Transcript Matrix Environmental Incorporated

3/27/2016
The reduction of the level of human illness from food-borne
pathogens is a public health goal in the European Community and
many countries worldwide.
As epidemiological studies show that poultry meat and eggs are
important sources for consumers' exposure to zoonotic pathogens
such as Salmonella and Campylobacter the reduction of the
prevalence of contaminated poultry meat or eggs is amajor area of
focus.
In addition, risk management strategies aim at communicating the
risks associated with the preparation and consumption of poultry
meat and eggs to consumers.
The aim of this risk communication is to raise awareness and to
change consumers' behaviour to avoid risky procedures while
preparing these foods. Examples for such messages are ‘cook
poultry meat and eggs thoroughly’ or ‘wash your hands after
handling raw meat.’
Generally, two pathways for human exposure to pathogens in
poultry meat and eggs exist, undercooking and cross
contamination (FAO/WHO, 2002, 2003).
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During frying or other cooking procedures for meat, fairly high
temperatures occur on the outside of the meat that most likely
will kill the bacteria located on the surface.
If the poultry meat is undercooked, some of the internal bacterial
pathogens may survive and viable bacteria may be ingested
while consuming the (under)cooked meat.
Whereas undercooking is mainly a risk associated with bacterial
pathogens located in eggs and inside of chicken or turkey meat,
cross-contamination events transferring bacteria from poultry
meat or egg shells directly or indirectly to other foods in the
majority of cases will involve bacteria located on the surface of
poultry meat and eggs .
It can thus be expected that the efficacy of risk communication
messages will depend on the distribution of pathogens in or on the
poultry food commodities.
For example, labelling a package of chicken meat to inform the
consumer of the need for thorough cooking prior to consumption
may reduce the risk of undercooking
but it will have no effect on the cross-contamination risk.

However, it does not raise awareness that bacteria from the
surface of the chicken meat can stick to the hands of the cook
or could be spread in the kitchen environment and
subsequently may contaminate ready-to-eat foods like salads
or already cooked foods accompanying the meal.
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The effectiveness of consumer communication strategies aiming at a
reduction of undercooking poultry meat or boosting the consumption
of hard-boiled instead of soft eggs will depend on the level of the
cross-contamination risk. In other words, the prevalence and level of
external contamination of these products with bacterial pathogens in
relation to the prevalence and numbers of bacteria inside of poultry
meat and eggs will determine the possible success of the message
aiming at reducing the undercooking rate.
This study is aimed at elucidating whether cross-contamination events
or undercooking are a greater risk for human illness from zoonotic
pathogens associated with poultry in order to prioritise what message
should be given to the consumer.
An analysis of the relative contribution of different exposure pathways
finally leading to ingestion of the pathogens and resulting in illness
will be performed.
this analysis will focus on the two major bacterial pathogens in
poultry, Salmonella spp. and Campylobacter jejuni and their
occurrence in poultry meat (chicken, duck, turkey) and chicken table
eggs.
A literature research has been performed in the time period from May
to June 2008 using the ISI Web of Knowledge databases by The
Thomson Corporation.
Mining for publications with data considering the location of
Campylobacter spp. or Salmonella spp. on the surface of or inside of
poultry meat and eggs was performed using the key words
“Salmonella” and “Campylobacter”, each in combination with the
terms “poultry”, “chicken”, “turkey”, and “egg⁎”. Moreover, these
search terms were combined with “quantitative”, “crosscontamination”, and “undercooking”.
3.1. Location of the bacterial pathogens
3.1.1. Poultry meat
During the literature research 16 studies have been identified which
either address the location of Salmonella and Campylobacter on the
surface of poultry meat products, or that determine the prevalence and
or concentration .
. An overview of these studies addressing the type of poultry meat and
the country of origin of the respective study is given in Table 1.
Six of the studies (thereof one with two datasets) simultaneously
looked at the prevalence of Campylobacter and Salmonella.
