A large outbreak of Salmonella Paratyphi A infection among israeli travelers to Nepal

Abstract

Background: In Asia, Salmonella Paratyphi A is an emerging infection, and travelers are increasingly at risk. During October 2009-November 2009, an outbreak in S. Paratyphi A infection was noted in Israeli travelers returning from Nepal.

Methods: An outbreak investigation included a standardized exposure questionnaire admitted to all patients and medical chart abstraction. Isolates were tested for antimicrobial susceptibility and pulsed-field gel electrophoresis (PFGE).

Results: During 1 October 2009-30 November 2009, 37 Israeli travelers returning from Nepal were diagnosed with S. Paratyphi A bacteremia. All 37 case isolates had an identical pattern on PFGE, and all were nalidixic acid resistant. Only 1 food venue was frequented by all the outbreak cases, with the largest number of exposures occurring around the Jewish New Year. All patients recovered without complications. Time to defervescence in 17 patients treated with ceftriaxone and azithromycin combination was 3.2 days (± 1.7), whereas in 13 cases treated with ceftriaxone monotherapy, the time to defervescence was 6.6 days (± 1.8; P < .001).

Conclusions: A point-source, "Paratyphoid Mary"-like outbreak was identified among Israeli travelers to Nepal. Combination Ceftriaxone-Azithromycin therapy may provide a therapeutic advantage over monotherapy, and merits further clinical trials.

Keywords: Salmonella Paratyphi A; disease outbreaks; enteric fever; foodborne diseases; travel.