Roundworms

Clinical picture of Lung Worm Disease

Of the helminths which parasitise in man and animal, the nematodes are those which are of the greatest economic importance worldwide. This is due to the tremendous variety of species and also to the special ontogenetic position occupied by this class of animals.

The damage which the nematodes inflict on the infested hosts ranges from organic lesions via anaemias, disturbances of the ion balance, gastric and enteric dysfunctions to major interferences with the hormonal processes and the immune mechanisms. However, the main features of the clinical processes in our domestic animals are usually diarrhoeas, pulmonary complaints (lung-worms, migrating larvae: cough, pneumonias, deaths), and reduced weight gains, which suggests that the chronic insidious forms are often of greater economic and epidemiological importance than the acute helminthoses (which are predominantly encountered in young animals). Phenomena such as colics and aneurysms (horses), developmental disorders, reduced milk production, poor wool quality, inferior carcase grades as well as metabolic diseases and sterility are frequent consequences of worm infestation. The resulting losses in profitability are substantial and highly relevant for the individual farm and the economy of the country as a whole.

Clinical Signs in Cattle

Lungworm (Dictyocaulus viviparus)

Lung affected by Dictyocaulus viviparus

Depending on constitution, age and immunity status of the cattle. infestation with Dictyocaulus runs a hyperergic or anergic course.

Beginning on the 7th day of infection, coughing, increased respiratory rate, fever, oedemas and emphysemas are the cardinal symptoms. Young animals tend to be more severely affected than old animals. Secondary bacterial pulmonary infections are quite common.

Brown stomach worm (Ostertagia ostertagi)

D.viviparus. Size comparison to match stick

Destruction of the gastric glands in the abomasum Ieads to digestive disturbances, Ioss of blood protein. diarrhoea and severe emaciation. The condition known as "summer ostertagiasis" affects mainly calves in their first grazing season: severe diarrhoea, dehydration, cachectic conditions resulting in death.

"Winter ostertagiasis" occurs primarily in young stock during the spring. When the dormant larvae which have hibernated inside the animal (hypobiotic larvae) reach sexual maturity, they cause severe diarrhoea, cachexia and substantial weight losses.

Wire worm (Haemonchus contortus)

Trichostrongylus spp in intestinal lumen

Gastritis leads to poor feed conversion, developmental disturbances and anaemias.

Hair worm (Trichostrongylus axei and Cooperia oncophora)

Changes in the pH of the abomasum, diarrhoea, inappetence, and in some cases consid-erable emaciation are the principal clinical symptoms

Thin necked intestinal worm (Nematodirus spp.)

Affects mainly young animals towards the end of the prepatent period: Diarrhoea, inappetence and weight loss are the clinical symptoms.

Hookworm (Bunostomum spp.)

Infection occurs mainly percutaneously. Via a migration through the body the hookworms reach the duodenum and the jejunum where they suck blood. Young cattle are more frequently affected. Progressive anaemia and heavy weight losses are the most obvious symptoms. Hookworm infestation occurs often in conjunction with trichostrongylidosis.

Nodule worm (Oesophagustomum spp.)

A characteristic feature is the nodule formation by infective larvae in the mucosa of ileum and colon. In re-infections the clinical symptoms increase considerably: diarrhoea, intestinal haemor-rhages and anaemia are the conspicuous symptoms of the acute form of the disease. Concomitant bacterial infections can lead to peritonitis.

Roundworm (Toxocara (=Neoascaris) vitulorum)

Infection of the calves takes place galactogenically. The development of the ascarids then proceeds without migration through the body. Severely inhibited weight gains and diarrhoea are the most obvious clinical symptoms In very heavy infestation intestinal occlusion and perforation of the intestine can occur.

Clinical Signs in Sheep and Goat

Thread worm (Strongyloides papillosus)

Worm-parasited sheep

Migrating larvae damage the lungs, thus activating bacterial and viral infections dysponea, cough, diarrhoea, reduced wool quality. Mainly in young animals, Deaths quite frequent. Often aggravated by coccidiosis.

Lungworms (Dictyocaulus filaria, Muellerius capillaris, Protostrongylus spp., Cystocaulus ocreatus, Neostrongylus spp.)

Massive infection of bronchi with sheep lung worm (D.filaria

Invasion of the bronchi dry cough, bronchitis emphysemas. Pneumonias due to secondary bacterial infections not uncommon.

Species-specific brood clusters and worm nodules spread over both lungs (Muellerius) cause chronic bronchopneumonias. With Protostrongylus, transplacental transmission is possible. Infection of grazing animals is only possible via an intermediate host (snail).

Cystocaulus is highly pathogenic in young animals. Considerable weight losses and greatly reduced fattening performance are the results. - The same symptoms, but less pronounced, are observed in Neostrongylus infestation.

Hair worm (Trichostrongylus colubriformis)

Wire worm (Haemonchus contortus) in abomasal mucosa

Acute outbreaks in the summer, ruminal paresis, diarrhoea and severe blood protein loss: chronic disease, poor food intake, weight losses and reduction ot wool quality.

Wire worm (Haemonchus contortus)

Female H.contortus shedding eggs

As a result of large egg production, rapid contamination of the pastures. At the beginning of winter hypo-biotic larvae in the abomasum. - Clinical picture characterised by gastritis and ulcers as well as changes in the pH of the gastric juice to almost a neutral level:

as a result considerable digestive disturbances. In addition there is fever, tachycardia, anaemia, swollen Iymph nodes and reduced oestrus. Development of immunity is very slow. In addition there is fever, tachycardia, anaemia, swollen Iymph nodes and reduced oestrus. Development of immunity is very slow.