Download Microbial risks to humans in Estonia in association with non

Microbial risks to humans in Estonia in association
with non-pasteurised milk consumption
Risk profile
Authors:
Prof. Arvo Viltrop, Department of Infectious Diseases, Institute of Veterinary Medicine and Animal
Sciences, Estonian University of Life Sciences
Prof. Mati Roasto, Department of Food Hygiene and Food Science, Institute of Veterinary
Medicine and Animal Sciences, Estonian University of Life Sciences
Tartu 2013
1
Introduction
According to the Veterinary and Food Board (VTA), there were 32 dairy companies in Estonia on 16
April 2013 that had been issued with veterinary certificates for marketing raw milk outside the farm
(markets, vending machines, shops, retail outlets). Eleven of these companies define themselves as
organic producers. Small quantities of raw milk are also sold to consumers directly from farms or via
various smaller marketing schemes. Consumption of unprocessed raw milk is becoming increasingly
popular among the population due to its promotion in public channels and the expansion of marketing
opportunities. This gives reason to assume that the population’s exposure to raw milk-borne pathogens is
potentially growing. It is therefore necessary to describe the threats related to raw milk and evaluate the
adequacy of the requirements and measures for guaranteeing the safety of raw milk.
This risk profile was prepared within the scope of the research project Raw Milk Safety Pilot
Study in Estonia, which was commissioned by the Ministry of Agriculture of the Republic of
Estonia. Its goal is to give an overview of the microbial pathogens present in Estonia that can
infect people via non-pasteurised milk, to describe the possible risks to people’s health
associated with this (risk characterisation), to summarise existing information about the
transmission of said microbes in Estonian dairy cattle and infection of people in recent years
(evaluation of exposure) and to give an overview of the presently effective official measures for
managing the risks related to raw milk (risk management methods).
The data published in scientific literature, the official statistics of Estonia and the results of
scientific research concerning Estonia, mainly for the last five years, were used to prepare the
risk profile. The information concerning disease outbreaks registered in foreign countries also
concerns earlier years.
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Potentially raw milk-borne zoonotic pathogens in Estonia and characterisation of
associated threats
Microbes usually get into raw milk from the environment surrounding dairy cows. Infected
animals also excrete many pathogens with milk. Microbes from the environment mainly gets into
milk during the milking process either directly from the udder skin or the milking equipment. A
less common reason is the unhygienic treatment of milk that has already been obtained by
milking. In dairy farms, pathogens can also be spread by flies. Pathogens are mainly excreted
into the environment by infected animals, but also by synanthropic birds, animals and insects.
The microbes excreted with milk are mainly those that can cause inflammation of the udder
tissue. Several microbes that cause systematic infections in animals are also excreted with milk.
2.1
Microbes from the environment
1) Escherichia coli. The E. coli strains found in cattle that are the most dangerous to humans
are enterohaemorrhagic or EHEC strains that cause bloody diarrhoea and the most significant
of which is E. coli O157:H7. The list of EHEC strains also includes other serotypes of E. coli
(O26, O91, O103, O104, O111, O113, O117, O118, O121, O128 and O145) (Spickler,
2009). In the European Union, the cases of disease caused by E. coli O157 comprise ca 52%
of all EHEC infections (ECDC, 2011). It is characterised by an extremely small infectious
dose: it only takes 10-100 bacteria to infect a human (Spickler, 2009). The infection can
therefore spread to people even with food that complies with all microbiological
requirements. EHEC infections in humans are most often associated with meat and meat
products, but it is not rare to become infected via milk and dairy products also (Gillespie et
al., 2005; Spickler, 2009; Farrokh et al., 2013).
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The EHEC infection may run its course in humans without symptoms, but it can result in
bloody diarrhoea and haemorrhagic colitis. A possible complication of the latter is permanent
renal failure as a result of hemolytic uremic syndrome (HUS), especially among children
under the age of 10, the elderly and other people with weakened immunity. 5-10% of patients
suffering from haemorrhagic colitis develop HUS. The lethality of HUS is 3-10% among
children and up to 50% among the elderly (Spickler, 2009). In Europe, complication with
HUS have been most often associated with E. coli O157 and O26 infections (ECDC, 2011).
The incidence of E. coli O157:H7 in the skin surface samples of cattle at slaughter in Estonia
has been studied within the scope of a monitoring plan of the VTA since 2011. Information
about other EHEC serotypes in cattle has been collected irregularly. According to the
Veterinary and Food Laboratory (VTL), the incidence of EHEC in the tested skin surface
samples (serotype O157 by the culture method) is 3.5-5.5% (Kramarenko, 2013).
However, EHEC was detected in 64% of the tested 120 skin surface samples when the PCR
method was used. In addition to serotype O157, which was found in 44 samples (37%), a
number of other serotypes were found: O145 in 57 samples (48%), O103 in 42 samples 35%,
O026 in 36 samples (30%) and O111 in 8 samples (7%) (Roasto et al., 2013).
Official statistics of the incidence of EHEC among people in Estonia indicate that overall
incidence from 2005-2009 was 0.2-1.4 causes per 100,000 residents (3-19 laboratoryconfirmed cases per year). No cases of HUS caused by EHEC were registered in Estonia
during this period (ECDC, 2011). In 2006 there was a registered case in Estonia where
EHEC was most probably transmitted with raw milk (EFSA, 2012).
The number of EHEC cases registered from 2010-2012 was 5, 4 and 3, respectively. Four
cases had been registered as at September 2013 (Health Board, 2013 c).
2) Soil and the intestines of infected animals (incl. wild animals) are the reservoir of Listeria
monocytogenes. Listeria is very resistant, can survive freezing and is also capable of
reproducing at low temperatures above zero. Infected animals excrete listeria in their faeces,
milk and uterine secretions. There are 13 serotypes of L. monocytogenes. Among them, 4b,
1/2b and 1/2a are the main ones that cause illness among people and animals (Spickler,
2005).
The pathogen enters the human body primarily with contaminated food of animal origin. The
foetus of an infected mother can become infected via the placenta during pregnancy. In the
case of late listeriosis, the newborn is infected during childbirth when passing though the
birth canal (Health Board, 2013).
Listeriosis is a serious problem mainly for pregnant women, newborns, elderly people and
those with weakened immunity. Pregnant women may develop light influenza-like
symptoms, or the illness may be subclinical. A few days or weeks later, it may be followed
by miscarriage, stillbirth, premature birth or septicaemia in the newborn. Babies may suffer
septicaemia, respiratory tract disorders, granulomatosis or meningitis, which can often result
in death. The elderly and people with weakened immunity usually develop meningitis or
meningoencephalitis; less frequently septicaemia. The formation of any symptoms is rare for
healthy adults. The new syndrome associated with foodborne listeria infection in adults is
gastroenteritis with a fever, which is usually self-limiting and passes in one to three days
(Spickler, 2005).
According to the Veterinary and Food Laboratory, clinical listeriosis in Estonian cattle was
diagnosed in 3-13 herds per year from 2008-2012. Sporadic cases have also been registered
in goat herds (Veterinary and Food Laboratory, 2009-2013).
2
L. monocytogenes has permanently been present in the raw milk samples collected on
Estonian dairy farms. It was found in 4.8-20.0% of samples from 2007-2011 (EFSA, 2012).
In humans, listeriosis has been sporadically diagnosed in Estonia (3-8 cases per year from
2007-2011) and there have been no major outbreaks (EFSA, 2012). Three cases of listeriosis
were registered in Estonia in 2012 and the number of cases as at September 2013 was two
(Health Board, 2013). Listeria enteritis has not been registered in Estonia.
3) Salmonella enterica
The most important S. enterica serotypes in cattle in terms of zoonoses are S. Dublin,
S. Typhimurium and S. Newport (Costa et al., 2012; Cummings et al., 2012). In developed
countries, salmonella infections in people are primarily related to consumption of
salmonella-contaminated food, including milk and dairy products (Flint et al., 2005; Mazurek
et al.,2003; De Valk et al., 2000). It is also possible to become infected via direct contact
with infected animals (Costa et al., 2012).
Infection results in acute enterocolitis with diarrhoea, fever, abdominal pain and headache,
plus nausea and sometimes vomiting, which results in fluid loss. The symptoms persist for
four to seven days. Septicaemia and organ damage may develop in serious cases (arthritis,
meningitis, endo- and pericarditis, pneumonia, pyelonephritis, etc.), which can result in the
patient’s death (Health Board, 2013). The disease is often more serious in children under five
years of age, elderly people and those with weakened immunity (Cummings, 2012).
Salmonellae are the food pathogens that cause the biggest number of deaths (Flint et al.,
2005).
