GRF 2nd One Health Summit 2013: Presentation by Felicia Wu, Michigan State University

1. Improving Food Safety for Human
and Animal Health
Lessons from Infectious Disease Control
Felicia Wu, PhD
John A. Hannah Distinguished Professor
Department of Food Science & Human Nutrition
Department of Agricultural, Food, & Resource Economics
Michigan State University, USA
GRF One Health Summit, Davos, Switzerland, 17 November 2013

2. Relevance to One Health
 Food safety is key to human, animal & environmental health.
 Mycotoxins – fungal toxins in food crops – among most
dangerous foodborne toxins

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Aflatoxin causes >100,000 cancer deaths/year worldwide
Mycotoxins impair child growth & immunity
 5 billion people worldwide exposed to uncontrolled
aflatoxin in food (mostly through maize, peanuts)
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3. Motivating question
“I told a man on the plane that I’ve been working for the last
30 years on how to get rid of aflatoxin in food. He probably
thought I was stupid. How could I have worked on this
problem for 30 years and still not have figured out how to
get rid of aflatoxin?”
– Dr. Gary Payne, Purdue University meeting
Short answer: Because it is difficult to control microorganisms.
Long answer…
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4. How can we control foodborne
mycotoxins, to protect human
& animal health?
Insights from other attempts to control microorganisms…
Infectious disease control

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What has worked  Similar in mycotoxin control in our food
What has worked  No analogy in mycotoxin control yet
 Success story: Smallpox eradication
What hasn’t worked: Lessons for food safety
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5. Top 10 causes of death, low- vs. highincome nations (WHO 2011)
Lower resp. infections
Diarrheal diseases
HIV/AIDS
Heart disease
Malaria
Stroke
Tuberculosis
Low birth weight
Birth traumas
Neonatal infections
Heart disease
Stroke
Respiratory cancers
Alzheimer/dementias
Lower resp. infections
COPD
Colorectal cancers
Diabetes mellitus
Hypertension
Breast cancer
0
2
4
6
8
10
12
0
2
4
6
8
10
12
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Low-income nations:
High-income nations:
Infections contribute highly to deaths
Infections contribute little to deaths
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6. Top 10 causes of death in US in 1900 look
similar to those of low-income nations today
CDC (2010). National Vital Statistics Report 58:19
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7. In US, infectious disease death rates have
dropped dramatically since 1900
Aiello AE, Larson EL (2002). Lancet Infectious Dis. 2:103-110.
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8. Mycotoxins: What are they?
 Toxic & carcinogenic chemicals
produced by fungi
 Long history of mycotoxins affecting
society

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Leviticus 14:37
11th c.: Claviceps purpurea produces ergot in
rye  St. Anthony’s Fire
Mysterious human & animal deaths in 1930s
(Great Depression horses)
1960 aflatoxin discovery: UK turkey deaths
Today: several dozen mycotoxins identified
↓
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9. Common mycotoxins in our
food supply
MYCOTOXIN
Produced by fungi…
In crops…
Human health effects
Aflatoxin
Aspergillus flavus, A.
parasiticus
Maize, peanuts,
tree nuts, dried
coconut, spices
Liver cancer, acute
liver failure, immune
toxicity, child stunting
Fumonisin
Fusarium verticillioides, Maize
F. proliferatum
Possibly esophageal
cancer and neural tube
defects
Deoxynivalenol
F. graminearum, F.
(DON, vomitoxin) culmorum
Maize, wheat,
barley, oats, beer
GI disorders, immune
toxicity
Zearalenone
See above
See above
Estrogenic effects
Ochratoxin A
Penicillium verrucosum,
A. ochraceus
Maize, dried fruits,
Nephritic syndrome,
possibly other kidney
conditions
wine, wheat,
chocolate, cereals,
dried meats, coffee

