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PARASITOLOGY - 1 > 2 – Intro to structures and life cycle stages > Flashcards

2 – Intro to structures and life cycle stages Flashcards

1
Q

Helminths

A
  • Nematodes – round worms
  • Cestodes – tapeworms (flat worms)
  • Trematodes – flukes (flat worms)
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2
Q

Nematodes

A
  • TUBES + TAILS
  • Parasitic and free-living stages and species
  • Tiny (<1mm) to enormous (1m)
  • Separate sexes (dioecious)
    o Sexual reproduction WITHIN definitive host
  • Eggs (oviparous), larvated eggs (ovoviviparous) or larvae (viviparous)
  • Direct and indirect lifecycles
  • Host and tissue specificity
  • Larvae can undergo complicated migrations and cause pathology
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3
Q

Nematode: head

A

 Alae (‘wings’)
 Buccal capsule
 Teeth
 Pharynx

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4
Q

Nematode: male tail

A

 Spicules
 Copulatory bursa

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5
Q

Direct cycle of nematodes

A
  • Within host
    o Adults mate
    o Eggs (Patent period)
  • External environment
    o Eggs hatch into it
    o First stage larvae (L1) -> moult
    o Second stage larvae (L2) -> moult
    o Third stage larvae (L3) -> moult and go (pre-patent period)
  • Within host
    o Fourth stage larvae (L4) -> moult
    o Adults
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6
Q

Cestodes

A
  • HOOKS + SEGMENTS
  • Cyclophyllid structure
  • All are parasitic (need the host) AND hermaphroditic (can reproduce themselves)
  • Tiny (2mm) to enormous (12+m)
  • Transmission: INGESTION (DH ingest IH, IH ingests eggs)
  • ALL have INDIRECT life cycle
  • Adults in DH parasitize the GI system
    o MAY cause few problems
    o Once produce eggs=immediately infective
  • Larval stages in tissues of IH may cause serious problems
  • Asexual reproduction may occur
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7
Q

o Scolex:

A

 Rostellum with hooks
 Suckers (4)
 Immature, mature and gravid segments

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8
Q

Cyclophyllid cestode life cycle

A
  • External environment
    o Egg with hexacanth larvae passed in feces -> ingestion
  • Intermediate host
    o Hatch
    o Hexacanth larvae develop to METACESTODE with one or more protoscolices (‘head part’) -> ingestion
  • Definitive Host
    o Protoscolices develop to scolex in adults
    o Egg with hexacanth larvae
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9
Q

Trematodes

A
  • SNAILS + SUCKERS* ALL parasitic
  • Tiny (1mm) to giant (10cm)
  • Most are HERMAPHRODITIC (except schistosomes)
  • Sexual reproduction in the DH
  • All have indirect life cycle with IH
    o First IH always a gastropod (snail or slug): asexual reproduction
  • Adults in DH parasitize GIT or lungs (often pathogenic)
  • Larval stages in IH parasitize many tissues (can be pathogenic)
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10
Q

Trematodes: structure

A

o Mouth
o Oral and ventral sucker
o Pharynx
o Caeca

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11
Q

Trematodes basic life cycle

A
  • External environment (water)
    o Egg with miracidium -> hatch
    o Miracidium -> foot penetration
  • Snail IH 1 – asexual reproduction
    o Sporocyst
    o Redia
    o Cercaria
  • IH 2 or vegetation
    o Metacercaria -> ingestion
  • Definitive host
    o Adults
    o Egg with morula -> passed in feces
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12
Q

Arthropods Groups

A
  • Arachnida
    o Mites and ticks
  • Insecta
    o Bugs
    o Lice
    o Fleas
    o Flies
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13
Q

Mites

A
  • Dorso-ventrally flattened
  • Larva: 6 legs
  • Nymph and adult: 8 legs
  • Variable host specificity
  • Microscopic
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14
Q

Types of mites

A
  1. Burrowing
  2. Surface
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15
Q

Burrowing mites

A

o Short legs
o Round body

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16
Q

Surface mites

A

o Long legs
o Oval body

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17
Q

Mites basic lifecycle

A
  • On host: complete in 10-14 days
    o Adults
    o Eggs
    o Larvae
    o Nymphs
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18
Q

Ticks

A
  • Dorso-ventrally flattened
  • Larva: 6 legs
  • Nymph and adult: 8 legs
  • Variable host specificity
  • Macroscopic (3-12mm)
19
Q

Types of ticks

A
  1. Hard ticks (Family Ixodidae)
  2. Soft ticks (Family Argasidae)
20
Q

Hard ticks (Family Ixodidae)

A

o High vetmed relevance
o Vectors for viruses, bacteria, protozoa, nematodes
 Tick paralysis
 Toxicosis
o Sexual dimorphism obvious
 Males: scutum over whole back
 Females: anterior scutum
o Scutum: ornate or inornate
o Festoons may be present
o Anal groove
 Extending anteriorly around anus
 Never extending anteriorly around anus

