6.3.6. Food and waterborne infections
Mass catering, intensified farming, industrial food
production, and a largely international food market have created new,
wide-ranging pathways along which infectious disease agents can spread. Changes
in consumer behaviour (and, consequently, in the production and distribution of
foods) have led to the situation that one contaminated part of food can affect
a large number of individuals, often in geographically distant areas. Large
multinational food-borne outbreaks are much more difficult to prevent and
control. Effective surveillance of this group of diseases is restricted by
variations in reporting systems and different degrees of coordination between
food, animal and environmental control authorities. Effective prevention and
control requires close collaboration not only between microbiologists and
epidemiologists in public health, but also with veterinary and food safety
authorities. At EU level, besides the ECDC, also the Commission, EFSA and WHO
EURO are important players.
For several of these diseases surveillance has improved
considerably in many Member States over the last decade, and it is difficult to
decide whether an increase in reported incidence reflects a genuine increase or
simply the improved detection. However, for two important infections,
salmonellosis (including typhi and paratyphi) and shigellosis, there seems to
be a declining trend in the EU. Campylobacter is the most commonly diagnosed
food-borne bacteria in the EU, and may have been slightly increasing over time,
while Cryptosporidium has caused waterborne
outbreaks in several Member States. Although the majority of the symptomatic Campylobacter and Salmonella infections do not
require any drug treatment, invasive infections do occur. Hence the monitoring
of antibiotic resistance is important and should be included in the
surveillance. The available vaccine for S typhi is used mostly for travellers
to endemic areas.
Besides these important infections, there are several food
or waterborne infections that are either of regional concern (brucellosis,
echinococcosis, trichinellosis), or of main concern in the immuno-compromised,
for the foetus or in the very young (listeriosis, toxoplasmosis). Indications
are that listeriosis may be declining, but for toxoplasmosis the data are quite
Hepatitis A is declining in Europe, but this also means
that more and more people remain susceptible to this virus, and outbreaks are
still seen in several countries. An effective vaccine is available but it is
recommended mostly for travellers.
Cholera is exclusively an imported disease to the EU, with
almost no secondary domestic cases seen in recent years. The available vaccine
is used mostly for travellers to endemic areas.
Norovirus and rotavirus infections are not reportable in
the EU, but are important causes of gastroenteritis all over the Union. It may
be that outbreaks caused by norovirus in confined places, such as schools,
hospitals and cruise ships are on the increase, but it should be noted that
methods for laboratory diagnosis have really been available only in the last
The true size of this problem is difficult to ascertain:
even the best national surveillance systems miss the majority of cases, namely
those patients who do not seek healthcare for their symptoms of
gastroenteritis. Surveillance of these diseases remains important, not only to
discover and, ideally, stop an outbreak, but even more importantly, to identify
weaknesses in food (and water) processing and handling in order to make
informed improvements in the future. An enhanced surveillance for all
food-borne diseases (covering all the diseases, but also enhancing the
collected information, including antibiotic resistance where appropriate) is
therefore a priority. Such a system should integrate laboratory data, in
particular from molecular sub-typing. The list of diseases currently under
surveillance needs to be reviewed with regard to food-borne viruses, and rapid
information exchange platforms should be established for all food-borne
Campylobacteriosis is a gastrointestinal disease caused by
the bacterium Campylobacter. The most frequent route of transmission is consumption of
contaminated food (mainly chicken) or water. Other risk factors include outdoor
swimming and direct contact with infected animals.
The incidence of campylobacteriosis showed a steadily
increasing trend from 85 000 cases in 1995, to 180 000–190 000
more recently, though this increase could be a result of better reporting
(Figure 6.7). The most affected age group is children under the age of five
years. The disease shows a characteristic seasonality with the highest reported
numbers in the summer. A disturbingly high proportion of the Campylobacter isolates are now
resistant against commonly used antibiotics such as fluoroquinolones and
Figure 6.7. Campylobacteriosis trends between 1995 - 2004
In 2005, more than 200 000 cases were reported, with
the highest incidence reported by the Czech Republic (296
per 100 000), followed by the UK (87.95 per 100 000).
Campylobacteriosis is the most commonly reported enteritis in the EU, but the
high degree of under-reporting known to occur in many countries makes direct
comparisons between them very difficult. Furthermore, the proportion of
imported cases varies considerably between countries with 99% domestic cases in
Czech Republic, Lithuania and Slovakia, whereas in Sweden
and Finland, respectively 61% and 52% of reported cases were imported.
Salmonellosis is a diarrhoeal disease caused by the
bacterium Salmonella. Poultry, pigs, cattle,
and other animals such as reptiles serve as its reservoirs. The most frequent
route of transmission is the consumption of contaminated food. After a peak in
1995, the incidence of salmonellosis in Europe has remained high, although
exhibiting a decreasing trend.