Eight studies (again one with two datasets) concentrated on
Campylobacter spp. and two studies looked at Salmonella, only.
Quantitative data were available from 11 studies.
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The nine datasets giving prevalence for Salmonella spp. on the
surface of poultry meat products encompassed 2936 samples.
The average prevalence of Salmonella on the surface of poultry
meat is 22.6%.
Only one study, the percentage of duck breasts that were internally
contaminated with Salmonella. 3.8% of 53 samples were internally
contaminated.
Thus, the prevalence of Salmonella on the surface of poultry meat
is about 6 times higher than the prevalence of this pathogen inside
of the meat.
The average prevalence for Campylobacter on the surface of
poultry meat was 62.3% (3235 samples, 14 datasets).
A total of 613 samples from five studies were analysed for internal
contamination with the pathogen. Average Campylobacter prevalence
inside of poultry meat was 10.3%.
In five studies meat samples were simultaneously analysed for
Campylobacter on the surface and inside of the meat. On average, the
prevalence of external contamination of poultry meat with
Campylobacter spp. is 6 times higher than a contamination deeper in
the meat.
Generally, the Salmonella prevalence on the poultry meat surface is
lower than the observed Campylobacter prevalence. Campylobacter
prevalence was 1.5 to 17 times higher on samples which have been
analysed for both pathogens.
3.1.2. Shell eggs
Literature data base research identified nine studies that looked at
the occurrence of salmonella or Campylobacter on the surface and
inside of table eggs. An overview of these studies including
information on the country of origin is given in Table 2.
Three of the studies simultaneously analysed eggs on the surface
and inside for Salmonella and Campylobacter spp.,
five studies address only Salmonella spp. and one study only
presents data for Campylobacter.
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Eight studies with a total of 14,343 pooled samples qualitatively
analysed the egg shell surface and the content of eggs for
Salmonella spp.
Surface prevalence ranged from 0.04% to 9.0% positives.
Only half of the eight studies showed Salmonella contamination of
the egg contents as well.
the contamination rate inside of the eggs was significantly lower
than on their surface.
In four studies table eggs were analysed for Campylobacter
prevalence. Eggs from a hatchery in one study were all negative
for Campylobacter.
two internally Campylobacter-positive composite egg samples out
of a total of 184 samples which were all negative for the pathogen
on their surface.
Two other studies a prevalence of 0.5% and 0.6% of
Campylobacter-positive egg shells. All egg contents in these two
studies were negative.
The prevalence of Salmonella on the egg surfaces in these studies
was almost twice as high as the prevalence of Campylobacter.
All of the published risk assessments for Campylobacter spp. In
chicken meat are addressing cross-contamination during preparation
of the chicken meat as exposure pathway.
Four of the risk assessments look as well at exposure via undercooked
chicken meat.
The first three of these quantitative risk assessment models consider
cross contamination as the dominant route of exposure, as compared
to undercooking for Campylobacter spp.
Their
model
simulations
revealed
that
74%
of
campylobacteriosis cases were caused by cross contamination
events involving Campylobacter spp. from the surface of
chicken meat during the preparation of meals in German private
homes.
In comparison, only 3% of cases could be attributed to
consumption of undercooked products and in 23% of cases
more than one exposure pathway (e.g. inadequate hand
washing, not cleaning the kitchen environment, or
undercooking) was involved in increasing the probability of
illness.
A quantitative risk assessment of Campylobacter in poultry meat
revealed that an elimination of the poultry meat products that are
highly contaminated will have a great effect in lowering the
campylobacteriosis risk.
Although this risk assessment model has a module with
consumer handling practices that considers undercooking and
cross contamination as exposure pathways, a comparison of the
contribution of these two pathways to consumers' exposure to
Campylobacter bacteria has not been performed
For Salmonella, the relative relevance of cross-contamination events
and undercooking to the exposure of consumers to this pathogen from
poultry meats has not been addressed by risk assessors in the same
magnitude as in the case of Campylobacter spp. and this food
commodity.
