[Shigellosis in Amsterdam, 1991-1998: incidence and results of contact tracing].

OBJECTIVE

To determine the incidence of reported shigellosis in Amsterdam (1991-1998) and the factors related to the secondary attack rate of shigellosis.

DESIGN

Retrospective.

METHODS

From an automated data bank data were collected on all registered shigellosis patients in Amsterdam in the period 1991-1998, and their contacts found by contact tracing.

RESULTS

567 Patients with shigellosis had been reported and a Shigella infection has been diagnosed in 96 of the 983 contacts. The annual incidence decreased statistically significantly from 13 to 8/100.000. 329 males and 334 females were infected. The highest number of cases was found in children from 0-4 years and among adults from 20-34 years. Of the 663 patients 106 (16%) required hospitalization; for children under 7 this proportion was 30% (32/108). Among the contacts (excluding the 14 contacts with the same foreign source and the same first sickness day as the index patient) the secondary attack rate was 8%. Young age, of both the patient and the contact was independently related to a higher secondary attack rate.

CONCLUSION

With contact tracing for shigellosis a large number of secondary infections were found. Given the high infection rate and large number of hospitalisations among children, contact tracing should focus at this young age group.