Veterinary Parasitology - Nematodes

Front 1

What are the general characteristics of the superfamily Metastrongyloidea?

Back 1

Very slender, mostly in the pulmonary system. L1 is in the egg, but hatches very quickly. Have an indirect LC, and use intermediate and paratenic hosts. Migrate in the DH via lymphatic/pulmonary migration.
L3 is the infective stage in both the IH and PH.

Front 2

Metastrongylus spp

Back 2

M. apri, M. pudendotectus and M. salmi.
Adults are located in the diaphragmatic lobes of the lungs, in the bronchi/oles.
Eggs are laid with the L1 in the faeces, ingested by the earthworm (IH) and then hatch.

Front 3

Muellerius capillaris

Back 3

Adults are located in the smaller airways of sheep. L1 passed in faeces, infects slug (IH)and develops to L3 which then infects the DH by ingesting the IH.

Front 4

Protostrongylus rufescens

Back 4

Has been reported in NZ sheep, located in the bronchioles, but not a significant cause of disease. LC as for Muellerius capillaris.

Front 5

Varestrongylus spp

Back 5

Found in the lungs of red deer. Not a significant cause of significant cause of disease, but can complicate the diagnosis of E. cervi. LC as for Muellerius capillaris.

Front 6

Elaphostrongylus cervi

Back 6

Found in the connective tissue (sometimes the CNS) of red deer and wapiti. L1 hatches from the egg and migrates to the lungs, and out through the GIT. L1 in faeces. Rest of the LC is the same as Muellerius capillaris. Generally only a problem because the presence in the tissue poses meat quality problems. Large numbers in the lungs may pose problems.

Front 7

Aelurostrongylus abstrusus

Back 7

Located in the bronchioles and lung parenchyma of cats. ~1cm long, and very delicate. L1 has a spine. Transmission is by a cat eating a bird (PH) which has eaten a mollusc (IH)

Front 8

Filaroides osleri
- this is the funny Metastrongylid

Back 8

Located at the tracheal bifurcation and stimulates the production of nodules. Has a DLC and L1 is the infective stage (perhaps classed in the wrong family). Spread via expectorated mucus, and doesn't generally survive passage through the gut.

Front 9

What are the general characteristics of the order Rhabditida?

Back 9

Primitive parasites, can be free living or parasitic. Transmission by PERCUTANEOUS infection, and can be transferred to the young in the milk or in utero.

Front 10

Strongyloides spp

Back 10

Has both a parasitic and non-parasitic LC. Only the females are parasitic and reproduce by parthogenesis. Offspring can either reinfect as L3 or become the free living stage consisting of males and females. Sexual offspring are either parasitic females or free living. Migration via the bloodstream, to the lungs, then swallowed and through the GIT. Females are ~ 1cm, very slender and have a very long oesophagus (about a quarter of their total length), no ovijector apparatus, and have eggs in the uterus containing L1 and the uterus and the intestine are entwined.

Front 11

Identify the spp name and host of the Strongyloides

Back 11

S. papillosus in sheep
S. ransomi in pigs
S. westeri in horses
S. stercoralis in man, dogs and cats
S. avium in the caeca of birds (ALL OTHER STRONGYLOIDES SPP ARE IN THE SI.)

Front 12

What are the general characteristics of the family Ascarididae?

Back 12

Enormous, small intestinal parasites that have no buccal capsules, lips, non bursate and the infective stage is the L2 IN THE EGG.

Front 13

Ascaris suum

Back 13

Adults found in the SI, infection gained by ingestion of the L2 in the egg or L2 in a PH. Generally DLC. Oral infection, and larvae migrate to the liver, and then onto the lungs. Enormous nematodes, females can be 40cm. Produce characteristic protein coated eggs.

Front 14

Parascaris equorum

Back 14

LC as for A. suum. Very common in young foals, again females can be quite large.

Front 15

Toxacara canis

Back 15

Located in the SI of dogs. Enormously common, almost 100% of pups are born infected. Infection is gained by 4 routes - ingestion of L2 in the egg, ingestion of the L2 in a paratenic host, ingestion of larvae from mothers milk and larve crossing the placenta to reach the developing foetus. PPP can be as short as 23 days.

Front 16

Toxacara cati

Back 16

Similar to T. canis, but usually smaller. Very common. LC similar to T. canis, but infection in utero doesn't occur.