It has shown that in the EU, among the food-borne cases of human
salmonellosis, eggs and egg products are still the most frequently
implicated sources.
Meat is also an important source of food-borne salmonellosis, with
poultry and pork implicated more often than beef and lamb. More
specific conclusions about raw meat brought into kitchens were not
possible.
However, to assess consumers' exposure by consumption of
Salmonella, only an uptake during consumption of undercooked
chicken meat is addressed.
The model does not consider cross-contamination events while
preparing a contaminated carcass in the kitchen.
Key findings of the risk assessment were that a reduction of
numbers of Salmonella on the surface of chicken carcasses and
even a small reduction in the frequency of undercooking.
Even though this exposure pathway was not included, the
authors of this risk assessment feel that cross-contamination may
in fact be the predominant source of risk of illness.
Data on the magnitude of cross-contamination in the domestic
kitchen, and the pathways of such cross-contamination are
identified as areas where future data collection and research
efforts need to focus.
It is outlined that the lack of addressing consumers' exposure by
cross-contamination in the assessment is a limitation and caveat.
These authors look at different egg products considering how
consumers handle them during preparation and make a
salmonellosis risk ranking for the different egg products.
The greatest risk was associated with foods containing raw eggs.
By Salmonella coming from the surface of eggs was not addressed.
A risk assessment addressing Campylobacter on or in eggs was not
available in published literature.
A more general model for all bacteria, which addresses individual
hygiene practices during food preparation and consumption
patterns in private homes, has been developed by Christensen et
al., 2005.
The model was used to estimate the probability of ingesting a
meal where precautions have not been taken to avoid the transfer
of microorganisms from raw food to final meal, exemplified by
the event that the cutting board was not washed during food
preparation.
The probability of ingesting a risk meal was highest for young
males aged 18–29 years and lowest for the elderly above 60 years
of age.
The simulated results show that the probability of ingesting a
chicken risk meal at home does not only depend on the hygiene
practices of the persons preparing the food, but also on the
consumption patterns of consumers, and the relationship between
people preparing and ingesting food.
Plenty of publications on the subject of communicating about
food safety risks to consumers exist, but only those
specifically addressing consumer handling during preparation
of poultry or eggs have been analyzed. The studies are very
diverse.
An analysis looking at the focus of the respective studies, their
observations, and the recommendations given for information
is presented in Table 3.
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Within the European Union, labelling requirements aiming at
reducing the risk of consumers' exposure to Salmonella in
poultry meat are laid down in Article 6 of Regulation 2073/2005
(European Commission, 2005).
Manufacturers have to label raw poultry meat intended to be
eaten cooked to inform the consumer of the need for thorough
cooking prior to consumption.
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In the case of eggs, provisions for the marking of packs are
laid down in Article 12 of Regulation 589/2008 (European
Commission, 2008).
As a measure to reduce the risk of multiplication of Salmonella
bacteria during storage of table eggs in private homes, an
indication advising consumers to keep eggs chilled after
purchase shall be on egg packs.
Both labeling requirements can be interpreted as measures
which may reduce European consumers' exposure to bacterial
contaminations in meat or inside of eggs.
Cross-contamination risks are not mentioned.
Fischer et al. (2007) conclude that cross-contamination and
inadequate cooking are the most important factors that
determine food safety during the preparation of poultry meat.
The question remains whether conclusions can be drawn on
the magnitude of exposure coming from cross-contamination
or undercooking events of poultry meat and eggs.
A first approach to finding an answer to this question was a
literature research for studies .
In the case of poultry meat more data sets specifically looking at
the prevalence on the surface and separately inside of the meat
were available for Campylobacter spp., whereas in case of eggs
more studies on Salmonella spp. were found.
