Changes

== The Rhabditids ==

== The Rhabditids ==

[[Image:Strongylus.jpg|thumb|right|150px|''Strongylus'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]

[[Image:Strongylus.jpg|thumb|right|150px|''Strongylus'' - Joaquim Castellà Veterinary Parasitology Universitat Autònoma de Barcelona]]

These are the interface between the parasitic and free-living nematodes. Most spend their whole life-cycles in soil or other inanimate environments, while some are parasitic on plants (such as the potato eel-worm). A few are facultatively parasitic on animals such as ''Pelodera'', which causes dermatitis in dogs and ''Halicephalobus'', which produces ataxia in horses (and other animals) on rare occasions. There is just one regularly parasitic genus in the superfamily: ''Strongyloides''.

These are the interface between the parasitic and free-living nematodes. Most spend their whole life-cycle in soil or other inanimate environments, while some are parasitic on plants (such as the potato eel-worm). A few are facultatively parasitic on animals such as ''Pelodera'', which causes dermatitis in dogs and ''Halicephalobus'', which produces ataxia in horses (and other animals) on rare occasions. There is just one regularly parasitic genus in the superfamily: ''Strongyloides''.

 

 

== ''Strongyloides'' Species ==

== ''Strongyloides'' Species ==

=== General Appearance ===

=== General Appearance ===

*Non-bursate.

*Non-bursate

*Superficially, adult parasitic forms look like trichostrongyloids, but:

*Superficially, adult parasitic forms look like trichostrongyloids, but:

**only females are parasitic

**only females are parasitic

**they have a very long pharynx.

**they have a very long pharynx

 

=== General Life-Cycle ===

=== General Life-Cycle ===

*Egg is small, thin-shelled and contains a larva.

*Egg is small, thin-shelled and contains a larva

*Egg → L1 → L2 → L3 on ground.

*Egg → L1 → L2 → L3 on ground

*L3 → '''either''' → L4 → free-living adult (male or female) on ground

*L3 → '''either''' → L4 → free-living adult (male or female) on ground

**'''or''' → L4 → parasitic adult (female only) in small intestine.

**'''or''' → L4 → parasitic adult (female only) in small intestine

*Infection is by penetration of skin or buccal mucosa.

*Infection is by penetration of skin or buccal mucosa

 

NOTE: in older animals, larvae accumulate under skin → mammary gland → vertical transmission.

NOTE: in older animals, larvae accumulate under skin → mammary gland → vertical transmission.