Parasitology - Nematodes - Fall 2Nd Year

Front 1

What % of nematodes are parasites of animals?

Back 1

15%

Front 2

How diverse and fecund are nematodes?

Back 2

Very.
They can lay up to 200K eggs/day and are the 2nd most diverse group of animals, behind only the insects

Front 3

What group of helminth is the the most important group in domesticated animals?

Back 3

Nematode.

Front 4

Do nematodes have separate sexes? What is that called? What are their physical characteristics?

Back 4

long thin tube, a hydrostatic skeleton

morphological elaboration concentrated around openings

straight gut with highly variable pharynx

sexes are _separate_(dioecious)

Front 5

What are the external anterior modifications of nematodes?

Back 5

Cuticular modifications at the anterior ends of many nematodes may include teeth, leaf crowns, vesicles, alae and papillae.

Front 6

What is a leaf crown?

Back 6

Leaf crowns: Rows of finger-like projections surrounding the rim of the opening to the buccal cavity. Strongyles of horses.

Front 7

What are vesicles as external modifications of nematodes?

Back 7

Vesicles: inflations of the cuticle around the mouth (cephalic) and the anterior esophagus (cervical).

Front 8

What are alae as external modifications of nematodes?

Back 8

Alae: "wing-like" expansions of the cuticle.

Front 9

What are the posterior external modifications of nematodes?

Back 9

Males Order Strongylida – the ‘bursate’ nematodes) caudal alae expanded to form copulatory bursa –
male to grasp the female during copulation.

During copulation it is greatly expanded and used to grasp the female.

Front 10

What is the internal morphology of a nematode? How many layers of body wall do they have?

Back 10

body is essentially an outer tube enclosing an inner tube (the digestive tract) supported by hydrostatic pressure.

The body wall has three layers:__cuticle_, hypodermis and an inner layer of muscle cells.

Front 11

what is the major variation between nematodes?

Back 11

Their mouth openings.

Variations in sizes of the mouth opening,  buccal capsule and esophagus.

Simple opening = a tiny buccal cavity leading directly to the esophagus e.g. Nematodirus

Large mouth opening, prominent buccal cavity, thick walls & teeth (e.g. Stongylus vulgaris).

Front 12

What determines the type of buccal cavity that nemaotdoes have?

Back 12

Type related to diet.
large: bite of mucosa, and drawing it into the buccal cavity where it is digested (e.g. the large strongyles of horses). Called ‘_plug feeders_’.

Simple opening = a tiny buccal cavity leading directly to the esophagus e.g. Nematodirus

Large mouth opening, prominent buccal cavity, thick walls & teeth (e.g. Stongylus vulgaris).

Small mouth opening: host fluids (e.g. Ostertagia)

Intermediate: “grazers”
(e.g. Oesophagostomum radiatum large intestine of swine).

Front 13

What are large mouth opening nematodes called? What's a big group that has these?

Back 13

large: bite of mucosa, and drawing it into the buccal cavity where it is digested (e.g. the large strongyles of horses). Called ‘_plug feeders_’.

Also in hookworms.

Front 14

What are intermediate sized buccal cavity nematodes called?

What do the small mouth opening nematodes feed on?

Back 14

Intermediate: “grazers”
(e.g. Oesophagostomum radiatum large intestine of swine).

Small mouth opening: host fluids (e.g. Ostertagia)

Front 15

What is the signifigance of the esophagus in nematodes?

Back 15

Esophagus: shape often used as an initial screening characteristic for identification.

Superfamily Strongyloidea: club-shaped (strongyliform) esophagus.
Superfamily Oxyuroidea (pin worms): prominent posterior bulb (separated from the rest of the esophagus by a narrow isthmus).

Front 16

Describe the female reproductive tract of nematodes.

Back 16

The female reproductive system tubular two ovaries, each of which connects to an oviduct, and a uterus.

Front 17

Is the nematode development direct or indirect? Do they use paratenic hosts?

Back 17

Life cycle can be direct or indirect (invertebrate intermediate hosts in some, lots with paratenic hosts)

Front 18

What happens to the nematode cuticle in development molting?

