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FA2 Public Health and Epidemiology > Lecture 24 10/17/24 > Flashcards

Lecture 24 10/17/24 Flashcards

1
Q

What is foodborne illness?

A

any illness resulting from the consumption of food contaminated by pathogenic bacteria, viruses, parasites, chemicals, or natural toxins

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2
Q

What typically results in foodborne illness?

A

-improper handling
-improper preparation
-improper storage

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3
Q

What is foodborne intoxication?

A

ingestion of food containing “preformed” chemical toxicants; the toxins cause illness instead of the bacteria that produced the toxins

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4
Q

What are examples of foodborne intoxication?

A

-staphylococcal food poisoning
-botulism

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5
Q

What is foodborne infection?

A

pathogens in food survive the digestive processes and overcome the host’s natural defenses

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6
Q

What is an invasive foodborne infection?

A

organism penetrates the lining of the GI tract and subsequently multiplies

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7
Q

What are the characteristic signs of an invasive foodborne infection?

A

-dysentery/blood in feces
-fecal leukocytes
-fever

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8
Q

Which pathogens are examples of invasive foodborne infections?

A

-EIEC
-Salmonella spp.
-Listeria monocytogenes

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9
Q

What is a non-invasive foodborne infection?

A

organism multiplies in the GI tract without penetrating the GI tract

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10
Q

What is the characteristic sign of a non-invasive foodborne infection?

A

watery diarrhea

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11
Q

Which pathogens are examples of non-invasive foodborne infections?

A

-ETEC
-Vibrio cholerae
-Clostridium perfringens

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12
Q

How does foodborne intoxication differ from foodborne infection?

A

intoxication:
-usually presents within 1 to 7 hours
-usually lacks a fever
infection:
-requires 8 hours to several weeks to present
-fever occurs due to inflammatory response to pathogens

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13
Q

What are the typical growth requirements for foodborne pathogenic bacteria?

A

-temp. between 40-140 deg. F
-pH greater than 4.6
-water activity greater than 0.85
-variable O2 and nutrient requirements

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14
Q

What are the top 5 foodborne pathogens that result in hospitalization?

A

-Salmonella spp.
-Norovirus
-Campylobacter spp.
-Toxoplasma gondii
-E. coli (STEC) O157

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15
Q

What are the characteristics of E. coli?

A

-gram neg. rod
-found in water and food contaminated with feces
-characterized by varying degrees of diarrhea

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16
Q

What are the six pathogenic strains of E. coli in humans?

A

-EHEC
-ETEC
-EIEC
-EPEC
-EAEC
-DAEC

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17
Q

What are the characteristics of Shiga Toxin E. coli (STEC)?

A

-E. coli that produces shiga-like toxins or vero toxins
-similar/identical toxin to Shigella dysentariae toxin
-neutralized by shigatoxin antiserum
-cytotoxic
-causes fluid accumulation in GI tract
-causes hemorrhagic colitis
-group of concern is EHEC, which includes O157 and non-O157 STEC

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18
Q

What are the characteristics of enterohemorrhagic E. coli (EHEC)?

A

-most virulent, with severe clinical disease
-most common strain is E. coli O157:H7
-cattle is primary reservoir host

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19
Q

What do the O and H stand for in E. coli serotyping?

A

O: cell wall antigen
H: flagellar antigen

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20
Q

What are the characteristics of E. coli distribution and prevalence?

A

-preferred temp. between 45 and 122 deg. F
-63,000 cases of EHEC in US each year
-world-wide distribution
-low infection rate in cattle and humans

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21
Q

What is the epidemiology of E. coli in humans?

A

-all ages susceptible, but most common and severe in children and elderly
-children under the age of 5 have highest overall incidence
-children under the age of 5 have highest incidence of hemolytic uremic syndrome

22
Q

What are the characteristics of E. coli transmission?

A

-incubation period of 3-4 days
-adults able to spread disease for 1 week
-children able to spread disease for 3 weeks
-common in summer and fall
-seen in rural pop.

23
Q

What are the clinical signs of E. coli in humans?

A

-diarrhea ranging from mild and watery to severe and hemorrhagic
-nausea
-vomiting
-abdominal pain
-possibly asymptomatic

24
Q

What are the characteristics of hemolytic uremic syndrome?

A

-thrombocytopenia
-hemolytic anemia
-main cause of acute renal failure in children
-case fatality rate around 3.5%

25
Q

What are the characteristics of thrombocytopenic purpura?

A

-neurologic symptoms
-thrombocytopenia
-hemolytic anemia
-mortality rate in elderly around 50%

26
Q

What are the potential routes of transmission for E. coli?

