Adult stages of nematodes contd...

ADULT STAGES OF NEMATODES

Ascaris suum (Large round worm of pig)

  • Host: Pig and man
  • Location: Small intestine
  • Head end
    • Has a wide head with distinct neck and prominent shoulders.
    • Mouth is surrounded by three prominent lips.

Parascaris equorum

(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.

Toxocara canis (Arrow headed worm)

  • Host: Dogs
  • Location: Small intestine
  • Head end
  • Anterior end is bent ventrally and hence the parasite takes 'S' shape with three lips.
  • Prominent cervical alae with coarse striations which give the appearance of arrow head to the worm.
  • Oesophagus with small posterior bulb.

T. canis (Male tail end)

  • Caudal alae well developed.
  • Digitiform appendage at the terminal end of caudal alae.
  • A pair of subequal, alate spicules.

Toxascaris leonina

(Male : 2-7 cm, Female : 2-10 cm)

  • Host: Dog and cat
  • Location: Small intestine
  • Head end
    • The three lips.
    • The finely striated cervical alae.
    • Absence of the bulb of oesophagus.

Toxocara vitulorum (Large intestinal worm of cattle and buffalo)

(Male : 17.5-25 cm; Female 15-30 cm)

  • Host: Cattle and buffalo especially in calves
  • Location: Small intestine
  • Body soft with translucent in appearance, cuticle thin, transparent, fragile.
  • Oesophagus has a posterior granular ventriculus.

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
    • The three 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.

Oesophagostomum radiatum (Nodular worm of cattle)

  • Host: Cattle and Buffaloes
  • Location: Large intestine
  • Head end
    • Prominent rounded mouth collar.
    • Well-developed cephalic vesicle, which is constricted behind its middle.
    • The cervical groove encircles the entire circumference of the oesophageal region.
    • Cervical papillae are placed lower down the cervical groove.
  • Male tail end
    • The dorsal ray cleft for about half the length with the branches having a short lateral twig.
    • Two equal alate Spicules.

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.

Ancylostoma caninum (Hook worm of dogs)

Male : 1-1.2 cm; Female : 1.4-1.6 cm

  • Host: Dog and cats
  • Location: Small intestine
  • Head end
    • Anterior end is bent dorsally and the mouth opens anterodorsally.
    • The buccal capsule is deep and bears 3 pairs of well developed teeth on the ventral margin.
    • A pair of triangular dorsal teeth present in the depth of the buccal capsule.
  • Male tail end
    • Well developed bursa with symmetrical dorsal lobe.
    • Dorsal ray is bifid, each being tridigitated.
    • Equal similar spicule, distinct gubernaculum.

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 trigonocephalum (Hook worm of sheep and goats)

Male : 1.2-1.7cm ; female : 1.9-2.6 cm

  • Host: Sheep and goats
  • Location: Small Intestine
  • Head end
    • The anterior end is dorsally bent.
    • Buccal capsule is well developed and bears on its ventral margin a pair of chitinous cutting plates.
    • A single well developed dorsal cone with a pair of sub ventral lancets is seen at the base of the buccal capsule.
  • Male tail end
    • Well developed lateral lobes.
    • Small asymmetrical dorsal lobe.
    • Alate and equal spicules.

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.

Stephanurus dentatus (Kidney worm of swine)

Male 20-30 mm; female 30-45 mm

  • Host : Pig
  • Location : Perirenal fat; pelvis of kidney, ureter and erratic parasites in liver, thoracic organs and spinal cord
  • Head end
    • Stout worms.
    • Cuticle transparent.
    • Cup shaped buccal capsule, thick walled, with 6 teeth at its base.
    • Its rim bears a leaf crown of small elements and six internal cuticular thickening (epaulettes).
  • Male tail end
    • Equal spicules.

Haemonchus contortus (Stomach worm or Barber's pole worm or Wire worm of ruminants)

Male : 1-2 cm; female : 1.8-3 cm

  • Host: Sheep, goats, cattle and buffaloes
  • Location: Abomasum
  • Head end
    • Small funnel shaped buccal capsule with a small dorsal lancet.
    • Cuticle transversely striated with longitudinal ridges (not prominent).
    • Pair of cervical papillae very near the anterior end.
  • Male tail end
    • The bursa has well developed lateral lobes supported by the long slender rays.
    • The dorsal lobe is asymmetrical and is supported by inverted 'Y' shaped dorsal ray.
    • Spicules are equal, short and end in knobs and are provided with barbs near the tip.
  • Female tail end
    • The vulva is covered by a cuticular flap-vulval flap.
    • In some worms it is large and tongue like (linguiform type).
    • In others, the cuticular flap is reduced to a small knob (Knob type).

