FOOD- AND WATERBORNE DISEASES
AND ZOONOSES
Kolářová M., EPI Autumn 2015
3. Food- and waterborne diseases and zoonoses
• Anthrax
• Botulism
• Brucellosis
• Campylobacteriosis
• Cholera
• Cryptosporidiosis
• Echinococcosis (hydatid disease)
• Shiga toxin/verocytotoxin-producing Escherichia coli (STEC/VTEC) infection
• Giardiasis
• Hepatitis A
• Leptospirosis
• Listeriosis
• Noroviruses
• Salmonellosis
• Shigellosis
• Toxoplasmosis (congenital)
• Trichinellosis
• Tularaemia
• Typhoid/paratyphoid fever
• Variant Creutzfeldt–Jakob disease (vCJD)
• Yersiniosis
Campylobacteriosis
Campylobacteriosis is a diarrhoeal disease caused by Campylobacter bacteria,
found in animals such as poultry, cattle, pigs, wild birds and wild mammals.
The most frequent way of getting infected is through the consumption of
contaminated food (mainly poultry) or water. Other risk factors include
swimming in natural surface-waters and direct contact with infected animals.
After an incubation period of 2–5 days (range 1–10 days) common
symptoms are severe abdominal pain, watery and/or bloody diarrhoea and
fever. Usually, symptoms last for a few days and the disease is self-limiting
but occasionally they will persist and result in hospitalisation. Antimicrobial
therapy is seldom needed.
Campylobacter infection has been associated with complications such as
later joint inflammation (5–10% of cases) and, on rare occasions, GuillainBarré
syndrome (a temporary but severe paralysis that may be total).
As a prophylactic measure, control of Campylobacter colonisation in poultry
is important, as well as hygienic processing of meat, and the protection and
control of private drinking water supplies.
Campylobacteriosis
Campylobacter is a genus of Gram-negative
bacteria. Campylobacter species are typically spira-shaped and able
to move via unipolar or bipolar flagella.
The animals such as poultry, cattle, pigs, wild birds and wild
mammals.
It is usually acquired from eating or drinking contaminated food and water;
nevertheless, it can also be caught directly from animals or, rarely, from
person to person though contact with infected faeces. Drinking raw or
inadequately pasteurised milk has caused outbreaks of campylobacteriosis
and cases have also been caused by birds pecking at milk in foil-topped
bottles. People have also been infected through drinking from streams when
trekking or canoeing. Contact with animals on farm visits and with infected
pets, especially puppies, can be a risk factor for children younger than five
years of age. Person-to-person spread can happen, although it is unusual,
and is most likely from children who have diarrhoea or are not toilet-trained.
General.
The source
of infection
Route of
transmission
Etiology:
Susceptibility
General
Preventive measures:
There is currently no vaccine against Campylobacter infection. Drinking pasteurised milk and chlorinated
drinking water is important in preventing contamination. Good hygiene in commercial and domestic
kitchens—especially avoiding cross-contamination—is important as is cooking meat properly, especially
poultry. Conventional disinfectants are active against Campylobacteriosis. Doorstep milk should be protected
against birds and it is important to wash hands carefully after contact with faeces, nappies, meat or animals,
including on farm visits.
Campylobacteriosis
• Symptoms
Campylobacter infection can vary from people who have no
symptoms at all to those who are severely ill. Most people with
symptoms have diarrhoea, abdominal pain and fever. Before
these symptoms patients may have fever, headache, malaise
and muscle pain. About a quarter of cases have vomiting or
blood in their stools.
• Complications
Complications include arthritis (inflamed joints), Guillain-Barré
Syndrome (which causes weakened muscles), and a type of
kidney failure known as haemolytic uraemic syndrome (HUS).
Some types of Campylobacter infection can lead to bacteria in
the blood, meningitis, infected blood vessels and abscesses.
Some types can also lead to more severe disease in people
with chronic conditions, like diabetes.
Campylobacteriosis
• Diagnosis
Laboratory tests on stool samples can be used to
diagnose Campylobacteriosis, as well as blood tests.
• Treatment
Most cases settle after 2–3 days of diarrhoea and 80–
90% settle within a week. Most people only need
treatment to relieve their symptoms and keeping
hydrated is important for those with diarrhoea.
However, some cases can be more prolonged or
severe. Antimicrobial therapy to treat Campylobacter
is not often needed but is available for severe
infections or those particularly at risk.
Salmonellosis
Salmonellosis is one of the most common and
widely distributed foodborne diseases and is
caused by the bacteria salmonella. It is estimated
that tens of millions of human cases occur
worldwide every year and the disease results in
more than hundred thousand deaths. For
salmonella species, over 2 500 different strains
(called "serotypes" or "serovars") have been
identified to date. salmonella is a ubiquitous and
hardy bacteria that can survive several weeks in a
dry environment and several months in water.
SalmonellosisSalmonella bacteria are generally referred to by the term ‘salmonellosis’
when they are due to Salmonella species other than Salmonella typhi and
Salmonella paratyphi.
Various animals (especially poultry, pigs, cattle, and reptiles) can be sources
for Salmonella, and humans generally become infected by eating poorly
cooked, contaminated food.
Salmonellosis in humans is generally contracted through the consumption of
contaminated food of animal origin (mainly eggs, meat, poultry and milk),
although other foods, including green vegetables contaminated by manure,
have been implicated in its transmission.
Person-to-person transmission through the faecal-oral route can also occur.
General.
The source
of infection
Route of
transmission
Susceptibility
Etiology:
Preventive measures:
Prevention requires control measures at all stages of the food chain, from agricultural production, to processing,
manufacturing and preparation of foods in both commercial establishments and at home.
National/regional surveillance systems are important means to detect and respond to salmonellosis and other
enteric infections in early stages, and thus to prevent them from further spreading.
Salmonellosis
Diarrhoea-causing Salmonellae are present worldwide.
The incubation period and the symptoms depend on the amount of
bacteria present in the food, the immune status of the person and the
type of Salmonella.
In general, 12 to 36 hours after the consumption of contaminated food,
a clinical picture characterised by fever, diarrhoea, abdominal pain,
nausea and vomiting may appear. Symptoms usually last for a few
days. Due to the effects of dehydration, hospital admission may
sometimes be required. In the elderly and otherwise weak patients
death sometimes occurs. Elderly patients are also more prone to
developing severe blood infection. In addition, post-infectious
complications, such as reactive joint inflammation occur in about 10%
of the cases.
Recommendations for the public
and travellers
• Ensure food is properly cooked and still hot when served.
• Avoid raw milk and products made from raw milk. Drink only
pasteurized or boiled milk.
• Avoid ice unless it is made from safe water.
• When the safety of drinking water is questionable, boil it or if this is
not possible, disinfect it with a reliable, slow-release disinfectant
agent (usually available at pharmacies).
• Wash hands thoroughly and frequently using soap, in particular after
contact with pets or farm animals, or after having been to the toilet.
• Wash fruits and vegetables carefully, particularly if they are eaten
raw. If possible, vegetables and fruits should be peeled.
• When travelling, refer to WHO's brochure A guide on safe food for
travellers.