10. ONE HEALTH: We can apply lessons from
controlling infectious diseases to
controlling food safety
 Prenatal care
 Sanitation
 Vaccines
 Quarantines
 Antibiotics
Plant breeding (conventional, GM)
Good agricultural practices
(GAP)
Biocontrol
Sorting
Fungicides
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11. Prenatal care
 Prenatal care: health services
pregnant women receive to
optimize maternal & child health
Problems endangering mother
or baby detected and treated
prior to birth:
 Neonatal infections, birth trauma,
low birth weight: 3 top killers in
low-income nations (WHO 2011)
Weight & blood pressure
measurement
 US: Babies with no prenatal care
5 times more likely to die in 1st
27 days (U.S. DHHS 2006)
Fetal heart rate measurement
Urine & blood tests
Nutritional & behavioral
counseling
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12. Plant breeding to reduce
fungal infection / toxins
As with prenatal care: optimize chances, before food crops
are planted, that they will resist disease
Conventional breeding
Transgenic breeding (GMOs)
Select for crop genotypes with
lower disease / mycotoxin levels
Bt maize: reduce mycotoxins indirectly
through reduced insect pest damage
RNA interference (RNAi)-based
host induced gene silencing to “turn
off” fungi’s toxin production
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13. Sanitation
Clean
water
Improved sanitation could reduce
global disease burden by 10% (WHO 2009)
Toilet
construction
Effective
sewer systems
Clean
food
Handwashing
with soap
2005: 1st time in 40 years that # children <5 dying annually fell
below 10M worldwide

Top reason: improved access to clean water & sanitation (WHO 2009)
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14. Good agricultural practices (GAP)
As with sanitation: GAP provides
environment that allows food crops
to grow healthily
Postharvest interventions reduced aflatoxin
by 69% in Guinea peanuts, West Africa
GAP: principles applied to on-farm
production processes  safer food,
agricultural sustainability

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Crop rotation, tillage, planting date,
irrigation, fertilization, pest control
Harvesting date, sorting, proper
drying & storage, pest control
(Khlangwiset & Wu 2010)

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Education on hand-sorting nuts, drying
Natural-fiber drying mats, storage bags
Wooden pallets for storage bags
Insecticides for storage room floor (Turner
et al. Lancet 2005)
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15. Vaccines
 Vacca: Latin for “cow”

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Named by Dr. Edward Jenner
1796: 1st smallpox vaccine from
cowpox pustule
1881 Pasteur “vaccine”: any
inoculated material that
produces immunity
Weakened or killed form of
microbe applied
Today: Vaccines for 14 viruses
& 11 bacteria in humans
 UN Millennium Development
Goal:

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If 90% children worldwide given
routine vaccines, prevent 2 million
deaths/yr by 2015 (WHO 2011)
GAVI (WHO & Gates
Foundation)


In 10 yrs: 288M children
vaccinated against diphtheria,
tetanus, pertussis, hepatitis B, Hib
5M deaths prevented
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16. Biocontrol
Photos: R Bandyopadhyay
 As with vaccines: apply
 Biocontrol: use of organisms to
“harmless” version of microbe, to
reduce incidence of pests or toxins
prevent damage from more

Not all Aspergillus flavus strains
harmful type
produce aflatoxin

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Competitively exclude toxigenic
strains with non-toxigenic strains
Can reduce aflatoxin  80%
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17. Quarantines
 Compulsory isolation to prevent spread of disease
 Venetian quarantena (quaranta giorni)

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1377: Venice helped curb bubonic plague by quarantining ships in
Ragusa (Dubrovnik) 40 days
1665: Villagers of Eyam, England, stopped plague spread by selfquarantine
 Today: many nations have quarantine laws

Protect human health (travelers with infectious diseases may face
isolation), animal health, plant health
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18. Sorting
As with quarantines:
Isolate infected individuals
(kernels) and remove, to
reduce mycotoxin load
 Hand sorting

Removing obviously moldy
kernels can significantly
reduce aflatoxin & fumonisin
contamination in food
(Afolabi et al. 2006, van der
Westhuizen et al. 2011)
 Industrial sorting
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UV light to detect aflatoxincontaminated kernels
Changing combine harvester
configurations to sort out
Fusarium-damaged grains
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19. Antibiotics
Compounds that kill bacteria or
slow their growth

1928: Alexander Fleming’s
staphylococcus cultures in lab

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Penicillium in one dish destroyed
bacteria
“Mould juice” (penicillin) found to
be effective against scarlet fever,
pneumonia, meningitis, diphtheria,
gonorrhea, syphilis, etc.
Today: >150 antibiotics
developed