Front 17

Toxascaris leonina

Back 17

Adults found in the SI of both dogs and cats. Smaller than both T. canis and T. cati. Infection gained by ingestion of the L2 in the egg or L2 in a paratenic host. Generally doesn't migrate in the DH (unlike T. canis and T. cati)

Front 18

Anisakis simplex

Back 18

Adults located in the stomach of marine mammals, larvae found in fish viscera and muscles. Infection gained by man by ingestion of raw fish (often associated with sushi). Clinically presents with acute GI upset mimicking appendicitis.

Front 19

Heterakis gallinarum

Back 19

Adults located inthe caeca of poultry. Transmits Histamonas meleagridis

Front 20

Ascaridia galli

Back 20

Adults located in the small intestine of birds. Fairly large parasite ~7cm. DLC, but uses earthworms as transport hosts.

Front 21

What nematode is responsible for visceral larval migrans?

Back 21

Toxacara cani, but T. cati has also been implicated.

Front 22

What are the general characteristics of the family Oxyuridae?

Back 22

Known as 'pinworms', inhabit the colon/rectum, have a DLC and operculate eggs.

Front 23

Oxyuris equi

Back 23

Adults found in the colon/rectum of horses. Marked sexual dimorphism, females are ~10 times larger than males. Females emerge from the anus to lay their eggs, producing irritation (pruritis ani). Infection is by ingestion of the L2 in the egg. Non-migratory.

Front 24

Probstmayria vivipara

Back 24

Adults are located in the colon/rectum horses. Very small nematodes ~3mm. Females are larviparous, so autoinfection is possible.

Front 25

Enterobius vermicularis

Back 25

Adults found in the colon/rectum of humans. Infection gained by the ingestion of L2 in the egg.

Front 26

Habronema spp

Back 26

Habronema microstoma, H. muscae and H. megastoma. Adults are found in the stomach of horses. Rare in NZ, but common in Australia. Adults 2-5cm. Can sometimes cause tumor-like nodules in the stomach (H. megastoma). Eggs are passes in the faeces, and eaten by a fly larvae (IH), in which the larvae develops to the L3.2

Front 27

What are the general characteristics of the order Spirurida?

Back 27

Parasites of the blood/lymph/connective tissue. IH are blood/lymph sucking flies. Females are larviparous, so microfilaria in host tissues. Development to L3 occurs in the IH.

Front 28

Dirofilaria immitis

Back 28

Adults are in the pulmonary artery and right ventricle of dogs. Very long, 30cm. Transmitted by mosquitos.

Front 29

Dipetalonema reconditum

Back 29

Adults in the IM/SQ connective tissue of dogs. IH are fleas.

Front 30

What are the general characteristics of the family Trichuridae?

Back 30

Known as 'whip worms' because of the very narrow anterior end. Eggs are lemon-shaped bipolar operculate. Males have a single spicule. Infective stage is the L1 in the egg, infection gained by ingestion. Adults mature in the caecum w/o migration.

Front 31

Identify the hosts for each of the Trichuris spp.

Back 31

T. ovis in sheep and cattle
T. globulosa in sheep and cattle
T. suis in pigs
T. vulpis in dogs
T. trichuria in man

Front 32

What are the general characteristics of the genus Capillaria?

Back 32

Like other Trichurids, the infective stage is the L1 in the egg, although adults mature in a number of places. LC is either direct or indirect. Capillaria are located in the upper alimentary tract and pulomary tree.

Front 33

Name the spp of Capillaria that occur in birds and state their location.

Back 33

C. contorta in the crop/oesophagus
C. caudinflata in the SI
C. obsignata in the SI

Front 34

Which of these spp have an ILC?

Back 34

C. contorta and C. caudinflata

Front 35

Name the spp of Capillaria that occur in mammals and state their location.

Back 35

C. bovis, C. longipes and C. brevipes in ruminants SI.
C. erinacei in dogs/cats stomachs although mostly in hedgehogs.
C. aerophila in the trachea/bronchi of cats/dogs.

Front 36

Which of these spp have an ILC?

Back 36

None. All mammmalian Capillaria spp have DLC.

Front 37

Describe the characteristics of T. spiralis.

Back 37

Adults are located in the SI, but L1 are encysted in muscle. Infection is gained by ingestion of L1 encysted in tissue, this is an important route of infection in humans.