High prevalence of delusional parasitosis in an Indian setting.

Epidemiology and the study of subtypes of delusional disorders is a poorly researched area. This study tries to fill this lacuna and provides the evidence contrary to the accepted fact that the persecutory type is the most common subtype of persistent delusional disorder (paranoia). Out of 4234 patients who attended psychiatry outpatient department during the year 1994-1997, 45 patients received the ICD-10 diagnosis of persistent delusional disorder. Charts of these patients were used for the study. The prevalence of delusional disorder and delusional parasitosis were around 1% and 0.5% respectively making delusional parasitosis the most common sub-type in our setting. Patients with delusional parasitosis had significantly lesser education compared to the patients with persecutory or jealous delusions. These observations are explained on the basis of cultural practices and linguistic competence.