Outbreak of domestically acquired typhoid fever in Leipzig, Germany, June 2004

In June 2004, three confirmed cases of typhoid fever were reported to the health authorities in Leipzig, Germany. The patients had been admitted to hospital with unexplained fever and otherwise mild symptoms. All were members of the same pony club, none had been abroad. A retrospective cohort study among pony club members was performed to identify the source of infection. A suspected case was defined as unexplained fever >=38.5°C over three or more days since 1 May 2004. Additional positive serology defined a probable case and Salmonella Typhi isolation from blood or stool cultures a confirmed case. All hospitals, paediatricians and general practitioners in Leipzig and surroundings were contacted to identify additional cases. In total, six cases were identified, all among pony club members: four confirmed, including the three originally reported cases, one probable and one suspected. The only exposure common to all cases during the probable time of infection was consumption of sandwiches with herb dressing from a snack bar on 25 or 26 May (May 25: RR=5.7; 95% CI 0.9-37.9; both days: RR=, P=0.007). Foods and workers from the snack bar tested negative. However, one worker, not previously registered with the health authorities, was identified during a site visit. It cannot be excluded that further unregistered individuals worked at the snack bar between May and June 2004. Despite intense case-finding activities, no further cases were identified among the population. The most likely vehicle in this outbreak was sandwiches with herb dressing, though the source of contamination remains unknown. Even without history of travel to endemic countries, physicians should consider typhoid fever when managing patients with unexplained fever.