For poultry meat and Campylobacter all studies looking at the
surface and inside showed higher prevalence and numbers of this
pathogen on the meat surface.
For Salmonella, only one study could be found that looked at the
prevalence of Salmonella inside of poultry meat.
However, it seems that as well for Salmonella bacteria the
prevalence of surface contamination is several times higher.
Generally, the prevalence and number of Salmonella pathogens is
lower than the contamination of poultry meat with Campylobacter.
In conclusion, the analysis of studies presenting prevalence data
and level of external contamination of poultry meat with
Salmonella spp. And Campylobacter spp. in relation to the
prevalence and numbers of the pathogens inside of these food
products revealed a six times higher contamination on the foods'
surface.
Assuming that bacteria located on the meat surface will be killed
during cooking procedures, these data clearly demonstrate the
superior importance of cross contamination events over
undercooking of the meat for consumers’ exposure to these two
bacterial pathogens.
The role of undercooking may be more relevant when whole
poultry carcasses (like turkeys prepared for Thanksgiving) are
considered.
In case of minced poultry meat a contamination will not be
restricted to the surface and Salmonella or Campylobacter bacteria
could also be present in the center of a portion.
More over, bacteria on the outside can survive for a relatively long
period of time during cooking under high temperatures.
A study by Atanassova et al. (2007)on the prevalence of
Campylobacter in turkey breast fillets and cuts demonstrated that
in Germany 58.3% of retail samples were positive for this
pathogen and recently published results from a European
monitoring study show an average prevalence of 30.7% of
Salmonella spp. In fattening turkeys (Anonymous, 2008b).
A Canadian study compared the prevalence of Salmonella and
Campylobacter in broiler chicken and turkey flocks at the time of
slaughter.
They found higher prevalence rates for both pathogens in turkey
flocks, giving evidence for the possible importance of turkey meat
for consumers' exposure with pathogens. Research on the number
of pathogens on the surface and inside of turkey meat should be
encouraged to gather data for risk assessment and management.
Epidemiological data tell us that egg consumption is the largest
contributor to salmonellosis cases in the population.
Studies showed higher
contamination (Table 2).
prevalence
levels
for
surface
Only one study from found Campylobacter inside of eggs and a
higher contamination rate of egg contents with Salmonella than on
the surface of the respective eggs.
prevalence of Salmonella was almost twice as high as the
prevalence of Campylobacter.
Bacterial transfer could be possibly prevented by
identification and elimination of certain tasks and activities
involving higher levels of cross-contamination.
The preliminary analysis of current risk communication
strategies showed that they mainly focus on getting consumers
to avoid undercooking of poultry meat and consumption of
dishes with raw eggs, and less on information that focuses on
avoiding cross-contamination.
a survey in The Netherlands where subjects had to imagine
situations involving chicken contamination and report how
they would react behaviourally if this situation occurred.
It was found that 60% of the subjects would allegedly avoid
the risks by not consuming chicken for a while.
Moreover, warnings that a food can be a health hazard based
on consumer behavior could also been seen as a way of
removing the legal responsibility from the producer to the
consumer.
the majority of study participants wanted to see such kind of
information on the food packaging.
Thus, labeling of poultry meat and eggs with warnings that this
food might be a source of cross contamination in kitchens can
be considered as a promising risk management option.
However, more research is needed to analyse the possible
public health effect of this risk communication strategy.
In conclusion, in order to reduce consumers' exposure to
pathogens such as Salmonella and Campylobacter in poultry
meat and eggs during preparation of these foods, management
activities should focus on cross-contamination risks.
More risk assessments addressing exposure through this
exposure pathway and research on the efficacy of risk
communication activities aiming at the reduction of crosscontamination events would be helpful to support future risk
management decisions.
Reference
Petra Luber,2009. Cross-contamination versus undercooking of poultry meat
or eggs — which risks need to be managed first?. International Journal of
Food Microbiology 134 , 21–28.