Lecture 4 - Nematodes of ruminant skin

What are Stephanofilaria stilesi? What species do they affect? Where are they found?

-Roundworm

-Affect cattle

-Found in North America

What is the intermediate host of Stephanofilaria stilesi?

Horn fly, stable fly, face fly, housefly

What is the prepatent period for Stephanofilaria stilesi?

6-8 weeks

What is the pathogenesis of Stephanofilaria stilesi?

-Alopecia

-Skin irritation

-Exudate

-Skin becomes dry and thickened over time

What is the diagnosis of Stephanofilaria stilesi?

-Characteristic wounds and behavior (scratching/rubbing against objects)

-H&E stain from deep skin scraping

How is Stephanofilaria stilesi treated and controlled?

-Treated through levamisole or ivermectin

-Control vectors

What is Rhabditis strongyloides? Where are they found? What species do they usually affect?

-Free-living nematode

-Found worldwide

-Affect cattle, dogs, sheep, horses, and cats

What is the life cycle of R. strongyloides?

Develop outside host in decaying organic material or moist soil and only enter host in L3 stage

What is the pathogenicity of R. strongyloides?

-Hyperkeratosis

-Alopecia

-Nodular or pustular dermatitis

How are R. strongyloides diagnosed?

Skin scraping or by squeezing pustules

How is R. strongyloids treated and controlled?

-Usually clear spontaneously if provided clean and dry bedding

-Control: clean and dry bedding, avoid straw

What is Parafilaria bovicola? Where is it found? Who does it affect?

-Filarial nematode

-Found in Asia, Europe and Africa

-Affects cattle

What is the life cycle of Parafilaria bovicola? Who is the intermediate host?

-Intermediate host: Musca spp (flies)

-Eggs or L1 are ingested by flies

-L1 develop to L3

-L3 are deposited when flies feed on lachrymal secretions or skin lesions

-L3 migrate to subcutaneous tissue and develop into adult worms

What is the pathogenicity of Parafilaria?

Focal cutaneous hemorrhages that ooze for hours

How is Parafilaria diagnosed?

-Fresh or dried blood from skin lesions mixed with water and centrifuged

-Superficial irregular, edematous greenish yellow lesions

-Histology of affected tissue

-ELISA

How is Parafilaria treated/controlled?

-Ivermectin or nitroxynil

-Prevention: fly control and screen imported animals