Introduction to Mycotoxin and Mycotoxicosis in animals Nuvee Prapasarakul, D.V.M., Ph.D. Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University What is Mycotoxins? Secondary metabolites of certain fungal species. Penillicium Aspergillus Fusarium Mycotoxins Metabolite in growing crops or stored feed Heat stable, low molecular weight Induce the disease by ingestion of contaminated plants Susceptibility can vary with species, age, and sex Non-contagious, but sporadic, seasonal associated with batches of feed. Clinical appearance and level of mycotoxin in feed and animal tissue indicate existence of mycotoxin 1
Fungal growth in stored feed Toxigenic fungi Growth on plant material Regional, seasonal and climatic factor Mycotoxin production Factor modifying clinical outcome Mycotoxins Animal - Type - Species, age, sex -Concentration in feed - Climatic influences -Effect on palatability - Duration of exposure - Organ or tissue affected Mycotoxicosis Fungal growth on crops and on pasture Characteristic of Mycotoxin Unlike many bacterial toxin, non-antigenic, not induce a protective immune response Many are active at low dietary levels Toxic effects include immunosuppression, mutagenesis, teratogenic and carcinogenesis. Accumulation in tissues of food-producing animals or excretion in milk may results in human exposure. Epidemiological and clinical feature Outbreaks usually seasonal and sporadic No evidence of lateral spread to incontact animal Ill-defined Severity mycotoxin-ingested Recovery exposure times Antibiotic medication is ineffective Confirmation by demonstration of toxin level S U B C L I N I C A L GENERAL SYMPTOMS Very difficult to see symptoms therefore little or no awareness ONLY AFFECTS THE IMMUNOLOGIC SYSTEM 2
Many diseases incorrectly diagnosed as the primary problem due to low levels of mycotoxins, which cause immunosupression. Vaccines do not work as the should, low titers If live vaccine is used, there are many problems Antibiotics as therapeutics do not perform even if used at a higher dosage or for longer periods S U B C L I N I C A L GENERAL SYMPTOMS Breeders and sows can not pass antibodies to offspring Respiratory diseases of unknown origin Diseases of unknown origin and / or difficult to diagnose 5 ppb of Aflatoxin B1 in feed = 50 ppt of Aflatoxin M1 in Milk Somatic cell count in milk Pigmentation of egg yolk and skin is affected by hypocarotenoidaemia caused by mycotoxins Toxicities varied by target organ Hepatotoxins; aflatoxins, ochratoxin, citrinin, sporidesmin Nephrotoxins; ochratoxin A, aflatoxin B1, rubratoxin Neurotoxins; ergot alkaloids, fumonisin, trichothecene Dermatotoxins; trichothecenes, sporidesmins Reproductive disturbance; zearalenone Aflatoxin Aspergillus flavus, A. parasiticus and etc Growth on cereals, groundnuts, and soya beans Aflatoxin B1, B2, G1, G2, M1, M2, etc Binding to macromolecule e.g. nucleic acid, nucleoprotien Reduce protein synthesis, carcinogenesis, teratogenesis, aplasia of thymic cortex Depressed CMI 3
Clinical findings Sensitive Ducking, turkey, poult, claves, pigs, and dogs Resistance Cattle, sheep Uncommon horses, goats Slowly developing ill thrift and reduce growth rate Increase prevalence of endemic infection (immunosuppression) Duck: ataxia, opisthotonus and sudden death Bird: subcutaneous haemorrhage. hepatopathy, diathesis Claves: blindness, circling, tenesmus, diarrhea, and convulsion. DIAGNOSIS Epidemiological feature and port-mortem finding Storage sample in 20 o C Technique request Thin layer chromatography High performance liquid chromatography Immunoassay e.g. EILSA Biological assay; embryo bioassay (chick, trout) Detoxify of aflatoxin in feed Tx with ammonia gas at high temperature and pressure Heat denature certain protein and vitamin in feed? Dilution of contaminated feed with uncontaminated feed < 20 ppm for piglets < 200 ppm for pigs Addition of hydrated Sodium calcium aluminosilicate (Harvey et al., 1989) Effect of AFLATOXIN in broiler growth at 42 days. T1 control T6 3 ppm + ADS ( 0.2%) T2 3ppm of AFLATOXIN 4
Fumonisins Fusarium verticillioides (formerly called Fusarium moniliforme). Fusarium proliferatum. Effect of AFLATOXIN in broiler liver a 42 days. T1- Control T6 3 ppm + ADS (0.2%) T2 3ppm of Aflatoxin Fusarium graminearum (also called Gibberella zeae). deoxynivalenol (DON) and zearalenone. Fumonisins Fumonisins Fusarium moniliforme Fumonisin B1 Sporadic neurological disease Horses donkeys mules Liquefactive necrosis in cerebrum sphingolipid Mycotoxic leukoencephalomalacia (Pulmonary edema in pig) Cause liver and throat cancers in rat at 25,000-50,000 ppb Food safety limit 500 ppb (EU) Fumonisins disrupt sphingolipid synthesis Folic acid deficiencies lead to improper development of nervous system 5
ZEARALENONE Symptoms of Fusarium kernel rot and fumonisin-induced neural tube birth defects of mice. Fusarium graminearum Estrogen-like substance Oestrogenic activity Vaginal and rectal prolapse Reduce litter size in mature sows Reduce fertility in cattle Trichothecenes Fusarium Myrotecium Trichoderma Cephalosporium Verticimonosporium Stachybotrys. 6
TRICHOTHECENES Trichothecenes toxicosis Macrocyclic Non-Macrocyclic Type A; T-2 toxin, HT-2 toxin, Diacetoxyscirphenol (DAS) Type B; Deoxynivalenol (DON or vomitoxin) Inhibit DNA or RNA synthesis Food refusal and emetic syndrome; DON Haemorrhagic syndrome; T-2 toxin, DAS Stachybotryotoxicosis (Stachybotrys atra), satratoxin, roridin stomatitis, necrotic lesion in alimentary tracts Myrotheciotoxicosis (Myrothecium verrucaria), roridin, verrucarin pulmonary congestion OCHRATOXINS Ergot Alkaloids Alternaria alutacena, Aspergillus ochraceus, etc. (Ochratoxin A) Species affected pigs and poulty Interfere DNA and RNA synthesis Degenerative renal changes/ polydipsia, polyuria in pigs Fall in egg production in bird Claviceps purpurea Ascospore and hyphae in ovarian tissue form a sclerotia (ergot) Sclerotia contains ergotamine, ergocristine and ergometrine. Alkaloid derivative of lysergic acid 7
Ergot naturally produces a wide range of chemical compounds, "Ergot Alkaloids", and include ergotamine, ergosine and beta-ergosine, ergonine, ergovaline, ergostine, ergotine and beta-ergotine, ergocornine, ergocristine, ergocryptine and betaergocryptine. STRUCTURE EFFECTS BY ERGOT Neurotoxicity and vasoconstriction Their other major medical effect is vasoconstriction which, if severe, can lead to gangrene of the extremities. Convulsion Gangrene of extremities, agalactia, hyperthermia in hot climate The ergot alkaloids all cause stimulation of smooth muscle, some being relatively selective for vascular smooth muscle, and others acting mainly on the uterus. 8
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