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Raw milk cheese risk assessment v3.0 08/11/16
1
STEC contamination in raw milk cheese : risk assessment This document should be read in conjunction with version 2.0 of the risk assessment. This version incorporates new information received by FSS since
14 September 2016 and does not reiterate all the factual information incorporated in version 2.0 - this remains the same.
1) STATEMENT OF PURPOSE AND APPROACH 1.1 Purpose This document assesses the potential risks to public health associated with shiga
toxin producing Escherichia coli (STEC)1 contamination of the raw milk cheeses
produced by Errington Cheese Limited (ECL), South Lanarkshire.
1.2 Definition of raw milk cheese
As version 2.0 1.3 Approach As version 2.0
This risk assessment is version 3.0 and is current as of 08 November 2016 to reflect
new information which has become available since version 2.0 (14 September
2016). It contains additional information on sampling results from cheese, new
sampling results from milk and updated epidemiological information.
2) HAZARD IDENTIFICATION
As version 2.0
3) EXPOSURE ASSESSMENT
3.1 Supply of raw milk to ECL As version 2.0
3.2 ECL’s raw milk specification As version 2.0
3.3 Current scientific literature on occurrence of STEC in raw milk As version 2.0
The Center for Science in the Public Interest (CSPI) has published a report on
Foodborne Disease Outbreaks and analysis from 1998-20072. This report includes
data on dairy products and there are numerous examples of outbreaks and recalls
1 STEC is synonymous with VTEC (vero-cytotoxin producing E. coli), as are vtx and stx genes.
2 http://www.milkfacts.info/Milk%20Microbiology/Disease%20Outbreaks.htm
Raw milk cheese risk assessment v3.0 08/11/16
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associated with raw milk (and raw milk cheeses) for a range of pathogens including
STEC.
3.4 ECL Cheese Product Descriptions
The following table summarises the cheeses made by ECL, which type of milk is
used to manufacture them and the type of cheese produced.
Cheese Milk Description
Dunsyre Blue Unpasteurised Cow
Blue cheese
Lanark White Unpasteurised Ewe
Semi-hard white cheese
Lanark Blue Unpasteurised Ewe
Blue cheese
Maisie’s Kebbuck
Unpasteurised Cow
Semi-hard white cheese
Corra Linn Unpasteurised Ewe
Hard white cheese
Sir Lancelot Unpasteurised
Ewe
Lactic cheese
Further information on the cheeses produced by ECL can be found on their website3.
3.5 Specification of cheese including critical controls.
The generic HACCP plan (annex 1 version 2.0) covers all 6 cheeses (Dunsyre Blue,
Lanark Blue, Lanark White, Maisie’s Kebbuck, Corra Linn and Sir Lancelot) made by
ECL. It covers all aspects of the cheese making process from collection of ewes’ milk
from the bulk tank at milk suppliers [name] and acceptance of cows’ milk from the
dedicated farm [names] delivered through [name].
3.6 Current literature on occurrence of STEC in cheese
Analysis of food incident date by the Horizon Scan system4, has shown that between
1st November 2014 and 1st November 2016, there have been at least 70 food safety
notifications worldwide relating to the presence of E. coli (including STEC) in cheese
products. At least 23 of these warnings related to unpasteurised products (not all
cheeses were defined as pasteurised or unpasteurised) and 58 related to cheese
produced within the EU (including 39 from France), 10 outside the EU and 2 were of
unknown origin. Fifty one safety warnings were issued by EU countries including 23
through the EC Rapid Alert System for Food and Feed. The data shows that other
member states are testing for a wide range of different STEC serotypes and that
some alerts are based on the detection of stx genes.
3 http://www.erringtoncheese.co.uk/cheese.php
4 https://horizon-scan.fera.co.uk/
Raw milk cheese risk assessment v3.0 08/11/16
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3.7 Epidemiology
Since 14 September, 4 further cases have been confirmed as part of the outbreak
bringing the total number of confirmed cases to 26. HPS are undertaking further
statistical analysis on the epidemiological evidence and this information will be
reported in the final IMT report.
3.8 Cheese production
Dunsyre Blue production as version 2.0.