Mecistocirrus digitatus

Male: 1.6-3.1 cm; female : 1.9-4.3 cm

  • Host: Cattle, buffaloes, sheep and goats
  • Location: Abomasum
  • Head end
    • Very prominent transverse striations.
    • Prominent cervical papillae.
    • Other characters of H. contortus.
  • Male tail end
    • The bursa has well developed lateral lobes like a pair of pincers.
    • Dorsal lobe is symmetrical with short dorsal ray, bifurcated each with 3 papillary terminations.
    • Spicules are equal, long and slender. They are united together to their whole length with membranous expansion of the tips.

Trichostrongylus axei (Black scour worm)

Male : 0.23-0.44 cm, Female : 0.32-0.6 cm

  • Host: Sheep, cattle, buffaloes, deer and horses
  • Location: Abomasum and anterior duodenum
  • Head end
    • Very slender, microscopic worms.
    • Head is not distinctly marked off.
    • Buccal capsule, teeth, cutting plates and leaf crows absent.
    • Excretory pore is situated on a notch at the anterior end.
  • Male tail end
    • Well - developed bursa especially lateral lobes.
    • Dorsal lobe very small, dorsal ray slender and distally cleft.
    • Characteristic short ventro-ventral ray.
    • Two unequal, dissimilar twisted and spatula shaped spicules (right longer than left).
    • Each spicule has a knob at the proximal aspect and a slender posteriorly directed spine like process on its inner aspect at about the middle.
    • Presence of gubernaculum.

Cooperia curticei

Male : 4.5 - 5.4 mm; Female : 5.8-6.2 mm long

  • Host: Sheep
  • Location: Small intestine
  • Head end
    • Cuticle at the anterior end forms a cephalic swelling.
    • The body cuticle presents longitudinal ridges, which are transversely striated.
  • Male tail end
    • The well developed bursa has a small dorsal lobe.
    • Spicules are short, stout, brownish pigmented and have a ridged wing like expansion at the middle.
  • Female
    • Vulva covered by a flap.

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.

Ostertagia circumcincta

  • Host: Sheep
  • Location: Abomasum
  • Morphological characters are similar to O. ostertagi.

Nematodirus spathiger

Male :10-15 mm; Female 15-23 mm

  • Host: Sheep, cattle and other ruminants
  • Location: Small intestine
  • Head end
    • Filariform anterior portion.
    • Cuticle inflated at anterior end.
    • 14-18 longitudinal ridges on body cuticle.
  • Male tail end
    • Elongate lateral lobe.
    • Covered internally by rounded or oval cuticular boxes.
    • Spicules are long, slender and ending in spoon shaped expansion.

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”.

Dictyocaulus viviparus (Lung worm of Cattle)

Male : 4-5 cm ; female : 6-8 cm

  • Host: Cattle
  • Location: Bronchi
  • It resembles D. filaria but spicule is shorter

Metastrongylus apri (M. elongatus)

Male: 2.5 cm long; female: 5.8 cm

  • Host: Pigs,
  • Location: Bronchi and bronchioles
  • Intermediate host: Earth worms
  • Head end
    • Six small lips or papillae around the oral aperture.
  • Male tail end
    • Bursa is small.
    • The antero lateral ray is large and has a swollen tip.
    • The medio-lateral and postero-lateral rays are fused.
    • The dorsal rays are much reduced.
    • Spicules are filiform and end in a single hook each.

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.

Spirocerca lupi (Oesophageal worm or Gullet worm of dog)

Male : 3-5.5 cm; Female : 5.4-8 cm

  • Host : Dog
  • Location: Oesophagus, cardiac end of stomach, aorta
  • Intermediate host: Coprophagus beetles
  • Transport host: Garden lizards, frogs, mice, chicken
  • Disease: Oesophageal tumour in dogs
  • Head end
    • Hexagonal mouth with 2 trilobed lateral lips.
    • Short funnel shaped pharynx.
  • Male tail end
    • Caudal end is coiled and blunt.
    • Spicules unequal and dissimilar.
    • The male tail bears lateral alae, four pairs and one unpaired median pre cloacal papillae and two pairs of post-cloacal papillae.
    • A group of minute papillae is situated at the tip.
    • Rudimentary gubernaculum.

