Buiktyfus in Amsterdam, 1991-2000, en vereenvoudiging van het landelijk protocol voor bron- en contactopsporing

To determine the incidence of patients reported with typhoid fever in Amsterdam (1991-2000) and to evaluate the contact tracing for those patients with the specific objective of examining whether contact tracing can be simplified.

Design

Retrospective.

Method

From an automated database, data were collected on all reported typhoid fever patients in Amsterdam during the period 1991-2000 and on their contact persons.

Results

One hundred and one patients with typhoid fever were reported during the study period, and Salmonella typhi infection was diagnosed in 12 of the 281 household contacts. For 96 of the 101 index patients, travelling abroad was the most likely source of infection. In 8 of the 12 contact persons with an S. typhi infection, the index person was the most likely source of infection, which is equivalent to a secondary transmission rate of 2.8 (8/277). Seven of the 8 secondary infected persons had symptoms indicative of typhoid fever infection and S. typhi was found in all their first stool samples.

Conclusion

Supported by these results, the national guidelines for source and contact tracing in the case of typhoid fever have been amended. In the case of index patients with bad toilet hygiene or who are responsible for food preparation, the faeces of all household contacts must be examined once. If the contact persons have symptoms indicative of an S. typhi infection and/or if their work involves food preparation, their faeces should also be tested once. The changes to the national protocol will markedly reduce the labour-intensity of tracing and testing the contacts of patients with typhoid fever, thereby maintaining the quality of the process. Tracing the source of infection in the case of patients with typhoid fever will also remain important in the future in order to detect potential transmission within the Netherlands at an early stage.