Despite the generally decreasing trend, some countries –
the Czech Republic, Denmark, Estonia, Finland, Latvia and
Lithuania - have reported a 5% or more increase in incidence since 2004 . This
could be due to improved surveillance systems (particularly in the new Member
States), but also to the occurrence of outbreaks. A global epidemic of
egg-related Salmonella enteritidis infections has heavily contributed to the European
salmonellosis epidemiology, and this serotype has been by far the most common
in Europe, and more dominant here than in most parts of the world.
In 2005, a total of 181 876 human salmonellosis cases
were reported by 27 countries, with the highest incidence reported in the Czech
Republic (322 per 100 000), followed by Slovakia (223.67 per
100 000). The highest incidence was reported in the age group 0–4 years
(27% of cases), decreasing steadily in the older age groups. Some countries,
notably Sweden, the Netherlands and Norway had a very high proportion of
imported cases (77–87%).
Alternative sources of standardised information, i.e.
returning travellers used as sentinels, indicate a very large under-reporting
of cases in some of the Member States.
Typhoid fever / Paratyphoid fever
Typhoid/paratyphoid fever is a potentially
life-threatening systemic disease caused by the Salmonella typhi and Salmonella paratyphi bacteria. Typhoid and
paratyphoid fever occur worldwide and humans are the only reservoir for these
bacteria. The mode of transmission is the consumption of contaminated food and
water. Preventive measures include good personal and food hygiene.
The overall incidence rate of typhoid/paratyphoid fever
has been steadily declining since 1995. The highest proportion (31%) of all
reported cases (n=20 746), was reported by Italy between 1995 and 2004
(6 440 cases). In 2005, a total of 1 364 human typhoid/paratyphoid
cases were reported by 26 countries. Norway, with 0.87 per 100 000,
reported the highest incidence rate, followed by the UK (0.79 per
Shigellosis is a disease caused by the bacterium Shigella with the only reservoir
in humans. Transmission occurs directly from person to person or indirectly via
contaminated food or water. General hygiene measures are crucial, and proper
hand-washing is the most effective individual way to prevent the spreading of
disease. However, an outbreak of shigellosis in Germany was described linking
the cause to sexual contacts between men who have sex with men.
The incidence has been declining over the last 10 years
with a slight peak in 2001. In 2005, a total of 7 425 human shigellosis
cases were reported by 26 countries. The European incidence rate was 1.82 per
100 000, with the highest incidence in children less than five year-old
(3.5 per 100 000), representing 10% of all cases. Lithuania (13.43 per
100 000 total population), followed by Slovakia (9.51 per 100 000)
reported the highest national incidence rates. As shigellosis is highly endemic
in many parts of the world visited by European tourists, information about
recent travel would be important to monitor for the future.
Verocytotoxin-producing Escherichia coli (VTEC) causes an
enteric infection, with often non-specific watery or bloody diarrhoea that in
some cases may proceed to a severe disease with renal failure and haemorrhages:
haemolytic uremic syndrome (HUS). HUS is the leading cause of acute renal
failure in children, and 3–5% of patients die. The main reservoir is cattle but
the bacterium has also been found in goats, sheep, pigs and wild game. The most
frequent route of transmission is the consumption of contaminated food
(especially beef and raw milk), or contaminated water. Direct contact with
infected animals and swimming outdoors in contaminated surface waters have been
shown as a possible route for acquiring the infection. Controls of VTEC
infections at the farm level are important in preventing the introduction of
the bacterium into the food chain. In addition, good hygiene practices in meat
processing and food handling are essential preventive measures.
In the last 10 years, the incidence has more than doubled,
rising from 1995 to 2002 and levelling off in more recent years. However, this
data may in some countries and for some of the years include both E. coli and VTEC. The most
affected age group appears to be 0–4 year one. In 2005, a total of 5 218 cases were reported by 25 countries. The Czech
Republic (16.72 per 100 000) followed by Sweden (4.27 per
100 000) reported the highest incidence. A total of six outbreaks were
monitored in 2005, with beef, lettuce and camembert cheese identified as the
Yersiniosis is caused by the bacterium Yersinia (species other than the
plague-causing Yersinia pestis). Yersiniosis occurs worldwide, but mostly in the
Northern hemisphere. Pigs and cattle are known reservoirs. Infection is often
acquired by eating contaminated, particularly raw or undercooked, pig meat.