According to the Veterinary and Food Laboratory, salmonellosis was detected as a clinical
disease in 1-12 cattle herds per year from 2008-2012. In addition to this, infection has been
detected every year in 1-12 herds sampled as part of a salmonellosis surveillance program
(VTA, 2009-2013). In 2011 and 2012 the surveillance programme carried out by the VTA,
detected salmonellosis in 4.4% and 3.7% of herds, respectively (VTA, 2012; 2013).
Salmonella has not been found in raw milk samples in Estonia in recent years. The most
common salmonella serotypes transmitted in cattle herds in Estonia are S. Dublin and S.
Typhimurium. S. Enteritidis infection is also often detected (VTA, 2012; 2013).
The serotypes most prevalent in humans are S. Enteritidis and S. Typhimurium (VTA, 2012).
Approximately 350-650 cases of salmonellosis are registered in Estonia per year. There have
been several outbreaks of food origin. Published data of the epidemiological studies carried
out by the Health Board do not specify whether or how many outbreaks can be associated
with the consumption of milk or dairy products (Health Board, 2013c).
4) Campylobacter spp.
Campylobacteria are the most frequent causes of human gastroenteritis in developed countries
(Flint et al., 2005). The zoonotic campylobacteria found in cattle include C. jejuni, C. coli
(Spickler, 2005) and C. ureolyticus which was recently defined as a possible cause of
gastroenteritis (Bullman et al., 2011; Koziel et al., 2012). So far, C. ureolyticus has only been
detected among animals - in cattle (Koziel et al., 2012). In many European countries, cattle
are a significant source of C. jejuni and C. coli in humans. The share of infections originating
from cattle in humans ranges from 10-20% (Mughini Gras et al., 2012; Roux et al., 2013).
People can become infected by consuming contaminated food (chicken and other poultry, raw
milk, mussels, etc.) or water, or as a result of contact with infected pets or agricultural
animals. Flies are effective mechanical transmitters of campylobacteria (Spickler, 2005). Most
cases of campylobacteriosis in humans in developed countries are sporadic. Outbreaks are
mostly associated with consumption of contaminated chicken or raw milk, or infection
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received from water (DuPont, 2007; Sahin et al., 2012). Campylobacteria usually spread into
water with faecal contamination, but in rarer cases they can also colonise a cow’s udder and
excrete directly into milk from there (Hutchinson et al., 1985).
The forms of campylobacteriosis in people vary from mild indigestion that self-limits in 24
hours to extremely acute and chronic colitis. Symptoms may include watery or sticky
diarrhoea (faeces may contain blood), fever, nausea and vomiting, headache and muscle pain
and severe abdominal pain with cramping. It may also cause enlargement of the spleen and/or
liver. Complications are rare, but the disease may result in reactive arthritis, HUS and
septicaemia, also meningitis, acute gall bladder infection and Guillain-Barré syndrome
(rapidly progressing polyneuropathy). Isolated cases of miscarriage caused by C. jejuni have
been registered (Spickler, 2005).
Since C. coli and C. jejuni do not ordinarily cause clinical illness in cattle, no attention is
given to their incidence in herds. This is why there is no data about their spread in Estonian
cattle herds. The incidence of Campylobacter has not been studied as part of a food safety
surveillance programme either, which is the reason why there is no information about its
prevalence in milk.
In Estonia, campylobacteriosis is one of the most prevalent diarrhoeal diseases among people.
154-214 cases per year were registered from 2008-2012 (VTA, 2012; Health Board, 2013c).
No official data about the food that was the source of the infection have been published.
5) Yersiniosis, which is caused by Yesrsinia enterocolitica, is one of the most frequently
registered foodborne zoonoses in developed countries, especially in the temperate zone
(ranking third after campylobacteriosis and salmonellosis). The strains of Y. enterocolitica,
which cause illness in people, belong to the bioserotypes of 1B/O:8, 2/O:5,27, 2/O:9, 3/O:3
and 4/O:3 (Atiqur et al., 2011). Most Y. enterocolitica infections in people are sporadic
whereby the source of the infection cannot be identified. Pigs are still considered the main
source of infection for people (Fredriksson-Ahomaa et al., 2006). The bioserotypes of Y.
enterocolitica that are pathogenic for people are detected in cattle less often and in smaller
quantities than in pigs (McNally et al., 2004; Galindo et al., 2011). Irrespective of this, cases
of the illness among humans related to the consumption of contaminated dairy products,
primarily pasteurised dairy products, have been registered in Europe and North America
(McNally et al., 2004; Ackers et al., 2000). The latter mainly refers to mistakes made in milk
handling in food businesses and/or the contamination of products after pasteurisation.
Pathogenic Y. enteroclitica strains in raw milk have been detected in Europe and the rest of
the world (Schiemann, 1978; Shahram, et al., 2012). However, no pathogenic strains were
found in raw milk during the study recently carried out in Finland (Ruusunen et al., 2013).
Rodents are probably also reservoirs of the infection and flies play an important role in the
transmission of the disease (Galindo, 2011).
People become infected when they consume food contaminated with the microbes. The
disease is most prevalent among babies and infants. Symptoms include diarrhoea (often
bloody), fever and abdominal pain. Complications (itching, joint pain, bacteriaemia) are rare
(Rahman, 2011).
Yersinia enterocolitica does not ordinarily cause clinical illness in animals, which is why it
is rarely identified in diagnostic tests. However, it has been found in cattle and goats
sporadically in Estonia. In cattle, Y. enterocolitica infection is often found due to serological
cross-reactivity with the antigens of Brucella abortus. In 2008 the infection was registered in
one cattle herd; in 2009 in 12 cattle herds and one goat herd (VTL, 2009-2010).
47-69 cases per year were registered in people in Estonia from 2010-2012 (3.5-5.1
cases/100,000 residents) (Health Board, 2013c). The sources of the infection are not known.
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6) Yersinia pseudoruberculosis belongs among enteropathogenic yersina alongside Y.
enterocolitica and causes infections of the intestinal tract in many animal species. The illness
may not have any symptoms in animals, but in the case of cattle it has been associated with
miscarriage, pneumonia and mastitis in addition to enteritis (Shwimmer et al., 2007). Y.
pseudotuberculosis also causes mastitis among goats (Jones et al., 1982). Y.
pseudotuberculosis can get into milk from the environment as well as directly from the
infected udder. There are many registered cases of people becoming infected via milk
(Shwimmer et al., 2007).
In people, pseudotuberculosis usually manifests itself with symptoms of gastroenteritis
(fever, abdominal pain) and mesenteric lymphadenitis. Most common complications include
reactive arthritis, erythema nodosum and itching. High-risk persons, i.e. those with a
weakened immune system, may develop sepsis and various associated complications (e.g.
chronic liver disease) (Rihmanen-Finne et al., 2009; Schwimmer et al., 2007).
There are no data from recent years about the incidence of Yersinia pseudotuberculosis
among ruminants. However, in Estonia it has been detected in pigs (Martinez et al., 2009),
which gives reason to assume that the infection can also be found in ruminants.
Pseudotuberculosis has also been registered in people in Estonia (Zolotuhhina et al., 1996).
7) Clostridium perfringens is an anaerobic spore-forming bacterium that is widely spread in the
environment and can often be found in the intestines of people and animals. It is often found
in raw animal meat and poultry, but also in raw milk (CDC, 2013; Rea et al., 1992). Some
strains of C. perfringens produce toxins that cause illness. All toxin-producing C. perfringens
Type A strains are associated with food poisoning (The Merck Manual, 2013).
People fall ill when a large quantity of C. perfringens bacteria gets into the intestines. The
spores of C. perfringens become active at temperatures from 12°C - 60°C and the bacteria
start reproducing (the reproduction rate being particularly high at 43°C - 47°C). This means
that preservation of food contaminated with a small amount of spores can lead to C.
perfringens reproduction at such a rate that the food can make a person ill (CDC, 2013).
Infected people suffer acute gastroenteritis, which manifests itself as diarrhoea and
abdominal cramps. Signs of the disease usually disappear in 24 hours. Severe illness and
death are rare (The Merck Manual, 2013).
In Estonia, C. perfringens has been registered in cattle in isolated cases (VTL, 2013).
Intestinal infections caused by C. perfringens in people are registered in Estonia every year
(Health Board, 2013 c). Data on the sources of infection have not been published.
8) Bacillus cereus is a spore-forming facultatively anaerobic bacterium that is widely
distributed environmentally. It is able to colonise the intestines of animals for a short time.
The spores of B. cereus in dairy products come from the farm environment or have spread
there in the course of cross-pollution during the handling process (Vissers et al., 2007).
