LAUSR

Society for Publication of Acta Dermato-Venereologica Delusional infestation is a mono-delusional psychotic disorder with a high disease burden and reduced social functioning (1). Patients have the delusional belief that they or their immediate environment is infested with living or non-living pathogens. Most commonly people believe that they are infested with insects, worms, parasites, or inanimate objects such as threads or fibres (1). Specialist clinics where psychiatrists see patients jointly with dermatologists or other physicians are rare. Patients tend to see multiple specialists without symptom improvement or engagement with meaningful treatment. Antipsychotics are highly efficacious but compliance is the main stumbling block to successful treatment (1, 2). In the 1980’s, two publications from a specialist clinic in Vienna suggested that later age of onset may be associated with poorer outcome in delusional infestation (3, 4). A study combining data from 4 specialist clinics in Europe, more recently suggested poorer outcome in patients with a long duration of untreated psychosis (5). We have updated the data from those 4 clinics (London and Liverpool in the UK, Bruneck in Italy, and Moscow in Russia) to include more patients and examined whether the association of older age of onset and the association of longer duration of untreated psychosis were confirmed as negatively associated with good outcome.