Recent surveys show a steady increase in infectious syphilis incidence among sexual transmitted infection clinic visitors in many industrialized countries. Untreated, 30% of patients develop symptomatic neurosyphilis, possibly presenting with a variety of behavioral en neurological symptoms. Neurosyphilis is diagnosed on specific abnormalities in cerebrospinal fluid (CSF).

Case reports on neurosyphilis in Dutch patients prompted us to explore the epidemiology of neurosyphilis with psychiatric co morbidity.

To estimate the incidence of neurosyphilis and psychiatric co morbidity in the Netherlands based on data of hospitalizations in general hospitals from 1999-2007.

Hospitalization data were collected from the Dutch National Medical Register. We included all records on hospitalizations with any kind of neurosyphilis, except congenital neurosyphilis, as discharge- or secondary diagnosis (ICD9-code 094 and subcategory codes).

Between 1999 and 2007, 542 cases of neurosyphilis were registered, approximately 60 cases per year. Of all cases, 76% were male. Co-infection with HIV was seen in 74 (14%) of hospitalized cases of whom 91% were male. In 35 (6%) cases one or more concurrent psychiatric disorders were diagnosed, including 10 organic psychiatric disorders, 8 dementia cases, 6 substance abuses, 4 affective disorders, 7 psychotic disorders, 2 personality disorders and 8 miscellaneous diagnoses.

Neurosyphilis is still diagnosed in patients admitted to Dutch general hospitals. Under diagnosis due to unfamiliarity with the recent syphilis surge is possible. Over reporting is also possible due to incorrect diagnosis not based on CSF results. The reemerging syphilis epidemic may result in an increasing neurosyphilis incidence.