B. cereus causes two types of illness in people: (1) the emetic form with a short incubation
period (1-6 hours) characterised by nausea, vomiting and abdominal cramps, and which is
caused by a thermostable emetic toxin; (2) the diarrhoeal form with a longer incubation
period (8-16 hours) characterised by severe, watery diarrhoea, caused by the thermolabile,
diarrhoeal enterotoxins Nhe and/or hemolytic enterotoxin HBL (Todar, 2013).
Since B. cereus does not cause ordinary clinical symptoms in cattle, it is not investigated in
routine diagnostic procedures. There are also no official statistics about incidence among
humans in Estonia.
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9) Cryptosporidium spp.
Cryptosporidia are protozoan intracellular parasites that are transmitted via the faecal-oral
route. Cryptosporidium parvum is the cryptosporidium in cattle that is the most dangerous to
people. The sporulated oocysts excreted in faeces are immediately infective. In a damp
environment, they remain infective for 2-6 months (Spickler, 2005). The infection spreads
both by direct contact from animals to people as well as via the environment, with
contaminated water and food, including milk (Fayer et al., 2000; Fretz et al.; 2003).
Cryptosporidiosis in people is characterised by severe, watery diarrhoea, abdominal pain and
cramps, nausea and a lack of appetite. Some people may vomit, lose weight and suffer from
fever and muscle pain. The illness is usually self-limiting in healthy adults, but it may
become chronic, exhausting and severe in people with weakened immunity, and cause death.
The pulmonary form is characterised by a cough with fever and severe diarrhoea (Spickler,
2005).
Cryptosporidia have been detected in 84% of cattle herds in Estonia (Lassen et al., 2009).
Cryptosporidiosis is very rarely registered in humans in Estonia, because the disease is
considered self-limiting and no tests are usually performed to identify it (Šljapnikova et al.,
1994).
2.2
Microbes excreted with milk that infect humans
2.2.1
Mastitis agents
1) Staphylococcus aureus causes various inflammatory conditions in animals and people, from
skin and wound infections to pneumonia and septicaemia. The toxins produced by S. aureus
also cause food poisoning and toxic shock syndrome in people (Todar, 2013).
S. aureus is a widely spread agent of sub-clinical mastitis in cows. S. aureus may get into the
milk consumed as food directly from an infected udder or the environment (dust, equipment,
etc.), as well as from people who handle milk and carry Si aureus in their nostrils or on their
hands (Argudin et al., 2010).
The food poisoning caused by S. aureus is an intoxication caused by the enterotoxins
produced by the bacterium, which is characterised by a short incubation period (2-8 hours),
nausea, severe vomiting, abdominal cramps and diarrhoea (although the latter may not
occur). The symptoms usually disappear by themselves within 24-48 hours. Infants, elderly
people and people with weakened immunity may sometimes require hospitalisation
(Spickler, 2004; Argudin et al., 2010).
Staphylococcus aureus is one of the most widely spread causal agents of mastitis in dairy
cattle. From 2007-2009 it caused 11.7% of the registered cases of sub-clinical mastitis and
16.6-22.8% of clinical mastitis (Kalmus et al., 2011).
Samples of raw milk where the content of S. aureus exceeds the established limit are
registered by the VTL in 2-3 cases every year (Kramarenko, oral information, 2013).
Cases of enteritis caused by S. aureus in humans are regularly registered in Estonia (Health
Board, 2013c).
2) Streptococcus agalactiae is a Group B streptococcus which is a widely spread causal agent
of clinical mastitis in cows in Estonia. Streptococci colonise the skin of the cows’ udders and
cause mastitis by penetrating the udder. The infection spreads from cow to cow via milking
equipment (Pyörälä, 1996). Streptococci spread into milk directly from the udder or the
surface of the udder.
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S. agalactiae causes endometritis in women; in pregnant women, it can cause sepsis,
osteomyelitis, endocarditis, meningitis and septic miscarriage. Group B streptococci are also
significant pathogens for newborns and the elderly, in whom they cause invasive infections
such as meningitis, sepsis and pneumonia (in children), endocarditis, soft tissue inflammation
and bone and muscle inflammation (in elderly people) (Spickler, 2005; Haguenoer et al.,
2011). The sepsis caused by S. agalactiae is the main cause of death among newborns in the
West (Apgar et al., 2005).
The strains of S. agalactiae detected in people usually spread from person to person. S.
agalactiae often colonise the mucous membranes of people without causing any disease
(Spickler, 2005). However, there is enough proof that transmission of S. agalactiae from
cattle to people has occurred, as there is a genetic link between the strains that are pathogenic
to people and strains isolated from cattle (Haguenoer et al.; 2011).
S. agalactiae is a common agent of mastitis in cows in Estonia, as it causes 9-14.7% of all
cases of sub-clinical mastitis per year (Kalmus et al., 2011).
From 2000-2002, S. agalactiae was registered in 3.3-7.8% of women tested in women’s
clinics or maternity wards in Estonia (Mändar, 2011).
2.2.2
Other zoonotic pathogens excreted with milk
1) Coxiella burnetii
The causative agent of Q fever is a small intracellular bacterium known as Coxiella burnetii,
which forms special spore-like structures that are highly resistant in the environment.
Animals mostly spread the causative agents of Q fever in faeces, but also in milk. This means
that raw milk is a possible source of infection (Spickler, 2007). Q fever in cattle, goats and
sheep may pass without noticeable clinical signs, but it may cause an abortion storm, still
births and weak offspring as well as placentitis, endometritis and infertility (Maurin &
Raoult, 1999; Eibach et al., 2012).
In humans, Q fever usually occurs with influenza-like symptoms, but it may also cause
pneumonia in severe cases. Chronic Q fever can lead to heart or liver damage, and cause the
patient’s death (Bacci et al., 2012).
C. burnetii infection has been detected in ca 25% of dairy herds in Estonia. In goat herds, the
infection has not yet been detected. The infection has also been detected in 1.4% (CI95%
0.6-2.9%) of tested people in Estonia (Neare et al., 2013). In Estonia, Q fever as a clinical
disease has not yet been detected in people. However, the possibilities for laboratory
diagnosis of the infection were lacking in Estonia until recently.
2) Toxoplasma gondii is an obligate, intracellular, parasitic protozoan carried in many species
of mammals, including ruminants. In infected animals, the disease is often sub-clinical
(Järvis, 2011). Both cows and goats excrete toxoplasmas with milk; they are more frequent in
goat’s milk (Dehkordi et al., 2013). Studies have indicated that the different developmental
forms of toxoplasma excreted with milk are infective and can be transmitted to people
(Hiramoto et al., 2001; Pereira et al., 2010).
Immunocompetent people who are not pregnant usually exhibit no symptoms when infected
with T. gondii. 10-20% of infected persons may develop lymphadenitis or light influenza-like
symptoms. In some cases, the disease can resemble infectious mononucleosis. Symptoms
usually disappear within a couple of weeks without treatment (Spickler, 2005). T. gondii is a
significant pathogen for immunocompromised (and sometimes also immunocompetent)
people, causing diseases of the central nervous system and the eyes. The infection may be
transmitted to the foetus when a pregnant woman becomes infected for the first time. This
7
results in brain and/or eye damage in the foetus. The earlier the stage in pregnancy that the
infection occurs, the more severe the damage (Pereira et al., 2010). Ocular toxoplasmosis
with uveitis is sometimes also detected in youngsters and young adults. It is usually a
delayed manifestation of asymptomatic foetal or postnatal infection (Spickler, 2005).
In Estonia, T. gondii infection has been detected in dairy cows on 91.1% of farms and in
24.1% of dairy cows (Jokelainen et al., unpublished data, 2013). The share of persons
positive for antibodies in the population is 56.4% (Janson et al., 2013).
3) Tick-borne encephalitis virus (TBEV) is an RNA virus of the genus Flavivirus in the family
of Flaviviridae, which is transmitted to humans by ticks, but whose natural reservoirs include
many species of wild animals and which also infects domestic animals, including cattle and
small ruminants. The latter may excrete the virus with milk, which may infect people
(Mansfield et al., 2009; Dobler et al., 2012). People are more commonly infected by goat’s
milk, but infection by cow’s milk containing the virus has also been registered (Juceviciene,
2005; Caini et al., 2012; Hudopisk et al., 2012).
Tick-borne encephalitis develops in two phases in people. The first symptoms, which last for
3-4 days, are fever, muscle pain, nausea and vomiting. These are often followed by an
asymptomatic period, which lasts for 2-10 days and can end in the person’s recovery. Acute
signs of damage to the central nervous system develop if the disease progresses to the second
phase (Kirkmann et al., 2007; Mansfield et al., 2009). The disease most often manifests as
meningitis, meningoencephalitis, polimyelitis or polyradiculoneuritis, or a combination
thereof (Kirkmann et al., 2007). The poliomyelitic form may result in long-term disability.