All types of cheese produced by ECL are batch coded as outlined for Dunsyre Blue
e.g. the letter denotes the month of production and the number corresponds to the
day of production.
Growth and survival of pathogenic E. coli is dependent on the simultaneous effect of
a number of environmental factors such as pH, aw and temperature. However, the
parameters outlined in version 2.0 remain the same regardless of cheese type.
FSS were provided pH and aw results from two batches of Dunsyre Blue sampled by
South Lanarkshire Council (SLC). However, FSS has not received any information
on the physico-chemical characteristics, predictive modelling of pathogen growth or
challenge testing for any of the other cheese types manufactured by ECL.
3.9 Microbiological Quality of Raw Milk and Cheese
ECL Sampling
As version 2.0
Local Authority Sampling
The following information is a summary of all of the testing results done to date,
detailing what information was known before and since version 2.0 of the risk
assessment (14 September 2016). A summary of all positive results to date are
attached in Annex 9.
Dunsyre Blue
As of the 14 September:
Batch F15: A stx2 positive non-O157 E. coli (STEC) had been isolated and
cultured in a sample from F15. Nine further samples from batch F15 had been
found to contain the stx2 gene, and were undergoing further confirmatory
analysis. Whole genome sequencing (WGS) of the F15 STEC demonstrated
the presence of an E. coli, O-unidentifiable:H20, stx2d, ST1308.
Raw milk cheese risk assessment v3.0 08/11/16
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Batch E24: Two samples taken from Batch E24 had been found to contain the
stx2 gene (i.e. presumptive positive for STEC).
Batch G12: One sample taken from Batch G12 had been found to contain the
stx2 gene (i.e. presumptive positive for STEC).
Other Dunsyre Blue samples: 22 other samples from additional batches
(n=21) were negative for both stx genes and E. coli O157.
Since 14 September:
Batch F15: WGS results of a second F15 isolate confirmed the same profile
as 1st F15 sample (i.e. the presence of an E. coli, O-unidentifiable:H20, stx2d,
ST1308).
Batch E24: no further results (i.e. the two samples remain presumptive
positive for STEC on the basis of the detection of stx2 genes).
Batch G12: no further results (i.e. the sample remains presumptive positive for
STEC on the basis of detection of the stx2 gene).
The results of 16 further batches of Dunsyre Blue have not been found to
contain E. coli or stx genes.
Lanark White
As of the 14 September:
Batch G14: A stx gene negative E. coli O157 had been isolated from a sample
from Batch G14.
Batch H24: A sample taken from Batch H24 had been found to contain the
stx2 gene (i.e. it was considered presumptive positive for STEC).
Since 14 September:
Batch G14: The original sample from Batch G14 was found by WGS to
contain E. coli O157:H42 ST P3216 stx negative. A further sample from
Batch G14 was found to contain a stx negative E. coli O157 and WGS results
confirmed that this organism was the same as that found in the other sample
(i.e. E. coli O157:H42 ST P3216 stx negative).
Batch H3: A stx gene negative E. coli O157 was found in this sample, WGS
confirmed it to be the same strain of organism as was contained in the sample
from Batch G14 (i.e. E. coli O157:H42 ST P3216 stx negative).
Raw milk cheese risk assessment v3.0 08/11/16
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Batch H24: this sample was also found to contain a stx gene negative E. coli
O157. WGS confirmed it to be the same strain of organism as was contained
in the sample from Batch G14 and H3 (i.e. E. coli O157:H42 ST P3216 stx
negative). The stx2 gene detected in the sample originally may belong to
another STEC present in the sample, or may be part of free DNA or a dead
organism, and is therefore uncultivable.
Lanark Blue
No positive Lanark Blue results were notified to FSS up to and including the 14th
September.
Since 14 September:
Batch E24: this sample has been found to contain a non-O157 E. coli with the
stx2 gene – i.e. an STEC. It is currently being whole genome sequenced at
PHE.
Other Cheeses produced by ECL
Limited sampling has been undertaken of the other cheeses produced by ECL.
Samples were taken from 1 batch of Maisie’s Kebbuck; 3 batches of Corra Linn and
1 batch of Sir Lancelot. No E. coli or stx genes were detected in these 5 samples.
