Veterinary Parasitology – Lung- & Whipworms (Module 5)

Vocabulary flashcards summarizing key parasites, diagnostic terms, life-cycle concepts, and distinguishing egg/larval features covered in Module 5.

Dictyocaulus arnfieldi

Equine lungworm; adults in bronchi/trachea of donkeys (patent, mild) and horses (non-patent, severe). Direct life cycle; L1 in feces become infective L3 on pasture.

Dictyocaulus filaria

Lungworm of sheep/goats. Larvated eggs coughed up and swallowed; L1 develop to L3 on pasture. Causes coughing, weight loss; Baermann diagnosis.

Dictyocaulus viviparus

Bovine/deer lungworm. Direct cycle, L3 on pasture; acute respiratory disease in young cattle. Diagnosed with Baermann technique.

Metastrongylus apri

Swine lungworm. Indirect cycle – earthworm IH. Larvated, thick-shelled 50×40 µm eggs. Pneumonia in young pigs.

Aelurostrongylus abstrusus

Feline lungworm in lung parenchyma; indirect cycle using snail/slug IH and various paratenic hosts. L1 with S-shaped tail; Baermann test.

Oslerus osleri

Canine tracheal/bronchial lungworm forming nodules. Direct cycle; L1 infectious immediately (possible autoinfection). Causes chronic cough.

Muellerius capillaris

Small ruminant lungworm; snail/slug IH. L1 with S-shaped tail & dorsal spine, no intestinal granules. Severe in goats, usually subclinical in sheep.

Eucoleus aerophilus (Capillaria aerophila)

Capillarid lungworm of dogs, cats, foxes. Egg 60×30 µm with rough, net-like shell; bipolar plugs offset. Earthworm IH possible; bronchitis & tracheitis.

Trichuris ovis

Whipworm of sheep/goats. Eggs 75×35 µm, golden-brown, bipolar plugs. Mostly subclinical; heavy infections cause bloody diarrhea.

Trichuris suis

Whipworm of pigs. Eggs 50–68×21–31 µm. PPP 6–8 weeks; heavy infections may cause weight loss & diarrhea; potential transient human zoonosis.

Trichuris vulpis

Canine whipworm. Eggs 75×40 µm; PPP ~3 months. Heavy burdens lead to large-bowel diarrhea; not considered zoonotic.

Baermann technique

Diagnostic method that uses warm water to stimulate active migration of live larvae from feces into a collection tube for microscopic identification.

Fecal flotation (centrifuge method)

Diagnostic test that uses a dense solution (e.g., zinc sulfate) and centrifugation to separate helminth eggs, making them float for microscopic examination.

Prepatent period (PPP)

Time between infection of the definitive host and appearance of diagnostic stages (eggs/larvae) in feces or sputum.

Direct life cycle

Parasitic life cycle requiring no intermediate host; infective stage develops in environment and is ingested by definitive host.

Indirect life cycle

Life cycle requiring at least one intermediate host in which larval development occurs before infection of the definitive host.

Larvated egg

An egg that already contains a developed first-stage larva (L1) at the time it is passed or examined.

S-shaped tail

Curved tail tip characteristic of larvae of Aelurostrongylus abstrusus and Oslerus osleri.

Spear-shaped tail

Pointed, elongate tail seen in larvae of Dictyocaulus arnfieldi.

Dorsal spine (larval tail)

Small dorsal projection near tail tip of Muellerius capillaris L1, aiding species identification.

Earthworm intermediate host

Required host for Metastrongylus apri and facultative host for Eucoleus aerophilus; larvae develop to infective stage within earthworms.

Snail/slug intermediate host

serve as obligate or facultative IH for Aelurostrongylus abstrusus and Muellerius capillaris.

Paratenic host (PH)

Transport host in which no parasite development occurs but which can transmit infective stages to the definitive host (e.g., frogs, lizards for A. abstrusus).

Autoinfection

Re-infection of the same host without leaving the body, seen with Oslerus osleri where L1 are immediately infective.

Zoonosis

Eucoleus aerophilus & Trichuris suis have rare zoonotic potential.

Capillarid-type egg characteristics

Smaller (≈60×30 µm), rough, net-like shell; cell mass fills egg; bipolar plugs usually asymmetrical (Eucoleus aerophilus).

Trichuris egg characteristics

Larger, smooth-shelled, golden-brown, barrel-shaped eggs with symmetrical bipolar plugs (T. suis, T. vulpis, etc.).

Bronchi & trachea

Preferred adult site for Dictyocaulus spp. and Oslerus osleri; inflammation produces coughing and respiratory distress.

Lung parenchyma

Functional lung tissue where adult Aelurostrongylus abstrusus resides, causing dyspnea in heavy infections.

Baermann vs Flotation

Larval detection (Baermann) is preferred for motile L1 lungworms, whereas flotation is optimal for heavier, non-motile eggs such as Trichuris.

Pasture management

Control strategy involving separation of infected and susceptible animals, rotational grazing, and preventing horse-donkey mixing (D. arnfieldi) or snail/earthworm exposure.

Heavy vs light infection

Light burdens often asymptomatic; heavy burdens produce clinical signs like cough (lungworms) or hemorrhagic diarrhea (whipworms).