Salmonella Typhi and Salmonella Paratyphi A, B and C, 2014 - 2018
Typhoid and paratyphoid infections are caused by Salmonella Typhi and S. Paratyphi A, B and C.
The most recent previous report on typhoid and paratyphoid fever infections was published in EPI-NEWS 11/14. In addition to registration in the laboratory surveillance system - which as from 2017 passed from registration via laboratory notifications to registration through the MiBa - typhoid as well as paratyphoid fever are notifiable for the treating physicians via the clinical notification system on Form 1515.
The statement provided here covers the 2014-2018 period, during which a total of 119 notified cases of S. Typhi and S. Paratyphi were recorded. A total of 117 cases were recorded via the laboratory surveillance system, and 112 cases were notified clinically on Form 1515 and subsequently registered in the Notification System for Infectious Diseases (NSID2) (Table 1). Upon closer inspection, 17 of the clinically notified cases proved to have been diagnosed with other serotypes than S. Typhi and S. Paratyphi. Two cases, which were registered via clinical notification only, had both been diagnosed abroad. Additionally, 26 cases had been registered in the laboratory surveillance system only.
The number of S. Typhi and S. Paratyphi A and B recorded in the laboratory surveillance system in the 2014-2018 period varied from one year to the next, but displayed no trend towards an increase or decrease (Figure 1). The increase in Paratyphi B infections recorded in 2017 was due to patients with closely related types who had travelled to Bolivia.
No cases of S. Paratyphi C were recorded in the period.
Among the recorded S. Typhi and S. Paratyphi A and B cases, 55% were women, and the frequency of notifications was higher among young persons, particularly among 16-20-year-olds.
Information about presumed country of infection was provided for 90 of 95 (95%) clinically notified cases of S. Typhi and S. Paratyphi A and B. The corresponding number for laboratory-notified cases was 84 of 117 (72%) cases. Among the laboratory-notified cases, including cases registered in the MIBA, seven cases were considered to have become infected in Denmark; and among the clinical notified cases, three were presumed to have become infected in Denmark.
In both systems, the majority of cases had become infected in India or Pakistan. The remaining cases were distributed among 19 and 22 cases for laboratory-notifications and clinical notifications, respectively (Table 2). The 2017 introduction of whole-genome sequencing for testing of samples submitted to the National Salmonella Laboratory Monitoring Initiative has made possible the determination of genetic types for S. Typhi and S. Paratyphi, and has, in some cases, identified patients affected by the same type, presumably infected in the same country.