14 - Food & Waterborne Outbreaks

Question 1

Three ways contamination occurs in food

Answer 1

• Pathogens residing in meat which is then undercooked (e.g. Toxoplasmosis)
• Pathogens contaminating and proliferating in meat during storage or preparation then infect and proliferate in humans (e.g. Salmonella)
• Pathogens producing toxins in food (e.g. B. cereus)

Question 2

Examples of food borne diseases

Answer 2

• Nuru
• Noravirus
• Salmonella
• Toxoplasmosis
• Fungal mycotoxins

Question 3

Examples of water borne diseases

Answer 3

• Hepatitis A and E
• Cholera
• Legionnaires
• Schistosomiasis
• Fungal infections

Question 4

Epidemiology of food borne diseases

Answer 4

• Can cause both acute and chronic diseases
• Can rapidly spread from infected food source
• Increasing number of reported outbreaks

Question 5

Pathogens in developed industrialized countries

Answer 5

• Salmonella
• Clostridium botulinum
• Verotoxin producing E. coli
• Campylobacter
• Hepatitis A

Question 6

Pathogens in developing countries

Answer 6

• Shigella
• Cholera
• Parasites
• Salmonella
• Enterotoxigenic E. Coli

Question 7

Food borne diseases epidemiology

Answer 7

• 54% of outbreaks due to bacterial infections
• 35% due to viral infections
• 11% due to toxins

Question 8

CDC Pulse Net

Answer 8

Surveillance for food borne diseases

Question 9

Sources of food borne diseases

Answer 9

• Meat, fish and dairy products
• Unhygienic food preparation
• Incorrect food storage

Question 10

What do food borne outbreaks depend on

Answer 10

• Changes in food production and food supply
• New and emerging antibiotic resistance
• Unexpected sources of foodborne illness (e.g. flour, onions)

Question 11

Groups most at risk of severe illness

Answer 11

• Children (most deaths diarrhea)
• Elderly (above 65 increases risk of severe disease)
• Immunocompromised (no resistance to common pathogens which become fatal)
• Hospitalised patients
• Those in war zones

Question 12

Prions

Answer 12

• Highly infectious proteins that convert normal PrP proteins to aberrant ones leading to fatal neurological disease
• Normally due to sporadic mutation (e.g. CJD, Kuru)

Question 13

Kuru

Answer 13

• Prion disease
• a CJD patient was consumed in cannibalistic ritual in Papua New Guinea
• The prions spread through the cultural consummation of
  human flesh to cause a disease called Kuru (shaking
  disease).

Question 14

Modern version of CJD

Answer 14

Bovine spongiform encephalopathy

Question 15

Noravirus

Answer 15

• Caliciviridae family
• Rapid incubation
• Fecal oral route
• Outbreaks common in daycare centers, nursing homes, cruise ships and food preparation areas that have poor hygiene
• Contaminated shell fish
• No vaccine

Question 16

Salmonella

Answer 16

• Gram negative bacillus
• 2500 serotypes
• Onset of gastroenteritis after a day or two, illness
  duration 4-7 days
• Fecal oral route, contaminates food
• Usually self resolving

Question 17

Toxoplasmosis

Answer 17

• Toxoplasma gondii
• Deaths mainly in HIV patients and neonates
• Parasite forms cysts in tissue of every warm blooded animal.
• Infects every nucleated cell
• Main route of contamination is via eating undercooked meat
• Food can also become contaminated with cysts from cat feces
• Most cases asymptomatic, persists for life
• No treatment to cure, no vaccine

Question 18

Fungal mycotoxins

Answer 18

• Fungal contamination of crops common, often occur in storage
• Liver and renal toxicity, Diarrhea, Neurotoxicity, carcinogenic
• Aflatoxins and others

Question 19

Water borne disease transmission

Answer 19

• Most commonly by drinking contaminated water (e.g. cholera, Hep A)
• Bathing (Schistosomiasis)
• Washing food in contaminated water (E. coli)

Question 20

Water borne diseases

Answer 20

• Many of the water borne pathogens can also be food borne
• Often are resilient pathogens capable of with withstanding environmental stress.
• Drinking water contaminated by fecal material

Question 21

Range of diseases cause by water borne pathogens

Answer 21

• Enteric diseases (cholera, giardia)
• Systemic diseases (Hep A)
• Respiratory diseases (legionella)

Question 22

How many global outbreaks of cholera have there been

Answer 22

7

Question 23

Despite many improvements in water treatment and quality, cases of water related infections are _____________________

Answer 23

increasing

Question 24

Hepatitis A

Answer 24

• Nausea, diarrhea, jaundice and fever
• Spread via fecal oral route

Question 25

Hepatitis E

Answer 25

• Similar epidemiology and disease phenotype to hepatitis A
• More dangerous in pregnant women where it can lead to fulminant liver failure

Question 26

Cholera

Answer 26

• Vibrio cholera
• Watery diarrhea leading to severe dehydration
• Bacteria in water can contaminate shellfish
• Symptoms 2 hours -5 days after exposure
• Mainly human only disease, can go to animals
• Outbreaks on ships due to limited water supply (yellow flag to show infected ship)

Question 27

Legionnaries disease

Answer 27

• Caused by Legionella pneumophila
• Spread via water, A/C, often inside amoeba
• Causes pulmonary infection with symptoms 2-10 days after exposure
• Most severe in elderly

Question 28

Schistosomiasis

Answer 28

• Very common parasitic infection in tropical and
  sub tropical parts of the world
• Parasites enter skin and causes acute inflammation in lung and skin, chronic disease in intestine, bladder, liver
• Associated with cancer
• Worms pair and live inside host for 10-20 years producing thousands of eggs per day

Question 29

Three species of Schistosoma

Answer 29

• S. mansoni
• S.haemotobium
  S. japonicum

Question 30

Fungal disease

Answer 30

• Atmospheric moisture is the single most important environmental factor influencing incidence and severity of fungal diseases
• Humidity will lead to increase in mycotoxins.
• Common skin fungal infections greater in moist humid environment
• Candidiasis proliferates in moist body sites