They cause round worm infection, or nematodiasis or parasitic gastro-enteritis The round worms contribute major economic loss in livestock production in the world. They are generally round in cross section, cylindrical, pointed at either ends and have smooth white cuticle. Each individual worm is male or female. They vary in length from 1 mm to 0.5 m. Their body structure comprise: The alimentary canal which starts with the mouth and is followed by the intestines and ends in the rectal opening near the tail. The worm feed through the mouth and pass the feed to the intestines where nutrients are absorbed through the intestinal wall. The reproductive organ of the male worm consists of along tube through which the spermatozoa are pumped. The female worm has the ovary, uterus and others at the same position as that of male. Male worms are assisted in copulation by the spicules which they use for attachment to the female. The spicules also direct the flow of sperms. In all cases, the male worm is smaller than the female.

In the direct life cycle, eggs hatch on the pastures into free living larvae which enter the host via the mouth or through the skin. In some cases, the eggs are picked by the host. In the in-direct life cycle, the eggs hatch into larvae then the larvae enters the intermediate host. Then the intermediate host is eaten by the final host. Sometimes, the eggs may be ingested by the intermediate host which is later taken by the final host. The larvae may as well penetrate through the skin of the host and later sucked by blood sucking intermediate host inside which they develop. The final host will then become infected by the bite of the intermediate host. In the life cycle of round worms, the intermediate host is always an invertebrate.

Is a type of round worm which occurs in the intestines of cattle and is present in most tropical countries. The worm has a thin translucent cuticle. Infection is more serious in calves than in mature cattle. Prenatal infection is very common. The worm has a direct life cycle whereby the eggs are swallowed and hatch inside the host. The larvae penetrates the intestinal wall and migrates to other tissues of the host especially the lung via the blood stream. The larvae would be coughed and then is reswallowed and then reenters then intestines. The larvae moult and become adult worms in the intestines where they produced eggs.

This is also called the large stomach worm. It is a common stomach worm of cattle and other ruminants. It is mainly found in the abomasums. The worm is distributed all over the world. It has a direct life cycle whereby the eggs are passed each day by worm and cab be observed in feaces. The larvae are ingested by the host and migrate in blades of grass when the grass is wet. Infective larvae can survive for several weeks in pasture under suitable climatic conditions. After the larvae are ingested by the host, they settle in the mucosa of the abomasums and pass through the fourth larval stage and become adult. The adult worms mate and the female worm pass eggs in the feaces of the final host.

There are several species of this worm widely spread in the tropics. The worm is brownish, pinkish in colour and is found in the abomasums and small intestines of cattle and other species of domestic animals including human. They have a direct life cycle similar with Haemonicus contortus. Infective larvae are ingested and settle in the alimentary canal of the host.

These are small and red colored worms found in the small intestines of most ruminant animals. They have a direct life cycle similar with Trichostrongilus.

They are mainly found in the abomasums and occasionally in the small intestines of ruminants. They have a dire ct life cycle and are able to survive longer outside the host even under harsh conditions.They normally infect pasture during the onset of the long rains.

They are found in the small intestines of ruminant animals. The eggs develop outside the host and the larvae hatch at the infective stage. Te larvae develop to maturity inside the host.

They are also known as the large mouthed bowel worms. They are found in the colon of most ruminants. They have a direct life cycle and infection of the host is by ingestion of the infective larvae. They larvae penetrate and embed in the wall of the colon. The adult worm passes eggs in feaces of the host.

However little the amount of worms may be, the host animal will appear stunted and emaciated due to competition on nutrients by the parasites.

Gastro enteritis sings are common in the species of worms which affect the intestines and bronchitic signs would appear in the worms which affect the lungs. The bronchitic symptoms would be accompanied by coughing. In almost all cases of round worm infestation, the symptoms would be more pronounced in calves than older animals. Death would occur as a general outcome depending on the worm load and the type of treatment.

Detailed diagnosis should be done by a qualified personnel to identify the type of worm that is in occurrence and should follow the normal diagnostic procedures.