Milk Samples
As of the 14 September, the only results notified to FSS relating to milk samples
were those taken by ECL as per their sampling plan. These results are detailed in
version 2.0 annex 3.
Since 14 September:
A sample of raw cows’ milk taken from the bulk tank on the 29 September
has been found to contain a stx2 positive non-O157 E. coli i.e. an STEC. It is
currently being sequenced at PHE.
A further sample of raw cows’ milk taken on the 19 October has been found to
contain a stx1 and stx2 positive non-O157 E. coli i.e. an STEC. It is currently
being sequenced at PHE.
3.10 Other potential sources of STEC contamination
As version 2.0
4) HAZARD CHARACTERISATION
Raw milk cheese risk assessment v3.0 08/11/16
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4.1 Disease symptoms
As version 2.0
4.2 Dose response
As version 2.0
4.3 Susceptible population
As version 2.0
4.4 Particular subtypes found in humans and cattle in Scotland
As version 2.0
5) RISK CHARACTERISATION
5.1 Likelihood of STEC being present in the raw milk
As version 2.0 although this specifically focusses on Dunsyre Blue and therefore the
supply of raw cows’ milk. Since version 2.0 of the risk assessment was finalised,
milk samples have been taken (on 29 September and 19 October) from the farm
supplying cows’ milk to ECL. STEC has been detected in two of these samples,
which provides evidence that the raw cows’ milk may periodically become
contaminated with pathogens. These positive STEC results show that the controls,
identified in ECL’s risk analysis document (annex 10), which have been implemented
to prevent STEC contamination of the incoming raw cows’ milk, are inadequate. The
detection of STEC in the raw cows’ milk also confirms previously published literature
(Farrokh et al., 2012; EFSA 2015) that STEC can occur in raw milk. With regards to
raw cows’ milk, these positive results have reduced the high level of uncertainty
expressed in version 2.0 on whether individual bulk milk samples may contain STEC
and confirms the statement ‘it is likely that over a period of time STEC will be present
in occasional batches of raw milk delivered to ECL’.
ECL has its own flock of sheep which are kept on Errington’s farm and milked on site
in their own milking parlour. The milk from the ewes is used to make Lanark Blue,
Lanark White, Corra Linn and Sir Lancelot cheeses. No milk samples have been
taken from the ewes as they are no longer producing milk. However, similar to raw
cows’ milk, the literature (Farrokh et al., 2012; EFSA 2015) has shown that STEC
can occur in raw ewes’ milk and additionally a study undertaken in 2005 showed that
a range of E. coli strains could be detected in sheep faeces in Scotland (Evans et al.,
2011).
In summary, there is high uncertainty on whether individual bulk ewes’ milk samples
contain STEC. However, since STEC is prevalent in Scottish sheep and there is
Raw milk cheese risk assessment v3.0 08/11/16
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scientific literature which reports that ewes’ milk can be contaminated by STEC, it is
likely (as seen with the cows’ milk) that over a period of time STEC will be present in
occasional batches of ewes’ milk.
5.2 Likelihood of STEC being present at the end of maturation
Version 2.0 remains accurate but predominantly concentrated on the production of
Dunsyre Blue.
The controlling factors (pH, aw and temperature) to prevent the growth and survival
of pathogenic E. coli are clearly documented in version 2.0 and remain the same
regardless of the type of cheese produced. ECL have a generic HACCP document
which covers the production of all six different types of cheese that they produced
(annex 1 version 2.0) and from the documentation the only difference in controlling
factor identified between the different cheeses is the cheesemaking acidity.
The pH for semi-hard cheeses has to be <5.2 the following morning after production,
whilst the lactic ladle curd has to have a pH <4.7. The optimum growth of E. coli
O157 is at pH 7 but it can grow in the range of pH 4.5 to 9. FSS has not received
make sheets for any of the non-blue cheeses and therefore cannot comment on how
the pH changes during the production of the other cheese types. However, the final
pH that is aimed for the morning after production would not by itself prevent the
growth of E. coli O157.
