Introduction Delusional parasitosis or Ekbom syndrome is a condition described mainly in the fields of psychiatry and dermatology, with a complex diagnostic and therapeutic approach. However, it is uncommon to assess patients with this disease in infectious disease units. The objective of this work is to describe the experience of three infectious diseases departments with respect to this entity. Methods A retrospective descriptive study of 20 patients diagnosed with delusional parasitosis in three Infectious Diseases Services was performed between 2003 and 2017. Results The median age of the patients was 54 years, with a female/male ratio of 1.5:1. In 9 patients, an endoparasitic delirium (mainly digestive) was described, in 5 an ectoparasitic form was described, and in the remaining 6, a mixed form was described. Fourteen patients presented some type of psychiatric disorder. Four patients had alcohol or drug abuse disorder. All patients had made consultations to other specialties with a median of three per patient (range 1–7). Ten patients received “empirical” antiparasitic treatment and 8 received some type of psychopharmaceutical treatment. The evolution was very variable: in 3 patients, the delusional parasitosis was resolved; in 9 patients, the clinical manifestations persisted, and the remaining patients were lost to follow-up. Conclusions Ekbom syndrome is a common process in infectious diseases, presenting some differences with other series evaluated by dermatologists and psychiatrists. Management of this disease should promote a multidisciplinary approach to enable a joint treatment, thus optimizing patient management and therapeutic adherence.