Food and Water Borne Diseases

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Food and Water Borne Diseases
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Food Borne Diseases

• Diseases caused by microorganisms in food
• Microorganisms present can cause
• Food to spoil
• Diseases

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Overview

• Clinical spectrum is vast
• Primarily affects the gastrointestinal tract
• Infection maybe mild? life threatening
• Some pathogens cause diseases that affect other
  systems
• Ex polio virus? food? affects the NS
• Botulism? toxin produced by C. botulinum? affects
  the CNS

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Prevention

• 3 factors must be considered
• The microbial pathogen the disease
• Their reservoir? each pathogen has a particular
  reservoir
• Their mode of transmission? feces plays the key
  role. Oral-Fecal Route

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• Do concept map
• Table for diseases

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Foodborne Diseases

• Usually called Food Poisoning ? caused by
  eating a particular food.
• Two main types
• Toxin is produced in the food (exotoxin) causes
  the disease ?true food poisoning
• Food is the mechanical carrier of the pathogen,
  when ingested the pathogen establishes its self
  to cause the disease

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Intoxication vs. Infection

• Infection
• Pathogen has to be ingested
• After a period of incubation ,pathogen
  establishes itself, usually in the intestine
• Causes infection

• Intoxication
• Manifested much more quickly
• Toxin is already present to cause harm
• Toxin is the direct cause of disease

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Transmission of Foodborne Diseases

• 4 main ways? 4Fs
• Food
• Feces
• Fingers
• Flies
• Food is the immediate source of the
  pathogen/toxin
• May be acquired by close contact w/ an infected
  person or a carrier
• Involves the fecal-oral route

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Fecal-Oral Route

• Pathogen is shed in feces
• Transmission occurs when another person comes in
  contact with this feces (food or person)
• EX Food handler (GI disease)? use the restroom,
  does not wash hands well? makes salad ? customer
  eats the salad, gets sick

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Prevention

• Depends on
• Knowing the sources of the etiological agents
• Their routes of transmission

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General Measures of Prevention

• Clean store produce properly
• Prepare food properly? cooking adequately
• Employ general sanitary procedures while handling
  food
• Eat cooked food promptly
• Restrict carriers from food preparation
• Protect food from insects, rodents
• Use pure water

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Staphylococcal Food Poisoning

• Staphylococcus aureus ? gm(), grape like
  clusters
• Humans harbor these organisms, present in boils,
  skin lesions
• Food poisoning is caused when staph is
  transferred from person to food
• Could come from an open boil, lesions sneeze, etc
• Salad bars --what is special?
• Sneeze shield

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Staphylococcal Food Poisoning

• Intoxication caused by 3 toxins
• True food poisoning
• Exotoxins are heat stable proteins known as
  enterotoxins (affects the intestines)
• Two ? inhibit water absorption from the intestine
  induce diarrhea vomiting
• Third one damages the intestinal lining? colitis

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Vehicle for Transmitting the Toxin

• Food usually protein in nature
• Ex ham, chicken salad, custard filling for
  dessert

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Typical Outbreak
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Symptoms

• Nausea, vomiting, abdominal cramps, diarrhea
• Onset? 1-6 hours after eating the contaminated
  food
• Key Feature? absence of fever, this distinguishes
  it from other food borne diseases

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Prevention

• Based on the route of transmission? two main ways
  of prevention
• Reduce the possibility of food handlers
  contaminating food
• ( education in general hygiene)
• Keep cold foods cold, hot foods hot
• ( serve foods when prepared or keep
  refrigerated, do not allow foods to sit at room
  temperature)

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Clostridium botulinum Botulism

• C. botulinum? Gm() , endospore forming organism,
  anaerobic
• Present in soil, ponds and lakes

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Botulism

• Infrequent, but fatal
• 50 cases/year in the US
• Caused by exotoxins produced by C. botulinum?
  most deadly biological toxin? neurotoxin and
  affects the CNS

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Botulinum Toxin

• 8 types ? 3 affect humans
• Exotoxins are very sensitive to heat? readily
  destroyed by heat
• Boiling for 3 mins will inactivate the toxin(
  10-20 min recom.)