There is no information on the physico-chemical characteristics of the different
cheeses during production and at the end of maturation and end-of-shelf life, or
predictive modelling of pathogen growth or challenge testing for any of the other
cheese types manufactured by ECL. However, the literature has demonstrated that
E. coli O157 can be isolated from a variety of different cheeses including raw milk
hard cheese (Honish et al., 2004). Additionally, STEC has been detected in batches
of Dunsyre Blue and Lanark Blue, which are made from cows’ milk and ewes’ milk
respectively. Furthermore, E. coli O157 has been detected in three different batches
of ewes’ milk Lanark White. This suggests that these organisms can survive the
maturation process for these three different types of cheese or that there was cross-
contamination of the cheeses during maturation.
5.3 Concluding remarks from risk characterisation 5.3.1 Outbreak
Investigation of food histories and product traceability has established an
epidemiological association between an outbreak of E. coli O157 PT21/28, involving
26 human cases, and Dunsyre Blue cheese. HPS are undertaking further statistical
analysis on the epidemiological evidence and this information will be reported in their
final IMT report
Raw milk cheese risk assessment v3.0 08/11/16
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5.3.2 Batch F15 (Dunsyre Blue)
As version 2.0.
In addition, since version 2.0 of the risk assessment a further STEC has been
isolated from batch F15 which has been confirmed by WGS as the exact same strain
as the first isolate (E. coli, O-unidentifiable:H20, stx2d, ST1308). Therefore, the risk
assessment summarised in version 2.0 remains unchanged but now applies to two
samples.
5.3.3 Batch E24 (Dunsyre Blue)
As version 2.0
5.3.4 Batch G12 (Dunsyre Blue)
As version 2.0
5.3.5 Batch G14 (Lanark White)
Two samples of batch G14 (taken on separate dates) of Lanark White cheese made
from unpasteurised ewe’s milk have produced positive results. Both samples
contained a stx negative E. coli O157, which were later shown by WGS to contain
the same organism (E. coli O157:H42 ST P3216 stx negative). The Scottish E. coli
O157/VTEC Reference Laboratory (SERL) have reported that stx gene negative
strains of E. coli O157 have been isolated from cases of human illness consistent
with E. coli O157 infection. Additionally, the Food Examiner at Edinburgh Scientific
Services (ESS) declared the samples to be “potentially injurious to health and/or unfit
for human consumption”. Therefore we would consider this batch of cheese (G14) to
be high risk that the cheese is hazardous to human health. There is a medium level
of uncertainty associated with this estimate due to lack of extensive information on
the pathogenicity of E. coli O157 without stx genes.
5.3.6 Batch H24 (Lanark White)
FSS were notified on 14 September that the stx2 gene had been detected in this
batch as outline in version 2.0. Further confirmatory analysis of this sample showed
it contained a stx gene negative E. coli O157, the same as that found in batch G14
(E. coli O157:H42 ST P3216 stx negative). Therefore, taking in to account the advice
from both SERL and the Food Examiner on the presence of stx negative E. coli
O157 we would consider this batch of cheese (H24) to be high risk that the cheese is
hazardous to human health. There is a medium level of uncertainty associated with
this estimate due to lack of extensive information on the pathogenicity of E. coli
O157 without stx genes.
5.3.7 Batch H3 (Lanark White)
Raw milk cheese risk assessment v3.0 08/11/16
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The same stx gene negative E. coli O157, as found in batches G14 and H24 (E. coli
O157:H42 ST P3216 stx negative) was detected in batch H3. Therefore, taking in to
account the advice from both SERL and the Food Examiner on the presence of stx
negative E. coli O157 we would consider this batch of cheese (H24) to be high risk
that the cheese is hazardous to human health. There is a medium level of
uncertainty associated with this estimate due to lack of extensive information on the
pathogenicity of E. coli O157 without stx genes.
5.3.8 Batch E24 (Lanark Blue)
Batch E24 of Lanark Blue has been found to contain a non-O157 E. coli with the stx2
gene (an STEC). Whole genome sequencing is currently being undertaken at Public
Health England and therefore the serogroup and stx2 subgroup is unknown to
assess this organism’s full pathogenicity. However, a considerable number of non-
O157 STECs have been reported to be pathogenic to humans (70 are listed in the
US by Gould et al., 2013). SERL has also communicated to FSS that a quarter to a
third of their isolates from human cases in Scotland are now non-O157 strains.