The mortality among diseased patients is 1-3% (Mansfield et al., 2009).
According to our data, the tick-borne encephalitis infection has been detected in 35% of
cattle herds and 56% of goat herds in Estonia (Viltrop, et al., unpublished data 2013).
Transmission of the virus to people by goat’s milk and cow’s milk has repeatedly been
detected in Estonia (Kerbo et al., 2005). The last case dates back to 2011, where the infection
was transmitted with goat’s milk (VTA, 2012).
4) Leptospira hardjo
Among the species and serovariants of leptospira that have adapted to cattle, L. hardjo is
considered to be the most dangerous to people. It often spreads asymptomatically among
cattle, mainly causing fertility problems and late abortions. At the same time, its zoonotic
potential is high. In many countries where L. hardjo is widely spread, it is the main serotype
of leptospira that infects people (Adler, de la Peña Moctezuma, 2010; Bolin, 2003). The main
risk factor in human infection is direct contact with infected animals (Spickler, 2005).
However, leptospiras may be excreted from the udders of infected animals straight into milk
(Thiermann, 1982) or reach it via the environment. Some data suggest that L. hardjo can
remain viable for at least 10 days in chilled milk, which is why its transmission to people
who consume unpasteurised milk cannot be excluded (Natale et al., 2012).
The course of leptospirosis in humans varies from infection without symptoms to acute
illness. In most cases, the illness has minimal or no clinical manifestations. The illness
usually develops in two phases. The first acute or septic phase starts suddenly with influenzalike symptoms - fever, muscle pain, photophobia and headache; in serious cases abdominal
pain, vomiting and jaundice. The first phase lasts 4-9 days, after which the fever and muscle
pain disappear and the person may recover. However, this can be followed by the second
phase of the illness (the immune phase). This phase can manifest itself as meningitis or
Weil’s disease, a severe form of leptospirosis that causes jaundice and which is characterised
by headache, rash, thrombocytopenia, liver and kidney damage and jaundice. The second
8
phase of the disease can also end with the patient’s death. Lethality is 1-5% in the case of the
form with meningitis and 5-10% in the case of the form with jaundice (Spickler, 2005).
In Estonia, L. hardjo infection has been detected in 17% of dairy herds. In goats, the
infection has not yet been detected (Viltrop, unpublished data, 2013). In Estonia, 2-8 cases of
leptospirosis in humans have been registered in recent years (Health Board, 2013c). The
serotypes detected in humans in 2012 were Leptospira pomona, Leptospira grippotyphosa,
Leptospira bratislava and, in two cases, unidentified Leptospira spp. (VTA, 2013). Infection
by milk is not probable in the case of the first three listed serotypes. However, the serotype
was not identified in the case of two patients, which means that L. hardjo infection cannot be
excluded.
5) Mycobacterium avium ssp paratuberculosis (MAP) belongs to the group of microorganisms known as M. avium-M. intracellulare (MAI). The reservoir hosts of the infection
are cattle and small ruminants. In cattle and small ruminants, the disease causes
paratuberculosis, which is a chronic disease with a very long duration. Infected animals are
carriers of the infection for a long period during which they transmit the MAP to the
environment via faeces and milk (Spickler, 2007). People can become infected with MAP,
which is epidemiologically related to Crohn’s disease (Sechi et al., 2005; Uzoigwe et al.,
2007). Crohn’s disease is a chronic inflammatory disease of the intestines, especially the
colon and ileum, associated with ulcers and fistulae. The main symptoms of the disease are
acute bouts of diarrhoea, abdominal pain and cramps, fever, weight loss and meteorism
(Uzoigwe et al., 2007).
In Estonia, seropositive animals have been detected in 3.5-9.6% of cattle in recent years
(VTL, 2008-2013).
1.4 cases per 100,000 residents of Crohn’s disease have been diagnosed each year in Estonia.
6) Borrelia burgdorferi is a bacterium transmitted by ticks causes borreliosis or Lyme disease
in humans. Small rodents are its main natural reservoir. Pets are incidental hosts who become
infected as a result of tick bites (Spickler, 2011). Borreliae have been detected in the urine
and milk of infected people and cattle (Schmidt et al., 1995; Lischer et al., 2000). However,
there are no registered cases of borreliosis infection whereby infection via the environment or
orally has been proven (Spickler, 2011). This means that based on existing scientific
information, it cannot be claimed that B. burgdorferi can infect people via milk consumed as
food.
7) In addition to the pathogens listed above, the spread of other rare infections via milk cannot
be excluded in Estonia, e.g. the causal agent of anthrax Bacillus anthracis and the causal
agent of human tuberculosis Mycobacterium tuberculosis, or the emergence of toxins due to
the contamination of milk with toxinogenic bacteria (Cl. botulinum; other Bacillus spp.
toxins).
3
Overview of outbreaks related to raw milk in the world
According to different opinions, 1-3% of the population of developed countries consume raw
milk and dairy products made from it that have not been heat-treated (Langer et al., 2012; CDC,
2002-2003). A number of factors determine whether or not a person who consumes raw milk
gets food poisoning or an infection. These factors include the level of virulence of the microorganisms (or toxicity of the toxins) in raw milk, the micro-organism (or toxin) count, the
infectious dose and the state of the person’s health (Lund & O’Brien, 2011).
9
Research into outbreaks related to milk and dairy products indicates that ca 70% of such
incidents in the US (Centers for Disease Control and Prevention, 2002-2003) and 50-60% in the
US and Europe (Gillespie et al., 2003; Langer et al., 2012) have been caused by infection from
products that were not heat-treated. In addition to the above, it has been found that on average 16% (Claeys et al., 2013; De Buyser et al., 2001) of outbreaks of bacterial diseases in the world
have been caused by the consumption of contaminated raw milk or dairy products. The statistics
of different countries indicate that the share of outbreaks caused by consumption of raw milk or
dairy products contaminated with pathogenic bacteria among all outbreaks was 6.1% in France,
5.7% in the Netherlands, 5.5% in Germany, 4.4% in England, 3.5% in Poland, 3.0% in Finland
and 2.2% in the United States (De Buyser et al., 2001). The data above may not be complete.
Namely, it has been noted that national surveillance systems do not register all diseases and
outbreaks related to raw milk (Oliver et al., 2009). There may be several reasons for this, e.g. not
all persons are hospitalised depending on the level of severity of the food poisoning, or not all
cases are diagnosed in respect of the pathogen.
However, various studies confirm that extensive consumption of raw milk can be associated with
large outbreaks of food poisoning and that the frequency of outbreaks is increasing (Newkirk et
al., 2011; Oliver et al., 2009). This is also confirmed in the latest report by the U.S. Centers for
Disease Control and Prevention, which states that after widespread sales of raw milk were
permitted in the United States, i.e. after it became freely accessible to consumers, the frequency
of outbreaks caused by raw milk increased significantly (Langer et al., 2012).
An overview of the outbreaks related to raw milk in the European Union and the United States
from 1949-2013 is given in Table 1. The most common food pathogens that have caused
outbreaks related to raw milk include Campylobacter jejuni, Listeria monocytogenes, Yersinia
enterocolitica, pathogenic Escherichia coli, Salmonella spp. as well as Staphylococcus aureus
(De Buyser et al., 2001; Gillespie et al., 2003; Newkirk et al., 2011; Langer et al., 2012).
The data in Table 1 suggest that outbreaks related to raw milk are more frequent in the United
States than in Europe. However, irrespective of the country in which the outbreak occurred, it
was caused by the fact that the people who suffered from food poisoning or foodborne infection
consumed raw milk or raw dairy products made without heat-treatment.
Food pathogens can get into raw milk via the microflora in a cow’s udder (if the cow has
mastitis) and from the external environment that surrounds the cow if strict milking hygiene
requirements are not complied with. For example, it has been noted that in one case the raw milk
that caused an outbreak became infected with E. coli O157 on the farm either during milking or
further handling of the milk as a result of faecal contamination due to the presence of one
asymptomatic cow in the dairy herd (Guh et al., 2010). This is why the conclusion made in the
given study was that raw milk can become contaminated on a farm even if the overall hygiene
situation there is excellent and the hygiene of raw milk production complies with requirements.
The examples of outbreaks given in Table 1 became possible due to the consumption of
contaminated milk that came from dairy cows kept on a small farm for own use, was purchased
directly from a large farm or was accessible to people from shops.
The outbreaks described in Table 1 cannot be used as a basis for highlighting the food pathogens
that have caused more cases of illness, because the submitted data are not final. However, it is
possible to conclude that in the United States, the biggest number of outbreaks have been
associated with the presence of C. jejuni and in Europe with the presence of L. monocytogenes
and Salmonella spp. in raw milk.
