NEIHPID

Haemonchus contortus (Cobb Cobb) Rudolphi 1803 Back

---

Taxonomy

Nematoda »
        SECERNENTEA »
              Trichostrongylidae (Leiper, 1908) Leiper, 1911 »
                     Haemonchinae (Skrhjabin et Schulz, 1937) Skrjabin et Schulz, 1952 »
                            Haemonchus Cobb, 1898 »
                                    Haemonchus contortus (Rudolphi 1803), Cobb 1898

Synonyms

(Strongylus contortus Rudolphi, 1803; H. cervinus  Baylis et Daubney 1922)

Host

Bos (indicus), Capra (hircus), Ovis (aries)

Habitat

Stomach

Locality

Shillong (Meghalaya), Nongstoin (Meghalaya), Jowai (Meghalaya), Markasa (Meghalaya), Riangdo (Meghalaya)

Description

GeneralÂ

Medium-sized worms, more or less filiform. Anterior tip of body with numerous symmetrically arranged longitudinal cuticular ridges of more or less equal height. Cervical papillae prominent, spine like, almost equidistant from anterior end. Head relatively large, without cuticular dilation. Head papillae inconspicuous. Buccal cavity small, containing inconspicuous slender tooth originating from its base. Oesophagus club shaped. Nerve ring little anterior to cervical papillae.

Male

Live specimens with even reddish colour, distinguishable from females, 15.0-18.0 mm in length, 0.24-0.29 mm in maximum width. Bursa very well developed, with large symmetrical lateral lobes, small dorsal lobe placed symmetrically on left side of median line; ventro-ventral and latero-ventral rays fused proximally, separated distally; externo-dorsal long, thin, arising separately from dorsal ray, curving slightly dorsally; dorsal ray stout, bifurcated each limb bi-digitate taking its origin from left side near externo-dorsal ray; medio-lateral and postero-lateral thicker than other lateral rays; antero-lateral more or less straight; widely divergent from other two lateral rays; latter parallel, curved dorsally. Pre-bursal papillae close to bursa, not prominent. Spicules relatively short, thick, unbranched, dark brown, each provided with small barb on its outer surface. Gubernaculum present, its edges not so distinct.

Female

Both linguiform and knobbed phenotypes occurring in single population. Body 18.0-26.0 mm in length, 0.25-0.34 mm in maximum width. Tail slender, sharply pointed, bearing a pair of papillae just near its tip. Vulva situated in posterior part of body, covered by prominent flap, projecting caudally (linguiform); in few specimens instead of a flap, a reduced small knob-like structure present at opening of vulva (Knobbed). Vagina small, runs anteriorly from vulva. Eggs segmented, thin shelled, 0.05-0.069 x 0.02-0.04 mm.

Remarks

Variations in the shape of the vulvar region were noted in a few specimens; the same was linguiform with a flap in some and in others knob-like and/or not as conspicuous as noted in the majority of the worms.

Baylis and Daubney (1922) recorded female specimens only (though one male specimen, too, but badly damaged) from spotted deer (Cervus axis) and described the same under the name Haemonchus cervinus. Whereas Le Roux (1929) and Das and Whitlock (1960) considered H. cervinus as a species inquirendum due to the absence of male's description, Baylis (1936a) and (Gibbons,1979) regarded it as synonym of H. contortus.

H. contortus has been reported from an array of hosts including man and a fresh water fish Wallago attu by Sahay (1966) in India. Vulvar configuration in H. contortus populations has been considered to be of taxonomic significance and a variety of sub-species were described by several workers principally on the basis of variations in the morphology of the vulvar region. H. contortus populations in sheep and goats from Orissa were described as var. utkalensis (Das and Whitlock 1960). Fotedar and Bambroo (1965) added H. contortus var. kashmirensis from Kashmir. Similarly the forms collected from sheep at Bangalore were designated as var. bangalorensis by Rao and Rahman (1967). However, Gibbons, (1979) considered the earlier two as synonym of H. contortus and the latter as species inquirendum.

In the females of H. contortus three phenotypes have been reported in India (Sood,1981) : these include linguiform, knobbed and smooth. Sood and Kaur (1976) found a greater percentage of knobbed and less of linguiform females from Ludhiana (Punjab). Rao and Rahman (1967), however, found large number of linguiform and less of knobbed forms in sheep from Bangalore (Karnataka). According to Sood (1981) variations in vulvar form among the various populations are due to geographical and climatic factors. Daskalov (1972, 1974) asserted that the host species is largely responsible for this phenomenon and further suggested it to be associated with the reproductive activity of the mature forms. He thus concluded that the vulvar flaps are rather age related and have no taxonomic value. Gibbons, (1979), in view of the dependence of vulvar configuration on several factors, stated that these cannot be relied upon for specific differentiation and rejected the validity of subspecies of Haemonchus.

The buccal tooth and the gubernaculum could not be seen distinctly in many of the specimens examined in the present study. Meghalaya forms a new locality record for this species.

Helminthological collections record

NEHU/Z - NM/18

References

Baylis, H. A. and Daubney, R.(1922) Report on the parasitic nematodes in the collection of the Zoological Survey of India. Memories of the Indian Museum, Calcutta. 7:pp 263-347.

Le Roux, P. L. (1929). A preliminary report on three members of the genus Haemonchus Cobb, 1898 from antelopes in South Africa, 15th Annual Report of the Director of Veterinary Services, Union of South Africa. pp 451-463.

Das, K. M. and Whitlock, J. H (1960) Subspeciation in Haemonchus contortus (Rudolphi, 1803). Nematode: Trichostrongyloidea. Cornell Veterinarian. 50:pp 182-197.

Baylis, H.A. (1936a) The Fauna of British India including Ceylon and Burma. Nematoda Vol. I (Ascaroidea and Strongyloidea). Originally published by Taylor and Francis, London (reprinted edition : Today

Gibbons, L. M. (1979). Revision of the genus Haemonchus Cobb,1898 (Nematoda: Trichostrongylidae). Systematic Parasitology. 1:pp 3-24.

Sahay, U. (1966). The accidental occurrence of Haemonchus contortus Cobb, 1898 (Trichostrongylidae, Nematoda) in the stomach of Wallago attu. Japanese Journal of Medical Sciences and Biology. 19: pp 509-510.

Foteder, D. N. and Bambroo, N. (1965). On a new trichostrongylid nematode from sheep in Kashmir. Kashmir Science. 2:pp 136-141.

Rao, N. S. K. and Rahman, S. A. (1967). The vulval flap formula of Haemonchus-contortus from local sheep. Mysore Journal of Agricultural Sciences. 2: pp 128-132.

Sood, M. L. (1981). Haemonchus in India. Parasitology. 83:pp 639-650.

Sood, M. L. and Kaur, R. (1976). Studies on vulvar configurations in Haemonchus contortus (Rud, 1803) from goats at Ludhiana, India. Rivista di Parassitologuica. 37:pp 13-33.

Daskalov, P. V. (1972). Haemonchus contortus : factors determining the polymorphism of linguiform females. Experimental Parasitology. 32:pp 364-368.

Daskalov, P. V. (1974). On the problem of the species and the intraspecies sub-divisions in Helminthology (Abstract) In: Third International Congress of Parasitology Munich, 25-31st August, 1974, Proceedings Vol. I No.4. Vienna, Austria : FACTA Publications . pp 470-471.