Recommendations for food handlers
• Both professional and domestic food handlers should be vigilant while
preparing food and should observe hygienic rules of food preparation.
• Professional food handlers who suffer from fever, diarrhoea, vomiting or
visible infected skin lesions should report to their employer immediately.
• The WHO Five Keys to Safer Food serve as the basis for educational
programmes to train food handlers and educate consumers. They are
especially important in preventing food poisoning.
• The Five Keys are:
– Keep clean.
– Separate raw and cooked.
– Cook thoroughly.
– Keep food at safe temperatures.
– Use safe water and raw materials.
Recommendations for producers of fruits and
vegetables
• The WHO "Five keys to growing safer fruits and vegetables" is an
educational manual for rural workers, including small farmers who grow
fresh fruits and vegetables for themselves, their families and for sale in local
market. It provides them with key practices to prevent microbial
contamination of fresh produces during planting, growing, harvesting and
storing.
• The five keys practices are:
• Practice good personal hygiene.
• Protect fields from animal faecal contamination.
• Use treated faecal waste.
• Evaluate and manage risks from irrigation water.
• Keep harvest and storage equipment clean and dry.
WHO response
• WHO promotes the strengthening of food safety systems, promoting good
manufacturing practices and educating retailers and consumers about
appropriate food handling and avoiding contamination. Education of
consumers and training of food handlers in safe food handling is one of the
most critical means to prevent foodborne illnesses including salmonellosis.
• WHO strengthens and enhances the capacities of national and regional
laboratories in the surveillance of Salmonella, the other major foodborne
pathogens and antimicrobial resistance in Salmonella and campylobacter
from humans, food and animals through the network called Global Foodborne
Infections Network (GFN) .
• WHO’s main tool to assist Member States in surveillance, coordination and
response to outbreaks is the use of the International Network of Food Safety
Authorities (INFOSAN) . which links national authorities in Member States in
charge of managing food safety events. This network is managed jointly by
FAO and WHO.
Escherichia coli (E.coli)
Escherichia coli (E.coli) are very common bacteria in
the gastrointestinal tract, and part of the normal
bacterial flora. However, some E.coli strains are
able to produce a toxin that could produce serious
infection. The main reservoir of such E.coli strains is
grass-feeding animals, cattle in particular. Their
meat might become contaminated by faecal matter
due to poor processing methods during slaughter,
and their faeces might end up contaminating other
foods (e.g. milk, vegetables) and water.
Escherichia coli (E.coli)Escherichia coli (E.coli) are very common bacteria in the gastrointestinal
tract, and part of the normal bacterial flora. However, some E.coli strains are
able to produce a toxin that could produce serious infection.
The main reservoir of such E.coli strains is grass-feeding animals, cattle in
particular. Their meat might become contaminated by faecal matter due to
poor processing methods during slaughter, and their faeces might end up
contaminating other foods (e.g. milk, vegetables) and water.
Transmission of STEC infection mainly occurs through contaminated food or
water and contact with animals. Person-to-person transmission is also
possible among close contacts (families, childcare centres, nursing homes,
etc).
The source
of infection
Route of
transmission
Etiology:
Susceptibility
General; However, about 8% of patients (children under five years old and the
elderly being the most susceptible) may develop “haemolytic uraemic syndrome”
(HUS), characterised by acute kidney failure, bleeding and neurological symptoms.
Antibiotic therapy is not helpful (it might even favour HUS development).
Preventive measures:
Shiga toxin-producing E. coli (STEC)
Shiga toxin-producing E. coli (STEC) is a group of pathogenic
Escherichia coli strains capable of producing Shiga toxins, with the
potential to cause severe enteric and systemic disease in humans.
The full serotype is usually defined by determining both O and H
antigens.
There are around 200 different E. coli O serotypes producing Shiga
toxin, of which over 100 have been associated with human disease.
Two major Shiga toxin types (Stx1 and Stx2) have been associated with
strains causing human disease. While the serotype O157:H7 is
considered as clinically the most important, it is estimated that up to 50%
of STEC infections are caused by non-O157 serotypes.
STEC is of public health concern because of the potential for outbreaks
and the risk of serious complications.
Haemolytic uremic syndrome (HUS) is considered as the most common
cause of acute renal failure in European children. Even if the clinical
presentation of non-O157 STEC infections may vary, they can be as
virulent as O157:H7 infections.
Shiga toxin-producing E. coli (STEC)
Transmission of STEC infection mainly occurs through
contaminated food or water and contact with animals.
Person-to-person transmission is also possible among
close contacts (families, childcare centres, nursing
homes, etc). A wide variety of food has previously been
implicated in outbreaks as suspected sources, including
raw (unpasteurised) raw milk and cheese, undercooked
beef, a variety of fresh produce (e.g. sprouts, spinach,
lettuce), unpasteurised apple cider, etc. Recently an
outbreak of STEC O157 infections in Canada and the
USA was linked to walnuts, thus new sources continue
to be identified. Various types of animals, in particular
cattle and other ruminants, can be healthy carriers of
human-pathogenic STEC that can be spread to humans
through faecal contamination.
Escherichia coli (E.coli)
The infective dose is very low. The incubation period ranges from three to eight
days. The typical presentation of infections with STEC is acute
gastroenteritis, often accompanied with mild fever and sometimes vomiting.
The typically bloody diarrhoea is in most cases mild and self-limiting and
most people recover within five to seven days. Around 15% of children
diagnosed with STEC O157 infection develop the severe complication of
HUS; this proportion is much lower among adults, and this proportion in
outbreaks of non-O157 outbreaks is not well documented. The severity of
STEC diarrhoea is determined by several factors, including the E. coli
serotype, the type of Shiga toxin produced and other virulence
characteristics of the bacteria. The patient’s age and the infecting dose also
play an important role. Children under the age of 5 years are at higher risk of
developing clinical disease when infected, and infants are at increased risk
of death from dehydration and septicaemia.
• While the confirmation methods of O157 STEC infection are well
established, this is not always the case for infections caused by STEC nonO157
serotypes. Therefore, underreporting of non-O157 STEC infections is
very likely, and their importance for clinical disease in humans is
insufficiently understood.
Escherichia coli (E.coli)
The treatment of STEC infections is mainly based on rehydration,
while antibiotic treatment is often contraindicated as it may
activate Shiga toxin release and therefore cause clinical
deterioration with a potential evolution to HUS.
• STEC infections in humans are under epidemiological
surveillance in the EU and in 2009 there were 3 573 reported
cases of which about half were caused by the STEC O157:H7
serotype.
• Since 2008, eight cases of STEC O104 have been reported in
the EU, by Austria (one case in 2010), Belgium (two cases in
2008), Denmark (one case in 2008), Norway (three cases in
2009), and Sweden (one case in 2010); three of these cases
were imported. In addition, between 2004 and 2009, Austria
and Germany reported some positive findings of STEC O104 in
food or animals. However, the suggested outbreak strain of
serotype STEC 0104:H4 has been rarely reported worldwide.
Shigellosis
Epidemiology
• Insufficient data exists, but conservative estimates suggest
that Shigella causes approximately 90 million cases of
severe dysentery annually, with at least 100,000 of these resulting in
death, mostly among children in the developing world. Shigella also
causes approximately 580,000 cases annually among travelers and
military personnel from industrialized countries.