46 outbreaks related to raw milk were registered in the United States from 1973-1992, and in
87% of cases raw milk was sold to consumers legally (Headrick et al., 1998). There were 45
outbreaks in North America from 2000-2001 which were caused by the consumption of raw milk
10
and dairy products made from raw milk, which caused 686 people to fall ill, eight of whom died
(BC Centre for Disease Control, 2012). Outbreaks have been caused by Campylobacter,
Salmonella and E. coli. Based on the examples given in Table 1, the number of people who have
fallen ill in outbreaks has been 2-148, but no cases have ended with death in recent years.
Outbreaks related to raw milk have also been rather common in Europe. For example, drinking
raw milk caused a lot of people to fall ill from 1949-1957 - ca 100 people suffered from
listeriosis as a result of this (Seeliger, 1961). A major outbreak was also registered in 1981 in
Scotland, when 654 people contracted salmonellosis as a result of raw milk consumption, two of
whom died (De Buyser et al., 2001). In the 1990s there were ca 100 milk-related outbreaks in
England and France (De Buyser et al., 2001; Gillespie et al., 2003). In 1997, for example,
consumption of raw-milk cheese resulted in 113 people contracting salmonellosis (De Buyser et
al., 2001). In the Netherlands, 34 people in 2005 and 16 people in 2007 contracted
campylobacter enteritis after consuming raw milk (Heuvelink et al., 2009).
Consumption of raw milk and raw dairy products has been associated with several outbreaks of
listeriosis in Europe (Lundén et al., 2004). Said outbreaks have mostly been associated with the
consumption of cheeses. The explanation for this is that L. monocytogenes can survive during the
technological process of cheese production as well as during the maturation of cheese in the
warehouse (Schvartzman et al., 2011). A serious risk to people’s health mainly emerges in cases
where unpasteurised milk is used as the raw material for making cheese. Cheeses made from
such milk have caused outbreaks mainly in France (Goulet et al., 1995). The presence of
Campylobacter jejuni and C. coli in raw milk has been associated with outbreaks in Europe
(Newkirk et al., 2011). For example, an outbreak of campylobacter enteritis occurred in a
farmer’s family in Finland where the family members had consumed raw milk from their own
farm (Schildt et al., 2006). Several studies have also confirmed the connection between
salmonellosis and consumption of raw milk (Dominguez et al., 2009). In 1995, for example, 25
people in France contracted salmonellosis after eating raw-milk cheese, five of whom died (De
Buyser et al., 2001). Raw milk and raw dairy products have also caused illness related to E. coli
O157 (Guh et al., 2010). For example, a person in Scotland who had eaten cheese made from
raw milk contaminated with E. coli O157:H7 got food poisoning.
11
Table 1. Overview of outbreaks related to raw milk
Time and country
April 2013
Minnesota, USA
Pathogen
Salmonella
April 2012
Missouri, USA
Escherichia coli
Source
Mexican-style
cheese made from
raw milk
Raw milk
April 2012, Oregon,
USA
Escherichia coli
Raw milk
January 2012
Pennsylvania, USA
Campylobacter
Raw milk
September 2011
New York, USA
Campylobacter
Raw milk
August - October
2011
California, USA
July 2011
North Carolina, USA
Escherichia coli
O157:H7
Raw milk
Campylobacter
jejuni
Raw milk
June 2011
Alaska, USA
Campylobacter
Raw milk
April 2011
Texas, USA
Salmonella
Raw milk
April 2010
USA
Salmonella
Raw milk
Diseased
(died)
Reference
25 StarTribune health: Salmonella outbreak that sickened 25 linked to raw milk
http://www.startribune.com/lifestyle/health/208248661.html
14 Food Safety News: Raw milk still suspect in 14 Missouri E. coli cases.
http://www.foodsafetynews.com/2012/05/missouri-says-14-e-coli-cases-may-befrom-raw-milk/#.Ui95FH9jYQM
21 KTVZ.com News: Oregon E. coli outbreak traced to raw milk.
http://www.ktvz.com/news/Oregon-E-Coli-Outbreak-Traced-to-Raw-Milk//413192/15292378/-/8i28tjz/-/index.html
148 Huffpost Healthy Living: Raw milk sickened 148 in Campylobacter outbreak last
year
http://www.huffingtonpost.com/2013/05/06/raw-milk-outbreak-campylobacter148-sickened_n_3223199.html
2 WBNG News: Campylobacter contamination found in raw milk in Tompkins
County
http://www.wbng.com/news/around-the-tiers/Campylobacter-ContaminationFound-in-Raw-Milk-in-Tompkins-County-130820728.html
5 News Release. California department of food and agriculture: Organic pastures
raw milk recall announced by CDFA.
http://www.cdfa.ca.gov/egov/Press_Releases/Press_Release.asp?PRnum=11-064
8 FDA: Foodborne outbreak associated with raw milk from Tucker Adkins
Dairy of York S.C., U.S. Food and Drug Administration, 2011
http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm263158.ht
m
3 State of Alaska Epidemiology. Bulletin. Ongoing raw milk Campylobacter
outbreak – southcentral Alaska, July 2011.
http://www.epi.alaska.gov/bulletins/docs/b2011_22.pdf
4 WFAA Local News: Raw milk under scrutiny after North Texas illness.
http://www.wfaa.com/news/local/Raw-milk-under-scrutiny-after-North-Texasillnesses-120321579.html
6 Deseret News: Salmonella outbreak linked to raw milk sold in Orem and Heber
http://www.deseretnews.com/article/700032391/Salmonella-outbreak-linked-to12
January 2010
USA
Campylobacter
Raw milk
July 2008
Connecticut, USA
November 2007
Kansas, USA
Escherichia coli
O157
Campylobacter
Raw milk
2007
The Netherlands
October 2007
Kansas, USA
Campylobacter
jejuni
Campylobacter
Raw milk
2006
USA
2005
The Netherlands
2003
USA
2001
USA
1997
France
Campylobacter
jejuni
Campylobacter
jejuni
Campylobacter
jejuni
Campylobacter
jejuni
Salmonella
Raw milk
1997
India
1997
France
Yersinia
enterocolitica
Listeria
monocytogenes
Raw milk
1996
France
Salmonella
Raw milk
Raw milk
raw-milk-sold-in-Orem-and-Heber.html
5 New York State Department of Health: Campylobacter contamination found in
raw milk
http://www.health.ny.gov/press/releases/2010/2010-0129_campylobactor_contamination_in_raw_milk.htm
14 Guh et al., 2010
19 Kansas Department of Health and Environment:
KDHE and KDA remind consumers of health risks tied
to raw milk
http://www.kdheks.gov/news/web_archives/2007/12042007a.htm
16 Heuvelink et al., 2009
Raw milk
67 Centers for Disease Control and Prevention
Campylobacter jejuni infection associated with
unpasteurized milk and cheese, MMWR 57(51&52):1377-1379.
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5751a2.htm?s_cid=mm5751a
2_x
6 Teufel, P. 2003. Campylobacter spp. In: Roginski, H., Fuquay, J.W., Fox, P.F.
(Eds.), Encyclopedia of Dairy Sciences. Academic Press, pp. 237-243.
34 Heuvelink et al., 2009
Raw milk
13 Teufel, 2003.
Raw milk
75 Teufel, 2003.
Raw-milk
Morbier cheese
Raw-milk
Livarot, PontL’évêque cheese
Raw-milk Mont
d’Or cheese
113 De Buyser, M.-L., Dufor, B., Maire M., Lafarge, V. 2001. Implication of milk
and milk products in food-borne diseases in France and in different industrialised
countries.-International Journal of Food Microbiology 67:1-17.
25 Barton, M.D. 2002. Yersinia enterocolitica. In: Roginski, H., Fuquay, J.W., Fox,
P.F. (Eds.), Encyclopedia of Dairy Sciences. Academic Press, pp. 2770-2776.