21
Q

Tick life cycle

A
  • 8 weeks to 2-3 years (host-dependent)
  • Host 1
    o Male + female adults mate
  • Environment
    o Eggs
    o Larvae -> onto host 2
  • Host 2
    o Larvae take blood meal -> molt to nymph
  • Host 3
    o Nymphs take blood meal -> molt to adults
22
Q

Lice

A

 Dorso-ventrally flattened
 1-8mm
 Adults: 6 legs, no wings
 *extremely host specific

23
Q

Types of lice

A
  1. Mallophage (Ischonocera)
  2. Anopluran
24
Q

Mallophaga (Ischonocera)

A

o Chewing/biting lice
 Feed on skin scruf
o Head wider than thorax
o Yellow

25
Q

Anopluran

A

o Sucking (blood feeder)
o Head narrower than thorax
o Shorter first pair of legs
o Gray to dusky red

26
Q

Lice life cycle

A

 ~3 weeks (on host)
 Adults (feed: blood or dander)
 Eggs
 Nymphs (feed: blood or dander)

27
Q

Fleas

A

 Laterally flattened
 6 legs, last pair very well developed
 NOT host specific

28
Q

Fleas: differentiate species based on presence of

A

o Combs
o Shape of head
o Spines

29
Q

Flea life cycle

A

 At least 3 weeks (complete metamorphosis)
 On host
o Adult
 In environment
o Eggs
o Larvae
o Pupae

30
Q

Arthropods: flies

A

 Nematocera
o Mosquitos
o Blackflies
o Midges
 Cyclorhapha
o Faceflies
o Hornflies
o Botflies
 Brachycera
o Horseflies
o Deerflies
 *highly variable life cycles depending on species and environment

31
Q

Informal classification of flies

A
  1. Biting flies
  2. Secretion feeding flies
  3. Myiasis flies
32
Q
  1. Biting flies
A

a. Mosquitoes
b. Midges
c. Horse flies
d. Stable flies
e. Sand flies

33
Q
  1. Secretion feeding flies
A

a. Face flies

34
Q
  1. Myiasis flies
A

a. Obligate: larvae MUST develop in live host
i. Bots/warbles (oestrids)
ii. Maggots (ie. Screw worms)
b. Facultative: larvae MAY opportunistically develop in live host
i. Maggots (ie. Blowflies)

35
Q
  • Sarcomastigophora (moves by flagella or pseudopodia)
A

-Sarcodina
-Mastigophora

36
Q

o Sarcodina

A

 Amoeboid movement
 Direct lifecycles
 Examples:
* Entamoeba

37
Q

o Mastigophora

A

 One or more flagella
 Direct or indirect lifecycles
 Examples:
* Leishmania
* Trypanosoma
* Histomonas
* Giardia
* Tritrichomonas

38
Q
  • Apicomplexa (apical organelle used to penetrate host cell)
A

-Coccidia
-Piroplasmidia
-Haemosporidia

39
Q

o Coccidia

A

 Obligate intracellular
 Sexual and asexual reproduction
 Environmental resistant oocysts/sporocysts
 Direct/indirect lifecycles
 Examples:
* Eimeria
* Toxoplasma
* Neospora
* Sarcocystis
* Cystoisopora
* Hammondia
* Cryptosporidium

40
Q

o Piroplasmidia

A

 Parasites of blood cells
 Sexual reproduction occurs in vectors (ticks)
 Indirect lifecycles
 Examples:
* Babesia
* Theileria
* Cytauxzoon
* Hepatozoon

41
Q

o Haemosporidia

A

 Parasites of blood cells
 Sexual reproduction occurs in vectors (blood sucking dipterans)
 Indirect lifecyles
 Examples:
* Plasmodium

42
Q

Giardia direct life cycle

A
  • Host: trophozoites
    o Asexual reproduction on mucosa
    o Cysts shed in feces
  • Environment: cysts
    o Ingested by trophozoites
43
Q

Coccidia lifecycle

A
  • Merogony:
    o Asexual multiplication
     Defined number of ‘generations’ for each species
  • Differentiate to microgametes and macrogamonts
    o Fertilization: microgametes invade macrogamonts and form zygote
    o Oocyst shed in feces
  • 2 sporocysts, 4 sporozoites
44
Q

Apicomplexans: reproduction

A
  • *alternate asexual and sexual
  • Merogony (asexual)
    o Intestine of DH: mother cell produces merozoites
    o Within IH: cyst forming coccidia -> fast dividing tachyzoites (systematic), slow dividing bradyzoites (within tissue cysts)
  • Gametogony (sexual)
    o Formation of gametes in intestinal epithelium
    o Macrogametocyte: FEMALE
    o Microgametocyte: MALE
  • Sporogony
    o Zygote divides into sporozoites -> infective for next host

PARASITOLOGY - 1 (14 decks)

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