Taking into account the literature on the ability of a wide range of non-O157 strains
to cause human illness, the isolation of a non-O157 STEC strain with stx2 (in the
absence of full WGS) in this batch of cheese indicates a high risk that the cheese is
hazardous to human health, however the level of uncertainty associated with this
estimate is medium due to the lack of definitive information on the isolated strain and
its pathogenicity.
5.3.9 Other batches of Dunsyre Blue, Lanark White and Lanark Blue cheese.
As per version 2.0 with regards to the other batches of Dunsyre Blue (and now
Lanark White and Lanark Blue), those that have tested negative for STEC are likely
to have a lower likelihood of STEC being present than batches which have tested
positive. However, negative test results do not guarantee that a product is free from
STEC contamination. STEC may be heterogeneously distributed and could be
present at very low levels in some cheeses making it difficult to detect other than
with extensive sampling and testing. In addition, the production method,
environment and source of milk, is likely to be the same or very similar, for batches
which have tested positive and ones which have tested negative. Importantly, there
does not appear to be any demonstrable evidence of steps in the production which
would eliminate STEC. Thus, the potential for STEC bacteria to be present in
matured cheese remains as demonstrated by the analysis of samples from batch
F15 Dunsyre Blue and Batch E24 Lanark Blue. A greater number of STEC negative
samples from a batch would increase confidence that STEC is not
present. However, statistical advice would be required to establish the number of
samples required for a given level of confidence.
Raw milk cheese risk assessment v3.0 08/11/16
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For those batches that have not been tested, the process of production does not
appear to eliminate STEC (as demonstrated in F15 and E24) so there is a possibility
that STEC could be present in the cheese.
5.3.10 Other batches of ECL cheese.
FSS has very little information or evidence on the other types of cheese produced by
ECL. In total 5 batches of other cheese made by ECL have been sampled and
tested (1 batch of Maisie’s Kebbuck; 3 batches of Corra Linn and 1 batch of Sir
Lancelot). No E. coli or stx genes were detected in any of these 5 samples.
Additionally, FSS has not been provided with any information on the physico-
chemical characteristics of the different types of cheese or predictive modelling
studies of pathogen growth or challenge testing to allow FSS to make an
assessment if the processes in place are adequate to control the growth and survival
of STEC in the product. However, there is evidence that STEC has been detected in
the raw cows’ milk supplied to ECL. Therefore without evidence to the contrary from
ECL on demonstrable steps that would eliminate STEC in the final product and
considering the scientific literature that STEC can be detected in a wide range of
cheese types, we would consider that there is the potential for STEC to be present in
the final matured product.
In summary, E. coli O157, toxin-producing non-O157 strains and presumptive
positives for STEC have been detected in ECL’s raw milk cheeses made from both
cows’ and ewes’ milk, which indicates lack of control for pathogenic E. coli for more
than one production line.
Raw milk cheese risk assessment v3.0 08/11/16
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REFERENCES
EFSA (European Food Safety Authority), (2015). Scientific Opinion on the public health risks related
to the consumption of raw drinking milk. The EFSA Journal 13, 3940.
Evans, J., Knight, H., McKendrick, I.J., Stevenson, H. Barbudo, A. V., Gunn, G. & Low, C. (2011)
Prevalence of Escherichia coli O157 :H7 and serogroups O26, O103, O111 and O145 in sheep
presented for slaughter in Scotland. Journal of Medical Microbiology 60, 653–660
Farrokh C, Jordan K, Auvray F, Glass K, Oppegaard H, Raynaud S, Thevenot D, Condron R, De Reu
K, Govaris A, Heggum K, Heyndrickx M, Hummerjohann J, Lindsay D, Miszczycha S, Moussiegt S,
Verstraete K, Cerf O., (2012) Review of Shiga-toxin-producing Escherichia coli (STEC) and their
significance in dairy production. In J Food Microbiol 162(2) 190-212.
