MYCOTOXICOSES

Prabin Shah BScMLT, MSc(Biochemistry)

DEFINITION

Mycotoxicoses is defined as an illness of man or animal due to ingestion of pre-formed substances produced by the action of certain molds or filamentous fungi on particular food-stuff.

MYCOTOXINS

Secondary metabolites produced by food-borne filamentous fungiVary in their severity :Carcinogen/allergenNon-volatile & low molecular weightSome are lethalCause identifiable diseasesWeaken the immune system without producing symptoms

FACTORS DEPENDS ON PRODUCTION

Temperature (4-32˚C)

Moisture (22-23% in grain)

Aeration (1-2% of O₂)

Relative humidity (>70%)

Substance on which the fungus is growing

Acute: Rapid onset from single exposure Chronic: Delayed onset from multiple long term exposure

Mutagenic: Causing damage to DNA

Teratogenic: Causing birth defects

TOXICITY

4 TYPES:

Respiratory problems

Reproductive problems

Liver, kidney or other organ damage

Cancer

Death

MYCOTOXIN CAN CAUSE:

Feeds Most Susceptible to Fungi-producing Mycotoxins

•Corn•Wheat•Oats•Barley• Sorghum

•Cottonseed•Peanut meal•Rye•Bread

SIGNIFICANT FUNGI

Most of the significant fungi producing mycotoxicoses mainly belong to toxigenic species of 3 genera:

Aspergillus Fusarium Pencillium

MEDICALLY SIGNIFICANT MYCOTOXINS

1.Aflatoxins

2.Fumonisins

3.Trichothecenes

4.Ochratoxins

5.Cyclopiazonic Acid

6.Zearalenone

7.Patulin

MYCOTOXINS

FUNGAL SPECIES

SOURCE OF EXPOSURE

CLINICAL CONDITIONS

Aflatoxins A.flavus,parasiticus,nomium,P.puberulum

Nuts,Maize Aflatoxicosis, Rey’sSyndrome

Fumonisins Fusarium moniliforme Maize ELEM,PPE

Trichothecens

Fusarium graminearum,F.sporotrichioides

Maize,Sorghum

HumanToxicosis,

Ochratoxins A.ochraceus,A.niger, P.verrucosum

Cereals,coffee-Beans,Bread

Nephropathies

Cyclopiazonic Acid

A.flavus,A.versicolor,A.oryzae,P.cyclopium

Groundnut,Corn,Meat

Co-contaminant,Kodua Poisoning

Zearalenones

Patulin

F.Graminearum

P.patulum/griseofulvum

Wheat,Maize,Barley,SorghumThought to be the antiviral antibiotic.

Genital disorders in animals ie, Pigs

AFLATOXINS(Aflatoxicosis)These toxins were discovered as a cause of mysterious disease termed as Turkey-X-disease during 1960s in England.Killed approx.1,00,000 birds and ruined turkey industry. Aflatoxins most commonly produced by A.flavus are B1 and B2.A.parasiticus produces G1and G2.

These are designated as B & G on the basis of their metabolites which exhibits blue(B) and green(G) fluorescence under U.V. light on TLC plates.

Aflatoxin B1 is the most important biologically active mycotoxin because of its common occurrence in food items and is highly toxic and carcinogenic.

AFLATOXIN TAINTED PRODUCTS

Poisoning that results from ingesting aflatoxins

2 forms:

Acute severe intoxication: Result in severe liver damage,And subsequent illness or death.

Chronic subsymptomatic aflatoxicosis: signs and symptoms are lethargy,anorexia and muscle weakness followed by spasm.

AFLATOXICOSIS

Reye’s syndrome: It is an acute aflatoxicosis in which patient presents with signs and symptoms of encephalopathy and fatty degeneration of viscera.This is an endemic disease of children in developing countries.

Reye’s syndrome

Fatty degeneration of liver

Aflatoxin Detection

Black Light test - BYG fluorescence

ELISA

Chromatography (HPLC)

Rapid immunochromatographic method

AFLATOXIN GROWING ON CORN IS DETECTED BY BLACK LIGHT TEST

FUMONOSINSSecondary metabolites produced by various species of fusarium.They are toxic and carcinogenicCommon contaminants of maize ,corn and their products.Cause fatal illness in animals like equine leukoencephalomalacia(ELEM)fatal disease in horses,Porcine pulmonary edema(PPE) in pigs,and hepatotoxic and carcinogenic effects in rats.

Cause toxicity by blocking ceramide synthetase which converts sphingosine & acetyl CoA to ceramide.

An outbreak has been reported in 1999 in poultry due to consumption of fumonisin-contaminated feed containing rain –damaged maize.

OCHRATOXINSNaturally occuring mycotoxin and is produced by various species of Aspergillus and pencillium.Originally isolated from Aspergillus ochraceous hence named ochratoxin.Out of many ochratoxins,ochratoxin A is medically significant.Natural occurrence of these toxins in grains and other plant products.

Human exposure to ochratoxin

Direct – consumption of contaminated plant foodIndirect – consumption of animal tissues exposed to contaminated materials.It produces fatal renal disease called as endemic nephropathy and urinary tract tumors.

TRICHOTHECENE

Produced by Fusarium species.

Most significant effect of these toxin is the depression of immune system in both human as well as animals.

Were implicated in biological warfare and putative incident of ‘yellow rain’ in Laos.

CYCLOPIAZONIC ACID

Produced by genous Aspergillus and pencilliumOccurs naturally in agriculture products such as ground nut and corn.Co-contaminant with aflatoxinClinical symptoms are: loss of weight,weakness, vomiting,diarrhoea,dehydration,convulsions and death.Causing symptoms of kodua poisoning (consumed kodo millet seed as staple food )

ZEARALENONE

Produced by Fusarium species

Found in variety of infected cereals like maize, barley, wheat grains and sorghum

Cause genital disorders in domestic animals

PATULIN

Derived from Pencillium patulum

It was initially thought to be the antiviral drug which relieve the symptoms of common cold

Subsequently realized as mycotoxin

Preventing MycotoxinsUse “clean” procedures.Prevent contaminationInhibit mold growth• Drying• Refrigeration•Mold inhibitors

MUCH BETTER TO PREVENT FORMATION

REFERENCE

Textbook of Medical mycology - Jagdish Chander