• An estimated 18,000 cases of shigellosis occur annually in the United
States. Infants, the elderly, and the critically ill are susceptible to the
severest symptoms of disease, but all humans are susceptible to some
degree. Individuals with acquired immune deficiency syndrome (AIDS)
are more frequently infected withShigella. Shigellosis is a more
common and serious condition in the developing world; fatality rates of
shigellosis epidemics in developing countries can be 5–15%.
Shigellosis
• S. sonnei: Most common symptoms are diarrhoea (which is sometimes bloody),
abdominal pain and cramps, and fever. Nausea and/or vomiting, loss of
appetite, headache or malaise can also occur.
• S. flexneri: Also causes diarrhoea, abdominal pain and cramps, and fever but is
often more severe than S. sonnei infection. Inflammation and ulceration of the
lower part of the bowel is also common and illness can be prolonged and more
severe.
• S. boydii: Can cause diarrhoeal diseases of varying severity, but mostly are
similar to those caused by S. sonnei.
• S. dysenteriae: This species causes more severe disease than other forms of
shigellae with higher death rates. Inflammation and ulceration of the lower part
of the bowel occurs in most cases, displaying itself as bloody stools.
•
Shigellosis
caused by one of four species of Shigella bacteria: Shigella sonnei, S.
flexneri, S. boydii and S. dysenteriae.
The causative organism is frequently found in water polluted with
human feces, and is transmitted via the fecal-oral route. The usual mode of
transmission is directly person-to-person hand-to-mouth, in the setting of
poor hygiene among children.
Shigellosis is largely a disease of children, with the highest number of cases
reported in children younger than five. Infection occurs most frequently in the
summer. People at highest risk include those attending daycare, travellers
abroad and men who have sex with men.
The source
of infection
Route of
transmission
Susceptibility
Etiology:
Preventive measures:
Simple precautions can be taken to prevent getting shigellosis: wash hands before handling food and
thoroughly cook all food before eating.
Since shigellosis is spread very quickly among children, keeping infected children out of daycare for 24 hours
after their symptoms have disappeared, will decrease the occurrence of shigellosis in daycares
Norovirus infection
• Norovirus cause gastrointestinal illness to humans. Norovirus
infection can cause vomiting, diarrhoea, and stomach pain. Less
common symptoms are low fever, chills and headache. Vomiting
can be sudden and frequent resulting in remarkable fluid loss. Death
is rare but remains as a risk especially for elderly or persons with
weakened immune system.
Recovery occurs usually in one or two days. The incubation period
ranges between 12 and 48 hours. Sometimes, symptoms can be
milder and last for a week but no long-term adverse health effects
have been reported.
•
Norovirus infection
• Noroviruses belong to the Caliciviridae family and they
are well known as causing “winter-vomiting disease” or
“stomach-flu” referring to their rapid spread in human
populations especially during winter months. Noroviruses
are relatively resistant in the environment: they can
survive freezing as well as high temperatures (up to
60°C). The viruses survive long periods on different
surfaces. Steam cooking of shellfish may allow them to
survive. It is important to notice that the viruses can
survive in up to 10 ppm chlorine, well in excess of levels
routinely present in public drinking water systems (less
that 2 ppm).
Norovirus infection
• Noroviruses are highly contagious and 10-100 viral particles may be
sufficient to infect an individual. They are transmitted primarily
through the faecal-oral route, either by consumption of contaminated
food or water, or by spreading directly from person to person.
Vomiting creates effectively aerosols with high content of virus
particles, which enter the oral mucosa or contaminate surfaces. The
virus survives long on different surfaces and thus, environment may
serve as a source of new infections. During one single outbreak of
norovirus gastroenteritis, several modes of transmission usually
occur. Even though the incubation period is relatively short (15-50
h), since the infective dose is very small, and asympomatic shedding
does occur, the origin of the outbreak is often difficult to confirm. For
example, initially food or water borne transmission is often followed
by secondary person-to-person transmissions to close contacts.
Virus shedding usually starts with the onset of symptoms (mainly
vomiting and diarrhea) and may continue for 2 weeks after
recovery.
Norovirus infection
• As the immunity may only last a few months and is strain-specific,
and given their genetic variability, infection can happen several
times in a lifetime and affects individuals of all ages.
Susceptibility to infection is probably genetically determined.
According to recent studies, persons of blood group 0 are at
greatest risk for infection.
Many different food items have been associated with norovirus
outbreaks. Raspberries and oysters have caused several national
and international outbreaks. In principle, any food item may become
contaminated if handled by infected person or if washed or
humidified with contaminated water. Norovirus infections spread
effectively from person to person in community settings like
hospitals, schools, day care centers and nursing homes. Several
outbreaks have been recorded in cruise ships, which provide an
ideal closed setting for the spread of infection.
Giardiasis
Giardia lamblia (Giardia intestinalis and Giardia
duodenalis are synonyms) is a cyst-producing
parasite, able to settle in the human and animal bowel.
The parasites could cause disease equally in humans
and animals such as dogs, cats, cows and sheep. In
the environment, major reservoirs of the parasite are
contaminated surface waters.
GiardiasisGiardia lamblia (Giardia intestinalis and Giardia duodenalis are synonyms) is
a cyst-producing parasite, able to settle in the human and animal bowel.
Giardia cysts can survive for extended periods of time in the environment
and chlorination of water alone cannot inactivate them.
The parasites could cause disease equally in humans and animals such as
dogs, cats, cows and sheep. In the environment, major reservoirs of the
parasite are contaminated surface waters.
A major pathway of disease transmission is personal contact with infected
patients or exposure to food or water contaminated by them.
Direct person-to-person transmission, again through contact with infected
faeces, is the other main source of infection. Foodborne outbreaks have
happened, usually linked to infected food handlers or their contacts.
An individuals in nursing homes or day-care centres are particularly
susceptible to outbreaks.
The source
of infection
Route of
transmission
Susceptibility
Etiology:
Preventive measures:
Normal water treatment processes should be effective in removing Giardia cysts from drinking water. Good
personal and food hygiene, especially hand washing, are important in preventing the spread of giardiasis,
especially in institutions like nurseries or care homes.
There is no vaccine to protect humans against giardiasis, although a vaccine may be available for pets.
Giardiasis
Symptoms
People who have swallowed Giardia cysts sometimes have no
symptoms; this is particularly common in children.
For those who have symptoms, the most common are diarrhoea,
malaise, flatulence, foul-smelling and greasy stools, abdominal
cramps, bloating, nausea, loss of appetite and weight loss.
Prolonged diarrhoea, weight loss and not absorbing nutrients
from food passing through the intestines are particular
symptoms of giardiasis.
• Complications
Symptoms can occasionally be very severe, especially in
young children or pregnant women. Symptoms can be acute,
chronic—lasting some time—or relapsing, clearing up and then
recurring.
Giardiasis
• People most at risk
Most cases happen in children aged 0–4, followed by those
aged 5–14 and then adults aged 25–44. Cases happen
throughout the year, with slight peaks in spring and autumn.