14 De Buyser et al., 2001
14 (1) De Buyser et al., 2001
13
1995
France
1995
France
1994
Canada
1993
France
Listeria
monocytogenes
Salmonella
1994
Scotland
1992/1994
USA
1991
Japan
Escherichia coli
O157:H7
Escherichia coli
O157:H7
Bacillus cereus
1990
France
Salmonella
1989
England and Wales
1988
England
Salmonella
1986
England and Wales
1986
Canada
1985
Finland
1985
Scotland
1985
USA
1985
Switzerland
Salmonella
Raw milk
Escherichia coli
O157:H7
Salmonella
Salmonella
Salmonella
Staphylococcus
aureus
Staphylococcus
aureus
Campylobacter
jejuni
Salmonella
35 (4) De Buyser et al., 2001
Raw-milk Brie de
Meaux cheese
Raw-milk Mont
d’Or cheese
Raw-milk soft
cheese
Cheese made
from raw goat’s
milk
Raw-milk soft
cheese
Raw milk
UHT milk,
pasteurisation
process failed
Cheese made
from raw goat’s
milk
Raw-milk soft
cheese
Raw-milk cheese
25 (5) De Buyser et al., 2001
35 De Buyser et al., 2001
273 (1) De Buyser et al., 2001
1 De Buyser et al., 2001
14 De Buyser et al., 2001
201 Christiansson, A. 2002. Bacillus cereus. In: Roginski, H., Fuquay, J.W., Fox, P.F.
(Eds.), Encyclopedia of Dairy Sciences. Academic Press, pp. 123-127.
277
De Buyser et al., 2001
42
De Buyser et al., 2001
155
300
Maguire, H.C.F., Boyle, M., Lexis, M.J., Pankhurst, J., Wieneke, A.A., Jacob, M.,
Bruce, J., O’Mahony, M., (1991). A large outbreak of food poisoning of unknown
aetiologic associated with Stilton cheese. Epidemiol. Infect. 106, 497-505.
De Buyser et al., 2001
Raw milk
46
De Buyser et al., 2001
Raw-milk farm
cheese
Raw goat’s milk
35
De Buyser et al., 2001
2
De Buyser et al., 2001
Raw milk
23
Raw milk
215
Teufel, P. 2003. Campylobacter spp. In: Roginski, H., Fuquay, J.W., Fox, P.F.
(Eds.), Encyclopedia of Dairy Sciences. Academic Press, pp. 237-243.
De Buyser et al., 2001
14
1984
England and Wales
1984
USA
1984
Canada
1984
Scotland
Salmonella
Raw milk
106
De Buyser et al., 2001
Campylobacter
jejuni
Salmonella
Raw milk
12
> 1700
27
De Buyser et al., 2001
1983
France
Staphylococcus
aureus
20
De Buyser et al., 2001
1983
England and Wales
1982
Canada
1982
England and Wales
1982
England and Wales
1981 Scotland
1976
Canada
1972
Romania
1970-1979
Scotland
1949-1957
Germany
Salmonella
Raw-milk
Cheddar cheese
Cheese made
from raw sheep’s
milk
Cheese made
from raw sheep’s
milk
Raw milk
Teufel, P. 2003. Campylobacter spp. In: Roginski, H., Fuquay, J.W., Fox, P.F.
(Eds.), Encyclopedia of Dairy Sciences. Academic Press, pp. 237-243.
De Buyser et al., 2001
182
De Buyser et al., 2001
Unknown
De Buyser et al., 2001
Salmonella
Raw-milk
Cheddar cheese
Raw milk
77
De Buyser et al., 2001
Salmonella
Raw milk
68 (1)
De Buyser et al., 2001
Salmonella
Yersinia
enterocolitica
Bacillus cereus
Raw milk
Raw milk
654 (2)
138
Raw milk
221
Salmonella
Raw milk
29
De Buyser et al., 2001
Barton, M.D. 2002. Yersinia enterocolitica. In: Roginski, H., Fuquay, J.W., Fox,
P.F. (Eds.), Encyclopedia of Dairy Sciences. Academic Press, pp. 2770 2776.
Christiansson, A. 2002. Bacillus cereus. In: Roginski, H., Fuquay, J.W., Fox, P.F.
(Eds.), Encyclopedia of Dairy Sciences. Academic Press, pp. 123-127.
Sharp et al., 1980
Listeria
monocytogenes
Raw milk
~100
Seeliger, H. P. R. 1961. Listeriosis. Hafner, New York.
Staphylococcus
aureus
Salmonella
15
4
4.1
Risk management measures
Measures applied in Estonia for managing zoonotic risks associated with raw milk
Requirements for milk to be marketed in the European Union are established with Regulation (EC) No
853/2004 laying down specific hygiene rules for food of animal origin (Annex III, Section IX). Such
requirements are also specified in Commission Regulation (EC) No 2073/2005 on microbiological criteria
for foodstuffs. In Estonia, requirements for raw milk were established with Minister of Agriculture
Regulation No 71 ‘Hygiene requirements for handling raw milk’ of 15 June 2006 (Riigi Teataja, 2006).
Pursuant to this regulation, a milk producer who wishes to market raw milk directly to consumers must hold
an animal-health certificate (issued for up to six months by an authorised veterinarian). The certificate is
issued on condition that the milk producer has carried out the following analyses within the scope of selfinspection (the acceptability criteria of results are given in brackets):
1) determining the number of bacteria in 1 ml of bulk tank milk at a temperature of 30 o C – twice a month
(≤ 100,000 *).
* Rolling geometric average over two months, at least two samples per month
2) determining the somatic cell count per 1 ml of bulk tank milk – once a month (≤ 400,000**)
** Rolling geometric average over three months, at least one sample per month
3) Staphylococcus aureus count in bulk tank milk – once every two months (< 500/m)
4) determining antibiotic residue – once a month (does not exceed permitted maximum)
A milk producer is also obliged to inform the competent authority and take appropriate measures to improve
the situation if norms are exceeded.
The above requirements do not apply to the small quantities of raw milk marketed directly from farms.
Pursuant to subsection 5 (1) of Regulation No 71 of the Ministry of Agriculture, marketed quantities are
considered small as follows:
1) raw cow’s milk – up to 100 kg per day or 700 kg per week;
2) raw goat’s milk – up to 20 kg per day;
3) raw sheep’s milk – up to 10 kg per day.
Within the scope of state supervision, additional samples of bulk tank milk are taken from directmarketing dairy farms on the basis of the risk assessment prepared by the VTA. A sample is taken once a
year, and in addition to the aforementioned quality indicators, it is also tested for the presence of L.
monocytogenes and the S. aureus count. The samples are tested for other pathogens in the case of suspicion
or tip-offs (VTA, oral information, 2013).
VTA takes samples for raw milk POS according to its monitoring plan and the tests are the same as those
done on samples obtained from dairy farms – the only difference is that the presence of L. monocytogenes is
determined as a total count of L. monocytogenes (VTA, oral information, 2013).
Also, selling raw milk directly to consumers is prohibited according to the rules of animal disease control
after certain zoonoses have been diagnosed or zoonotic pathogens have been detected in a herd. Such
zoonoses are bovine tuberculosis, bovine brucellosis and bovine salmonellosis (Riigi Teataja, 2011; 2004;
2013). The sale of raw milk is also prohibited pursuant to control rules (Riigi Teataja, 2010) when animals
infected with the enzootic bovine leukaemia virus are detected in a herd, although this virus is not a threat to
humans. Marketing unpasteurised goat’s and sheep’s milk is prohibited if brucellosis in sheep and goats is
suspected or diagnosed, or when salmonellosis is detected in the flock (Riigi Teataja, 2008).
Pursuant to §§ 451-453 of the Infectious Animal Disease Control Act, restrictions can be imposed on the
herd or flock if an infectious disease is detected in respect of which there are no infectious animal disease
control rules, but which threatens the health of animals or people according to risk analysis. It is possible to
impose restrictions on the sale of milk on the basis of the above (Riigi Teataja, 2012).
16
4.2
Overview of measures applied in some European Union Member States for managing zoonotic risks
associated with raw milk
We received feedback from 11 EU Member States to the survey we conducted: Finland, Italy, Sweden,
Denmark, Belgium, Slovakia, Germany, Latvia, Lithuania, the Netherlands and France.
Sweden, Denmark and the Netherlands are the only countries among those that gave feedback where selling
raw milk via retail channels is not permitted. In Sweden, only special traditional small-scale farms have the
right to produce and sell raw milk-based dairy products for sale in small quantities during a summer season
through farm gate (fäbod).
In addition to the safety and quality criteria for marketed milk established with Regulations (EC) No
853/2004 and 2073/2005 of the European Parliament and of the Council, national requirements have been
established in the following countries: Finland, Italy, Germany, Latvia, Lithuania, the Netherlands and
France.
The national criteria for raw milk established in Member States are very different. The criteria of the aerobic
bacteria and somatic cell count in most countries complied with Regulation (EC) No 853/2004, although
they are established for raw milk meant for industrial pasteurisation. Stricter requirements of the bacteria
count have been established in Finland, Germany, the Netherlands and France. The maximum aerobic
bacteria count established in said countries is 50,000 per ml of raw milk (rolling geometric average),
whereas several subsamples must be analysed in Germany.
Even larger differences in criteria became evident in respect of pathogenic microorganisms. The list of
pathogenic microorganisms and biotoxins for which raw milk is tested in various countries included the
following: S. aureus (coagulase-positive staphylococci in Germany), L. monocytogenes, Campylobacter
spp., EHEC, Salmonella spp and aflatoxins.
