ANSC 100

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ANSC 100
2012-10-20 00:00:42
Infectious diseases

infectious disease
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  1. Can diseases be infectious or non infectious?
  2. Define infectious
    body is invaded by pathogenic agent which, under favorable conditions, multiplies and produces effects which are injerious
  3. List the agents responsible for infectious diseases
    • Bacteria
    • Fungi and yeasts
    • viruses
    • prions
    • parasites= protozoa, worms, athropods
  4. how are prions like an agent responsible for infectious diseases?
    non-living and not really infectious they just act likie infections
  5. What are the types of parasites
    • Protozoa: ie giardia
    • worms: heart worms in dogs which lice in blood vessels and float to the heart when the dog dies
    • arthropods: ticks, fleas, lice
  6. What are microorganisms?
    (aka microbes) organisms too small to be seen by the naked eye
  7. Which infectious disease agents are prokaryotic and which are eukaryotic?
    • Prokaryotic: bacteria (no nucleus or nuclear membrane)
    • Eukaryotic: fungi, algae, protozoa (cell membrane etc)
  8. which infectious diseases agents are acellular?
    viruses and prions
  9. what do pathogenic organisms do?
    cause disease
  10. obligate pathogens vs opportunists
    • obligates: cause disease nearly every time they invades a healthy animal even in low numbers
    • opportunist: low virulence and causes disease only if administered in high doses or immune defenses are impaired (so contact but may not infect)
  11. Bacteria are prokaryotic. What are prokaryotes?
    single celled organisms that do not have a nucleus, mitochondria or any other membrane bound organelles (DINA= free floating)
  12. How doe bacteria reproduce
    by fission in any environment: cell elongates and DNA is replicated, cross wall beigns to form and seperate divided DNA, cells seperate
  13. Classification of Bacteria:
    A. Microscopic characteristics
    • Size: 1 to 100 microns (small)
    • Shape
    • Arrangement
    • Gram staining
    • other staining
    • spores
    • Flagella
  14. Compare the size of the host cell, large bacterium, large virus, small virus
    • Common bacteria are small enough that many average sized bacteria would fit inside a single cell
    • viruses are much smaller than bacteria
  15. What are the different kinds of shapes for microscopic characteristics in classifying bacteria
    • Spherical: coccus -staphylococcus
    • Rod: bacillus -bacillus sp.,salmonella
    • Comma: vibrio -campylobacter
    • Spiral: spirillium -leptospira
    • filament: -nocardia
  16. What are the different types of arangments for micrscopic characteristics
    • single
    • pairs
    • chains
    • clusters
    • irregular
    • clumps
  17. What are the gram stains
    • gram positive: purple eg: staphylococcus
    • gram negative: pink eg: E.coli
  18. what are some other strains
    eg acid stains: mycobacterium (tuberculosis, johne's) etc...
  19. What are some spore characteristics?
    • In rod-shaped bacteria
    • May be visible microscopically
    • Differential-staining spots or "clubbing" of ends
    • Resistant to heat, dessication, chemicals
    • E.g. Bacillus spp., Clostridium spp.
    • *spores allow bacteria to be highly resistant in environments
  20. What are the Flagella characteristics
    • confer "motility" or movement
    • delicate, thread like
    • many species of bacilli, spirilli, and vibrios
    • few cocci are flagellated
  21. Classification of Bacteria
    B) Macroscopic Characteristics
    • Culture:
    • plates: size, morphology, activity (hemolysis) of colonies
    • media (type of gel)
    • aerobic/ anaerobic
    • tubes: biochemical reactions -indicators
    • antimicrobial susceptibility (what antibiotics they are resistent to)
    • serological response (antibodies in blood to surface the antigens of the bug)
  22. Classification of bacteria:
    C. molecular/ genetic characteristics
    • Rapid advances in molecular biology in the past 30 years
    • Allow identification of many subtypes of bacteria
  23. How do the classification of bacteria: molecular/ Genetic characteristics - allow for identification of many subtypes of bacteria?
    • Gene sequencing (same or not?)
    • polymerase chain reaction detection
    • ID of unculturable bacteria
    • analysis of whole communities of bacteria
    • relate individual cases to an outbreak of infections
    • establish an association between an outbreak of food poisoning and a specific food vehicle
    • study variations in pathogenicity, virulence and antibiotic resistance of individual strains within a species
    • trace source of contaminations within a manufacturing process
    • Study the microbial ecology of complex communities such as biofilms (usually a group of bacteria = disease, problem in long term implants like catheters)
  24. Why characterize a microbrial isolate beyond species level and determine its sub-species, strain, or even sub-strain?