Other sources of infection have been vegetables kept in chilled stores for long
In the last 10 years, the incidence rate of reported cases
has been relatively stable, but clear peaks were seen in 1998 and 2002. In 2005, 23 countries notified a total of 9 564 cases of human yersiniosis with Lithuania
(14.63 per 100 000) followed by Finland (12.2 per 100 000) reporting
the highest incidence rates. The overall incidence in the EU was 2.23 per
100 000 per year, with children under five years old having the highest
incidence (30.4 per 100 000 per year).
Listeriosis is a disease caused by the bacterium Listeria monocytogenes. The infection is
mostly mild and self-limiting, but may lead to abortion in pregnant women. In
immuno-compromised or elderly people, listeriosis may take a severe course. Listeria is ubiquitous in the
environment, and food-borne outbreaks have been detected worldwide. Many
animals carry the organism in their faeces, and consumption of contaminated
food is the principal route of transmission. Control measures are directed at
the farm and food-processing level to prevent the contamination of food
products. Preventive measures include providing appropriate information for
consumers about the risks.
The annual incidence in Europe decreased between 1995 and
1998, but since then it has shown a sustained increasing trend. The incidence
in 2004 (0.28 per 100 000 per year) was similar to that for 1995.
Twenty-six countries reported 1 491 cases in 2005. Denmark (0.85 per 100 000),
followed by Finland (0.69 per 100 000) reported the highest incidence
rates. More than half the reported cases occurred in individuals over 65 years
of age. In 2005, 96 listeriosis cases were associated with pregnancy. These
were reported by Germany (56 cases), France (37 cases) and Denmark (three
Brucellosis is a disease caused by Brucella genus
bacteria. The reservoirs for these bacteria are sheep, goat, swine and cattle.
Humans become infected by direct or indirect contact with animals or animal
products (including milk and dairy products) or by inhalation of aerosols.
Control measures to prevent the disease in humans include controlling and
eliminating the disease in animals by vaccination and/or the test-and-slaughter
of infected animals and proper pasteurisation of dairy products. The number of
cases steadily decreased from 1999 (just under 4 000 cases (0.87 per
100 000)) to 2004 (1 743 cases (0.38 per 100 000)). Twenty-six
countries reported 1 429 cases in 2005, with an overall incidence of 0.31
per 100 000. Portugal (1.40 per 100 000), followed by Ireland (1.29
per 100 000) reported the highest incidence rates.
Botulism is a rare but serious paralytic illness caused by
a nerve toxin produced by the bacterium Clostridium botulinum. Eating food that
contains the botulism toxin causes food-borne botulism, while wound botulism is
caused by toxin produced from an infected wound. Botulism appears to be a
serious problem in only a few countries in Europe, and the trend of the disease
seems to have been stable over the years. Poland reported the most cases over
the 10-year period. In 2005, a total of 152 cases were reported by 22 countries
but only five reported 20 or more cases, with Lithuania reporting the highest
incidence (0.15 per 100 000).
Cholera is an acute enteric infection caused by the
Humans are the only important reservoir, even though the bacteria can survive
for a long time in contaminated coastal waters, transmitting diseases through
infected seafood. Cholera is not an endemic disease in Europe. The number of
imported cases has remained small; a peak of 40 cases was observed in 1998 but
subsequently dropped to lower levels. In the last 10 years, 237 cases were
reported ( <0.01 per 100 000
per year). In 2005, 34 cases were reported by 20 countries, of which twenty
were from the UK.
Hepatitis A is a viral disease of the liver caused by
hepatitis A virus (HAV). Up to 90% of HAV-infected young children do not have
any symptoms. Transmission is through close contact with an infected person, or
through ingestion of contaminated food, though recently sexual transmission
among men who have sex with men has been described. A very effective vaccine is
available. Almost 210 000 cases have been reported in Europe between 1995
and 2004, and during this period a steady decrease was observed from a peak in
1996–97 to 2000 and has remained stable since then. In 2005, 6 695 cases
were reported by 25 countries. Slovakia (9.81 per 100 000) and Latvia
(6.29 per 100 000) are the only countries with incidences of more than
five per 100 000 per year. The highest incidence was seen in children
under the age of 15.
Toxoplasmosis is caused by the protozoan parasite Toxoplasma gondii. The infection is
asymptomatic in most humans, but can be life-threatening in immuno-compromised
individuals. Infections in pregnant women can cause congenital toxoplasmosis,
with varying degrees of foetal damage. The definitive host of T. gondii is cats. Humans are
usually infected through direct exposure to faeces from infected cats or from
inadequately washed contaminated fruits or vegetables, but can also become
infected from the ingestion of raw or undercooked meat.
There is wide variation in the consistency of reporting,
as well as in the reporting criteria. Reporting from most countries in Europe
started in 1996, following the highest incidence observed in 1995 (1.68 per
100 000 per year), and has shown a steadily decreasing trend since then.