Higher rates of infection are seen in refugees, people living in
institutions, travellers abroad, gay men and people whose
immune systems are compromised.
Giardiasis
Diagnosis
Giardiasis can be diagnosed by looking at samples
from stools under a microscope and by other
laboratory tests.
• Treatment
Antimicrobial treatment is available for giardiasis.
Giardiasis
How to avoid getting giardiasis
Normal water treatment processes should be effective
in removing Giardia cysts from drinking water. Good
personal and food hygiene, especially hand washing,
are important in preventing the spread of giardiasis,
especially in institutions like nurseries or care homes.
There is no vaccine to protect humans against
giardiasis, although a vaccine may be available for
pets.
• What to do if you have giardiasis
Food handlers, healthcare workers and affected
nursery children should stay at home until 48 hours
after their symptoms have ceased in order to avoid
spreading the infection.
Cholera
The illness caused by bacteria called Vibrio cholerae. It causes diarrhoea and
can lead people to become severely dehydrated very quickly, which can be
fatal. It is a major public health problem in many parts of the world and a
threat to Europeans travelling to these areas.
Cholera can range in severity from a mild illness which may show no
symptoms through to very severe symptoms. The first signs are nausea
and discomfort in the abdomen, followed by sudden watery diarrhoea and
vomiting. Vomiting tends to disappear after around 12 hours, although the
diarrhoea may continue. Cholera often causes people to painlessly loose
large amounts of liquid stools – often called “rice water” stools because of
their appearance. People with cholera often have extremely painful muscle
cramps.
•
CholeraVibrio cholera of serogroups O1 or O139. Vibrios can survive for a
long time in coastal waters contaminated by human excreta
Humans.
Consumption of contaminated water and food, especially
seafood eaten under-cooked, results in infection.
The source
of infection
Route of
transmission
Etiology:
Susceptibility General
Preventive measures:
In areas where cholera is more common, improved sanitation and water supplies and food hygiene
measures are important in reducing the spread of cholera. Water should be chlorinated or boiled before it is
considered safe to drink. Although this is a low risk, travellers to countries where cholera is more common
should be aware of the possibility of contracting it and drink only boiled or mineral water.
A vaccine is available that is effective against cholera.
Cholera
• Complications
If cholera is untreated, severe dehydration and
“hypovolemic” shock can happen, which leads to
symptoms including sunken eyes, wrinkled skin, a
very fine and scarcely perceptible pulse,
undetectable blood pressureand reduced levels of
consciousness. Severe untreated cholera can cause
kidney failure and, in 50% of cases, death. In
children, a condition called hypoglycaemia (low blood
sugar) can occur which can be severe and cause
convulsions and coma. In pregnant women, cholera
can cause miscarriages and premature birth.
Cholera
• Diagnosis
Cholera can be confirmed by testing a sample of a patient’s stools in a
laboratory. Rapid tests are also being developed, which do not need to be
done in laboratories –. However, where there are outbreaks of large
numbers of cases, laboratory tests would not be carried out on all patients
and doctors would be able to diagnose patients based on their diarrhoea
and vomiting symptoms.
• Treatment
As previously mentioned, if cholera is not treated, up to 50% of people who
have it can die. However, as long as treatment is given, this is reduced to
around 1% of cases. Rapidly rehydrating patients is the most important
treatment for cholera. The majority of cases can be rehydrated by drinking
Oral Rehydration Salt solution. Severely dehydrated patients will need
intravenous fluids and may also be treated with antibiotics. Using antidiarrhoeal
drugs is not recommended in patients with cholera. Infection
control measures are important with cholera patients, because the bacteria
are highly infectious. Patients in hospital or being cared for at home should
be isolated and strict hygiene measures implemented to reduce the risk of
spreading the infection.
Typhoid and Paratyphoid Fever
Typhoid and paratyphoid fevers are systemic diseases.
Humans can carry the bacteria in the gut for very long
times (chronic carriers), and transmit the bacteria to other
persons (either directly or via food or water contamination).
After 1-2 weeks incubation period, a disease characterised
by high fever, malaise, cough, rash and enlarged spleen
develops. Diarrhoea may be present at some stage. When
Salmonella typhi is the cause, intestinal perforation and
haemorrhage may occur. Salmonella typhi blood stream
infection can also cause infection in all organs. Antibiotic
therapy has radically changed the prognosis of typhoid,
which, untreated, has a 10% death rate.
Typhoid and Paratyphoid Fever
Salmonella typhi and Salmonella paratyphi
Humans are the only reservoir for Salmonella typhi (which is
the most serious), whereas Salmonella paratyphi also has
animal reservoirs.
Humans can carry the bacteria in the gut for very long times
(chronic carriers), and transmit the bacteria to other persons
(either directly or via food or water contamination).
The source
of infection
Route of
transmission
Etiology:
Susceptibility
General
Preventive measures:
Preventive measures include good personal and food hygiene. An effective vaccine is also available.
Antrax
• Anthrax is…
…a zoonotic disease that humans can catch from
animals. Sources are grass-eating animals, and the
spores can survive in the environment for decades.
The disease is endemic in several regions of the
world, including southern and eastern Europe.
• It causes serious illness.
• It used to be largely occupationally related but has
also been used deliberately in bio-terrorist attacks.
Antrax
The spore-producing bacterium Bacillus anthracis. The spores can
survive in the environment for decades.
Anthrax spores can be found in soil and animals, like cows, can then
acquire the infection while grazing.
Humans can catch the spores by eating contaminated or insufficiently
cooked meat, through contaminated flies that bite, by a having a break in the
skin and then being in contact with contaminated animal skins, bones, wool,
hair or tusks or by breathing in spores (e.g., in wool sorting, bonemeal or
hide processing factories).
General. Those most at risk of cutaneous anthrax are butchers, famers, vets
or people working in the animal hide industry.
The source
of infection
Route of
transmission
Etiology:
Susceptibility
Preventive measures: Control measures include the correct disposal of dead
animal: disinfection, decontamination and disposal of contaminated materials and
decontamination of the environment.
Protective equipment must be used by workers.
Vaccination of exposed animals and humans is required.
Antrax
The symptoms depend on how the anthrax was acquired by the infected person.
Close physical contact with infected livestock or contaminated dead animal
products can cause anthrax affecting the skin also known as cutaneous
anthrax. This is the most common form of the disease.
A small pointed and inflamed elevation appears on the skin, usually on the face,
hands or forearms. Over 2–3 days, this ulcerates to become a dry, black,
painless scab, surrounded by a ring of small cysts. This is always accompanied
by substantial swellings containing fluid, which extend a long way from the scab.
The scab dries and falls off within 1–2 weeks, with little scarring. Patients with
cutaneous anthrax usually recover, provided they receive prompt treatment with
antibiotics.
Swallowing anthrax can cause gastrointestinal anthrax, the form most common in
children. Gastrointestinal anthrax can affect either the upper throat or the
intestines. The form affecting the throat usually starts with a flu-like illness with a
high temperature, followed by throat ulcers and a visible swelling of the neck.
