Ostertagia
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This article is still under construction. |
| Ostertagia spp. | |
|---|---|
| Kingdom | Animalia |
| Phylum | Nematoda |
| Super-family | Trichostrongyloidea |
| Genus | Ostertagia |
| Species | O. osteragi |
Overview
Ostertagia spp. are small bursate nematodes that parasitse the gastrointestinal tract of mammals and birds. These species are responsible for mortality and morbidity in a number of ruminants especially O. ostertagi which is widely considered the most important parasite of cattle.
Ostertagia ostertagi
| Also known as: | O. ostertagi
O. lyrata |
These worms are found throughout the world, and are considered the most important parasite of cattle, especially in temperate regions. The primary host is cattle but they can also be found in deer and goats occasionally.
Identification
The adult O. ostertagi worms are thread like, reddish worms with short buccal cavities. The males can measure 6-8mm, the females 8-9mm. There are several cuticle morphologies used to identify these worms at a microscopic level. The head of both sexes is square and the adults have 16 gut cells. The anterior cuticle has transverse striations, where as the rest of the body has longitudinal ridges. Male spicules are brown and curved, they split at the posterior to form 3 hooks. In the females the tail tapers to a fine end with a rounded tip and the vulva is covered by a cuticular flap.
Life-Cycle
O. ostertagi have a direct, non-migratory life-cycle. Calves are infected following ingestion of L3 that under moist conditions migrate from the faeces to pasture. The larvae are swallowed, pass through the forestomachs and develop in the abomasal gastric glands to the L4 stage, emerging as adult (L5) worms after nearly 3 weeks. Adult female worms then produce strongyle eggs which are passed out with the faeces. The prepatent period is 16 - 23 days (5-6 months if arrested at early (E)L4 stage).
Epidemiology and Pathogenesis
The epidemiology of O.ostertagi is complex due to the hardyness of the eggs in the environment and the ability of larvae to hyperbiose. Clinical infections of this worm are termed Ostertagiosis, the clinical page explains the pathophysiology and the epidemiology of the disease.
Teladorsagia (Ostertagia) circumcincta
This is a major abomasal worm of sheep and goats, that is found worldwide.