How many molts do nematodes undergo?

Back 18

During development molting occurs and old cuticle is shed (occasionally retained as a ‘sheath’)

Usually 4 molts (ecdyses)

Front 19

What are the stages of nematode development?

NEED TO KNOW

Back 19

Stages: egg → L1→ L2→ L3 → L4 → L5/adult
"L" means larval

Also called “J1 through J5”
"J" means juvenile - more appropriate, but the other is more widely used.

NEED TO KNOW

Front 20

ID

What's the number one clinical sign we see with nematodes?

Back 20

Canine ancylostomosis – hemorrhagic enteritis, small intestine

Anemia

Front 21

Where are we likely to find nematodes in the host?

What is the most damaging life cycle of nematodes?

Back 21

We'll likely find them in the intestines.

The adults can be damaging, but often, like strongyles, the migrating juveniles are the most damaging.

Front 22

ID

Back 22

Strongylus sp. attached to mucosa of horse large intestine

Front 23

ID

Back 23

Ascaris of pigs – small intestine

Front 24

What is a roundworm?

Back 24

Any nematode.

Typically referring to toxocara canis.

Ascarid is also referring to something general too....look into this, or ask someone!

Front 25

ID

Back 25

Toxocara canis – fatal infection in puppy

Front 26

ID

Back 26

Lungworm in the bronchii and trachaea of cattle

One of the nematodes that is more dangerous in the adult form.

Front 27

what are the clinical signs of nematode infection?

Back 27

impaired weight gain
impaired food conversion
reduced fitness, eg heartworm

Front 28

What is the particular danger of toxocara to humans?

Back 28

Visceral & _Ocular Larval Migrans
Toxocara spp.

Front 29

What are the six orders of veterinary importance in the nematode class?

Back 29

Rhabditida -
Strongylida - strongyles
Ascaridida
Oxyurida - pinworms
Spirurida
Enoplodida

Front 30

What is the superfamily of Oxyurida order of parasites?

What kinds of animals are they found in?

Back 30

Order: Oxyurida (pinworms)
SuperFam: Oxyuroidea

Simple life cycle
Mostly in large intestine
Humans, horses, _lab rodents_

Front 31

What is the superfamily of Rhabditida of Nematodes?

Back 31

Order: Rhabditida
SuperFam: Rhabditoidea

Front 32

What are the superfamilies of the order Strongylida of Nematodes?

Back 32

Order: Strongylida
SuperFam:Trichostrongyloidea
[hair worms (some lung)]

SuperFam: Strongyloidea
[‘true strongyles’]

SuperFam: Metastrongyloidea
[lung worms]

Front 33

What is a strongyloides vs a strongyles?

What is a hookworm in this bucket of nonsense?

Back 33

Genus Strongyloides (order Rhabditida)
The true strongyles (order Strongylida)
Many families and genera, lots in large animals.

Hookworms (also order Strongylida) but not referred to as usually not referred to as strongyles

Front 34

What is the superfam of the order Ascaridida of Nematodes?

Back 34

Order: Ascaridida (big roundworms Ascarids)

SuperFam: Ascaridoidea
[ascaridoids/ascarids]

Front 35

What are the superfamilies of the order Spirurida of Nematodes?

Back 35

SuperFam: Spiruroidea
[spirurids]

SuperFam: Filarioidea
[filarial worms]

Front 36

What is the superfamily of the order Enoplodida of Nematodes?

Back 36

SuperFam: Trichuroidea
[enoplids]

Front 37

In summary, what are the important concepts to keep in mind in sorting through these worms?

Back 37

Very general idea of nematode anatomy
Some idea of distinguishing features
How functional morphology relates to biology e.g. feeding, reproduction, movement
Life Cycles: Variability in the post-embryonal development exists and it relates to diagnosis
(i.e. unembryonated, embryonating, embryonated, L1 stages released – fecal exam)
Variables in response to abiotic stimuli impact on epidemiology and effectiveness of treatments (hypobiosis)