25 ml of bulk tank was usually analysed to detect pathogens, while the sampling plan required obtaining five
subsamples (n=5) and their laboratory testing. None of the subsamples could contain the pathogen for which
it was tested (c=0). Testing for L. monocytogenes and Salmonella and determining the S. aureus count are
required in most countries. The strictest requirements of the S. aureus count have been established in
Germany (m=10, M=100, n=5), which can be explained by the ability of mentioned microbe to produce
toxins.
L. monocytogenes was usually analysed in bulk tank farm milk, with the requirement being its absence in 25
ml (n=5, c=0), but according to received information the criterion in France is 100 CFU/ml during the shelflife period (n=5, c=0, m=M).
As for the production hygiene indicator bacteria for which raw milk is tested, the E. coli count is determined
in France and the enterobacteria count is determined in Finland and Germany.
The frequency of sampling depends on the quantity of raw milk sold; the larger the quantities of directly
marketed raw milk, the more frequently laboratory tests have to be carried out. In Belgium, the existence of
the HACCP system on the farm is required in the case of very large quantities of raw milk (more than
60,000 litres per year).
Sellers of raw milk in all of the countries that responded are required to inform the consumer one way or
another about the need to heat-treat the milk, and in most countries the relevant information also had to be
given in writing on the packaging.
A detailed overview of the effective requirements in different Member States is given in Annex 1.
5
Summary
There are numerous pathogens in Estonia that are hazardous to people and can potentially be found in milk.
The majority of widespread pathogens in Estonia that are transmitted by milk do not cause serious illness or
a high number of death among people. The exceptions here are EHEC and salmonellas, which are
17
potentially very dangerous, especially to risk groups (children, elderly people, ill people), and whose
prevalence in cattle herds in Estonia is relatively high.
The prevalence of pathogens in appropriately produced milk is usually small and their count is low.
However, the infective dose of some pathogens is so small that even if raw milk complies with the highest
quality requirements, it may still be infectious (e.g. EHEC). It is important to keep in mind that several
microbes can reproduce in milk and become infectious when preserved at temperatures higher than in a
refrigerator, or produce toxins that pose a threat to people’s health. Also, some significant food pathogens
are psychrotrophic, i.e. able to reproduce at low temperatures above zero (e.g. Listeria monocytogenes and
Yersinia enterocolitica). In addition, it is impossible to check the risks related to viruses and parasites (e.g.
tick-borne encephalitis virus, Toxoplasma gondii) with bacteriological quality and safety criteria.
The registered incidence of potentially milk-borne zoonoses among people is low in Estonia in the case of
most infections. Salmonellosis and campylobacteriosis are the exceptions here, as their incidence is
relatively high. The way the pathogens were transmitted has often not been clarified in the case of foodborne
zoonoses. Illnesses can only rarely be connected to the consumption of raw milk. The connections have been
clearest when people are infected with tick-borne encephalitis (mainly due to the consumption of infected
goat’s milk). A connection between the consumption of raw milk and the EHEC infection has also been
identified. However, there are obvious shortcomings in Estonia in the system for registration of human
infectious diseases and in capacity to carry out epidemiological studies to identify the sources of infection.
The risk management measures presently implemented in Estonia rely mostly on self-inspection by
producers, and the studies carried out within the scope of such self-inspection for determining quality and
safety indicators. Studies carried out within the scope of supervision in addition to self-inspection by
producers are relatively rare. The quality and safety requirements established for directly marketed raw milk
do not differ significantly from the requirements of the milk sent to milk processing companies for
pasteurisation. Compared to the studies of directly marketed raw milk in many other countries, the sampling
scheme implemented here is relatively less sensitive (n=1) in terms of pathogen detection.
The studies carried out in Estonia at present focus on studying the milk produced and do not cover the
numerous significant zoonotic pathogens that are widespread in Estonia (EHEC, salmonella et al.). The
potential prevalence of zoonotic pathogens in animals is also not considered as a permanent source of risk
for milk contamination in herds from which raw milk for marketing is obtained. For example, proving that a
herd is free of salmonella, EHEC, leptospira or another significant zoonosis is not required if the pathogen
has not been found in bulk tank milk samples or the disease has not been diagnosed or detected in the herd
due to a study carried out for different reasons.
In conclusion, it can be said that the raw milk marketed in Estonia cannot be considered safe enough to
recommend its consumption without pasteurisation. The risk management measures currently in place in
Estonia are not sufficient to guarantee the safety of raw milk for consumers, but even if the efficiency of
testing were boosted, it would still be impossible to fully guarantee safety. It is therefore important to inform
consumers about potential risks and advise them to consume heat-treated milk, and to definitely not give
unprocessed milk to people in risk groups (children, the elderly and ill people).
18
6
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25
Annex 1. Raw milk intended for direct selling to customers.
National criteria/requirements
ESTONIA
33 (raw milk
selling directly
from farm, other
selling point or at
vending machine)
Regulation
(EC) No
853/2004
Section IX
Raw milk,
colostrum,
dairy products
and colostrumbased products
Ministry of
Agriculture
Regulation
(EE) No. 71
≤ 100.000**
≤ 100.000
(bulk tank
milk)
≤ 400.000
***
≤ 400.000
(bulk tank
milk)
NR
NR
(ones
< 500
per
(ones per
month;
two
bulk
months)
tank
milk)
Aflatoxins
Enterobacteria
Salmonella
VTEC/STEC
Campylobacter
L. monocytogenes
S. aureus/CPS
CFU per ml
Antibiotic residues
Legislation
Somatic cell
count per
ml
Country
Number
of
holdings*
Aerobic plate
count CFU at
30 °C per ml
Criteria for raw milk
Sampling frequency and location
Comments
Has to meet all
requirements and criteria
of the Regulation (EC) No
853/2004 Section IX.
General hygiene rules
according to Regulation
(EC) No 853/2004.
Veterinary certificate is
needed what is given
by official veterinarian
after every 6 months if
all requirements are
fulfilled
26
Absence
in 25 ml;
n=1, c=0
(has been
sampled in
very few
cases
only; bulk
tank milk)
According to risk
assessment; Regulation
(EC) 2073/2005 has been
considered with regard to
RTE
Aflatoxins
Enterobacteria
Salmonella
VTEC/STEC
Comments
Campylobacter
L. monocytogenes
Antibiotic residues
Somatic cell count
per ml
National
legislation
Plate count CFU
at 30 °C per ml
Country
S.
aureus/CPS
CFU per ml
< 500
(ones per
year; bulk
tank milk)
State
surveillance
program
Absence
in 25 ml
(ones per
year; bulk
tank milk;
n=1,
c=0));
100
cfu/ml
[m=M;
n=1
c=0] when
from
selling
point
e.g.
27
FINLAND
National
requirements
Ministry of
Agriculture
and Forestry
Regulation
NB: there are
no vending
machines in
Finland yet.
50.000 (n=1,
c=0)
250.00
(n=1,
c=0)
NR
Absence in
25 ml bulk
tank milk
n=5, c=0
STEC O26,
O103, O111,
O145, O157
Absence in
25 ml bulk
Absen
tank milk
ce in
n=5, c=0
Absence in
25 ml
25 ml bulk
goat
O157
tank milk
milk
n=5, c=0
Absence in
n=5,
faecal material
c=0
(ones in a
period from
July to
November;
dairy farm)
m=100
cfu/ml;
M=500
cfu/ml;
n=5,
c=2
Obligatory consumer
information in written
form: Product is the raw
milk and may contain
pathogenic
microorganisms; heat
treatment needed for risk
groups (children, elderly,
pregnant, diseased)
Self-control program
together with sampling
plan and frequency;
Constructional and
functional demands to the
building etc.
28
≤ 400.000
NR
Abs
ence
in 25
ml;
n=5,
c=0
Aflatoxins
Absence
in 25 ml;
n=5, c=0
VTEC O157
Absence in
25 ml;
n=5, c=0
Enterobacteria
L. monocytogenes
Absence in
25 ml; n=5,
c=0
Salmonella
≤ 100.000
n=5,
m=500
,
M=20
00
VTEC/STEC
Provisions of
ISR 2007
(Intesa Stato
Regioni,
2007a):
Regional
Competent
Authority is
responsible for
devising and
implementing
monitoring
plans for raw
milk safety
and hygiene
and for
continuous
control of
microbiologica
l criteria
Comments
Campylobacter
The sale of raw
milk for
human
consumption
by self-service
vending
machines has
been allowed
in Italy since
2004.
1032 dairy
herds in 2010.
