The incidence of typhoid fever has become very low (0.15 per 100,000) in mainland France, and more than 80% of reported cases occur upon return from travel to endemic countries. In October 2003, several cases of locally acquired typhoid fever were reported among residents of the Île-de-France region. An investigation was launched to determine the source of these clustered cases and implement appropriate control measures. A case was defined as a person residing in metropolitan France who had not traveled to an endemic country in the month preceding the onset of symptoms and who, since September 2003, had presented with clinical signs suggestive of typhoid fever; for a confirmed case, this included isolation of Salmonella enterica serotype Typhi (S. Typhi) and, for one probable case, an epidemiological link to a confirmed case. Cases identified through mandatory reporting and the National Salmonella Reference Center were interviewed about possible sources of contamination (travel, places and restaurants visited, contact with cases, foods consumed) during the month preceding the onset of symptoms. The food establishment suspected of being the source of the cluster of cases identified by the epidemiological investigation was inspected. Its employees were interviewed regarding their history of typhoid fever, their travel to endemic countries, their contact with individuals who had typhoid fever or were returning from endemic countries, their workstations, and their hygiene practices. Six successive stool cultures were performed on all staff members at 24- to 48-hour intervals. The S. typhi strains were typed using lysotyping, ribotyping, and pulsed-field gel electrophoresis. Seven cases (6 confirmed and 1 probable) occurring between September 28 and October 16, residing in 4 departments of the Île-de-France region, were identified. Six cases had visited the same sandwich shop in Paris, where they had all consumed mixed salads. None of the 7 employees of the sandwich shop had recent symptoms or a history of typhoid fever. One of them, who was responsible for preparing the salads, had traveled to an endemic country during the summer of 2002; S. Typhi was isolated from the fourth of six stool cultures performed on this employee. He was treated with quinolone antibiotics followed by a cholecystectomy due to gallstones. S. Typhi was isolated from bile collected during the procedure. The six consecutive stool cultures from the other six employees were negative. The serotypes and pulsotypes of the S. Typhi strains isolated from the cases and the employee were indistinguishable. The sandwich shop’s customers were informed via a press release of possible exposure to S. Typhi so that this diagnosis could be considered early and secondary transmission to others could be prevented. The sandwich shop was closed for cleaning and disinfection of the premises, and staff were trained in controlling the risk of food contamination by microorganisms. In conclusion, this cluster of 6 cases of typhoid fever is linked to the consumption of salads sold at the same Parisian establishment, which were contaminated during preparation by an asymptomatic carrier of S. typhi. It demonstrates, like the outbreaks that occurred recently in the Alpes-Maritimes in 1997 and in the Île-de-France region in 1998, that indigenous typhoid fever outbreaks remain possible. It underscores the importance of applying good hygiene practices in food service establishments and the need for staff to be trained in these practices. (R.A.)