Gould LH, Mody RK, Ong KL, Clogher P, Cronquist AB, Garman KN, Lathrop S, Medus C, Spina NL,
Webb TH, White PL, Wymore K, Gierke RE, Mahon BE, Griffin PM; Emerging Infections Program
Foodnet Working Group. (2013) Increased Recognition of Non-O157 Shiga Toxin–Producing
Escherichia coli Infections in the United States During 2000–2010: Epidemiologic Features and
Comparison with E. coli O157 Infections. Foodborne pathogens and disease, Volume 10, Number 5,
453-460.
Honish, L., Predy, G. Hislop, N. Chui, L., Kowalewska-Grochowska, K. Trottier, L., Kreplin, C., &
Zazulak, I., (2004) An Outbreak of E. coli O157:H7 Hemorrhagic Colitis Associated with
Unpasteurized Gouda Cheese. Revue Canadienne de Santé Publique 96:3 182-184.
Raw milk cheese risk assessment v3.0 08/11/16
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Annex 9: Positive Results from Cheese and Milk Samples.
ESS Lab Number
LA Ref Date sampled
Batch Number
LA sample description
Stx1 Stx2 E. coli WGS result
50425565 46204 23/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve Non-O157 E. coli O unidentifiable H20 stx2d ST1308
50426130 046257, Tag 453
29/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve Non-O157 E. coli O unidentifiable H20 stx2d ST1308
50426405 046275, TAG 0005
31/08/2016 G14 Lanark White, Batch G14
-ve -ve O157 E. coli O157:H42 ST P3216 stx negative
50427280 046292 - TAG 00447
13/09/2016 G14 Lanark White Cheese - G14
-ve -ve O157 E. coli O157:H42 ST P3216 stx negative
50427273 046285 - TAG 00016
13/09/2016 H3 Lanark White Cheese - H3
-ve -ve O157 E. coli O157:H42 ST P3216 stx negative
50427275 046287 - TAG 0000019
13/09/2016 H24 Lanark White Cheese - H24
-ve -ve O157 E. coli O157:H42 ST P3216 stx negative
50428221 046333 - SM058853
29/09/2016 Bulk milk tank
Milk- Raw Bulk Tank
-ve +ve Non-O157 Awaited
50426402 046272, TAG 0000038
31/08/2016 E24 Lanark Blue, Batch E24
-ve +ve Non-O157 Awaited
50429903 46486 19/10/2016 Raw milk Raw milk +ve +ve Non-O157 Awaited
50426128 046255 Tag 451
29/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve N/A
Raw milk cheese risk assessment v3.0 08/11/16
13
50426129 046256 Tag 452
29/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve N/A
50426131 046258 Tag 455
29/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve N/A
50426132 046259 Tag 454
29/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve N/A
50426133 046260 Tag 443
29/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve N/A
50426134 046252 Tag 457
29/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve N/A
50426135 046253 Tag 458
29/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve N/A
50426136 046254 Tag 459
29/08/2016 F15 Dunsyre Blue Cheese, Batch F15
-ve +ve N/A
50426163 046238 TAG 474
29/08/2016 G12 Dunsyre Blue Cheese, Batch G12
-ve +ve N/A
50426399 046261, TAG 0000013
31/08/2016 E24 Dunsyre Blue Cheese, Batch E24
-ve +ve N/A
50425867 046221 26/08/2016 E24 Dunsyre Blue Cheese Batch E24
-ve +ve N/A
Raw milk cheese risk assessment v3.0 08/11/16
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Annex 10
HJ Errington & Co
RISK ANALYSIS – PRIMARY PRODUCTION OF RAW MILK
Although HACCP in Primary Production is not yet a legal requirement (preamble 852/2004), the manufacture of
raw milk cheeses is dependent upon strict pathogen control in husbandry practices and during milking and the
reduction of risk in the development of Staphylococcus aureus toxin
PRO CESS
STEP
PO TENTIAL
HAZARD
RISK ANALYSIS PREREQ UISITE CO NTRO L
MEASURES
Additional
Comments
Grazing
E coli 0157
Campylobacter
Salmonella
Giagardia
Cryptosporidium
Faecal deposits from birds, rodents, other
wildlife and muckspreading on grazing areas.