Thelazia rhodesii (Eye worm or extra ocular worm of cattle)

  • Host: Cattle and buffaloes
  • Location: Lachrymal ducts and conjunctival sac
  • Intermediate host: Musca viscina in India
  • Head end
    • Small buccal capsule with inconspicuous lips.
    • Cuticle bears prominent transverse striations.

Thelazia callipaeda (Eye worm of dog)

Male : 0.45-1.3 cm; Female : 0.6-2 cm

  • Host: Dogs
  • Location: Nictitating membrane
  • Fine, stout, whitish worms.
  • Inconspicuous lips.
  • Buccal capsule is short.
  • Cuticle has fine transverse striations.

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.

Setaria digitata (Peritoneal worm of herbivores)

Male : 4.6 cm ; Female : 6-12 cm

  • Host: Cattle and buffaloes
  • Location: Peritoneal cavity
  • Intermediate host: Mosquitoes
  • Disease: Cerebrospinal nematodiasis / kumri
  • Immature forms are found in central nervous system of horses, sheep and goats
  • Head end
    • Presence of peribuccal ring
    • Prominent notched dorsal and central processes
    • Prominent triangular crescent shaped lateral processes
  • Male tail end
    • The hind end is twisted and is tapering.
    • Spicules are unequal and dissimilar.
    • A pair of finger like lateral processes are present on either side of the tail end.
  • Female tail end
    • Tail ends in a simple button (smooth knob).
    • Two prominent rounded lateral appendages on either side of tail end.

Dirofilaria immitis (Heart worm of dog)

Male : 20 cm; Female : 30 cm

  • Host: Dogs
  • Location: Right ventricle of heart and some times pulmonary artery
  • Intermediate host: Mosquitoes - Culex, Anopheles, Aedes sp
  • Head end
    • Lips absent.
    • Cephalic papillae present.
    • Vulva situated just behind oesophagus.
    • Muscular and glandular portions of oesophagus without a sharp line of demarcation.
  • Male tail end
    • Spirally coiled blunt end.
    • Unequal and dissimilar spicules.
    • Left spicule is long and pointed.
    • Right spicule is short, spatula shaped and blunt caudal alae and papillae present.
  • Female tail end
    • The uterus is filled with larvae.

Microfilaria (Unsheathed)

  • Size : 218-329 x 5.6 m

Parafilaria bovicola

Male : 3 cm; Female : 5 cm

  • Host: Cattle
  • Location: Subcutaneous tissues
  • Disease: Haemorrhagic nodules or haemorrhagic filariosis in cattle.
  • Head end
    • Few elliptical and circular papilliform elevations at anterior extremity.
    • Prominent transverse cuticular ridges.
    • Mouth with two lateral lips.
  • Male tail end
    • Spicules unequal.
    • Caudal alae with pedunculated pre and post anal papillae.
  • Female tail end
    • Vulva close to mouth.

Stephanofilaria assamensis

Male : 2.3-3.2 mm; Female : 6.1-8.5mm

  • Host: Cattle
  • Location: Skin - hump region
  • Intermediate host: M. conducens
  • Disease: Hump-sore in cattle
  • Head end
    • Cephalic end non-striated.
    • Cone shaped.
    • Mouth opening is surrounded by a spiny collar.

Microfilaria (Sheathed)

  • Size : 50 m long

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.

Trichinella spiralis

  • Host: Pig and man
  • Location: Small intestine
  • Disease: Trichinosis
  • Male tail end
    • Claw like appendages at the caudal end.
    • Absence of spicule.
  • Muscle section
    • Numerous cysts are found between the muscle fibres.
    • Larvae are spirally coiled and encapsuled in the lemon shaped cysts.

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.

Trichuris vulpis

  • Host: Dog
  • Location: Large intestine

Dioctophyma renale

  • Host: Carnivores occasionally in pig, horse, cattle and man
  • Location: Kidney and other organs
  • Intermediate host: Lumbriculus variegatus (Annelid)
  • Paratenic host: Fish
  • Largest nematode.
  • Blood red in colour.
  • Male tail end
    • Muscular bell shaped bursa without supporting rays.
    • Single bristle like spicule.
Last modified: Saturday, 24 September 2011, 9:18 AM