Adult stages of nematodes

ADULT STAGES OF NEMATODES

Parascaris equorum (Equine ascarids)

(Male : 15-28 cm, Female : 50 cm)

  • Host : Horses
  • Location : Small intestine
  • Head end
    • The distinct wider head separated by a prominent neck.
    • Three prominent lips.
    • Three inter labia in between the lips.
  • Male tail end
    • A pair of equal spicules.
    • The cuticle of the worm is very thick and hence not fragile.

Ascaridia galli (Large round worm of poultry)

(Male : 5-7.5 cm; Female : 7.5-11.5 cm)

  • Host: Poultry
  • Location: Small intestine
  • Head end
    • Three large lips.
    • Club shaped oesophagus without posterior bulb.
  • Male tail end
    • Caudal end is provided with narrow alae.
    • Many papillae are present at the hind end and are short and sessile.
    • Spicules are equal and similar.
    • A precloacal sucker present.

Heterakis gallinae (Caecal worm of poultry)

  • Host: Fowls, turkeys
  • Location: Caecum
  • Head end
    • The three lips, well developed cervical alae extending some distance down the sides of the body.
    • Oesophagus possess a distinct posterior bulb containing valvular apparatus.
  • Mail tail end
    • Well developed caudal alae.
    • Pedunculated papillae.
    • A Pre-cloacal sucker present .
    • Un equal and dissimilar spicules; the right one is slender and very long, while the left is alate, broad and short.

Subulura brumpti

(Male : 6-10mm; Female 9-18 mm)

  • Host: Fowls, turkeys and guinea fowls
  • Location: Caecum
  • Intermediate host: Beetles – Dermestes sp, Opatroides sp, Alphitobius sp
  • Head end
    • Lateral alae.
    • Small buccal capsule with 3 teeth at its base.
    • Oesophagus with a small swelling posteriorly followed by a deep constriction and a spherical bulb.
  • Male tail end
    • Lateral alae.
    • Precloacal sucker is an elongate slit, surrounded by radiating muscle fibres.
    • Spicules equal, alate.

Oxyuris equi (Pin worm of horse / False whip worm)

  • Male : 0.9-1.2 cm; Female : 4-15 cm
  • Host: Equines
  • Location: Large intestine
  • Head end
    • Inconspicuous lips.
    • Hour-glass shaped oesophagus.
  • Male tail end
    • Truncated.
    • Caudal alae supported by papillae.
    • Single pin-like spicule.

Strongyloides spp.

  • Host: Cattle, buffaloes, sheep and goats
  • Location: Small intestine
  • Small thin worms, indistinct lips.
  • Long filariform oesophagus.
  • Uterus contains a single row of eggs.
  • Caudal bursa of Strongyle sp.
  • Presence of three lobes - one dorsal and two lateral.
  • Dorsal lobe with dorsal ray and externo dorsal ray.
  • Lateral lobe with three lateral rays - postero, medio and antero-lateral rays.
  • Two ventral rays - ventro-ventral and latero-ventral.
  • Two equal spicules.

Strongylus vulgaris (Red worm of horses)

Male : 1.4-1.6 cm; Female : 2-2.4 cm

  • Host: Equines
  • Location: Large intestine
  • It causes aneurysm of anterior mesenteric artery.
  • Head end
    • A large and deep buccal capsule.
    • Mouth opening is surrounded by external and internal leaf crowns.
    • A dorsal tooth with bifid tip (ear shaped) is found at the base of the buccal capsule.
    • The thickening of the internal wall of the buccal capsule forms the dorsal gutter.

Chabertia ovina

Male : 1.3-1.4 cm; Female : 1.7-2.0 cm

  • Host: Sheep and goats
  • Location: Colon
  • Head end
    • Anterier end is curved slightly.
    • Large bell shaped buccal capsule opens anterior-ventrally.
    • Oral aperture is surrounded by a double row of small cuticular elements representing leaf-crowns.
    • Cephalic vesicle is inflated slightly.
  • Male tail end
    • Bursa is well developed.
    • Spicule is 1.3-1.7 mm long with a gubernaculum.

Oesophagostomum columbianum (Nodular worm of sheep)

Male : 1.2-1.6 cm; Female : 1.5-2.2 cm

  • Host: Sheep and goats
  • Location: Large intestine
  • Disease caused: Pimply gut
  • Head end
    • The cuticle at the anterior end is slightly swollen and cone shaped, separated from rest of the body by a constriction forming 'mouth collar’.
    • Buccal capsule is shallow.
    • External and internal leaf crowns present.
    • A groove at the oesophageal region (cervical groove) is present on the ventral aspect only.
    • The cuticle anterior to the cervical groove is slightly inflated to form a cephalic vesicle.
    • Two finger like projections (cervical papillae) found just below the cervical groove.

Syngamus trachea (Gape worm of poultry)

Male : 0.2-0.6 cm; Female - 0.5-4 cm

  • Host: Fowls
  • Location: Trachea
  • Transport hosts: Earth worms, slugs, snails and several arthropods
  • Worms are blood red in colour when fresh.
  • The adult male and female are found in permanent copulation.
  • Male is small and slender and female is large and stout.
  • Buccal capsule is cup shaped.
  • Vulva in the female is in the anterior third of the body and is connected by the bursa of male while in copulation.

