[Induced "acarophobia"].

Although only ablut 240 cases of 'acarophobia' are on record in zoological and medical literature, it can be seen that this delusional syndrome without doubt leads to psychoses of association more frequently than any other mental disturbance. The literature contains many references, and the author can give two examples from personal esperience. At least every sixth patient suffering from delusions of parasitosis 'infects' relations. This really remarkable tendency to spread by psychological contagion on one or more dependent persons has been ignored by many writers. The supposition that such occurrences are very rare proves to be false. Sometimes the associated who acquired the symptons in an absolutely identical fashion seem to be more worried by the vermin they hallucinate than the initiators are. The number of patients constituting an affected group is following a Neyman distribution. Emphasis is laid on the finding that the proportion of consanguineous persons within the sample of patients who showed an induced delusion of parasitosis is by far less high than in other psychopathological forms of communicated insanity.