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Botulism

• Associated with home or commercial canned low
  acid foods, ex veggies fruits
• Smoked meat
• Toxin is preformed acts readily
• Vomiting, diarrhea, constipation may occur BUT
  neurological symptoms are inevitable w/in 12-36hrs

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Neurological Symptoms

• Blurred or double vision, slurred speech, labored
  breathing, difficult to swallow, dry mouth
• Evidence of paralysis and reflect loss of ability
  to transmit nerve impulses
• Death may occur w/in 12-24h from respiratory
  failure

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Diagnosis Therapy

• Fatality rate is low due to accurate diagnosis
  and supportive therapy
• Suspected cases must be hospitalized and give IM
  or IV antitoxin and respiratory support.
• Recovery may be slow? months to years

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Prevention

• Endospores present? may not be removed by washing
• Proper canning
• After canning? avoid bulging can/jar

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Infant Botulism

• 3 wks to 8 months
• Results in ingestion of endospores not toxin
• Endospores germinate in colon and produce
  exotoxin
• Symptoms poor muscle tone (floppy baby),
  lethargy, weak cry
• 5 of SIDS

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Clostridium perfringes

• Anaerobic spore former
• Present in soil intestines of humans and
  animals hence also in sewage
• Typical illness ?diarrhea, abdominal cramps,
  nausea and vomiting
• Sickness lasts a day, incubation period is
  usually 6-24 hours
• Prevention refrigerate food and cook adequately

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Bacillus cereus

• Anaerobic spore former present in soil
• Produces a heat stable toxin
• Usually associated with Chinese food
• Common in uncooked rice? rice is cooked and left
  at room temp, spores germinate produces the
  toxin that is not destroyed by brief cooking stir
  frying)
• Symptoms Prevention ? same as C. perfringes

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Listeria monocytogenes

• Nonspore forming gm() rod
• Disease is associated with dairy products , hot
  dogs fruits vegetables
• Reservoir ?forage, silage , infected animals and
  humans
• Can reproduce in phagocytic macrophages

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Listeria monocytogenes

• Causes meningitis, general sepsis or bacteria in
  blood
• Meningitis? inflammation of the membrane covering
  of the brain
• Onset by fever, intense headache, nausea
• Pregnant women, newborn, elderly
  immunosuppressed individuals are affected
• Pregnant women can transmit L. monocytogenes to
  fetus? spontaneous ab, still birth, miscarriage

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Gram Negative Bacteria

• Salmonella
• Escherichia coli
• Shigella
• Vibrio cholerae

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Salmonella

• Gm(-) rod
• Facultative anaerobe
• Causes salmonellosis
• Two strains? S. enteritidis, S. typhimurium

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Salmonellosis

• Infection caused by salmonella transferred in
  food (fecal contamination)
• Bacteria enter adhere to the intestinal mucosa
• Infection is limited to the intestinal mucosa

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Symptoms

• Headache, chills, vomiting, nausea, abdominal
  cramps fever
• Onset sudden and violent after ingestion of
  contaminated food
• 12-36 hrs incubation period
• Lasts for 1 wk? can cause severe dehydration in
  infants
• May eventually spread to the blood stream

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Reservoir

• Wide variety of animals? poultry, cattle, swine,
  rodents
• Pets? chicks, dogs, cats, reptiles
• Annually 100,000 cases are traced to pet reptiles
• Reptiles should not be allowed to roam freely w/
  children under 1 yr

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Transmission

• Raw undercooked foods
• Meat, poultry, eggs, milk
• Person-person
• Fecal-oral route

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Prevention

• Thaw meat in refrigerator
• Cook eggs meat till well done
• No more sunny side up and preparations that
  have raw eggs (sickness caused by Hollandaise
  sauce)
• Salmonella is destroyed by conventional cooking

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Classic Outbreaks

• Milk? 1985? 195,000 people got sick in Northern
  Illinois? improper pasteurization of milk
• Poultry? 1986-200 student and school staff sick?
  improperly cooked chicken (chicken cont. during
  processing?)
• Red Meat? 1977? 3 outbreaks in NY assoc. w/
  precooked roast beef /deli meats

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Typhoid Fever

• Caused by S. typhii
• Different from salmonellosis
• Reservoir? humans, especially long term carriers
• Typhoid is not typical gastroenteritis? high
  fever that gradually increases over 3 wks

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Symptoms

• Typically starts w/ ingestion of 103-107 bacteria
• Incubation ? 2weeks
• Disease begins with
• Chills, general malaise, headache, ab.
  tenderness, distention, vomiting
• Constipation is more common than diarrhea
• Fever increase in a stepwise manner, peaks at
  104o F
• Rose spots in ab area
• Later stages ? severe intestinal hemorrhage

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Chronic Carrier

• S. typhii replicates in the GI tract? enters the
  lymphatic system ? spread to the body
• Reproduces in the monocytes
• Can be excreted in urine feces
• Is resistant to bile estab. In the gall bladder
  continuously reenters the SI
• Persistence in the GB SI ? chronic carrier

