Imported typhoid fever in Switzerland, 1993 to 2004.

BACKGROUND: In industrialized countries, typhoid fever occurs mainly in returned travelers. To determine the need for preventive strategies, eg, for vaccination, continuous monitoring is needed to assess where the risk for travelers is highest. METHODS: To investigate where the risk for travelers to acquire typhoid fever is highest, 208 patients with typhoid fever and recent travel were matched with travelers' statistics collected by the Swiss Federal Office of Statistics. RESULTS: At the beginning of the study period, up to 30 infections with Salmonella typhi were recorded per year in Switzerland. Since 2001, less than 15 confirmed cases per year occurred. A majority of the 208 (88.5%) typhoid cases were associated with recent travel. Countries with highest risk were Pakistan (24 per 100,000), Cambodia (20 per 100,000), Nepal (14 per 100,000), India (12 per 100,000), and Sri Lanka (9 per 100,000). CONCLUSIONS: We found that over a 12-year period (1993-2004), the travel-associated risk of typhoid fever is highest for destinations in the Indian subcontinent. All other regions showed a decline, most markedly in southern Europe. Our results suggest that typhoid fever vaccination should be recommended for all travelers to countries in South Asia. Otherwise, vaccination of tourists to frequently visited low- and intermediate-risk areas is not necessary, unless there are behavioral risk factors.