The form affecting the intestines causes ulcers in the bowel, leading to nausea
and vomiting, loss of appetite and high fever with abdominal pain, vomiting
blood and bloody diarrhoea.
Anthrax which is breathed in causes inhalational anthrax. This illness comes in
two phases beginning with non-specific mild fever, malaise, muscle aches, dry
cough and chest pain; disorientation is also common. Within 1–6 days, the
illness progresses to the second phase with fever, acute shortness of breath, a
harsh, grating sound when breathing and blue-tinged skin, rapidly leading to
respiratory failure, shock, a drop in body temperature and death, if untreated.
Antrax
Complications
Complications are rare in cutaneous anthrax
although secondary infections are possible.
Gastrointestinal and inhalational anthrax can lead
to inflammation of the brain: a flu-like illness,
sometimes with an intense headache, rapidly
progresses to seizures, delirium and coma, with
collapse and sometimes death.
Antrax
Diagnosis
Anthrax can be detected by doing laboratory tests on specimens from an
infected person.
Treatment
Anthrax can be treated with antibiotics. Respiratory support in an intensive
care unit (ICU) is likely to be necessary for cases of inhalational anthrax.
How to avoid getting anthrax
Vaccines are available that protect against anthrax.
Vaccination is recommended for vets, abattoir workers, those working with
animal hides or furs, laboratory workers and armed forces in areas of high
risk of exposure. Animals can be vaccinated to prevent them from being
infected and passing the spores onto humans.
Fatal case of anthrax following animal
exposure in Bulgaria
On 21 July 2015, Bulgaria reported a fatal
case of B. anthracis in a 53-year-old breeder
of sheep and cows who died on 17 July in
Varna after having slaughtered a sick
animal.
Further investigations revealed that a meatprocessing
plant used the contaminated
meat. The plant was closed and disinfected
and all products were confiscated.
Botulism
Botulism is a serious paralytic illness caused by a nerve toxin produced by
the bacterium Clostridium botulinum. The disease may occur after eating
foods containing the toxin or due to development of the spores within the
intestine of young children or within wounds.
Food botulism is the dominating form of the disease, and paralytic
symptoms generally appear after an incubation period of 12–36 hours (up
to several days) after consumption of the toxin-containing food. The
symptoms may be very severe, and require intensive-care treatment and
the administration of an anti-toxin. Even where these are available,
between 5 and 10 % of the patients die.
Due to the extremely high potency of the toxin, botulism is included among
the potential bio-terrorist threats. Following laboratory accidents, the toxin
has also caused symptoms on inhalation, with a substantially reduced
incubation period.
Botulism
Clostridium botulinum is a Gram-positive, rod-shaped, sporeforming
bacterium. It is an obligate anaerobe, meaning that oxygen
is poisonous to the cells.
Botulism spores are widespread in the environment and can be found in
dust, soil, untreated water and the digestive tracts of animals and fish. Foods
that have led to botulism outbreaks have included the following: meat
products, such as sausage and cured ham; canned, vacuum-packed,
smoked or fermented fish products; vegetables preserved by canning or
stored in oil; baked potatoes; honey; and cheese. Many outbreaks have
occurred due to home-preserved foods. Intestinal or infant botulism usually
takes place after swallowing botulinum spores, sometimes from food, which
then produce toxins in the gut. Wound botulism usually happens from
inoculating botulinum spores which then grow in the inoculation wound and
produce toxins.
General.
The source
of infection
Route of
transmission
Etiology:
Susceptibility
Preventive measures: There is no routine vaccination against botulism. Care should be taken when
canning food, either commercially or at home, and when preserving fish, meat and vegetables to make sure
botulinum is destroyed before storage.
Do not eat food from containers that are obviously bulging (which could be caused by gas from the botulinum)
or containers that are damaged. Boiling food for ten minutes before eating it would inactivate the toxin in
home-canned foods. Potential botulism cases should get urgent medical response and investigation.
Prevention work with intravenous drug users is also important
BotulismSymptoms
Botulism causes paralysis by affecting the nerves which allow the brain to
stimulate muscles and part of the central nervous system. It initially affects
the nerves in the skull and may cause blurred vision, difficulty swallowing,
double vision, stammering or stuttering, vocal disturbance, drooping eyelids,
facial weakness and weakness of the tongue. Weakness in the neck and
arms follows, after which the respiratory and lower body muscles are
affected. Respiratory problems may be severe enough to need ventilation in
hospital. Other symptoms may include dry mouth, urinary problems and
dysfunction of the stomach, intestines, heart and blood vessels. Patients do
not usually have a fever, and have no loss of sensory functions or
awareness. Botulism caught from food usually affects the stomach and
intestines, causing nausea, vomiting, constipation, diarrhoea and abdominal
cramps. Botulism in a wound causes inflammation around the wound,
followed by low blood pressure and circulatory collapse. Patients with wound
botulism often look and feel quite well before deteriorating dramatically over
a few hours. Babies with botulism may have constipation, lethargy, feeding
difficulties, floppy muscles, increased drooling and a weak cry.
Botulism
Ways to catch botulism
Botulism spores are widespread in the environment and can
be found in dust, soil, untreated water and the digestive tracts
of animals and fish. Foods that have led to botulism
outbreaks have included the following: meat products, such
as sausage and cured ham; canned, vacuum-packed,
smoked or fermented fish products; vegetables preserved by
canning or stored in oil; baked potatoes; honey; and cheese.
Many outbreaks have occurred due to home-preserved foods.
Intestinal or infant botulism usually takes place after
swallowing botulinum spores, sometimes from food, which
then produce toxins in the gut. Wound botulism usually
happens from inoculating botulinum spores which then grow
in the inoculation wound and produce toxins.
Botulism
People most at risk
Rates of botulism in the EU are generally low, with
around 200 cases each year (0.03 cases per 100
000 people). The highest levels of cases over the
past 10 years have been reported from Poland and
Lithuania. Wound botulism in intravenous drug users
is now the most common type of botulism in some
European countries, such as the UK and Ireland.
Infant botulism, which is very rare in Europe, usually
affects children younger than two, with most being
under six months old.
Botulism
Diagnosis
Laboratory tests can detect botulinum toxin in
faeces, serum, stomach contents, a swab from a
wound or in samples from contaminated food.
• Treatment
Patients need to be admitted to hospital for
investigation and treatment. Botulinum antitoxin is
available and reduces the length of illness and
fatality rates, but may have serious side effects.
Treatment can be given based on a doctor’s
diagnosis of symptoms, without waiting for laboratory
confirmation. Wound botulism can be treated with
antibiotics and surgery to remove dead tissue.
Brucellosis
Brucellosis is an infection caused by Brucella bacteria. The common reservoirs
for Brucella bacteria that may infect humans are cattle, dogs, sheep, goats,
and pigs. Brucellosis occurs worldwide but the Mediterranean region has
been particularly affected. Humans become infected by direct or indirect
contact with animals or with contaminated animal products (including
unpasteurised milk and dairy products) or by the inhalation of aerosols.
After an incubation period of five to 60 days, symptoms may appear either
acutely or insidiously. Untreated, the disease may become chronic. The
various symptoms are both general (fever, weakness, joint pain) and organspecific
(including infections in the brain infection and heart valves).
