Which syndrome involves delusions of infestation?

Ekbom's syndrome, also known as delusional parasitosis, is characterized by the firm belief that one is infested with parasites, insects, or other organisms, despite medical evidence to the contrary. This delusion can lead individuals to engage in various behaviors to alleviate what they perceive as an infestation, such as intense scratching or seeking out numerous medical opinions.

This condition is particularly notable because individuals often go to great lengths to prove their delusions, which can result in significant distress and impairment in their daily functioning. Treatment usually involves a combination of psychotropic medications and psychotherapy, aimed at addressing the underlying psychological distress.

In contrast, the other syndromes mentioned do not specifically feature delusions of infestation. Cotard's syndrome involves the belief that one is dead or does not exist, Rett syndrome is a developmental disorder affecting mostly females characterized by a loss of purposeful hand skills and social engagement, and Tourette's syndrome is primarily associated with involuntary tics and vocalizations. Therefore, Ekbom's syndrome stands out as the correct answer regarding delusions of infestation.