Download aflatoxin2

Want to understand:
(1) How does the scientific process
helps us solve health problems?
(2) What are aflatoxins? Are they
relevant to human and animal health?
(3) How do organisms’ interactions with
each other and their environment
influence disease?
http://www.oardc.ohio-state.edu/ohiofieldcropdisease/Mycotoxins/aspergillus1.jpg
4 spp. shown to produce toxins:
A. flavus
A. parasiticus
A. nomius
A. niger
4 major
aflatoxins
M2
2 metabolic
products
Aflatoxin distribution
• Exposure mainly from:
– A. flavus: global distribution,
produces B classes of aflatoxins
– A. parasiticus: Africa and the
Americas, produces B and G classes
of aflatoxins
Partial list of foods:
• Cereals
– maize, sorghum, millet, rice, wheat
• Oil seeds
– groundnut, soybean, sunflower, cotton
• Tree nuts
– pistachio, almond, walnut, coconut
• Spices
– paprika, chile, black pepper, coriander,
turmeric, ginger
• Figs
• Milk, cheese,
meat, eggs
Pre-harvest risk factors:
– High temperatures
– Chronic drought
– Heavy rains
– Crop insect damage
– Poor fertility
– Weed competition
– High crop densities
Post-harvest risk factors:
–High temperatures
–Humidity
http://digilander.libero.it/BodyMindCare/kapil/moremedi.htm
Liver function
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One of the largest internal organs
Produces bile used to digest food
Metabolizes carbohydrates and lipids
Stores glycogen (for energy), key nutrients
Breaks down toxic substances
Cytochrome P450 oxidase:
• Found in high densities in liver
• Oxidative enzymes that modify
and degrade toxins
• Absorb light at 450 nm
http://www.biochem.ucl.ac.uk/bsm/proLig/pdbEntries/1pha/
http://www.gps.caltech.edu/~fry/winter2003/winter2003.html
Bioactivation:
• Enzymes can convert a chemical into something
even more reactive or toxic
• Ex.: Ethanol  via Alcohol dehydrogenase 
Acetaldehyde
Williams, J.H., T.D Phillips, P.E. Jolly, J.K Stiles and D. Agga. 2004. Human aflatoxicosis in
developing countries: a review of toxicology, exposure, potential health consequences, and
interventions. Am. J. Clin. Nutr.Nov;80(5):1106-1122.
No aflatoxin
Rat livers
http://www.ansci.cornell.edu/plants/toxicagents/aflatoxin/image9.html
Highest dose
Toxicology
• Acute aflatoxicosis
– high dosage over short time
– hemorrhage
– acute liver damage
– edema
– altered digestion,
absorption, and metabolism
– death
Toxicology
• Chronic aflatoxicosis
– impaired food
conversion
– slower growth
– immunity problems
– cirrhosis
– liver cancer
Documented outbreaks
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1974, rural NW India: 397 ill, 108 dead
High fever, jaundice, ascites
Preceded by same symptoms in dogs
Traced to maize w/ major A. flavus
infestation
• Chronic drought, unseasonable rain, poor
storage, ignorance of dangers of moldy
food
Documented outbreaks
• 1981, rural Kenya: 20
hospitalizations, 12 deaths
• Abdominal discomfort, anorexia,
malaise, fever, jaundice, dark
urine
• Doves died, then dogs ill, then
people ill
• Contaminated maize
• Heavy rains, drought, and proteindeficient diets thought to contribute
1) The scientific process is investigative
and helps us solve health problems
(2) Aflatoxins are fungal toxins that
pose serious risks to human and animal
health
(3) Organisms’ interactions with each
other and their environment determine
whether or not disease outbreak occurs