    • Relate individual cases to an outbreak of infections
    • Establish an association between and outbreak of food poisoning and a specific food vehicle
    • Study variations in pathogenicity, virulence and antibiotic resistance of individual strans within a species
    • trace sources of contaminants within a manufacturing process
    • Study the microbrial ecology of complex communites such as biofilms (problems in long term ie catheters)
  25. iClicker question:
    Why do bacteria have spores
    May have spores that allow them to be highly resistant in environments
  26. Describe clostridial disease
    • disease is of considerable economic importance
    • ubiquitous in soil and ingesta
    • may be prevented by vaccination
    • polyvalent vaccines with up to 7 or 8 key antigens
    • lambs unable to rise and have stiff gait and internal hemorrhages
  27. What is tetanus and what kind of disease is it?
    • clostridium tetani
    • a clostridial disease
    • causes generalized hypertonia: paralysis of muscles, especially the jaw
    • most common in horses, then humans, then dogs
    • organisms commonly present in feces or soil
    • continously shed --> sporulate and persist in environment
    • infection from wound contamination, especially punctures
    • incubation of 1 to 3 weeks
    • bacteria remain localized and begin producing toxin in 4-8 hours
    • treatment: debride wound (clean out), penicillin, neutralize circulating toxin (tetanus anittoxin) supportove care
    • prevention: vaccination
  28. What is Botulsim what type of disease?
    • clostridium botulinum
    • type of clostridial disease
    • fatal progressive flaccid paralysis of all voluntary muscles
    • ingestion of botulinum toxin in contaminated food or water
    • cattle, sheep, goats are more affected than pigs, dogs, cats (becaue carnivores tolerate higher levels of toxins)
    • often from a carcass, or decaying plant material
    • Epizootics occur in waterfowl in eastern alberta lakes (epidemic because the bugs eat the decaying plants and the bugs concentrate the toxins- ducks eat the bugs which are like toxin pills and then they drown becaue their neck muscles cant hold up their heads)
    • Treatment: supportive, only possible in subacute cases
    • Prevention: good husbandry, disposal of carcasses, discard spoiled feed (silage), vaccination in enzootic areas
  29. What is Blackleg & what type of disease is it?
    • Clostridium chauvoei
    • peracute (comes on too fast before know effected), noncontagious, highly fatal
    • gaseous edema of muscles, severe toxemia
    • common in young cattle, rare in sheep
    • soil born
    • route of entry probably from eating in pasture and in outbreak settings, so get animals out of the field!
    • mostly in hot months
    • high economic losses (sometimes 100% mortality)
    • Anaerobic, motile, spore-forming
    • C/S (clinical signs): found dead, lameness, swelling
    • R/O: anthrax, lightning strike
    • treatment: usually too late
    • Prevention: vaccinate, move from affected pastures, burn or deep burial of carcasses
    • so may occur if vaccine failure
  30. What is Clostridial Enterotoxemia & what type of disease is it?
    • Clostridium perfringens
    • Clostridial disease
    • Ubiquitous environment
    • may be isolated from GIT of most healthy animals
    • 5 types: A to E
    • Types A, C, D not common in North America
    • Prevention: vaccines
    • treatment: antibiotics if animal is still alive
  31. What are some examples of clostridial diseases?
    • Bacteria
    • Tetanus, Botulism, Black leg, Clostridial enterotoxemia
  32. What are some of the characteristics of Fungi?
    eukaryotic, lack chlorophyll

    • chemotropic (nutrition by absorption)
    • grow in many forms depending if they are facultative anaerobes or strict aerobic
    • widely distributed (air, water, soil, decaying organic debris)
    • approx. 100 species are pathogens to humans and animals (many others to plants)
  33. Define mykos
  34. define mycosis
    disease caused by a fungus
  35. define mycology
    study of fungi
  36. What are the different types of fungal groups?
    Yeasts, molds, dimorphic
  37. What are some of the different classes of Mycosis?
    • superficial (hair, skin, nail, cornea)
    • Dermatophytes: ring worm, athletes foot, jock itch
    • subcutaneous: grow under skin
    • opportunistic- right enviro(nasal, respiratory, oral, urogenital, alimentary etc...)
