background  Cerebral infections with herpes simplex virus may induce psychosis. Whether cerebral latency of herpes simplex viruses raises the odds for acute schizophrenic psychosis is not known. aims  To find out wether acute infection with herpes simplex virus induces schizophrenic psychosis. To compare the immunological and clinical response of the host upon cerebral infection with the changes during schizophrenic psychosis.
methods  An extensive literature survey was performed using the Medline database from 1966-2001, using as key words 'schizophrenia and disorders with psychotic features', 'central nervous
system infections' and 'cytokines'.
results  Herpes simplex virus latency of the human brain is confirmed. Immunological responses to an acute infection, such as raised antibodies and cytokines, appear to be specific for acute schizophrenic psychosis and for herpes encephalitis. There is a striking resemblance between the psychotic behaviour of patients in the early phase of encephalitis and the psychosis of schizophrenic patients. There may be subtle neuropathological signs of viral infection in schizophrenic subjects.
conclusions  Multiplication of herpes simplex in the brain may cause 'functional' psychosis. To test the hypothesis of intracerebral herpes reactivation, prospective research on cerebral viral presence in psychotic patients is necessary.