Parasite 6: Nematodes 5

Question 1

Order Spirurida is described as?

Answer 1

Very long and thin

-confused with ascrid

Question 2

What do all members of Spirurida have?

Answer 2

have an arthropod as intermediate host

Question 3

Are Spirurida usually in the GIT?

Answer 3

NO not usually

Question 4

What is the super family Filaroidea of Spirurida located?

Question 5

What do Spirurida Filaroida a larvae (oviviparous) called?

Answer 5

Pre L1 = microfilariae

Question 6

Dirofilaria immitis (Heart worm) is what kind of
host?
where is it located?
shape/length?

Answer 6

Definitive host = DOGS

Parasite of pulmonary arteries primarily (not IN HEART)

Long, thin; females up to 28cm in length

Question 7

What is the life cycle of Dirofilaria immitis (Heart worm)?

Answer 7

Mosquito feeds and ingests microfilariae with blood

microfilaria matures in mosquito to infective L3 larva, 2 weeks post infection

infective larvae deposited during subsequent bites migrate through wound and into host

Question 8

What is the PPP of Dirofilaria immitis (Heart worm)?

Answer 8

6 months

Question 9

How long is the patency of Dirofilaria immitis (Heart worm)?

Answer 9

5 years

Question 10

What is the pathogenesis of Dirofilaria immitis (Heart worm)?

Answer 10

Damage roughly proportional to worm numbers
* Probably no clinical signs with lower numbers

Disease components
* Some physical obstruction of vessel by worms
* Worms cause inflammation in vessel wall
* Progressive fibrosis in vessel (sclerosis)

Reduced cardiac output and compensatory right heart disease with severe disease
* Right heart enlargement and failure

Potential thromboembolism

Question 11

Clinical signs of Dirofilaria immitis (heart worm)?

Answer 11

Chronic cough

Dyspnea

Decreased excercise tolerence

Question 12

Where is the Prevalence of Dirofilaria immitis?

Answer 12

Highest:
along the MISSISSIPPI
and east coast

Question 13

What is the best way to diagnosis Dirofilaria immitis?

Answer 13

Annual test recommended

Antigen tests: most sensitive and widely used

Microfilaria check
–> check peripheral blood sample for MF

Covered in detail in breathing and circulating

Question 14

What is the treatment for Dirofilaria immitis?

Answer 14

PREVENTATIVES

Treatment is harsh and accompanied by risk of thromboembolism

Question 15

What role of WOLBACHIA in Dirofilaria immitis?

Answer 15

Many, but not all filarid parasites have symbiotic bacteria,
Wolbachia

*If bacteria is removed, the reproduction of the worms is blocked, reduces severity of disease

*Doxycycline now being used in treatment of heartworm infections

Question 16

What is the abnormal host of Dirofilaria immitis?

Answer 16

Cats
-more likely to migrate to abnormal sites than in dogs
-NOT showing sign
-worms die soon after infections

Question 17

Other Filaroidea in North America?

Answer 17

Not common!

subQ tissue in dogs
dermatitis in horses
good indication when parasite NOT in GIT and microfilariae detected

Question 18

Habronema and Draschia spp.

Answer 18

• Live in nodules in equine stomach
• IH: Stable and house fly
• L3 can be deposited by mistake in other locations
  -Mucocutaneous junction
  -Wounds
  -Larvae invade areas and survive but don’t develop
• Causes “summer sore”
  -Persistent cutaneous granuloma
  -Can be mistaken for exuberant granulation tissue, neoplasia

Question 19

Non-Filaroidea examples are

Answer 19

Physaloptera
- Stomach parasite of wild animals, occasionally in dogs and
cats

Thelazia
- Eye worm - Zoonotic

Question 20

The order Enoplida is part of phylum nematoda and it’s described as?

Answer 20

Without many common characteristics

*Most in domestic animals produce eggs with 2 polar plugs

*Infective larva develops and remains inside the egg

*Eggs very resistant to environmental conditions

Question 21

Trichuris vulpis - Whipworm

Answer 21

• Large intestine of dogs, worldwide
• Whip shaped body
• Anterior end entwined within layer of epithelial cells
• Direct life cycle**
• Bipolar eggs passed in feces
• Infective larva develops in eggs (at lest 2 weeks):
• EMBRYONATED EGG IS THE INFECTIVE STAGE
• Diagnosis:
• egg detection

*Clinical disease:
- Diarrhea with/without blood (anemia)
-can be asymptomatic

Question 22

What is the PPP of Trichuris vulpis is?

Answer 22

3 months

this does NOT effect young animals mostly adults

Question 23

Are Tichuriss spp. can effect other animal?

Answer 23

Pigs

Ruminants

NOT cats – only FL and other countries

people their own species
Trichinella spp- Human disease: Trichinellosis or Trichinosis

Question 24

Order Oxyurida big identifiers?

Answer 24

PINWORMS

• Usually small adults in large intestine
• Species in horses, rodents, ruminants, reptiles, people
• Usually NOT very pathogenic
• Direct life cycle
• Egg may have polar plug, often flattened appearance on one side
• Diagnosis by detection of eggs in feces of perianal swabs

Question 25

Oxyuris equi

Answer 25

• Common equine pinworm
• Life cycle
  -Infection from ingestion of eggs
  -Fertilized females migrate from LI and rectum onto skin, glue eggs to hairs in perianal area
• Causes pruritus, irritation from worm movement and egg glue
• “Rat tailed” appearance
• Diagnosis by finding eggs on perianal skin

Question 26

Rhabditida

Answer 26

• Most members are free living soil nematodes
• Only one animal parasite genus: Strongyloides
• Tiny adults (about 6 mm) in SI
• Species specific for ruminants, horse, dog, pig, human
• Strongyloides eggs common in manure samples from young ruminants, rare to see disease

Question 27

What are host and the species name of order Rhabitida?

Answer 27