  38. What are some types of myscosis
    ringworm, yeast, mould
  39. Describe a yeast
    • fungus
    • unicellular
    • microscopic: oval to round, reproduce by budding, bud= blastospore, pseudohyphae
    • macroscopic: pasty colonies (that resemble bacteria) ie brown goo in ears = thrush
  40. Describe mould
    • fungus!
    • multicellular, long, branching, filamentous
    • Microscopic: hyphae, spores
    • Macroscopic: surface texture: cottony, wooly, velvety, granular  , pigmentation observed from reverse of colony
    • (hen can grow mould in air sacs from dusty dry foods, and a horse in neck from mouldy feed, in gutaral ouch)
  41. What are the major developments in mycology ?
    • increased in number of immunocompromised patients which lead to:
    • newly developed antifungal drugs,
    • antifungal susceptibility testing,
    • resistance to antifungal drugs
  42. T or F: An important development in the past few decades is the increase in proportion of patients that are highly susceptible to opportunistic mycotic infections
  43. What are some characteristics of viruses?
    • acellular
    • contain DNA or RNA core and protein "capsid" coat
    • often have an envelope (phospholipid) derived from host cell membranes
    • -may take chunks out of host and wrap themselves in it
    • -not cells and not really living: bundle of packed DNA envelope
    • essentially genetics elements (DNA or RNA) that can replicate independently of a cell's chromosomes
    • obligate intracellular reproduction ("parastic" on host cell mechanisms
    • must replicate in their specific host cell
    • very small compared to bacteria and fungi (20-300nm)
    • virus penetrates cell membrane and injects nucleic acid into cell- then replicates- and new ones packed and released
  44. What are the different kinds of viral morphology?
    helical symmetry (measles), icosahedral symmtery, enveloped virus (rabies), complex viruses (T4 bacteriophage)
  45. Animal Viruses: give examples of RNA and DNA viruses
    • RNA virus:
    • -coronavirus: corona virus is most mammals
    • -rhabdovirus: rabies in humans and animals
    • -retrovirus: HIV, FelV, avian leukosis, bovine leukemia and many others
    • DNA virus:
    • -Herpesvirus ( wide variety of disaeases, humans and animals- chicken pox, cold sores, IBR, Equine Rhino, FVR etc
    • -poxvirus- largest virus - cow pox
    • many others
  46. What is sponigform encephalopathies
    • prion disease
    • scrapie: sheep, loose wool
    • BSE: (bovine spongiform encephalopathy) cows
    • CWD: muledeer, elk (chronic waisting disease)
    • TME: transmissinle mink encephalopathy
  47. What are exapmples of prion diseases in humans and what are some syptoms
    • CJD (creutzfeld-jacob disease), GSS (gerstmann-strassler-scheinker syndrome), FFI (fatal familial insomnia), kuru, alpers syndrome
    • loss of motor control, demenita, paralysis wasting and eventually death, typically following pneumonia
    • both infectious and hereditary diseases
  48. What are the different groups of parasites?
    • protozoa (single celled)
    • helminths (worms)
    • arthropods (insects)
  49. What is the distribution of parasites in a host population?
    • 80% of the distribution lives in 20% of the herd
    • ie large number of horses with few parasites and few numbers of horses with lots of parasites
  50. What are protozoa and give examples
    • single celled animals
    • wide variety of size and morphology
    • ciliated protozoa: parasites with many host species
    • amoeboid protozoa: cause of ameobic dysentery
    • flagellate protozoa: giardia lamblia (suck on gut), trichomonas vaginalis (carried through reproduction)
    • spore forming protozoa: coccidia (simple life cycle, sporulate eggs in pasture, get eaten and reproduce in gut, make cists) -diff types for each species
  51. Describe Helminths
    • Worms
    • often complex life cylces
    • often have intermediate hosts
    • platyhelminths (flatworms):
    • -cestodes: tapeworms
    • -trematodes: flukes
    • nematodes: roundworms
    • -equine strongyles
    • "geuinea worm" dracunculus in african feet snails = intermediate hosts
  52. Describe Flukes
    • Unsegmented, leaf like
    • oral sucker
    • simple ventral sucker for attachment
    • mostly hermaphrodites
    • 2 or 4 host life cyc;e
    • eg Fasciola hepatica- sheep liver fluke
  53. Describe tapeworms
    • Endorparasites, usually it GIT
    • segmented: proglottids, joined by a neck to a head (segmented can break off and indivi, dually move)
    • each proglottid hermaphroditic