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Carriers

• 40 ? carry for several wks
• 5 ? 1 yr
• 2-3 ? permanent carriers continually excrete
  106-109 in feces

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Typhoid Mary
NY? Mary Mallon in 1900 AKA typhoid Mary died
in 1938
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Escherichia coli

• Gm(-) rod, facultative anaerobic
• Causes gastroenteritis, bladder infections,
  Kidney infections, gall bladder infections,
  septicemia, pneumonia
• Urine infection in 90 of non hospital patients,
  30 in nosocomial patients

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4 Major Types

• EPEC ? Enteropathogenic E.coli
• ETEC? Enterotoxigenic E.coli
• EIEC ? Enteroinvasive E.coli
• EHEC ? Enterhemorrhagic E.coli

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EPEC

• Associated with severe diarrhea,
• Adheres to intestine epithelium causes illness
• Food exposed to fecal contamination is strongly
  suspect.
• Outbreaks most often affect infants, especially
  those that are bottle fed

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ETEC

• Associated with travelers diarrhea,
• Produces 2 toxins
• Affects the intestinal mucosa
• Results in fluid loss copious watery diarrhea
• Disease is usually self-limiting, infants,
  elderly ?appropriate electrolyte replacement
  therapy may be necessary.

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EIEC

• Affects the large intestine
• Illness known as bacillary dysentery
• Penetrates the epithelial cells
• Multiplies destroys cell
• Results in bloody mucus stools
• Often mistaken for dysentery caused by Shigella
  species

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EHEC

• Present in 1-2.5 meat/ undercooked meat, also in
  fruit juices (must be pasteurized)
• Causes severe abdominal cramps, copius bloody
  diarrhea with no pus
• Produces a powerful exotoxin
• GI disease can lead to kidney damage

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Shigella

• Gm(-) rod
• Four species? S. boydii, S. dysenteriae, S.
  flexneri, S. sonnei,
• All cause bacillary dysentery
• Produces a potent toxin Shiga toxin

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Symptoms

• Incubation period 48 hr followed by fever
• Severe abdominal cramps, frequent intense
  diarrhea w/ blood mucus and pus
• Developed country ? self limiting

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Reservoir/ Transmission/ Virulence

• Reservoir humans
• Transmission person-person, F-O-R, as few as
  10-200 organisms can cause disease, young
  children are at risk, malnutrition poor
  sanitation plays an imp role
• Virulence ?penetrates the mucosal lining of the
  LI
• Produces exo endotoxin

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Vibrio cholerae

• Gm(-) curved rod, facultative anaerobe
• Extremely motile
• Two serotypes? cholerae and eltor
• Causes cholera, one of the most explosive
  communicable diseases
• 1991 epidemic in Peru, spread to south and
  central America? 750,000 people got sick, 6000
  died

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Symptoms

• Debilitating watery diarrhea that can be fatal
• After ingestion, V. cholerae colonizes the SI?
  incubation is 2-3 days? abrupt onset of profuse
  painless watery diarrhea
• Diarrhea leads to rapid dehydration electrolyte
  imbalance
• Flecks of mucous in stool? rice water
• Untreated may cause circulatory failure w/in few
  hours

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Reservoir/ Transmission

• Reservoir natural aquatic ecosystems, V.
  cholerae degrades dead shell fish, attaches to
  plankton and travel up the food chain
• Epidemics initiated by algal blooms (hypothesis)
• Transmission Fecal contamination of water?
  drinking , irrigation

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Controlling Cholera

• Key Measures
• Safe drinking water
• Adequate sewage disposal
• Transmission via food can be controlled by
  adequate cooking peeling of fruits vegetables
• Treatment
• Oral rehydration therapy (glucose, NaCl, KCL
  NaHCO3)to replace water electrolytes

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Foodborne Waterborne Viruses

• Rotavirus? most common cause of severe
  dehydrating diaarhea
• Hepatitis A Virus? causes inflamation of the
  liver
• Enteroviruses? gateway for the virus to cause
  more serious disease
• Norwalk Agent? winter vomiting disease( older
  children adults)

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Other Organisms

• Amoeba
• Giardia
• Entamoeba histolytica
• Cryptosporidium
• Fungi? 100s of poisonous mushrooms
• Amanita
• Aspergillus ? aflatoxins
• Claviceps? hallucinogens
• Algae? certain marine algae produce neurotoxins?
  contaminate shell fish