1. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Introduction Aflatoxins are one of the most potent toxic substances that occur naturally. These are a group of closely related mycotoxins produced by fungi Aspergillus, flavus and A. parasiticus. The name Aflatoxin comes from A (Aspergillus) FLA (flavus) toxin Aflatoxicosis is poisoning that result from ingestion of aflatoxins in contaminated food or feed. Aflatoxin poisoning is reported from all parts of world in almost all domestic and non domestic animals like cattle, horses, rabbits, and other non human primates. Aflatoxicoses is also reported in humans in many parts of the world.

2. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Natural occurrence of Aflatoxin Food products contaminated with aflatoxins include – Cereal (maize, sorghum, pearl millet, rice, wheat), – Oil seeds (groundnut, soybean, sunflower, cotton), Spices (chillies, black pepper, coriander, turmeric,zinger), – Tree nuts (almonds, pistachio, walnuts, coconut) – Dairy products (Milk, Cheese, Fluid milk) – Green coffee – Dry fruits – Human biological fluids (human urine, milk and blood samples.) – Eggs Liver – Medicinal plant

3. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Types of aflatoxins Although 17 aflatoxins have been isolated, only 4 of them are well known and studied extensively from toxicological point of view. Characterized the chemical and physical nature of the aflatoxins B1, B2, G1 and G2 Two other familiar aflatoxins are M1 and M2. – presence in milk of animals previously exposed to B1 and B2. in all the above-named aflatoxins, aflatoxin B I (AFB1) is the most acutely toxic to various species A. flavus = produce only aflatoxins B1 and B2, A. parasiticus = produce aflatoxins B1, B2, G1 and G2

4. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Other metabolites  Aflatoxins B2 a,  Aflatoxicol,  Aflatoxicol H1  Aflatoxins P1  Aflatoxins Q1 Aflatoxin M1 is a metabolite of aflatoxin B1 in humans and animals. Aflatoxin M2 is a metabolite of aflatoxin B1 in milk of cattle fed on contaminated foods.

5. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Aflatoxin and animal diseases Aflatoxin poisoning (Aflatoxicosis) mainly on animal liver injury, the injured individual species of animals, age, gender and nutritional status vary

6. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS The adverse effects of aflatoxins on animal can be categorized into two general forms. Acute Toxicity:is caused when large doses of aflatoxin are ingested – signs – decrease in liver function – edema of the lower extremities – abdominal pain, and – vomiting. Chronic Toxicity :-due to long term exposure of moderate to low aflatoxin concentration The symptoms include o Decrease In Growth Rate, o Lowered Milk Or Egg Production, And o Immuno suppression due to the reactivity of aflatoxins with T-cells, decrease in Vitamin K activities, and a decrease in phagocytic activity in macrophages.

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8. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Aflatoxin risk 1.Moderate risk 2.High risk 3.Low risk Some species are more sensitive than others  Highly susceptible: Rabbits, ducks, cats, swine, rainbow trout One teaspoon of aflatoxin is enough to kill 2,500 rabbits

9. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS  Moderately susceptible: – Dogs, horses, calves, turkeys, guinea pigs, sheep,  Relatively resistant: Chickens, rats, mouse, hamsters, shrimp, honey bees Dairy and beef cattle are more susceptible to aflatoxicosis than sheep Young animals are more susceptible than adult. nutrition deficiency increase susceptibility Birds are more susceptible than mammals and susceptibility among bird species is variable

10. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Cellular effects Aflatoxins are inhibitors of nucleic acid synthesis because they have a high affinity for nucleic acids and polynucleotides. They attach to guanine residues and form nucleic acid adducts. Aflatoxins also have been shown to decrease protein synthesis, lipid metabolism, and mitochondrial respiration cause an accumulation of lipids in the liver, causing a fatty liver. This is due to impaired transport of lipids out of the liver after they are synthesized.

11. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Major animal diseases caused by aflatoxins consumption CATTLE The signs most commonly acute Anorexia Depression, Dramatic Drop In Milk Production, Weight Loss, Lethargy, Ascitis, Icterus, Tenesmus, Abdominal Pain (Animals May Stretch Or Kick At Their Abdomen), Bloody Diarrhea, Abortion,, Other signs with acute aflatoxicosis include blindness, walking in circles, ear twitching, frothy at the mouth, keratoconjunctivitis and rectal prolapse

12. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Cattle Cont… chronic aflatoxicosis  symptoms including Decreased Milk Production, Birth Of Smaller And Healthy Calves, Diarrhea, Acute Mastitis, Respiratory Disorders, Prolapsed rectum and hair loss

13. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Sheep and goats Anorexia, depression and icterus. nasal discharge and dark brown urine). Diarrhea excessive salivation, tachypnea and pyrexia Heavy mucous diarrhea Lesion :- centrilobular necrosis of the liver. periportal congestion of the liver,

14. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Horses symptoms included anorexia, icterus and rapid weight loss immediately prior to death. post mortem examination the liver was described as being black, of firm consistency and enlarged Histopathological examination revealed marked centrilobular hepatic necrosis and necrotic areas were engorged with erythrocytes. Kupffer cells were prominent and many contained phagocytosed haemosiderin, which was the likely cause of the black colored liver. Bile-duct hyperplasia, congestion of renal vessels and adrenal cortex were found.

15. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Chickens Broiler-type chickens are considered to be more resistant to aflatoxin toxicity than are other poultry species

16. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Aflatoxins metabolism and mutagenesis aflatoxin B1 may not itself be a toxic molecule but is metabolized in the animal body in a complex network of reactions and it is the result of this metabolism which determines both the acute and chronic toxicity When AFB1 is ingested, once inside the body, it is absorbed by the intestine and carried to the liver. There, AFB1 is activated and metabolized by cytochromes p450 (CYP) of hepatocytes to AFB1- 8,9-exo-epoxide and AFB1-8,9-endo-epoxide

17. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Physical and chemical properties: Aflatoxins are potent toxic, carcinogenic, mutagenic, immunosuppressive agents, produced as secondary metabolites by the fungus Aspergillus flavus and A. parasiticus on variety of food products. Among 18 different types of aflatoxins identified, major members are Aflatoxin B1 (AFB1) is normally predominant in amount in cultures as well as in food products.

18. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Aflatoxin Mi and M2 are major metabolites of aflatoxin B1 and B2 respectively, found in milk of animals that have consumed feed contaminated with aflatoxins.

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20. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Dairy and beef cattle are more susceptible to aflatoxicosis than sheep. Young animals of all species are more susceptible to the effects of aflatoxins than mature animals. Pregnant and growing animals are less susceptible than young animals but more susceptible than mature animals.

21. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Toxic Effects Aflatoxins are mutagenic, teratogenic, and hepatocarcinogenic. Aflatoxin B1 is one of the most potent naturally occurring carcinogen, extensive research was primarily done on this toxin. The main target organ of AF is the liver. AFB1 also affects other organs and tissues including the lungs and the entire respiratory system. For the carcinogenic effects, rats, rainbow trout, monkeys, and ducks are most susceptible and mice are relatively resistant. Consumption of AFB1-contaminated feed by dairy cows results in the excretion of AFM1 in milk. AFM1, a hydroxylated metabolite of AFB1, is about 10 times less toxic than AFB1; but its presence in milk is of concern for human health.

22. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Symptoms of Aflatoxin B1 exposure 1. Liver damage 2. Liver necrosis 3. Liver cirrhosis 4. Fever 5. Progressive jaundice 6. Limb swelling 7. Pain Vomiting 8. Enlarged liver

23. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Aflatoxins can also transfer to animal products If animals eat feed with aflatoxins some is metabolised and transferred to the milk, eggs, meat or offal. Milk and traditionally dried/smoked foods have highest levels of aflatoxin and so should be given highest attention. Withholding aflatoxin-contaminated feed from livestock for 3-4 weeks before slaughter may be enough to clear toxins from muscle and organ meat.

24. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Aflatoxicosis in humans If animal feed intended for use for dairy cattle contains the fungal metabolite aflatoxin B1, it will be metabolised by the cow in the rumen. Between one and four percent of the aflatoxin B1 metabolite (known as aflatoxin M1) will be transferred into the milk. aflatoxin M1 The syndrome is characterized by vomiting, abdominal pain, pulmonary edema, convulsions, coma, and death with cerebral edema and fatty involvement of the liver,kidneys, and heart

25. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Routes of Aflatoxin contamination

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28. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Animal Health Impact of Aflatoxin Livestock and poultry losses liver damage including cancer recurrent infection due to immune system suppression reduced growth rate losses in feed efficiency decreased milk and egg yield embryo toxicity (reduced reproductivity) death (cattle, turkey, poultry, swine..)

29. JIMMA UNIVARSTY DEPARTMENT OF VETERINARY PATHOLOGY MVSc PROGRAM TYPE OF NECROSIS Animal Health Impact of Aflatoxin Livestock and poultry losses liver damage including cancer recurrent infection due to immune system suppression reduced growth rate losses in feed efficiency decreased milk and egg yield embryo toxicity (reduced reproductivity) death (cattle, turkey, poultry, swine..)