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Before antibiotics, infections
caused >33% all deaths in US
>200M lives saved by penicillin
(Roberts & Ingram 2001)
Dangers of overuse
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Adverse gastrointestinal effects
Antibiotic-resistant bacteria
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20. Fungicides
 As with antibiotics: kill
pathogen outright
 Effectiveness depends on:

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Local weather conditions
Timing
 Azole fungicides (e.g.,
Prosaro®) inhibit sterol
 Fungal prediction models help
biosynthesis in Fusarium;
growers assess when to apply
control scab & toxins in oats,
fungicides
barley, wheat (Paul et al. 2011)
(De Wolf et al. 2003, Schaafsma &
Hooker 2007, Schmidt-Heydt et al. 2011)
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21. What has worked in public health, but has
no analogy (yet) in mycotoxin control
 Case study: Smallpox eradication
 Smallpox caused by viruses Variola major, minor

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High fever, extensive rash: 30% mortality
Blindness, permanent disfiguration in survivors
Sanskrit medical texts: 1500 BCE
 1700s: killed ~400,000 Europeans/yr
 Devastated previously unexposed populations (50-80% mortality)
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1241: Iceland
1500s: Aztecs, Mayans, Incans
1700s: North American natives
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22. Discovery & use of
smallpox vaccine
Cowpox on human arm
 Observation: dairymaids had no smallpox

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Mild cowpox instead (caused by related Vaccinia virus)
1796: Dr. Jenner scratched cowpox pus from dairymaid into arm of
8-year-old boy
6 weeks later, scratched his arm with smallpox pus: boy immune!
 Vaccinia-based smallpox vaccine spread globally

1967: WHO began effort to eradicate global smallpox, led by DA
Henderson
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23. How did the world become smallpoxfree by 1980?
1. Government support
2. Cost-effective solutions
 $2.4 million/yr from WHO
 Cooperation from nations
 “Ring vaccination”
 Public engagement in finding cases
 Bifurcated needle
Source: DA Henderson, Smallpox: The Death of a Disease, 2009
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24. But molds, mycotoxins, & other food
contaminants differ from smallpox…
Smallpox
 Only reservoir: humans
 Easily identifiable disease
 Solution cheap, globally
effective, globally feasible
 Lifetime immunity if
vaccinated once
Fungi/food contaminants
 Multiple natural reservoirs
 Disease not always visible
 Multiple partial solutions,
with limited applicability
 “Lifetime” different for crops
& animals vs. humans
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25. What lessons can we take from smallpox
eradication for food safety efforts?
 Government support critical

Convince policymakers that mycotoxins are important
 Public involvement critical

Engage public in surveillance & adoption efforts
 Not enough for interventions to be cheap: they should also
be applied cost-effectively

What’s minimum amount needed to achieve desired food safety in
low-income regions?
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26. Public health mistakes in infectious
disease control, & lessons learned
 Hepatitis C virus from antischistosomal syringes (Egypt)
 Arsenic in well water (Bangladesh)
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Scenario
Mistakes made
Lessons for food safety control
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27. Hepatitis C virus (HCV) from
antischistosomal syringes (Egypt)
 Schistosomiasis endemic in Egypt: 1960s-70s treatment
campaign using repeated emetic tartar injections
 Mistakes made: Hepatitis C spread by unsterilized needles:
Egypt has highest HCV rate in world (14-20%)
 Lessons for food safety control: Ensure delivery method of
intervention is safe
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28. Arsenic (As) in well water
(Bangladesh)
 1970s, Bangladesh: polluted surface waters  high
infant mortality
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UNICEF: >8M wells
Infant mortality halved, but ~50% population exposed to
As >> 50 µg/L (Smith et al. 2000)
Blackfoot disease; skin, lung, bladder cancers
 Mistakes made: lack of learning from past mistakes
Photos: Smith et al. (2000).
(Taiwan)
WHO Bull 78(9)1093.
 Lessons for food safety: Consider risks of
interventions; be well-informed of past mistakes
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29. Summary
 Public health & food safety control follow similar principles.
 “How could I have worked on this problem for thirty years and
still not have figured out how to get rid of aflatoxin?”


Eradicating smallpox took ~200 years since 1st vaccine; >3500 years
since first documented
Eradication of mycotoxins and food contaminants unlikely, but
thoughtful prevention & control are crucial
 One Health: Not only are health & agriculture/food safety
linked, but we can learn lessons from each other’s fields.
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