A

-indirect fecal-oral route in food
-direct fecal oral route between humans or animal and human

27
Q

What are the common sources of E. coli outbreaks?

A

-raw/undercooked ground beef/beef products
-raw milk
-unpasteurized fruit juices
-various water sources
-petting zoo animals
-person-to-person
-various produce

28
Q

What are the prevention steps at the individual level for E. coli?

A

-wash hands, kitchen surfaces, and utensils
-avoid cross-contamination of other foods
-do not eat raw/undercooked ground beef/products
-cook ground beef to 160 deg. F internal temp.
-practice personal and food safety hygiene at petting zoos

29
Q

What are the prevention steps at the community level for E. coli?

A

-surveillance
-notification of disease to health officials
-pasteurization and hygienic slaughter
-waste disposal
-public education and awareness

30
Q

What are the prevention steps at the livestock level for E. coli?

A

-proper animal husbandry
-vaccination
-probiotics
-stress reduction
-antemortem inspection

31
Q

What are the clinical signs of E. coli in animals?

A

-EHEC: usually asymptomatic
-ETEC: colibacillosis

32
Q

What are the top five foodborne pathogens that result in death?

A

-Salmonella spp.
-Toxoplasma gondii
-Listeria monocytogenes
-Norovirus
-Campylobacter spp.

33
Q

What are the characteristics of Listeria monocytogenes?

A

-gram pos. rod
-13 serotypes
-reportable disease
-ubiquitous in environment
-found in moist environments, soil, and decaying vegetation
-persistent in food manufacturing environments

34
Q

What makes Listeria monocytogenes hard to kill in food?

A

-can grow at refrigeration temps
-salt tolerant

35
Q

What is the epidemiology of Listeria monocytogenes?

A

-reservoirs include domestic and wild mammals, birds, and man
-may be free living
-can survive in soil for months to years
-widely distributed by farming techniques and spreading of manure
-can contaminate vegetables, animal feed, and water

36
Q

What are the characteristics of non-invasive listeriosis?

A

-fever
-muscle aches
-nausea
-diarrhea
-generally resolves in healthy people

37
Q

What are the characteristics of invasive listeriosis?

A

-causes septicemia and meningitis
-pregnant women more susceptible
-mother likely to recover while fetus does not survive

38
Q

What are the characteristics of listeriosis mortality?

A

-severe form has a case fatality rate of 15-30%
-increases to 70% with meningitis
-increases to 50% with septicemia
-increases to 80% in perinatal/neonatal infections

39
Q

What are the incubation periods for listeriosis?

A

non-invasive: 9-48 hrs
invasive: 2-6 weeks

40
Q

What are the food sources of Listeria?

A

-raw milk
-raw or smoked fish/seafood
-meat (including deli meat)
-cheese, especially soft
-ice cream
-raw fruits and vegetables

41
Q

How is Listeria diagnosed?

A

-culture from tissue, blood, CSF or sterile site
-stool culture not helpful due to intestinal carriers

42
Q

How is Listeria treated?

A

antimicrobial therapy consisting of ampicillin +/- gentamicin; cross BBB

43
Q

How do humans acquire trichinosis?

A

eating raw/undercooked meat from animals infected with Trichinella cysts

44
Q

What is the epidemiology of trichinosis?

A

-Trichinella spiralis is most common cause in humans
-worldwide dist.
-most cases in US come from eating undercooked wild game rather than pork

45
Q

What are the clinical signs of trichinosis?

A

1-2 days:
-GI signs
2-8 weeks:
-muscle pain
-swelling of face
-weakness/fatigue
-chills
-itchy skin/rash
-cough
-fever
-headache
-constipation

46
Q

How are trichinosis and taeniasis prevented and controlled?

A

-cook whole cuts of meat to 145 deg. F and allow to rest for 3 minutes before consumption
-cook poultry to 165 deg. F and allow to rest for 3 minutes before consumption
-cook ground meat and all wild game to 160 deg. F

47
Q

What are the characteristics of Taeniasis?

A

-Taenia saginata/beef tapeworm
-Taenia solium/pork tapeworm
-can lead to cysticercosis in humans
-infections from eating raw/undercooked beef or pork

48
Q

What are prions?

A

family of rare progressive neurodegenerative disorders affecting humans and animals

49
Q

What are the characteristics of prions?

A

-long incubation periods
-spongiform changes associated with neuronal loss
-failure to induce inflammatory response

50
Q

What is the theory behind bovine spongiform encephalopathy pathogenesis?

A

agent is a modified form of normal protein that changes into pathogenic form to damage CNS of cattle

FA2 Public Health and Epidemiology (41 decks)

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