Each herd can
supply one or
more vending
machines; 1424
authorized
vending
machines
(02.11.2012);
Vending
machines can
be installed at
farm or
market
S.
aureus/CPS
CFU per ml
Ordinance by
the Ministry
of Health:
vending
machine
should display
information
that raw milk
should be
boiled
Antibiotic
residues
ITALY
Somatic cell
count per
ml
National
legislation
Plate count CFU
at 30 °C per ml
Country
≤
50
ppm
29
SWEDEN
DENMARK
Aflatoxins
Enterobacteria
Salmonella
VTEC/STEC
Campylobacter
L. monocytogenes
S.
aureus/CPS
CFU per ml
Antibiotic residues
Somatic cell
count per
ml
National
legislation
Plate count CFU
at 30 °C per ml
Country
Comments
Traditional production in
small scale farms during the
summer season is possible for
direct sales at the farm gate
(fäbod). It is related with
unpasteurised milk products
(cheese stored at least 60
days, whey products and
butter). Based on traditional
farming where the dairy cows
are kept on pastures away
from the main farm and
dairies.
Not allowed to
sell raw milk
through the
normal retail
channels
Not allowed to
sell
BELGIUM
National
Regulation
will be soon
introduced,
based on Reg.
No 853/2004
and 852/2004
NR
≤ 100.000**
≤
400.000
***
Rapid
test
may
be
used
Sales channels:
On the production
site; Itinerant trade;
Milk vending machine;
Local retail trade (selling
directly to final
consumers).
Sampling frequency is based
on raw milk quantities –
smaller quantities frequency
reduced by half (to once a
month).
30
Aflatoxins
Enterobacteria
Salmonella
NR
VTEC/STEC
≤
400.000
Comments
Campylobacter
≤ 100.000**
L. monocytogenes
Indication on
vending
machine that
raw milk
should be
boiled prior
consumption
S.
aureus/CPS
CFU per ml
SLOVAKIA
Antibiotic residues
National
legislation
Somatic cell count
per ml
Country
Plate count CFU
at 30 °C per ml
Smaller quantities: up to
15.000 litres of cow milk and
2000 litres from other species
per year.
Larger quantities: up to 60.000
litres cow milk and 8.000 litres
from other species per year.
If unlimited quantities
than HACCP is
required.
***
31
Bottled raw
milk shelflife max 96
hours
at +8 °C
(max.)
Tierische
LebensmittelHygieneverord
nung (TierLMHV), §17,
18 and Annex
2
m=20.000
M=50.000
n=5
c=2
m=200.0
00
M=300.0
00
n=5
c=2
NR
Coagulas
epositive
Staphyl
o cocci
(CPS)
m=10
M=100
n=5
c=2
Aflatoxins
Enterobacteria
Salmonella
VTEC/STEC
Comments
Campylobacter
L. monocytogenes
S.
aureus/CPS
CFU per ml
Generally not
allowed but
farmer may
request specialty
to sell raw milk
(Vorzugsmilch)
directly to retail
stores or from
farm
Antibiotic residues
GERMANY
Somatic cell
count per
ml
National
legislation
Plate count CFU
at 30 °C per ml
Country
Sampling monthly basis and all
conformities with criteria have
to be verified within farm selfcontrol program
Absence in
bulk tank
milk
Absence in
bulk tank
milk
Absence in
bulk tank
milk
m=0
M=0
n=5
c=0
Enterob
acteriac
eae
m=10
M=100
n=5
c=2
Abse
nce in
bulk
tank
milk
No foodborne pathogens
and their toxins
No mastitis pathogens
Phosphatase test has to be
positive
Sensory control
Haemolytic streptococcus
bacteria (ones per months)
Absence in 1 ml
32
Instruction of
Cabinet of
Ministers No.
123/2010
Regarding raw
milk and raw
milk products.
This national
legislation act
has direct bond
with
Veterinary
Law in Latvia
as well as with
Regulation
(EC) No
853/2004
Section IX
(raw milk)
Aflatoxins
Enterobacteria
Salmonella
VTEC/STEC
NR
Campylobacter
≤ 400.000
L. monocytogenes
≤ 100.000
Comments
S. aureus/CPS
CFU per ml
Antibiotic residues
LATVIA
Somatic cell count
per ml
National
legislation
Plate count CFU
at 30 °C per ml
Country
On the vending machine it
should be the following
information: Raw milk, boil
before consumption, use by
date (no longer than 48h after
milking); address and name of
the producer. If the machine
is fully automatic the same
information should be on
bottle too.
Milk in vending
machine should be only
from one farm.
Some rules just for vending
machines: material,
temperature requirements
etc. Farmer can also sell the
raw milk directly to
consumers but requirements
related with Act No.
123/2010 should be
fulfilled.
33
≤ 100.000
≤ 400.000
NR
n=5; c=2;
m=500
cfu/ml;
M=2000
cfu/ml
Aflatoxins
Enterobacteria
Salmonella
VTEC/STEC
Comments
Campylobacter
L. monocytogenes
S.
aureus/CPS
CFU per ml
Regulation
(EC) No
853/2004
Also
1661/2009
regulation
III annex IX
section.
Hygiene Norm
HN 26:2006
“Microbiologi
c al criteria for
food products”
Antibiotic residues
LITHUANIA
Somatic cell count
per ml
National
legislation
Plate count CFU
at 30 °C per ml
Country
n=5;
c=0;
abse
nt in
25
ml
34
NETHERLAN
DS
Warenwetbeslu
it hygiene van
levensmiddele
n, Artikel 8
≤ 50.000**
NR
m=100
M=500
n=5
c=2
Abs
ence
in
25g
n=5
c=0
Aflatoxins
Enterobacteria
Salmonella
VTEC/STEC
Comments
Campylobacter
L. monocytogenes
S.
aureus/CPS
CFU per ml
Antibiotic residues
Somatic cell count
per ml
National
legislation
Plate count CFU
at 30 °C per ml
Country
Raw milk (cow), intended
for direct selling to
customers, is only
present: 1st on the farm
where the milk is
collected;
2nd in a recipient not suitable
to sell directly to the
customer. (So not bottled.)
When the raw milk isn’t
sold within 2 hours after
milking, it is chilled:
a) When sold within
24 hours: 8 ºC or
lower.
b) When sold after 24
hours: 6 ºC or lower.
On or in the direct
environment of the recipient
is displayed the following
information:
RAW MILK, BOIL
BEFORE USE
(Rauwe melk voor
gebruik koken.)
35
For
sheep
and goats
≤ 500.000
rolling
geometric
average
while
sampling
frequency is
based
on risk
analyse
Bulk tank
milk
Abse
nce
in
25g
n=5
c=0
durin
g
selflife
For sheep
and goat
milk E. coli
n=5
c=0
m=10 cfu/ml
M=100
cfu/ml
Bulk
tank milk
Aflatoxins
For cattle
milk E. coli
n=5
c=0
m=10 cfu/ml
M=100
cfu/ml
Bulk
tank milk
Enterobacteria
Salmonella
Campylobacter
L. monocytogenes
For cattle
milk:
n=5, c=0
m=M
100
cfu/ml
during
product
self-life
Comments
VTEC/STEC
For cattle
milk
≤ 50.000
rolling
geometric
average
while
sampling
frequency is
based on risk
analyse
Bulk
tank milk
S.
aureus/CPS
CFU per ml
Recent
national
regulation:
Arrete of
13/07/2012
Applicable to
raw milk of
cows, sheep,
goats
Antibiotic
residues
FRANCE
Somatic cell
count per
ml
National
legislation
Plate count CFU
at 30 °C per ml
Country
Need of approval from
district vet services. Cooling
of raw milk immediately
after milking, kept at 0-4 ºC,
except if selling less than 2
h after milking.
Only milks of 2 successive
milking or milking within
24 h can be mixed.
Selling in hermetically
sealed individual packages
or vending machines, with
requirements described in
Article 7.
Microbiological criteria for
L.m.; Salmonella; E. coli
and total count.
36
* The number of holdings with permission of raw milk selling for direct consumption purpose in big quantity,
except selling in small quantity (up to 100 kg cow’s milk per day or 700 kg per week; goat milk up to 20 kg
per day; ewe raw milk up to 10 kg per day).
** Rolling geometric average over a two month period with at least two samples per months
*** Rolling geometric average over a three-month period, with at least one sample per month
NR, no residues [Raw milk is not placed on the market if either: it contains antibiotic residues in a quantity that,
in respect of any one of the substances referred to in Annexes I and III to Regulation (EEC) No 2377/90, exceeds
the levels authorised under that Regulation; or the combined total of residues of antibiotic substances exceeds any
maximum permitted value].
NB: Information from different countries has been collected through contact persons at veterinary authorities.
37