Untreated, brucellosis can lead to death. Prolonged antibiotic treatment is
usually effective.
Brucellosis
Brucella is a genus of Gran-negative bacteria.
Cattle, dogs, sheep, goats, and pigs.
Humans become infected by direct or indirect contact with
animals or with contaminated animal products (including
unpasteurised milk and dairy products) or by the inhalation of
aerosols.
General.
The source
of infection
Route of
transmission
Etiology:
Susceptibility
Preventive measures:
Control measures include animal vaccination and/or test-and-slaughter of infected
animals, as well as pasteurisation of milk and dairy products.
Cryptosporidiosis
In humans, infections without symptoms are common. Especially healthy individuals,
may, after an incubation period averaging one week, get a diarrhoea that spontaneously
resolves over a couple of weeks. By contrast, patients with impaired immune system
may develop profuse, life-threatening, watery diarrhoea that is very difficult to treat with
currently available drugs.
Outbreaks have been reported in hospitals, day-care centres, within households, among
bathers (affecting participants in water sports in lakes and swimming pools), and in
municipalities with contaminated public water supplies. Water distribution systems are
particularly vulnerable to contamination with Cryptosporidium, which can survive most
disinfection procedures such as chlorination
Cryptosporidiosis
Cryptosporidia are intestinal parasites infecting a variety of animals (e.g.
cattle, sheep, rodents, cats and dogs, but also birds, fish and reptiles).
Human infections occur due to Cryptosporidium parvum, a species that also
affects domestic animals.
Cryptosporidium eggs (oocysts) can survive for months in moist soil or water
and survive harsh environmental conditions (e.g. heat, cold, droughts) for
extended periods of time.
Person-to-person or animal-to-person disease transmission occurs mainly
through contaminated water and food..
The source
of infection
Route of
transmission
Etiology:
Susceptibility
Everyone is susceptible to the infection but the highest numbers of cases are found
in children, with those aged younger than two years at the most risk.
Preventive measures:
Good quality drinking water, swimming pool hygiene and general hygiene measures are all important in
preventing cryptosporidiosis. Good hand-washing, taking care when preparing food and carefully disposing
nappies are all important in limiting the spread of infection. People whose immune systems are compromised
should avoid contact with animals with diarrhoea and young pets, and avoid swallowing water when
swimming. If drinking water supplies are affected, water should be boiled before drinking.
Cryptosporidiosis
• Symptoms
The most common symptom of cryptosporidiosis is acute,
watery diarrhoea. Pain in the abdomen may also occur, along
with other symptoms like malaise, headache and fever. The
disease is usually self-limiting, but can last up to 14 days and
can cause significant weight loss. In humans, the illness can
vary in severity from no symptoms at all to those who suffer
from persistent diarrhoea, with up to 40% of cases suffering a
return of diarrhoea after recovering from the initial illness.
• Complications
In children, especially in developing countries, cryptosporidiosis
can cause persistent diarrhoea and lead to wasting and stunted
growth. People whose immune systems are deficient, including
patients with HIV and AIDS, can also develop a more severe
and persistent infection.
Cryptosporidiosis
Ways to catch cryptosporidiosis
Cryptosporidium parasites can be caught by swallowing
infected water (either drinking water or through leisure
activities), eating contaminated food, direct contact with animals
carrying the germs, or passed from person to person by direct
contact. Drinking water is a frequent source of infection and
causes outbreaks around the world. This occurs where water is
contaminated with sewage or waste water overflow, or if there
has been a technical failure at a water treatment plant. Personto-person
infection is also common and Cryptosporidium can be
easily spread in households, nurseries and schools. Changing
nappies has been identified as a significant risk factor. In
Europe international travel, contact with another case, contact
with cattle, use of swimming pools and toileting of children
younger than five years have all been shown to be risk factors
for contracting cryptosporidiosis.
Cryptosporidiosis
Diagnosis
Cryptosporidiosis can be confirmed by carrying out
laboratory tests on a sample of faeces from an
infected patient.
• Treatment
In most generally healthy people, treatment may not
be necessary for cryptosporidiosis as it is usually selflimiting.
As with all illness causing diarrhoea, it is
important to monitor patients to make sure they do not
become dehydrated. Drugs are available that may be
used to treat patients who develop persistent
diarrhoea.
Echinococcosis
Echinococcosis is a zoonotic disease (transmitted from animals to humans) caused by
the larval stage (hydatid cyst) of tapeworms. Eggs are excreted in the faeces of
infected dogs and foxes and can be ingested by humans either by close contact with
these animals or through contaminated food.
• The most common location of cysts is the liver, but cysts may develop in almost any
organ, including lungs, kidneys, spleen, nervous tissue, etc, years after the ingestion
of the echinococcus eggs. In the case of cystic disease, symptoms usually appear
due to the large size of the cysts. Cysts in the lungs invades tissues in a cancer-like
fashion and if untreated always leads to death.
• Patients are treated with surgery and the specific anti-helminthic drugs. The disease
occurs in areas where dogs have access to animal inner organs, usually of sheep
and cattle (intermediate hosts), containing cysts. The lung form is restricted to
northern countries, where foxes abound.
• Poor hand hygiene, close contact with infected animals and consumption of
undercooked, unwashed food contaminated with echinococcus eggs (e.g.
vegetables) are all risk factors.
•
EchinococcosisThe genus Echinococcus includes six parasite species.
The infection is most often spread from dogs, wolves and foxes but can also
come from sheep, goats, cattle, camels and horses.
Infected humans do not excrete eggs.
People get echinococcosis by swallowing the eggs of parasites when they
eat contaminated food or drink water contaminated with the faeces of
animals which have been infected with the tapeworm.
The source
of infection
Route of
transmission
Etiology:
Susceptibility
General
Preventive measures:
Good hygiene measures are important to avoid getting echinococcosis. Vaccines are available for animals to
reduce the risk of their spreading the parasite to humans.
Echinococcosis
Symptoms
People who are infected with echinococcosis usually do not have any
symptoms. Symptoms are usually caused when the cysts formed by the
infection restrict or compress other parts of the body. Cysts can also leak
and cause secondary bacterial infection in the body, abscesses or immune
reactions. People get echinococcosis by swallowing the eggs of parasites
after eating contaminated food. The eggs hatch into tapeworms in the
person’s intestines and these pass through the membranes lining the body
and get into the circulation. The tapeworms turn into cysts in the intestines
and bowels which can grow and multiply, especially in the liver or lungs.
However, it can also spread beyond the liver to any organ including the
brain, heart and bones.
• Complications
Complications can include various diseases of the liver and the parts of the
body around the liver. If cysts leak or rupture, they can cause allergic
reactions which are sometimes severe.
Echinococcosis
Ways to catch echinococcosis
People get echinococcosis by swallowing the eggs of
parasites when they eat contaminated food or drink
water contaminated with the faeces of animals which
have been infected with the tapeworm. The infection is
most often spread from dogs, wolves and foxes but
can also come from sheep, goats, cattle, camels and
horses. Infected humans do not excrete eggs.
