2.1 Introduction: the risk of microbial foodborne disease
Accurate estimates of foodborne diseases are difficult to make because of
underreporting. If estimates are made, however, one can see that orders of
magnitude of the various organisms differ so much that even with these
uncertainties, global conclusions remain appropriate. It is estimated that in the
USA there is a chance of about 1 in 3 per year of getting a foodborne illness, a
chance of 1 in 800 of getting hospitalised, and a chance of 1 in 55 000 of dying
(Meadet al., 1999). It is useful to compare this estimate with other causes of
death, to put it in perspective (Table 2.1). From this comparison one can
conclude that although foodborne diseases are not among the most relevant
causes of death, they are relevant and more important than minor causes such as
lightning.
2.1.1 Microorganisms responsible for foodborne diseases
Comparing the various organisms can also show relevant trends (Table 2.2), we
can see that in the USA noro-viruses, Campylobacterand Salmonellaare
responsible for more than 90% of the diseases, and for deathsToxoplasmaand
Listeriaare also of relevance. So only five organisms give rise to more than 90%
of the problem (Meadet al., 1999). That does not mean that one should not look
at other organisms, since these are only estimates, which may change over time.
The comparison of different countries will result in different outcomes,
because of real differences in risks since other products, procedures, habits are
used, but also because of different surveillance systems. The contributions of
2
The range of microbial risks in food
processing
M. H. Zwietering and E. D. van Asselt, Wageningen University,
The Netherlands