than 10 000 restaurants in Denmark, with the
most prominent being a large 6-week outbreak of
S. Enteritidis PT 34 infection which originated at a
Chinese restaurant in central Copenhagen during
the summer of 1999 [16]. However, although rare,
these outbreaks may affect more people than
restaurant outbreaks caused by contaminated
food because they may last longer. The period
in which individuals infected with non-typhoid
Salmonella strains shed the bacteria varies with
age and serotype, but 40% of non-symptomatic
infected cases have been found to excrete Salmonella
after 4 weeks, falling to 14% after 8 weeks
[17]. An investigation by the Minnesota Department
of Health [18] showed that 10% of staff at
restaurants associated with Salmonella outbreaks
shed the bacteria, with most of the positive staff
being asymptomatic.