Infective Nematodes

Toxocara: Common Name

roundworm

Toxocara: Species (3)

• Toxocara canis (Canines)

• Toxocara cati (Felines)

• Toxocara Leonina (Canines & Felines)

Toxocara: Location

Small Intestine

Toxocara: Transmission Route

• Ingestion of egg containing infective larva (direct)

• Transplacental (vertical transmission)

• Transmammary (vertical transmission)

Toxocara: Prepatent Period (2 diff.)

• T. canis/felis: 21-35 days

• T. leonina: 74 days

Toxocara: Diagnosis (2)

• Fecal Flotation

• Visualization either in stool or vomitus

Why do animals vomit toxocara?

Toxocara does not attach to the small intestine. Instead, they swim and will occasionally migrate to the stomach and cause vomiting.

Baylisascaris Procyonis: Location

Small Intestine

Baylisascaris Procyonis: Transmission Route

ingestion of egg containing infective larva (direct)

Baylisascaris Procyonis: Prepatent Period

28-35 days

Why are we concerned about Baylisascaris procyonis?

Highly zoonotic to humans and canines can act as a vector

Baylisascaris procyonis: Diagnosis

Fecal Flotation

Ancylostoma: Common Name

hookworm

Ancylostoma: Species (4)

• Anyclostoma caninum (canine)

• Uncinaria stenocephala (canine)

• Ancylostoma tubaeforme (feline)

• Ancylostoma braziliense (canine & feline)

Ancylostoma: Host

Canine & Feline

Ancylostoma: Location

Small Intestine

Ancylostoma: Transmission Route

• ingestion of egg containing infective larva (direct)

• penetration of host skin (direct)

• transplacental (vertical transmission)

• transmammary (vertical transmission)

Ancylostoma: Prepatent Period

typically 2-9 days

Ancylostoma: Diagnosis

Fecal flotation via centrifugation

Why is fresh feces best when testing for ancylostoma?

There is rapid embryonation. This means the eggs turn into larva/adults fairly quickly, making finding eggs via fecal flotation difficult.

Trichuris: Common Name

whipworm

Trichuris: Species (3)

• Trichuris vulpis (canine) ****

• Trichuris campanula (feline)

• Trichuris serrata (feline)

What species cannot be infected by trichuris?

Horses

Trichuris: Host

Mostly Dogs, rarely cats

Trichuris: Location

Cecum & Colon

Trichuris: Transmission Route

ingestion of egg (either eggs present in prey animals or in stool)

Trichuris: Prepatent Period

70-90 days

Trichuris: Diagnosis

Fecal Centrifugation

Strongyloides: Common Name

Intestinal Threadworm

Strongyloides: Species (3)

• Strongyloides stercoralis

• Strongyloides tumiefaciens

• Strongyloides felis

Strongyloides: Host

• Dogs & Human (Strongyloides stercoralis)

• Cat (S. tumiefaciens, S. felis ± S. stercoralis)

Strongyloides: Location

• S. stercoralis/felis: Small Intestine

• S. tumiefaciens: Large Intestine

Strongyloides: Transmission Route

• Skin

• Transmammary

Strongyloides: Prepatent Period

5-21 days

Strongyloides: Diagnosis

• Fecal Flotation with Zinc Sulfate

• Baermann Technique ***

Rhabditiform Larvae

early developmental stage that are not infectious

Filariform Larvae

infectious stage (L3)

Describe the Life Cycle of Strongyloides.

• All parasitic worms are female (Parthogenesis)

  • Female worms can reproduce individually inside the animal (Autoinfection)

• Larvae in the enviornment can mate and reproduce.

  • Larvae in the enviornment infect the definitive host by penetrating the skin

Rhabditis Stronglyoides: Host

Canine

Rhabiditis Strongyloides: Location

• Skin (ventral surfaces of limbs)

Rhabditis Strongyloides: Transmission Route

• Contact with contaminated bedding (straw)

Where can you find Rhabditis Strongyloides in the environment?