Too high cow population on area of grass –
faecal-oral route.
Resident & high population of pests.
Risk increases if land is near haylage bails,
landfill skips or meat/poultry processing
plants.
LO W Grazing on fields cut for silage
only and out of season
Solids to arable & liquid to
lagoon.
Ratio- animals to land area &
land rotation
Control of rodent and bird pests,
usually absence of feedstuffs to
attract and elimination of nest
sites.
See SCA
Code of
Practice
Dioxins, PCBs
(plastic waste with
carcinogens),
radiation
Carcinogens from breakdown petrochemical
products. High risk if ---- located near
incinerator site
- located near nuclear power plant
- spillages eg. road tanker accidents, refinery
incidents.
V LO W N/A Ref:
dioxins in
Bolsover in
Derbyshire
1993
See ‘New
Scientist’
articles
Pesticide, herbicide
residues
Spraying nitrates & fertilisers.
Down wind of spraying. V LO W Sheep housed until end of season
Drinking
Water
Pathogens
Spring water LO W
Water Authority Analysis Report
In house testing
Water
Authority
analysis Dioxins, pesticides, PCBs,
Radiation
Heavy metals eg.
manganese
Silage Listeria spp
Clostridium
Bacillus
Poor acid devpt , moisture and soil
Sporeforming, psychrotrophic bacteria in soil
contaminating cut and stored silage. Can
survive fermentation process.
Clostridium is a poor competitor against lactic
acid-producing bacteria.
Most probable, but still rare, is non-pathogenic
C butyricum (spoilage only – gas holes & poor
flavours)
LO W Reduction of soil in cut and
stored silage.
Prevention of secondary
fermentation.
.
Face of silage must be clean
before use or the front is
removed.
E coli 0157
& 026
Bird faeces in or on silage Sheeted and netted (adequately
covered) and not located near
waste matter which may attract
them to the vicinity
Ref 026 in
Raw milk
Camembert
, France,
2006
Raw milk cheese risk assessment v3.0 08/11/16
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Bought-in
Feed-
(list)
Antibiotics
Supplied by reputable supplier
(currently [name])
Analysis can be provided.
LO W Animal Feedstuffs Regulations
PCBs etc
Pesticides,
herbicides
Mycotoxins from mouldy cereals
AnimalBy-Products Regs
1774/2002
GM
Infected animal by-
products
Feed Storage Pathogens, urine &
faeces from vermin
during storage
V LO W Pest Control contract.
Stored in closed bins/silos.
Turnover of stocks.
Removal of redundant stocks.
Animal
Health-
general
Mycobacterium sp.
avium
paratuberculosis
Linked with Johne’s disease in cattle
(prevalent in Jersey breed) and Crohne’s
disease in humans. No scientific conclusive
evidence for that link, the transmission
through milk or destruction by pasteurisation.
Awaiting
further
research
Associated with bird faeces – see
‘Grazing’
Mycobacterium
tuberculosis
Sheep
N/A EC/853/2004 Section
IX.Ch.1.1.2b.
DEFRA & veterinary checks 12-
monthly) Do not make raw milk cheese
with milk from suspect herd.
Brucella
melitensis/aborti
Negligible risk if milk from a Brucellosis –
free herd (DEFRA)
V LOW EC/853/2004 S.1X. Ch 1.1.2.a
Bovine spongiform encephalopathy
No evidence of transmission to humans through milk.
V LOW Animal Feed Regs
Foot & Mouth virus
Destroyed by lactic acid and caustic solutions.
Not transmitted through fermented products.
LOW EC/853/2005 S.1X. Ch 1.1.1 Ref Meat
Hygiene
Service reference
books.
Animal
health –
digestive
tract
Salmonellae spp
Destroyed by lactic acid in matured cheese. As
blue and moulds develop acididty increases
therefore risk decreases
LOW EC/853/2005 S.1X. Ch 1.1.1
Diarrhoea
‘New
Scientist’
article
E coli 0157
Some cows are carriers.
Mostly associated with calves.
