Internal Parasites

Question 0

Phyla: Sarcomastigophora

Answer 0

Protozoans. Example: Giardia spp, Toxiplasma gondii and Eimeria spp.

Question 1

Phyla: Nemathelminthes

Answer 1

Roundworms. Class Nematoda

Question 2

Phyla: Platyhelminthes

Answer 2

Flatworms example: Class Tremetoda flukes and Class Cestoda tapeworm.

Question 3

Phyla: Acanthrocephala

Answer 3

Thorny-headed worms

Question 5

Class Nematoda

Answer 5

Superfamilies: Ascaridoidea/Ascarids, Oxyuroidea/pinworms, Metastrongyloidea/ lungworms, Trichostrongyloidea, Rhabditoidea, Strongyloidea, Filarioidea, Trichuroidea.

Question 6

superfamily: Ascaridoidea

Answer 6

Ascarids-Large roundworms.

Toxocara canis & felis, Parascaris equorum, Ascaris suum, Heterakis gallinarum

Question 7

Common roundworms (aka Ascarids)

Answer 7

Toxocara canis (dogs) 
Toxocara cati (cats)
Toxascaris leonina (cats and dogs)
Parascaris equorum (equine)
Ascaris suum (pigs)
Heterakis gallinarum (poultry)
Ascaridia galli (poultry)
Baylisascaris procyonis (raccoons)

Question 8

Common lungworms (superfamilies Trichostrongyloidea, Metastrongyloidea, Trichuroidea)

Answer 8

Dictyocaulus viviparous (cattle and deer)
Dictyocaulus filaria (sheep)
Dictyocaulus arnfieldi (donkeys, horses)
Protostrongylus stilesi (big horned sheep)
Protostrongylus ruschi (big horned sheep)
Protostrongylus rufescens (sheep and goats)
Muellerius capillaris (sheep and goats)
Aelurostrongylus abstrusus (cats)
Metastrongylus apri (pigs)
Filaroides osleri (dogs)
Capillaria aerophila (foxes, occasionally dogs and cats)

Question 9

Common threadworms (Rhabditoidea)

Answer 9

Strongyloides stercoralis (canine, also cats, foxes, humans, other primates)
Strongyloides westeri (horses- usually foals 2 weeks- 6 months)

Question 10

Common hookworms (Strongyloidea)

Answer 10

Ancylostoma caninum (dogs, wild canids, raccoons and badgers)
Ancylostoma braziliense (cats and dogs)
Ancylostoma tubaeformae (cats and wild felines)
Unicineria stenocephala (dogs and wild canids)

Question 11

Strongyles (superfamily Strongyloidea)

Answer 11

• 2 groups- small strongyles and large strongyles.
• mixed infections are common.
• direct life cycles
• common clinical signs: anaemia, diarrhea, ill-thrift
• prolific egg producers
• most frequently clinical problems occur in the spring due to activation and emergence of large numbers of dormant migrating larvae
• it can be assumed that all grazing horses are infected to some degree

Question 12

Large Strongyles (superfamily Strongyloidea)

Answer 12

-Strongyles equinus
-Strongyles edentatus
-Strongyles vulgaris***
-direct life cycles
-complicated migration pattern: 1st stage larvae develop in ova, hatch, become free-living 2nd and 3rd stage larvae. Once 3rd stage larvae penetrate caecal mucosa they migrate to various areas of the body.
S. edentates and S. equines leave caecum sand migrate to the peritoneum and liver, ultimately returning to the caecum
S. vulgarism leaves the caecum and migrates extensively through the cranial mesenteric artery and its branches before returning to the caecum. The resulting venomous thrombosis and arteritis may result in obstruction and occlusion of the cranial mesenteric artery which supplies the intestinal tract.

Question 13

Trichostrongyles (superfamily Trichostrongyloidea)

Answer 13

Haemonchus contortus (cattle, sheep, goats and llamas)
Ostertagia ostertagi (cattle, sheep, goats and llamas)
Trichostrongylus axei (horses, cattle, sheep, goats and llamas)
Cooperia spp (cattle, sheep, goats and llamas)
Nematodirus spp (cattle, sheep, goats and llamas)
-simple, direct life cycle
-mucosal migration only
-zoonotic (fecal ingestion)
-are capable of hypobiosis during periods of environmental stress
-typical strongyle ova (except Nematodirus), so impossible to identify genus and species by fecal floatation alone.
-control: pasture rotation and regular deworming.

Question 14

Ostertagiasis

Answer 14

-refers to and infestation of Ostertagia spp.
-3 stages/types of infestation:
type 1: larvae mature and reproduce
pre-type 2: no clinical signs. 4th stage larvae in the abomasum are inhibited in gastric glands and accumulate over winter (hypobiosis)
type 2: inhibited larvae mature at the same time, resulting in increases on abomasal pH and mucous production. Severe diarrhea and dehydration result.

Question 15

Blood parasites (Superfamily Filariodea)

Answer 15

Dirofilaria immitis (dogs, cats, human)
Dipetalonema reconditum (dogs)
-both are found in the circulating blood

Question 16

Dirofilaria immitis

Answer 16

• Heartworm
• adult inhabit the right ventricle (heavy load can cause obstruction of pulmonary artery)
• presence of only 1 or 2 worms can be fatal in a cat
• no treatment (adulticide or filaricide) available for cats
• adult males: 12-20 cm long
• adult females: 25-31 cm long
• clinical signs: exercise intolerance, cyanosis, congestive heart failure, or no clinical signs.
• indirect life cycle (intermediate host is the mosquito)
• prepatent period extremely important for diagnostics and control- prophylactic treatments only effective against the initial infective larval stage, not the adult.
• common heart worm tests are sensitive to the antigen produced by the adult female parasite.