• People most at risk
The parasites that cause echinococcosis are found all
over the world. Studies have shown that the infection
tends to more often affect older people rather than
children. Dog owners and people who work with
sheep, goats or cows can be more at risk.
Echinococcosis
Diagnosis
Most of the time, untreated cysts remain undetected and are
often found by chance when other complaints are being
investigated. X-rays and ultra-sound scans can detect the cysts
caused by echinococcosis and a biopsy can detect the
infection.
• Treatment
Usually, treatment is only offered to those who are suffering
symptoms as a result of the cysts caused by echinococcosis.
These can either be treated surgically, by chemotherapy or by
using ultrasound scans to guide a doctor to remove the cyst
fluid using a needle.
Leptospirosis
Leptospirosis is a zoonotic disease caused by Leptospira bacteria. Although more
common in tropical areas of the world, the disease is also present in temperate
areas, including Europe. Different species of domestic and wild animals act as
maintenance hosts. Humans acquire leptospirosis either from direct contact with the
urine of infected animals, or from contact with material contaminated by it, such as
water or soil. After exposure, the incubation period ranges between two and 30 days
(with an average of 10 days). The clinical presentation is variable. Fever, muscle
ache and eye infection are very frequent. Liver, kidney, lung, heart, and more rarely
brain involvement and bleeding characterise the most serious clinical presentations.
Timely antibiotic treatment is effective, and the death rate is low, but does increase
with advancing age and may reach up to 20% or more in complicated cases with
severe disease.
• Preventive measures include controlling rodent populations, avoiding contaminated
areas and covering cuts and abraded skin when operating in the environment.
Immunisation of persons at occupational risk of exposure has been carried out in
some countries (Italy, France, Spain).
•
LeptospirosisLeptospirosis is caused by spirochatae bacteria belonging to the genus
Leptospira. 21 species of Leptospira have been identified. 13 species cause
disease or have been detected in human cases.
About 160 mammalian species have been identified as natural carriers of
pathogenic leptospires. These include feral, semi-domestic and farm and pet
animals as important infection sources.
The route of transmission is via broken skin and through mucous
membranes of eyes, mouth and nose (consumption, inhalation).
Transmission may also occur via sexual contact and mother’s milk. In-uterus
transmission can lead to reproductive failures such as abortion.
The risk of acquiring leptospirosis is associated with contact with animals and
thus with occupations such as farmers, veterinarians and sewer workers.
Case severity is associated with physical condition and increasing age.
Leptospirosis as a recreational disease in travellers is increasing in Western
countries.
•
The source
of infection
Route of
transmission
Susceptibility
Etiology:
Preventive measures: Prevention and control mainly focus on the identification and reduction of
the infection source and the prevention of penetration of leptospires into the accidental host.
Prevention of transmission can be achieved by wearing protective clothing.
Leptospirosis
• NAME AND NATURE OF INFECTING ORGANISM Leptospirosis is a
zoonosis occurring worldwide, caused by pathogenic spirochaetes of the
genus Leptospira. Pathogenic leptospires live in the kidneys of a large
variety of mammalian species and are excreted into the environment with
the urine. Indirect infection through contact with leptospires secreted into the
environment is probably the main route of acquiring leptospirosis.
Pathogenic leptospires survive longer in a warm and humid environment.
Therefore, the disease is particularly prevalent in wet tropical and
subtropical regions. The bacterium is sensitive to dry conditions, extreme
temperatures and detergents. Currently nearly 300 serovars have been
identified, divided into 25 serogroups. Seven main pathogenic species are
known.
• Leptospirosis is the most widespread and most prevalent zoonotic disease.
The disease is (re-) emerging globally and numerous outbreaks have
occurred worldwide during the past decade. In Europe, leptospirosis occurs
mainly in the Mediterranean and East European regions.
Leptospirosis
• 2. CLINICAL FEATURES
• The incubation period varies from 2 to 30 days, with an average
of 7–10 days. Leptospirosis varies from mild to severe clinical
presentation, and may cause potentially fatal conditions such
as Weil’s syndrome and the emerging Severe Pulmonary
Haemorrhagic Syndrome (SPHS). Generally, leptospirosis is an
acute biphasic illness: the first phase (4–9 days) presents with
an abrupt onset of a flu-like illness, with a severe headache,
chills, muscle aches, and vomiting, while in the second phase
the patient develops fever, jaundice, abdominal pain and
diarrhoea. In severe cases there may be organ failure. If
untreated, recovery may take several months.
Leptospirosis
• 3. TRANSMISSION
• 3.1 Reservoir
• About 160 mammalian species have been identified as natural carriers of pathogenic
leptospires. These include feral, semi-domestic and farm and pet animals as
important infection sources. The infectious period of natural hosts can be lifelong.
Accidental hosts can act as intermediate infection source, and may shed leptospires
for days or months.
• 3.2 Transmission mode
• The route of transmission is via broken skin and through mucous membranes of
eyes, mouth and nose (consumption, inhalation). Transmission through waterweakened
skin is controversial. Transmission may also occur via sexual contact and
mother’s milk. In-uterus transmission can lead to reproductive failures such as
abortion.
• 3.3 Risk groups
• The risk of acquiring leptospirosis is associated with contact with animals and thus
with occupations such as farmers, veterinarians and sewer workers. Case severity is
associated with physical condition and increasing age. Leptospirosis as a
recreational disease in travellers is increasing in Western countries.
Leptospirosis
• . PREVENTION MEASURES
• Prevention and control mainly focus on the identification and reduction
of the infection source and the prevention of penetration of leptospires
into the accidental host. Prevention of transmission can be achieved
by wearing protective clothing. Prophylactic treatment with
doxycycline is protective to some extent. Vaccination is available in a
limited number of countries, but currently not considered as a
generally applicable option.
• Improving water and food storage conditions, increasing public
awareness about the disease and infection risks, as well as the control
of rodents, may reduce the risk of transmission. Infection risk from
domestic animals can be reduced by vaccination or treatment of
carriers. Both approaches should be combined with herd management.
Vaccines are available for cattle, dogs and pigs, and provide a shortterm
serovar-specific protection.
Leptospirosis
• 5. DIAGNOSIS
• The confirmation of a clinically suspected leptospirosis case is usually
done through culturing and the Microscopic Agglutination Test (MAT);
both are quite laborious and require well-equipped laboratories with
experienced staff. Several rapid tests for humans are currently
available, mainly for screening purposes, and results must be
confirmed by standard tests.
• 6. MANAGEMENT AND TREATMENT
• Early diagnosis is critical in the treatment of patients with
leptospirosis. In severe cases, high doses of intravenous penicillin are
recommended, but Jarish-Herxheimer reactions may occur. In less
severe cases, oral antibiotics such as amoxycillin, ampicillin,
doxycycline or erythromycin are administered. Third generation
cephalosporins and quinolone antibiotics also seem to be effective.
Listeriosis
• L. monocytogenes was not identified as a cause of foodborne
illness until 1981, however.
• An outbreak of listeriosis in Halifax, Nova Scotia, involving
41 cases and 18 deaths, mostly in pregnant women and
neonates, was epidemiologically linked to the consumption of
coleslaw containing cabbage that had been contaminated
with L. monocytogenes-contaminated sheep manure.