Can be eliminated by increased roughage in
the feed, eg hay, barley. and more solid faeces
LOW/
MED risk
in U/P hard
cheese
Animal
health –
udders
Mastitis caused by
Staphylococcus
aureus
E coli 0157
Can be transmitted by humans
Can be present with no clinical signs
Toxin is produced above 10°C and is heat
stable.
Udder with discharge and swelling.
Blood/clots in foremilk
LOW/
MED risk
in U/P hard
cheese
EC/853/2005 S.1X. Ch 1.1.1
Hand washing (II.C)
Somatic Cell Counts
Geometric average:
< 400,000 /ml (853/2004)
(1X.III. 3.a)
Visual inspection of udders.
‘Red flag’ control
Listeria
monocytogenes
Environmental. Ensure clean udders especially
in wet & windy conditions
Good milking hygiene prevents cross-
contamination onto udder from faeces
LOW
Raw milk cheese risk assessment v3.0 08/11/16
16
Destroyed by pasteurisation and lactic acid in
matured cheese
Antibiotic residues Minute traces may be present despite PASS
results. Very low probability of occurrence but
traces may induce anaphylactic reaction to
vulnerable consumers, esp beta-lactams or
penicillin types.Can dilute in large bulk tanks.
Would generally cause starter failure. If make
is successful, most A/Bs are associated with
whey phase.
Some ‘drying off’ drugs may associate with the fat phase.
We have never had a possibtive test due to
dedicated suppliers
V LOW
In
Cheese
Low in
milk
EC MRLs set in 2377/90 & EC
853/2004 (!X.4 a&b)
Raw milk checks with Delvotest
SP test once per month
Occurrence
s in 2006:
None
since1/1/20
02
MILKING
PARLO UR
Smashed glass
Metal fragments or
swarf
V. Serious implications for injury but
negligible risk of occurrence because of in-
line filters
LOW
Farm Assurance schemes
including Glass Policies.
In-line filters
- ex-bulk tank
- tanker
- milk intake line
- pasteurisers
Centrifugal separation
Pest Matter
See Feed Storage MED Maize stored ½ mile from farm Ecolab
contract
Phenolic type
chemical taints
(eg. Jeyes Fluid,
Dettol, flysprays,
paints, wood
preservatives, solvents, glues, non-
food grade plastics)
Considered low by the industry but DDS knows of frequent
unpublicised occurrences,plus ref to Pickerings Dairy circa
1992 causing chemical food poisoning/ hospitalisation of
consumers in Liverpool from contaminated liquid milk.
Significant proportion of the population genetically unable to
taste these chemicals . Can cause illness in all population
categories with disastrous consequences for subsequent dairy operations. Possibility of unsuccessful decontamination
measures.
LOW
Prohibited use for any
application in or around the
milking parlour area
Iodine taints Cleaning of equipment now commonly caustic.
Approved teat dips only LOW
EC/853/2004
Milking
Equipment
clusters and bulk tanks
Survival and growth
of pathogen
contamination
through poor cleaning, milkstone &
contaminated water
ITEM MAINTENANCE/CLEAN CO NTRO L MEASURES
Vacuum 6-monthly plant test
(No jars)
O rings, seals,rubbers
Pipework 6 monthly inspection
Bulk Tanks Service contract with Noblet Refrigeration and callout. (Main
Office)
GENERAL CLEANING SCHEDULE Chemical: Sodium Hydroxide (caustic) 600gms in 80 galls. (Single use)
CirculationTemp: not less than 75 deg C throughout T ime:
not less than 5 mins, then cold rinse 5 mins
Supplementary Manual cleans as required
Raw milk cheese risk assessment v3.0 08/11/16
17
Bulk Tanks Growth of
Mesophilic Pathogens , viz
Salmonellae
S aureus, &
development of S
aureus toxins
Prevent introduction of these with
control measures detailed above.
S aureus toxin develops above 10 deg
C
LOW EC/853/2004
- cool to < 8° C for
daily use/collection - cool to <6° C for not
daily collection
- to reach dairy bulk
tanks at not more than
10° C
Listeria
monocytogenes
E Coli 0157
Clostridium
Bacillus
Will grow at chill temps.
Best prevented by previously listed
control measures
LOW -