• Soil

• Decaying organic matter (leaves, tree stumps, etc)

What kind of parasite is Rhabditis Strongyloides?

Facultative parasite

Rhabditis Strongyloides: Diagnosis

Superficial skin scrapes

What parasite can be confused with heartworm?

Acanthocheilonema Reconditum

What is an alternative name for Acanthocheilonema reconditum?

Dipetalonema reconditum

A. Reconditum: Location

• SQ tissue (rare)

• Blood

A. Reconditum: Transmission Route

• bite from infected flea

• Decaying matter

A. Reconditum: Diagnosis

• deep skin scrapes

• Peripheral blood draws

  • Modified Knotts Test

Why is it important to differentiate between A. Reconditum and heratworm?

A. Reconditum is non-pathogenic

Aelurostrongylus Abstrusus: Common Name

Feline Lungworm

Aelurostrongylus Abstrusus: Host

Cats

Aelurostrongylus Abstrusus: Transmission Route

Ingestion of larva

Aelurostrongylus Abstrusus: Location

Bronchioles and alveolar ducts

Aelurostrongylus Abstrusus: Prepatent Period

30 days

Aelurostrongylus Abstrusus: Diagnosis

• fecal flotation

• Baermann

• Tracheal Wash

• Fine Needle Aspirate

Aelurostrongylus Abstrusus: Life Cycle

Indirect

• Snails and slugs serve as an intermediate host and are eaten by mice and birds.

• Cats eat the mice and birds and get infected.

Filaroides: Common Name

Canine lungworm

Filaroides: Species (3)

• Filaroides osleri

• Filaroides hirthi

• Filaroides milksi

Why is Filaroides unique?

First stage larvae is infective

• NO DEVELOPMENT NEEDED OUTSIDE OF HOST

• Internal autoinfection possible

Filaroides: Location

Bifurcation of trachea and bronchioles

Filaroides: Transmission Route

• Saliva

• Respiratory secretions

• Vomitus

• Ingestion of feces

Filaroides: Prepatent Period

10 weeks

Filaroides: Diagnosis

• fecal flotation (zinc sulfate)

• Baermann

• Transtracheal Wash ***

• Bronchoscopy ***

What are the largest parasitic nematodes of domestic animals?

Dioctophyma Renale & Pearsoema Spp.

Dioctophyma Renale: Host

Canine

Dioctophyma Renale: Location

Right Kidney

• eats away at the functional part of the kidney until only the capsule remains

Dioctophyma Renale: Transmission Route

Ingestion of an annelid worm

Dioctophyma Renale: Prepatent Period

18 weeks

Dioctophyma Renale: Diagnosis

Centrifugation and sedimentation examination of urine

Pearsoema: Species (2)

• Pearsoema plica (canine)

• Pearsoema feliscati (feline)

Pearsoema: Transmission Route

Ingestion of an annelid worm

Pearsoema: Prepatent Period

8 weeks

Pearsoema: Diagnosis

• centrifugation and sedimentation examination of urine

• Endoscopy

Describe Dioctophyma Renale’s life cycle.

1. Unembryonated larvae passed in the urine.

2. Eggs embryonate in water and ingested by aquatic annelid worms.

3. Worms can get ingested by a paratenic host.

4. Carnivores eat the paratenic host.

5. Larvae travel to the liver and enter the kidney

What are earthworms considered in Pearsoema and Dioctophyma?

Essential intermediate host

Thelazia Calidorniensis: Common Name

Eyeworm

Thelazia Californiensis: Location

Conjunctival sac & lacrimal ducts of the eye on the medial canthus

Thelazia Californiensis: Transmission Route

Infection by infective larvae of intermediate host

• Fruit flies

• Muscoid Flies

Thelazia Californiensis: Prepatent Period

2 weeks

Thelazia Californiensis: Diagnosis

• Ocular exam

• Examination of lacrimal secretions (ova can be found there)

Ovovivipary

Young develop from eggs retained in the mother’s body