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Animal Health & Disease > lecture #3: Fungus > Flashcards

lecture #3: Fungus Flashcards

1
Q

what is fungus?

A

a plant like organisms which grow by continuous extension and branching (hyphae)

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2
Q

why are fungi difficult to kill?

A

because they are eukaryotes and are similar to host cells, which makes it difficult to kill them without causing host cell damage

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3
Q

Most pathogenic fungi are ___________.

A

dimorphic

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4
Q

what are some types of fungi morphology? give an example of each.

A
  • some grow only as yeasts (Cryptococcus)
  • some grow only as molds (Aspergillus)
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5
Q

mold growth is favored by ________ temperatures and ________ moisture content.

A

HIGH, HIGH (>13% in corn, >12% in soy beans)

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6
Q

what are some examples of fungi toxins or mycotoxins?

A
  • Aflotoxicosis: aflotoxins (Ex: Aspergillus flavus and Aspergillus parasiticus)
  • Estrogenism: zearalenone or F2 toxin (Ex: Fusarium graminearum)
  • Leukoencephalomalacia: fumonisins (Ex: Fusarium moniliforme and Fusarium proliferatum)
  • Ergotism: ergot alkaloids (Ex: Claviceps purpurea)
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7
Q

what are some qualities regarding Alflatoxicosis?

A
  • growth on peanuts, cottonseed meal, soybeans, sorghum, corn (high moisture and temp)
  • susceptible: poultry, pigs, cattle, sheep, dogs,
  • adult cows, sheep and goat are more resistant to the acute form
  • dietary lvls of aflotoxins< 50ppb are tolerated
  • aflotoxin metabolites can be excreted in milk of cattle
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8
Q

what is the pathogenesis of alflatoxicosis?

A
  • aflotoxins bind to nucleic acid and nucleoproteins
  • liver is the primary organ affected
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9
Q

what are some toxic effects of aflatoxicosis pathogenesis?

A
  • mutagenesis
  • affect protein synthesis and function (metabolic enzymes and structural proteins)
  • decrease lipid metabolism
  • mitochondrial respiration
  • cause immunosuppression
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10
Q

what do high doses (acute toxicity) of aflotoxins cause?

A

hepatocellular necrosis with fatty accumulation, icterus and hemorrhages. Death can occur after a short period of inappetence (>1000ppm)

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11
Q

what do low dosees (chronic toxicity) of aflotoxins cause?

A
  • liver enlargement with fibrosis
  • edema of gallbladder
  • tubular degeneration in the kidneys
  • decreased feed intake and feed conversion, reduce weight gain, eggs or milk production reduced, immunosuppression
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12
Q

What do Zearalenone or F2 toxin typically contaminate?

A

growing plants and stored feeds (corn, wheat, barley, sorghum)

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13
Q

what is a characteristic of Zearalenone (F2 toxin)?

A

it is a potent estrogen and binds to estradiol receptors

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14
Q

what are some other toxins binding to estradiol?

A
  • vomitoxin
  • fumosin
  • moniliformin
  • DAS
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15
Q

what can Zearalenone (F2 toxin) cause in pigs?

A
  • vulvovaginitis,
  • hypertrophy of mammary gland and uterus,
  • reduce fertility and litter size,
  • cause fetal mortality and anestrus,
  • affect spermatogenesis (testicular atrophy),
  • reduce feed intake
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16
Q

what can F2 toxin cause in cattle?

A
  • affect fertility
  • cause abortion
  • vaginal discharge
  • nymphomania
  • weight loss
17
Q

what can F2 toxin do to chicken?

A
  • can cause digestive problems
  • reduce feed intake
  • mucosa lesions
  • affect bone marrow and lymphoid organs
18
Q

what causes Equine leukoencephalomalacia?

A
  • Fumonisins toxins (B1, B2,& B3)
  • feeding of moldy corn for several weeks
19
Q

which animals are effected by leukoencephalomalacia? what happens to them?

A

horses, mules and donkeys.

neurological disorders: muscle tremors, blindness, paralysis or facial and pharyngeal muscles (Can’t swallow), circling, hyperesthesia, ataxia, depression, recumbence,

20
Q

leukoencephalomalacia also affects pig, cattle and sheep and poultry. what happens to them?

A

pig: pulmonary edema, dyspnea (shortness of breath), cyanosis of mucosa membrane, weakness, abortion , death

cattle, sheep & poultry: inappetence, weight loss, liver damage

21
Q

what is the characteristic lesion of equine leukoencephalomalacia?

A

lesion that is liquefactive necrosis of white matter of the cerebrum. some horses have hepatic necrosis

22
Q

What causes Ergotism?

A

ingestion of sclerotia of the parasitic fungus Claviceps purpurea, which replace the grain of rye and other small grains or forage plants (bluegrasses, ryegrasses) the black sclerotia may contain varying quantities of ergot alkaloids (ergotamine and ergometrine)

23
Q

what animals can ergotism affect?

A

cattle, sheep, pigs & poultry

24
Q

what does ergotism cause?

A
  • arteriolar spasm (vasoconstriction)
  • endothelial cell injury and restrict circulation
  • blood stasis can lead to necrosis of extremities due to thrombosis (mainly in a cold environment)
25
Q

what can ergot alkaloids inhibits?

A

they can inhibit the release of prolactin, causing a failure of mammary development and initiation of milk secretion

26
Q

what are some symptoms of chronic ergotism in cattle?

A
  • lameness
  • gangrene of extremities
  • increase in body temp, pulse and respiration
27
Q

what are Helminths ?

A

worms which are the largest parasites that infect animals. they are multicellular organisms

28
Q

what three groups are helminths classified into based on their shape?

A
  • nematodes (or roundworms)
  • cestodes (or tapeworms)
  • trematodes (or flukes)
29
Q

what are some factors influencing the pathogenesis of parasites?

A
  • the migratory pathway in a host
  • the anatomical site where a parasite develops
  • feeding habits
  • the propensity of stimulate hyperactive immunological responses in the host
  • the potential of the parasite to transmit other infectious agents (arthropods)
30
Q

what are the important features in a parasite life cycle? why is it important to understand the life cycle?

A
  • acquisition of infection
  • predilection site
  • return to environment or intermediate host
  • life cycle stages leaving the host important for the control and treatment in order to intervene or break this cycle
31
Q

what is a direct life cycle?

A

one animal only

Ex: Oesophagostomum or Stephanurus dentatus

32
Q

what is an Indirect life cycle?

A

intermediate host required for development or as a vector for the preparasitic larvae –> usually spends part of its life in an insect or other animal ex: snail ex: dirofilaria immitis and Fasciola hepatica

33
Q

What are some characteristics of protozoa?

A
  • unicellular eukaryotes
  • flexible cell membrane
  • movements can be ameboid or directed by cilia or flagella
  • often have complex life cycles with intra and extra animal stages
34
Q

what are some reservoirs for protozoa?

A
  • other animals, insects or free forms of the parasite found in the external environment (food contaminated with Toxoplasma gondii oocysts from cat feces)
35
Q

how are pathogenic protozoa often transmitted?

A

by living vectors such as flies, mosquitoes and ticks

Animal Health & Disease (7 decks)

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