also named Ekbom’s syndrome (1). The delusion may exist as a core symptom in patients with delusional disorder, somatic type, or it may be one of the symptoms in other psychiatric disorders. We describe a patient with major depressive disorder who suffered from delusion of parasitosis of the oral cavity. To our knowledge, there is only one previous report of oral parasitosis.
Case Report
The patient is a married housewife, aged 31 years, with a Grade 10 education. She lives in Kerman, a city in the south of Iran. The patient’s symptoms started 4 months prior to her referral. She was restless and suffered from deep depression. She said that she hated the world, that there was no future for her, and that everything was meaningless. She stated that she was only a moving corpse. Since the beginning of her illness, she had heard voices telling her that she would return to life on the day of resurrection and that, because she would be hungry, she would have to eat lizards, beetles, and crickets. After hearing these voices, she felt these organisms in her mouth. To remove them, she repeatedly chewed and swallowed, also feeling the taste of chewed materials. She thought that she was sinful and being punished by God. She had insomnia and anorexia and lacked energy to do her duties.
A mental state examination revealed that she had gustatory, tactile, and auditory hallucinations associated with somatic delusions, together with the conviction of being orally infested with tormenting organisms. Her cognition was intact, physical and neurologic examinations were normal, and brain magnetic resonance imaging showed no abnormality. The patient was treated with 150 mg imipramine and 8 mg pimozide daily. She became well 2 months later.
Discussion
Our patient suffered from the delusion that she was infested with several living organisms, including lizards. To our knowledge, all previous case reports describe patients who complained of being infested with only a single small organism; a large organism has not been previously reported. Delusion of parasitosis mainly targets the skin, although a report exists of 4 patients with ocular parasitosis associated with self-inflicted trauma (2). There is only one prior report of delusion of oral parasitosis: Maeda and others reported the case of an old man with a previous left-sided cerebral infarct who suffered from a delusional conviction that something like a thread was coming out from between his teeth. He could feel worms but not see them. This patient improved with pimozide treatment (3).
One interesting aspect of our patient is her auditory hallucination, which is not directly related to her somatic delusion. A second interesting aspect is that, to remove the disturbing organisms, she repeatedly chewed and swallowed them and then experienced a gustatory hallucination of chewed materials. This phenomenon has not been reported before and can only be observed where delusion of oral parasitosis exists.
Many patients with depression have irrational guilt feelings. Our patient had such guilt feelings; in her case, they were rooted in her religious beliefs, which could have had a special role in forming her delusion.
Our patient improved with combined drug therapy that included pimozide. Since its introduction, pimozide has been regarded as the specific treatment for delusion of parasitosis (4).
References
1. Enoch D, Ball H. Uncommon psychiatric syndromes. 4th ed. London (UK): Arnold; 2001. p 209–23.
2. Sherman MD, Holland GN, Holsdaw DS, Weisz JM, Omar OH, Sherman RA. Delusions of ocular parasitosis. Am J Ophthalmol 1998;125:852–6.
3. Maeda K, Yamamoto Y, Yasuda M, Ishii K. Delusions of oral parasitosis. Prog Neuropsychopharmacol Biol Psychiatry 1998;22:243–8.
4. Munro A. Monosymptomatic hypochondriacal psychosis manifesting as delusions of parasitosis. A description of four cases successfully treated with pimozide. Arch Dermatol 1978;114:940–3.
Alireza Ghaffari Nejad, MD
Khatereh Toofani, MD
Kerman, Iran
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