Since then, a number of cases of foodborne listeriosis have
been reported, and L. monocytogenes is now widely recognized
as an important hazard in the food industry.
ListeriosisListeria monocytogenes is a Gram-positive bacterium. The genus
Listeria currently contains 10 species; only L. monocytogenes is consistently
associated with human illness.
Researchers have found L. monocytogenes in at least 37 mammalian
species, both domesticated and feral.
L. monocytogenes has been associated with such foods as raw milk,
pasteurized fluid milk, cheese (particularly soft-ripened varieties), ice cream,
raw vegetables, fermented raw-meat sausages, raw and cooked poultry, raw
meats (of all types), and raw and smoked fish. Its ability to grow at
temperatures as low as 0°C permits multiplication in refrigerated foods.
Reported cases in Europe are highest among those over 65 and children
younger than four.
The source
of infection
Route of
transmission
Susceptibility
Etiology:
Preventive measures:
Pasteurising dairy products is important as the process kills Listeria.
Listeriosis
• Symptoms
Listeriosis can cause a range of symptoms. Some patients can have no
symptoms at all. Previously well, non-pregnant people often get symptoms
of acute gastroenteritis—inflammation of the stomach and intestines. This
can cause headache, fever, abdominal pain, sleepiness, nausea and
diarrhoea. Fatigue, aching muscles, painful joints, vomiting and a sore throat
may also occur.
• Complications
Listeriosis can also cause serious illness, most often in those with long-term
health conditions, the elderly, or people whose immune systems are
compromised. Severe symptoms can include the following: blood poisoning;
inflammation of the brain and its lining; abscesses; inflammation of the lining
of the heart; and infected or inflamed joints.
• Pregnant women who get the infection may only have mild illness, but can
suffer miscarriage, premature delivery or stillbirth. Newborn babies can also
suffer from severe symptoms, including meningitis, which can lead to death.
Listeriosis
• Ways to catch listeriosis
The bacteria that cause listeriosis are widespread in the environment and
can be found in soil, surface water, vegetation and a range of wild and
domestic animals. Most humans catch the infection by eating contaminated
food. The bacteria can grow at low temperatures and are tolerant of salt and
therefore can survive in processed, preserved and refrigerated foods. Foods
that have been associated with spreading listeriosis include the following:
processed meat and fish, cold meats and hot dogs; dairy products, such as
soft cheese, butter and milk, especially if unpasteurised; and pre-prepared
salads, sandwiches and salads. Other sources of infection include direct
contact from animals or the environment. Pregnant women can pass the
infection to their babies during birth or through the placenta.
• People most at risk
Reported cases in Europe are highest among those over 65 and children
younger than four.
Listeriosis
• Diagnosis
Laboratory tests are carried out on samples of blood
or cerebrospinal fluid to diagnose the infection.
Laboratory tests are also carried out on food and
environmental samples to look for Listeria.
• Treatment
Antibiotics can be used to treat patients.
Listeriosis
• How to avoid getting listeriosis
Pasteurising dairy products is important as the process kills Listeria. Cookchill
and ready-to-eat foods should not be stored for too long and should be
thoroughly reheated before serving. Raw vegetables, fruits and salads
should be thoroughly washed before eating.
• Pregnant women and people whose immune systems are compromised are
advised to avoid soft cheeses, pâté and pre-packed salads, contact with
pregnant or newborn animals and silage.
• Hand washing is effective at reducing the risk of gastroenteritis from many
organisms and may be made even more effective by using antibacterial
soap.
• There is no vaccine against listeriosis.
Toxoplasmosis
is a parasitic disease caused by Toxoplasma gondii.
Infections with toxoplasmosis usually cause no symptoms
in adult humans. Occasionally there may be a few weeks or
months of mild flu-like illnesssuch as muscle aches and
tender lymph nodes.
In a small number of people, eye problems may develop. In
those with a weak immune system, severe symptoms such
as seizures and poor coordination may occur.
Toxoplasmosis
Toxoplasma gondii is an obligate intracellular, parasitic protozoan
Cats are the reservoir of the parasite.
They excrete cysts in the environment, able to infect many other animals,
and humans can become infected either by ingesting the cysts (by direct
contact with cats or through food or water contaminated by cat faeces), or by
eating poorly cooked meat containing cysts, especially pork and mutton.
Furthermore, pregnant or immunocompromised people are at higher risk of
becoming infected or transmitting the parasite to their fetus.
.
The source
of infection
Route of
transmission
Susceptibility
Etiology:
Preventive measures:
Basic food handling safety practices can prevent or reduce the chances of becoming infected with T. gondii,
such as washing unwashed fruits and vegetable and avoiding raw or undercooked meat, poultry, and seafood.
Other unsafe practices such as drinking unpasteurized milk or untreated water can increase odds of infection.
Oocysts in cat feces take at least a day to sporulate and become infectious after they are shed, so disposing of
cat litter daily greatly reduces the chances of infectious oocysts being present in litter.
Toxoplasmosis
Usually toxoplasmosis goes with no symptoms in humans (and
animals), but healthy individuals may experience swollen lymph
glands. However, it may also cause life-threatening disease in
individuals with impaired immune defence.
During pregnancy the infection can affect the foetus.
Pregnant women, also without symptoms, may transmit the
infection to the foetus, which can result in abortion, still-birth,
perinatal death (due to disseminated toxoplasmosis), or
congenital infection with severe malformation affecting the eyes
and the brain. Infection in individuals with impaired immunity
tends to seriously affect the central nervous system, but also
other organs may be affected. Such patients may require
prolonged (sometimes life-long) therapy.
Variant Creutzfeldt-Jakob disease
Variant Creutzfeldt-Jakob disease (vCJD) is a relatively
new and rare neurological disease, classified as a
Transmissible Spongiform Encephalopathy (TSE). It was
first identified in March 1996 in the UK, when 10 cases of a
new disease with neurological symptoms were reported
and soon associated with the Bovine Spongiform
Encephalopathy (BSE), “mad cow”-disease. Patients with
vCJD have prominent psychiatric (frequently depression,
anxiety and withdrawal) or sensory symptoms and delayed
onset of neurologic abnormalities, including ataxia within
weeks or months, and dementia and myoclonus late in the
illness. The disease always progresses to death. Disease
duration is 14 months on average.
Variant Creutzfeldt-Jakob disease
Causative agents of vCJD are prions, composed of misfolded prion proteins
(PrPSc), which form aggregates in neurological tissue leading to progressive
brain damage and characteristic signs and symptoms of the disease. Prions
are stable and relatively resistant to proteases, high temperatures, UV
radiation, and commonly used disinfectants.
Cats are the reservoir of the parasite.
Most reported vCJD cases appear to have been infected through the
consumption of bovine meat products contaminated with the agent of BSE.
In three cases, reported by the UK, the mode of transmission is thought to be
through receipt of blood from an asymptomatic, infected donor.
vCJD tends to affect younger individuals, with an average age of onset of
around 28 years, compared to sporadic CJD, which tends to affect middleaged
and elderly individuals.
The source
of infection
Route of
transmission
Susceptibility
Etiology:
Preventive measures: