Lecture 17: Waterborne and Foodborne Diseases

Question 1

What are the characteristics of waterborne and foodborne diseases?

Answer 1

bacterial pathogens that cannot be eliminated

Reservoir is food/water and not transmitted from human to human

Question 2

What kinds of epidemics can food/waterborne diseases cause?

Answer 2

common source epidemics

Question 3

What is the single most important factor for public health?

Answer 3

Clean water w/ no iological/chemical contamination

Question 4

What is monitored in maintaining water quality?

Answer 4

Chemicals, radioactive substances, microorganisms

Question 5

What is GenX?

Answer 5

Industrial chemical used in teflon

produced by chemours (DuPont) companies

Question 6

GenX is unregulated y EPA, what is the criteria for regulation?

Answer 6

1. Adverse effect on public

2. High risk to occur in public H2O

Question 7

How are we studying GenX in Wilmington?

Answer 7

Cross sectional study w/ 400 residents

Measuring:

1. Blood and urine
2. Household drinking water
3. PFAS

Question 8

What are some water purification methods?

Answer 8

Filtration
-effective + expensive

Chlorination
-effective + inexpensive

Question 9

How do we monitor microorganisms when monitoring water?

Answer 9

Look for Fecal Coliforms

• bacteria present in intestines of humans
• indicator of water contamination not quality

Coliform Cultures

Question 10

What are the rules of the revised total coliform rule for monitoring water quality?

Answer 10

1. Sites representative of system
2. Collection occurs at regular time intervals
3. Number of collections depends on population size
4. Each positive result is retested

Question 11

What are some waterborne diseases?

Answer 11

Drinking water outbreaks
-contaminated drinking water

Recreational water outbreaks
-contaminated pools and lakes

Question 12

What is cholera?

-pathogen

Answer 12

waterborne disease

pathogen - vibrio cholera

Question 13

Is vibrio cholera Gram (+) or (-)? What is its reservoir?

Answer 13

Gram (-)

reservoir - coastal + marine habitats

Question 14

What is the pathogenesis of cholera?

Answer 14

caused by ingestion of contaminated water

-attached to wall of small intestine and produces cholera toxin

Question 15

How is cholera diagnosed?

Answer 15

presence of V. cholera cells in feces

Question 16

How is cholera prevented?

Answer 16

Vaccine for some strains

maintain adequate sewage treatment and safe drinking water

Question 17

How is cholera treated?

Answer 17

fluid replacement and antibiotics

Question 18

What is legionnaires disease?

• pathogen
• gram (+) or (-)
• reservoir

Answer 18

waterborne disease

• pathogen: Legionella pneumophila
• gram (-)
• reservoir: lakes and streams

Question 19

What is the pathogenesis of legionairres disease?

Answer 19

airborne transmission and infection in lungs

• mild infection = pontiac fever
• severe infection = pneumonia

Question 20

How is legionairres disease diagnosed?

Answer 20

cultures from body fluids

Question 21

How is legionairres disases prevented and treated?

Answer 21

air conditioning maintenance and hyperchlorination

Treated with antibiotics

Question 22

What is the first line of defense against foodborne diseases?

Answer 22

food preservation

Question 23

What are the major food categories?

Answer 23

1. perishable - fruit
2. semi-perishable - potatoes
3. nonperishable - flour

Question 24

How do we reduce microbial growth on food?

Answer 24

1. Low temp - refrigeration
2. Low pH - pickling
3. Low water - drying
4. Low Oxygen - vacuum

Question 25

What are chemical preservatives used for

Answer 25

increase shelf life and perceived quality of food

Question 26

What are some other preservation methods for food?

Answer 26

High pressure processing

• pascualization
• high hydrostatic pressure kills microbes

Irradiation
-ionizing radiation kills microes

Question 27

What is the difference between food poisoning and food infectIon?

Answer 27

Food poisoning

• ingestion of food containing microbial toxins
• immediate

Food Infection

• ingestion of food containing vialbe pathogens
• takes longer for symptoms to appear

Question 28

What kinds of bacteria cause food poisoning?

Answer 28

Staphylococcus spp.

• produce enterotoxins
• reservoir=meat, poultry, cream

Clostridium spp

• C perfingens
• reservoir= raw meat
• most commons
• C botulinum
• improper garlic canning
• most dangerous

Question 29

What are some treatment and prevention of food poisoning?

Answer 29

supportive treatment (fluids)

sanitation in food production

Question 30

What bacteria cause food infection?

Answer 30

• Salmonella spp.
– Diverse virulence factors
– Severe Cases: Typhoid Fever
– Chronic Carriers: Typhoid Mary

• Camplyobacter spp. (most common)
– Resident in poultry intestines (90%)
– Treated with antibiotics for severe cases

• Listeria monocytogenes (Listeriosis, most severe)
– Psychrotolerant + common in prepackaged food
– Severe Cases: septicemia + meningitis

Question 31

What are the virulence factors for food/waterborne diseases?

Answer 31

Adherence

• motility
• attachment

Invasion

• toxins
• avoid host defenses