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Understanding Health Risks of Aflatoxins and Disease Ecology

Learn about how the scientific process aids in solving health issues, the impact of aflatoxins on human and animal health, and how organism interactions and the environment influence disease outbreaks.

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Understanding Health Risks of Aflatoxins and Disease Ecology

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  1. 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?

  2. http://www.oardc.ohio-state.edu/ohiofieldcropdisease/Mycotoxins/aspergillus1.jpghttp://www.oardc.ohio-state.edu/ohiofieldcropdisease/Mycotoxins/aspergillus1.jpg

  3. 4 spp. shown to produce toxins: A. flavus A. parasiticus A. nomius A. niger

  4. 4 major aflatoxins 2 metabolic products M2

  5. 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

  6. 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

  7. Pre-harvest risk factors: • High temperatures • Chronic drought • Heavy rains • Crop insect damage • Poor fertility • Weed competition • High crop densities

  8. Post-harvest risk factors: • High temperatures • Humidity

  9. http://digilander.libero.it/BodyMindCare/kapil/moremedi.htm Liver function • 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

  10. 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/

  11. 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

  12. 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.

  13. No aflatoxin Rat livers Highest dose http://www.ansci.cornell.edu/plants/toxicagents/aflatoxin/image9.html

  14. Toxicology • Acute aflatoxicosis • high dosage over short time • hemorrhage • acute liver damage • edema • altered digestion, absorption, and metabolism • death

  15. Toxicology • Chronic aflatoxicosis • impaired food conversion • slower growth • immunity problems • cirrhosis • liver cancer

  16. Documented outbreaks • 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

  17. 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 protein-deficient diets thought to contribute

  18. 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

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