Journal of the Louisiana State Medical Society
recently, Freudenmann and Lepping have recommended a broader term, “delusional infestation,” rather than more disease-oriented descriptions, such as parasitosis and phobia. 4 Approximately 5%-15% of pa- tients with delusional infestations will exhibit delusions shared with a spouse or relative ( folie à deux ) or shared with more than one family member or close friend ( folie partagé ). 5 The most common shared delusions are between husband and wife; be- tween siblings, especially twins; or between a parent, usually the mother, and a son or daughter. 2, 5 Patients with delusional infestations all harbor intense anger and resentment for phy- sicians who do not quickly confirm their perceived infestations. Theywill dismiss their initial doctors quickly to seek other medical opinions from a variety of specialists ranging from dermatologists to internists and infec- tious disease specialists. 2 In 1992, Bourgeois and coauthors reported a case of shared delusional infestations between husband and wife ( folie à deux ) in which a 58-year- old woman was institutionalized for attempting to kill her general prac- titioner who refused to confirm her delusions. 5 In some cases, patients with delusional infestations have killed their pets to rid themselves of their perceived delusions. 2 All of the cases presented in this series have demonstrated the pathognomonic behavioral features and clinical manifestations of delu- sional infestations, including: (1) onset in well-educated, middle-aged adults who are pet owners (Cases 2, 3, and 4); (2) production of purported specimens of causative parasites in what is called the “matchbox sign” (Cases 1 and 4); (3) pesticide overtreatment of themselves, their households, and their pets with oral (ivermectin) and topical (ivermectin, pyrethroids) insecticides (Cases 2 and 3); (4) excessive cleaning or vacuum-
Figure 2: The life cycle of several species of avian schistosomes of resident and migratory waterfowl whose eggs are passed in bird feces and hatch into ciliated miricidia that penetrate aquatic snail intermediate hosts. Infected snails later release infective cercariae into freshwater sources to penetrate the skin of definitive bird hosts or inadvertent or dead-end hosts, such as man, causing self-limited, intensely pruritic cercarial dermatitis. Source: US Centers for Disease Control and Prevention, DpDx Image Library. No copyright permission required. Available at http://www.dpd.cdc.gov/dpdx/HTML/ CercarialDermatitis.htm. Figure 3: The typical, self-limited, intensely pruritic,
papulovesicular rash of cercarial dermatitis or swimmer’s (duck hunter’s) itch caused by penetration of the skin by the cercariae of avian (waterfowl) schistosomes. Source: US Centers for Disease Control and Prevention, DpDx Image Library. No copyright permission required. Available at http://www.dpd. cdc.gov/dpdx/HTML/ CercarialDermatitis.htm.
Karl Ekbom, a Swedish neurologist, described “delusions of animals on the skin,” but his long German description was so cumbersome ( Dermatozoenwahn ) that the condition was called Ekbom’s syndrome instead until 1946, when Wilson and Miller coined “delusion of parasitosis.” 3 More
ing of their households (Case 3); (5) intense anger and resentment directed towards physicians failing to confirm their self-diagnoses (Case 4); and (6) sharing delusional symptoms with their spouses or partners in the folie à deux phenomenon (Case 2), or with others in the folie partagé
156 J La State Med Soc VOL 166 July/August 2014
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