In 2005, 1 519 toxoplasmosis cases were reported by 14 countries, with
Lithuania (6.86 per 100 000), followed by Slovakia (4.85 per 100 000)
reporting the highest incidence. As toxoplasmosis is a very common infection in
humans and animals, the reported cases only reflect a minute proportion of all
cases, and very few conclusions can be drawn from the data.
Giardiasis is a parasitic infection caused by Giardia intestinalis (also called Giardia lamblia), causing both acute
and chronic diarrhoea. Infants and children are at particular risk. Domestic
and wild animals carry the parasite, although the major reservoirs are
contaminated surface waters and humans. Infection occurs after ingestion of
contaminated food or water, and several large waterborne outbreaks have
occurred in Europe. As for many diseases, large differences between
surveillance systems make comparisons between countries very difficult. However,
the available data suggest a relatively stable trend over the last 10 years. In
2005, some 15 103 cases were reported by 18 countries. Estonia (24.28 per
100 000), followed by Iceland (14.65 per 100 000) reported the
highest incidence rates.
Cryptosporidiosis is a parasitic disease caused by Cryptosporidium, infecting many species
of large and small animals. Humans can be infected from other people or from
the environment. Cryptosporidiosis can be life-threatening in immuno-deficient
patients. Outbreaks have been reported in child day-care centres, in families,
from lakes and swimming pools and through contaminated drinking water.
Cryptosporidiosis is not reportable in many countries, and trend data are
scanty. In 2005, almost 8 000 cases were reported by 16 countries, with
Ireland (13.75 per 100 000) and the UK (9.26 per 100 000) reporting
the highest incidence rates. Most cases occurred in the age groups under 15
years. Comparisons between reporting countries are complicated due to
differences in the surveillance systems.
Echinococcosis is a zoonotic parasitic disease, caused by
the larval stage of the tapeworm Echinococcus. Humans are infected through close
contact with infected animals (sheep, cattle, goats, horses, pigs) or through
ingestion of undercooked infected food. The number of reported cases has been
steadily decreasing since 1996. In 2005, altogether 337 cases were reported by
22 countries. Lithuania (0.44 per 100 000), followed by Slovenia (0.30 per
100 000), reported the highest incidence rates. The real number of cases
is probably considerably higher than those reported given the slow progression
of the disease over many years.
Trichinellosis is a zoonotic disease caused Trichinella. The main source of
human infection is the consumption of raw or undercooked meat products from
pigs, wild boar and horses. As a preventive measure, all slaughtered pigs and
horses undergo an investigation for Trichinella larvae in meat
inspection in the EU. The risk remains higher in imported and wild animal meat
and consumption of such undercooked or raw meat should be avoided.
In the last 10 years, the incidence of trichinellosis in
Europe has shown an overall decreasing trend despite peaks in Slovakia, France
and Italy in 1998, in Poland 1999, in Latvia in 2000, and in Lithuania in 2001.
Since 2000, the incidence has been relatively stable. In 2005, 153 cases were
reported by 25 countries. Latvia (2.12 per 100 000), followed by Lithuania
(0.35 per 100 000) reported the highest incidence rates. The two most
affected age groups are children 5–14 years of age and adults 45–64 years of
Variant Creutzfeldt-Jakob disease
Variant Creutzfeldt-Jakob disease (vCJD) is a novel form
of human spongiform encephalopathy (prion disease), which has been causally
linked to bovine spongiform encephalopathy (BSE). The disease is fatal, with a
mean survival of about 14 months. The main suspected route of transmission is through
past consumption of infected beef products, although recently human-to-human
transmission has been described through blood transfusion. Preventive measures
include ensuring that the BSE prions do not enter the human or animal food
chains, and that blood or tissue for transplants from potentially infected
persons are not used in medical care.
The transmission of vCJD through prions in the food chain
has had profound political, social and economic implications. Because of the
long incubation period, extending to years or even decades, there has been
uncertainty about the likely extent of a future outbreak of variant CJD in the
UK and in other countries. Current data are relatively reassuring, as the
number of deaths from vCJD in the UK has declined over recent years after a
peak registered in 2000. However, uncertainty remains about the possibility of
increased numbers of cases in the future, particularly as there is now evidence
of transmission of vCJD through blood transfusion.
Since 1995, vCJD has been detected mainly in the UK but
has also been seen in six other European countries. The highest reported annual
number of cases (30) was in 1999. Since 1999, the number of reported cases
declined steadily until 2004
In 2005, a total of 21 cases were reported by 18 EU Member
States. Slovakia reported 11 cases; however, the criteria for reporting these
cases may have been different from those used in the other countries. Six cases
reported in France, two in Ireland and one each in Estonia and in the Netherlands
make up the remainder of the cases reported.