    • gut absent- absorbs nutrients
    • eg taenia sginata of beef (cists in beefs muscle, cists eaten by people for get cists in stomach)
    • canine <--> cows--> humans
  54. describe nematodes
    • endoparasites
    • species infect almost any organ
    • "vermiform" -cylindrical, nonsegmented
    • 2 seperate sexes
    • cycles with or without intermediate host
    • eg ascaris -pigs, humans
  55. What is Bovine ostertagiasis
    • nematode worm (helminth)
    • ostertagia ostertagi ****
    • affects gut (gastritis ie inflammation of gut)
    • most common cause of parasitic gastritis in cattle
    • weight loss, diarrhea
    • primarily young cattle in first grazing season
    • heard outbreaks, sporadic individual adult cases
    • direct life cyle
    • pathogenesis
    • C/S inappetance, weight loss, diarrhea in light infection, sub-optimal weight gain
    • 2 types
  56. What is the direct life cycle of bovine ostertagiasis
    • eggs passed in feces
    • under optimal conditions develop within fecal pat to infective 3rd stage within 2 weeks
    • L3 larvae emerge under moist conditions in grass
    • after ingestion L3 moults in the rumen then develops in the lumen of an abomasal gut
    • 2 more moults occur, then adult emerges about 18 days later and becomes sexually mature on mucosal surface
    • cow poops--> grass grows through, worms live on grass--> calves eat--> molt into L4 stage-- more stages--> affects glands in abomasum and causes inflammation--> adults live in microbrial surfaces
  57. What is the pathogenesis and C/S of Bovine ostertagiasis
    • Pathogenisis:
    • -ostertagi in numbers in abomasum causes severe damage
    • -in heavy infections, up to 40 000 worms may be present
    • C/S:
    • inappetance, weight loss, diarrhea, in lig infection -sub optimal weight gain
  58. Describe the two types of Bovine Ostertagiasis
    • Type 1: symptoms seen in new calves grazed intensively the first season, as a result of larvae ingested 3 to 4 weeks earlier, usually occurs mid July and onwards
    • Type 2: symptoms occus in yearlings usually in late winter or early speing following their first grazing season
    • results from maturation of larvae ingested previous autumn, larvae enter arrested development in the calf's abomasum, then activate when animal's immune system is weakened (in harsh winter)
  59. What is the diagnosis, treatment and control for Bovine ostertagiasis?
    • Diagnosis:
    • clinical signs, season, grazing history, fecal egg counts, hypoproteinemia (type 2: fluid leaks into tissues because of low protein= not thick blood = bottle neck),  ventral edemia, post mortem exam
    • Treatment: responds to modern dewormers such as ivermectin
    • Control:  routine deworming of calves, rotational grazing
  60. Explain BVD- Bocine viral diahrrhea
    • RNA virus
    • acute, contagious disease of cattle
    • worldwide prevalence
    • spreads rapidly by contact
    • virus in feces and urine
    • spread on fomites
    • Different disease forms due to different strains: (higher virulence) cytopathic, (lower virulence) noncytopathic
    • all ages susceptible
    • usually occurs between 6 to 24 months of age
    • colostral antibody protective to about 6 months
    • resevoir in persistently infected cattele (if prego, gives it through placenta = usually abortion)
    • calf may be born infected (transplacental infection) or be aborted or be born and have malformations
  61. How is BVD a mucosal disease complex
    decrease exposure by
    • Calves: rapid onset of fever, dry cough, oral/nasal discharge, oral ulcers; diarrhea; 10-50% of calves under 6 mo may die
    • Cows: weight loss, decreased milk production, abortion, fetal mummification
    • Treamtment; only symptomatic- often no use
    • prevention: prevent introduction of infected animals, buy vaccinaed animals from healthy hers, isolate after arrival, etc
    • Decrease exposure by: preventing manure contamination of feed, water and animals coats; housing dairy calves in individual hutches, isolating sick animals
  62. Define prion
    "small proteinaceous particles which resist inactivation by procedures that modify nucleic acids"
  63. define spongiform encephalopaties
    • post mortem appearance of the brain with large vacoules in the cortex and cerebellum (infectious proteins)
    • prion diseases
  64. Describe Arthropods
    • vast number of parasitic species
    • endo and ecto parasites
    • usually seperate sexes
    • arachnids: mites, ticks, spiders, scorpions
    • insects: lice, fleas, flies
    • ie the moose tick: dermacentor albipictus