Risk factors for typhoid fever in travelers

Abstract

Background: The incidence of typhoid fever in the developing world remains high and has been estimated at 540 cases per 100,000 of the population per year. International travelers to such areas are at risk of infection, especially if they travel under low hygienic standards. Methods: In order to identify the risk factors leading to infection in travelers and expatriates, travel histories, anamnestic and clinical features of 31 patients with typhoid fever, who presented to a German travel clinic, were investigated. Results: Compared to the total patient population of the outpatient clinic during the period of investigation (n = 17,029 patients), patients who presented with typhoid fever were older (39 years versus 31 years, p < .001) and traveled longer (58 days versus 19 days, p < .001). While only 19.2% of the total patient population had traveled to the Indian subcontinent prior to referral, 35.4% of the patients with typhoid fever had acquired the infection there (p < .001). Similar results were obtained for South East Asia and Indonesia: twenty percent of the total patient population traveled there in contrast with 32.2% of patients with typhoid fever (p < .001). Latin America was visited by 16.3% of all patients, but only 6.4% of patients with typhoid (p < .001). Conclusions: The risk of infection appears to be highest when making an extended journey to the Indian subcontinent. Short-term visitors to Latin America and Africa are apparently at a markedly lower risk. Three travelers were infected despite oral vaccination against typhoid fever prior to departure. Risk factors as age of the traveler, time, duration, and destination of the journey should be considered in pretravel counseling. It should, however, be made clear that vaccination does not provide complete protection against infection with typhoid fever.