Page 175 - The Veterinary Laboratory and Field Manual 3rd Edition

144 Susan C. Cork and Mani Lejeune

are infected by ingestion of the L3 from pas- hardly visible to the naked eye. They cause
ture, exsheathment of L3 occurs in the rumen diarrhoea, loss of body condition and infected
and further development occurs in the lumen animals go off their feed. Disease associated
of an abomasal glands. The entire life cycle of with Cooperia spp. is commonly seen in young
the parasite may take as little as three weeks ruminants.
if conditions are favourable. In some cases • ‘Hookworms’ (Ancylostoma sp. and Bunostomum
the L4 may become arrested in development sp.). Red in colour with teeth or cutting
and only progresses to the L5 adult stage after plates in the ventral margin of buccal capsule.
4–6 months (hypobiosis). Not all anthelmin- Hookworms are very vigorous blood suckers
tics are effective against the arrested stages of causing anaemia, loss of condition and hypo-
Ostertagia sp. Diagnosis is based on identifi- proteinaemia with associated swelling under
cation of typical eggs in the faeces but blood the jaw (oedema) due to the collection of fluid.
samples may also be useful to assess the Uncinaria sp. and Ancylostoma sp. are the canine
3
degree of abomasal damage. hookworms. Infection occurs by penetration
Owing to the fact that ovine ostertagiasis of the skin by the infective larvae (L3). These
is not caused by O. ostertagia it is generally hookworms may infect humans causing a skin
safe to rotationally graze cattle and sheep rash but the infection does not become pat-
together. Mixed grazing reduces the burden ent. Control requires attention to hygiene.
of species specific parasites. Periodic use of Bunostomum sp. occur in the intestine of cattle,
fields for crops may also be beneficial to avoid sheep and other ruminants.
overutilization of ‘problem’ areas where • ‘Long necked worm’ (Nematodirus spp.).
previous egg contamination has occurred. Similar in size to the hookworm but with a
• Stomach or ‘hair worm’ (Trichostrongylus sp.). curled up neck. Nematodirus battus is espe-
These are the smallest of stomach worms. cially important as a cause of severe diarrhoea
This parasite is a common cause of enteri- in young sheep. Other species, for example,
tis and weight loss in various host species N. spathiger, can infect cattle as well as sheep
(cattle, sheep, goats, horses and rabbits). and goats.
Trichostrongylus axei lives in the abomasum of • Capillaria sp. Occur in the small intestine
ruminants and in the stomach of horses and (and oesophagus) of mammals and birds.
pigs. T. colubriformis occurs in most ruminants The worms can cause severe diarrhoea and
and T. capricola and T. vitrinus occur in sheep weight loss. Effective control requires identi-
and goats. Mixed grazing of horses and rumi- fication of the parasite (Figure 3.22). Recent
nants may lead to the buildup of T. axei. taxonomic classification has led to members
• ‘Stomach worm’ (Hyostrongylus sp.) – H. rubi- of this genus being placed under some newly
dus causes severe gastritis in pigs. created genus.
• ‘Stomach worm’ (Habronema spp.) – causes • Trichinella spiralis. This nematode worm is
gastritis in horses and donkeys. The life cycle zoonotic and is the cause of trichinosis. There
involves Muscid flies as the intermediate are both sylvatic and domestic life cycles. The
host. adult worms can occur in the small intestine
of rodents and other omnivores. The worms
migrate to muscle tissues. The infective lar-
Nematodes found in the small intestine
vae present within cysts in muscle tissue may
• ‘Bankrupt worm’ (Cooperia punctata, C. oncophora, then be consumed by pigs, bears, humans and
Cooperia spp.). These very small worms are other omnivorous hosts. Death in humans

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