90 Chapter 3
reported in England in 1953, Japan in 1955,
Puerto Rico in 1956, and Japan in 2000. In
the Puerto Rico outbreak, 775 school chil-
dren were affected with toxin, demonstrated
in the powder, although no Staph. aureus
cells were recovered (Armijo et al., 1957 ).
Staphylococcus aureus enterotoxin (SE) pro-
duction could take place in raw milk and
subsequently survive powder production heat
treatments. However, the detection of Staph.
aureus i n the fi nal product may occur due to
a limited survival of the organism during
spray drying or is indicative of contamination
during manufacture. Whereas the earlier out-
breaks associated with dried powder milk
occurred in schools and canteens, the most
recent outbreak in Japan, in 2000, occurred
in a number of households that had used the
powdered skim milk as a manufacturing
ingredient in causative foods sold at retail
outlets (Asao et al., 2003 ). In the latter out-
break, involving more than 13,000 cases, SE
was detected in the end food product and
milk powder ingredient. Simulation studies
showed that the SE subjected to three heat
treatments (130 ° C for 4 to 5 seconds) in low -
fat milk retained immunological and biologi-
cal activity (Asao et al., 2003 ), thereby
emphasizing the need for good quality raw
milk with minimum Staph. aureus levels for
milk powder production (Soejima et al.,
2007 ).
Cronobacter sakasakii (formerly Entero-
bacter sakasakii ) is now recognized as an
emerging foodborne pathogen associated
with milk - powder - based and other rehy-
drated powder infant formulas (Farber, 2004 ;
Lehner and Stephan, 2004 ; Gurtler et al.,
2005 ; Mullane et al., 2007 ; Van Acker et al.,
2001 ). The outbreaks and sporadic cases
have been primarily associated with neonates
with a mortality rate of 40% to 80% (Gurtler,
2005 ). Surveys have shown that the inci-
dence of Cron. sakasakii in powdered infant
milk formula ranges from 3% in the UK
and Ireland (Iversen and Forsythe, 2004 ;
Mullane et al., 2007 ) to 13% in Southeastrelated to dried milk have been associated
with each of these microorganisms. Numerous
cases of salmonellosis were identifi ed in the
UK in 1985, mainly affecting infants (46
cases) who had been fed a brand of powdered
milk. The implicated serotype, S. ealing, was
recovered from samples of the product (Rowe
et al., 1987 ; Ryser, 2001 ). The infection was
traced to a malfunctioning spray dryer. A
total of 141 confi rmed cases under 12 months
of age were associated with S. agona in a
powdered infant formula in France (Brouard
et al., 2007 ). Low levels of salmonellae, not
recovered in routine plant sampling, were
detected in two formula types produced in
the same production line following investiga-
tions. This low level of salmonellae in dried -
milk - based infant formula is a common
feature of such outbreaks as well as rare sero-
types being the causative agent. In 2005 an
outbreak of salmonellosis was linked to the
consumption of contaminated milk powder
by hospitalized elderly patients. The incrimi-
nating serotype, S. worthington, was isolated
from environmental samples taken at the
manufacturing plant, in milk powder pro-
duced in March 2005, and in milk powder
produced in December 2004 and stored in the
manufacturing plant (Lepoutre et al., 2005 ).
Gastroenteritis infections due to Salmonella
spp. caused signifi cant morbidity and mortal-
ity at three hospitals in Tunisia in 2000.
Infective baby powder milk was determined
to be the main cause of these infections
(Dhiaf et al., 2004).
Investigations recovered injured salmo-
nellae from samples in this study, highlight-
ing the fact that heat - stressed salmonellae
may occur in the fi nal product, which makes
detection by routine analysis diffi cult. Licari
and Pather (1970) demonstrated that Salmo-
nella spp. are not completely eradicated from
milk powder by spray drying and are only
reduced slightly but not eliminated during
storage in milk powder at 25 ° C and 35 ° C.
Staphylococcal food poisoning due to
ingestion of dried milk powder has been