Dr Alison M. Heru, MD

Emotional overinvolvement in undifferentiated enmeshed families is central to the diagnosis of shared delusional disorder. One example of a shared delusion is delusional parasitosis. This is a rare delusional disorder where the patient is convinced of being infested with worms, insects, parasites, or bacteria while no objective evidence exists to support this belief. Somatic delusions are shared with one or more members of a family in 5%-15% of cases (J. Behav. Health 2014;3:200-2 ).