Agriostomum vryburgi

Male : 9-11 mm; Female : 13.5-15.5 mm

  • Host: Zebu and Ox
  • Location: Small intestine
  • Head end
    • Buccal capsule opens antero-dorsally and is relatively shallow.
    • A very large oesophageal funnel which contains 2 small subventral lancets.
    • Oral margin is provided with 4 pairs of large teeth and a rudimentary leaf crown.
  • Male tail end
    • Spicules equal.
    • Gubernaculum present.

Bunostomum phlebotomum (Hook worm of cattle)

Male : 1-1.8 cm; female : 2.2-2.8 cm

  • Host : Cattle
  • Location: Small intestine
  • Morphology similar to B. trigonocephalum.


Ostertagia ostertagi (Brown stomach worm)

Male : 6.5-7.5 mm; Female : 8.3-9.2 mm

  • Host: Cattle
  • Location: Abomasum
  • Head end
    • Cuticle of anterior end slightly inflated and transversely striated.
  • Male tail end
    • Spicules are pigmented brown, short and end in 2 or 3 processes.
  • Female tail end
    • Vulva covered with a short anterior flap.

Dictyocaulus filaria (Lung worm of sheep)

Male: 3-8 cm; Female: 5-10 cm)

  • Host: Sheep and goats
  • Location: Larger bronchioles
  • Head end
    • Simple oral opening is guarded by four small lips.
    • Absence of buccal capsules.
  • Mail tail end
    • Spicules are equal, stout and dark brown in colour and are “boot or sock shaped”.

Muellerius capillaris

Male: 1.2-1.4 cm; female: 1.9-2.3 cm

  • Host: Sheep and goats
  • Location: Lungs
  • Intermediate host: Slugs, snails
  • Male tail end
    • The posterior end is spirally coiled and there is no bursa.
    • A number of papillae surround the cloacal opening.
    • Spicules are 0.15 mm long and curved.
    • Each consists of a proximal half which is alate and two distal serrated arms ending in sharp points.

Protostrongylus rufescens

  • Host : Sheep, goat and deer
  • Location: Small bronchioles
  • Worms are slender and reddish in colour.
  • Bursa is short and strengthened dorsolaterally by a chitinous plate on either side.
  • Spicules are long tubular with broad membranous expansions.

Draschia megastoma (Stomach worm of equines)

  • Male : 0.7-1 cm; female 1.1-3 cm
  • Host: Equines
  • Location: Stomach (tumours)
  • Intermediate host: Musca domestica
  • Head end
    • Head is prominent and is separated from the body by a constriction forming the shoulders.
    • Two trilobed lateral lips present around mouth.
    • Pharynx is funnel shaped.

Gongylonema pulchrum (Gullet worm of ruminants)

Male : 6.2 cm; Female : 14.5 cm

  • Host: Sheep, goats, cattle, pigs, buffalo, less in horse, camel,donkey, wild boar also man
  • Location: Oesophagus embedded in zigzag fashion in mucosa or submucosa.
  • Head end
    • Small inconspicuous lips.
    • Short buccal capsule.
    • Anterior part of the body bears a number of rounded cuticular cordons arranged in rows on both the sides.
    • Cervical alae well developed.

Onchocerca indica

Male : 3.0-5.3 cm; Female : 14-19 cm

  • Host: Cattle and buffaloes
  • Location: Subcutaneous tissues especially brisket and hind limbs
  • Intermediate host: Culicoides sp and Simulium sp.
  • Disease : “Worm nest”
  • Head end
    • Slender worms and lie tightly coiled in tissue nodules.
    • Cuticle is transversely striated and bears characteristic spiral thickenings.
    • Microfilariae are not sheathed and 240-280 m.
  • Tail end
    • Tail is curved ventrad.
    • It bears small lateral alae and six to nine papillae on either side.
    • Spicules are unequal in length.


Dracunculus medinensis (Guinea worm or Medina worm)

Male : 1.2-4 cm; Female : 32-400 cm (gravid)

  • Host: Human beings
  • Location: Subcutaneous tissues
  • Gravid female
    • Long and thick worm.
    • Dome shaped anterior end.
    • Uterus distended and filled with larvae.
    • Coiled end terminates in a small conical process.
    • Vulva atrophied in gravid female.
    • Viviparous parasite.

Genus Trichinella

  • Small worm, body nearly uniform throughout becoming slightly thicker posteriorly.
  • Male do not possess spicule.
  • Vulva is situated at about the middle of the oesophagus.
  • Worms are ovoviviparous.
  • Larval and adult stages are seen in the same host.

Trichuris ovis (Whip worm)

Male : 5-8 cm; Female : 3.5-7 cm

  • Host: Sheep, goats and cattle
  • Location: Caecum and colon
  • Head end
    • Simple mouth without lips.
    • Long oesophagus lined by single layer of cells (stichosome).
    • The posterior part is thicker, while the anterior end is long and slender - looks like a whip.
  • Male tail end
    • Posterior end is coiled – inrolled.
    • A single spicule is provided with a spiny sheath and protruding out and ending in a point.
    • Spines are also present in the bulbous portion.
  • Female tail end
    • The hind end is not coiled.
Last modified: Saturday, 24 September 2011, 9:14 AM