ABSTRACT
ABSTRACT Introduction: Delusional infestation is a rare psychiatric disorder defined as a condition in which the patient has the unshakable belief and perception of being infested with parasites. Its treatment is difficult, and frequently includes antipsychotic medications (such as olanzapine or aripiprazole). Non-pharmacological treatment, particularly psychotherapy, can be used for less severe cases. Dermatologists and psychiatrists must take a multi-disciplinary approach (preferably in a psycodermatology dedicated clinic) since this type of patients sometimes refuse treatment. Case description: A 53-year-old female businesswoman describes a clinical history of five years of visual hallucinations, depressive symptoms, and generalized pruritus, along with the use of toxic substances to "clean" her skin and cloths. She reports similar symptoms in some relatives but they were not evaluated. Blood tests and analyses of the "specimen" brought by the patient were performed, yielding negative results. The patient had never been assessed by any specialist, and showed disoriented during the consultation. Follow-up was not possible due to the reluctance of the patient to follow the indications and seek psychiatric treatment. Moreover, the patient did not respond to further communication attempts. Discussion: Delusional infestation is an uncommon disease that endangers the patients and the people around them. Its treatment is difficult and long, and not conducting proper follow-up is a great risk. Its prevalence and incidence is variable and generally unknown. It can affect the patient, their next of kin, pets or the environment, and the "pathogen" can be a living organism or an inanimate object. Conclusion: This case is important as it shows the hardships of treatment, adequate follow-up and care, as well as the need to improve how these patients are approached. Additionally, both classical and uncommon signs and symptoms could be observed as the patient stated that her relatives were affected (possible delusional infestation by proxy).