Saturday, July 20, 2024

Internal Parasites of Ruminants and Control Measures

A parasite including in ruminants, is a living organism that depends upon a living host for survival. It lives either inside or outside the host and thereby causes discomfort or inefficiency in the productive life of the host. Those that live inside the host are called internal parasite and those outside are referred to as external parasites.

Internal Parasites of Ruminants

Most of the internal parasites including that of ruminant animals are either worms or flukes which are collectively referred to as helminths. They live in the lungs, liver, stomach and the intestines of animals.

1. Round worms

Roundworms found in the gastro-intestinal tracts are called nematodes. The organism that causes the most offensive damage is Haemonchuscontortus or twisted worm.

Others include Ostertagia (brown stomach worm), Trichostrongylus asei and Trichostrongylus vitrinus. They vary in their sizes from tiny thread-like structure of about 5 mm long to over 300 mm.

The worms mate and lay eggs inside the abomasum of the ruminants which are expelled along with the dungs.

They hatch and develop to the larva stage on the pasture where they are picked up by grazing animals.

The larva cannot survive harsh and dry weather but thrive well in moist and warm weather even up to two years. They develop to mature roundworm within twenty-one days from the time the egg was laid.

In the intestine, the worms damage the inner lining so that blood, nutrients and water are lost in the faeces or urine.

Infestation of worm is often accompanied by diarrhea, dehydration and loss of appetite. The implication of this is that nutrients in the feed will be poorly utilized for growth and production purpose.

While sheep and goats suffer from the same species of roundworm, cattle has a different species. Hence sheep and goats can graze together without fear of cross infestation.

Worms are often controlled by developing programmes that will match the seasonal occurrence. Routine drenching with chemicals such as benzimidazole, levamisole and organophosphate is necessary.

The herd should be de-wormed about 6 to 8 weeks after they might have started grazing during the rainy season and repeated two weeks after.

This action is repeated shortly before late rains and the onset of the dry season. The herd must not be allowed to graze infested pasture.

Figure: Life Cycle of Roundworm in Cattle

2. Lung worms

Lungworm is caused by Dictyocaulus filaria or Dictyocaulus viviparus. They infect the lungs of the animal causing a considerable damage to them and the bronchial tube which leads to coughing.

The symptoms are irregular breathing, coughing associated with worms and blood-stained discharge being expelled from the mouth. The infected animal tends to stand in distress on pasture and take little or no interest in grazing. There is also loss of body condition.

The adult lay eggs in the air passages of the lungs where they live. The eggs are coughed up into the back of the throat and swallowed. The eggs then passed through the alimentary canal of the animal and hatched into immature larvae which are expelled along with the dungs on to the pasture.

Animals that are grazing easily pick up the larva, pass them down through the alimentary canal where they infest the walls and find their ways into the blood vessels. They are subsequently carried to the heart and the lungs.

On getting to the lungs, they bore through the tissues of the tiny air space causing a lot of damage. They are at this stage capable of laying eggs which are coughed out to the back of the throat and the cycle is re- started.

Lungworms are controlled by the use of appropriate anthelmintics as may be advised by the veterinarian.

However, the use of live oral vaccine as a routine immunisation before turning the animals to pasture have been reported in Northern Europe only. This is very important for young animals like calves.

3. Tapeworms

Tapeworms (gestoda) belongs to the phylum platyhelminthes and are related to the flukes (trematodes). They have segmented bodies that are tape-like and also host specific. They infect both animals and human.

The adult tapeworm cause fewer problems especially in animals under poor plane of nutrition. They are also non-pathogenic. However, the larva of some specie travel to the brain or the spinal cord and cause nervous disorder called coenurosis.

When a dog eats the carcass of infected sheep or ruminants, the cysts develop into tapeworm inside the intestine of the dog. The matured worm lay eggs that passed along with the dog’s faeces.

Grazing ruminants pick the eggs while on pasture which hatches and moves into the blood vessels and eventually found their way to the brain or the spinal cord. If dog eats carcass of infested ruminants, the cycle is re-started.

For a control measure and to break the cycle, dogs must not be allowed to eat the carcass of infested animals. Benzimidazole can be used for treatment.

Internal Parasites of Ruminants
Figure: Life Cycle of Tapeworm in Goats

4. Trypanosomiasis

This is a protozoan infection which affect both man and animals especially ruminants. It is caused by trypanosomes parasites which could be trypanosoma vivax, or Trypanosoma brucei or Trypanosoma evansi.

They invade the blood stream and cause symptoms such as recurrent fever (with about twelve days in between), anaemia, and discharge from the eyes, nervous signs and loss of condition. The animal may be infected for months before it dies finally.

The vector for this disease is tsetse fly which is very prevalent in sub- Saharan Africa. There exist some wild animals that are infected but showing no symptoms and are therefore carriers of the parasites.

These wild animals are buffaloes, giraffes and warthogs. Tsetse fly sucks blood from these wild animals and thereby maintains the cycle of the parasites. Human being are also suceptible when they are bitten by these vectors.

Trypanosomiases is treated by the use of trypanocidal drug such as diminazene aceturate, and homidium chloride. Because of the prevalence, prophylactic drugs are available and use by injection to last for about three months.

Such drugs include isometamidium chloride and quinapyramine prosalt. Regular spraying of the environment with insecticides to kill tsetse fly is another control measure apart from prophylaxis.

Read Also : External Parasites of Ruminant Animals

5. Liver Fluke

This is one of the most widely distributed and harmful parasites that affects cattle sheep and goats. They are caused by Fasciola hepatica or Fasciola gigantica of the trematodes.

The disease symptoms include paleness of the eyelid and the gum, pot-bellied condition, appearance of soft watery swelling under the jaw, weakness, anaemia and loss of condition.

When carcass of infested ruminants is posted, the flukes are found in the liver if opened. It causes a disease called schistosomiasis.

While in the sheep, the adult fluke lay eggs in the bile duct. The eggs are passed into the intestine and expelled along with the dung on to the pasture. Here they can stay up six months if it is on wet environment or they die if on dry land.

They hatch into miracidium (after about nine days to eight weeks) which swims and flow with streams or brooks or any water in the drains around. The miracidium is picked up by the water or mud snails (Limmaea truncatula) and after about seven weeks they develop and produce another form called cercariae.

An average of 1000 cercariae is produced from one miracidium. The cercariae moves and attach itself to the leaves of the plants or grasses around where grazing ruminants pick them up in the encysted form.

They migrate into the liver of the animal via the blood vessels and develop into liver fluke after about six weeks. The flukes begin to lay eggs after another six weeks in the ruminant host which are again expelled along with the dungs and the cycle continues.

Liver fluke is treated with benzimidazole and salicylanilides. It controlled by the elimination of the intermediate host- mud snail. This is achieved by spraying the streams, brooks and every drain around the grazing pasture regularly during the wet season.

Internal Parasites of Ruminants and Control Measures
Figure: Life Cycle of Liver Fluke in Cattle

6. Coccidia

This is a protozoa disease caused by the Eimeria spp of bacteria. The parasites live in the intestine of the animal. The main symptom is blood- stained diarrhea where ruminants especially young ones are raised intensively.

It can be treated by the administration of sulpha drug and antibiotics. Control measure is by preventing the animals from eating feeds contaminated with faeces.

In summary, in this article, you have learnt the following:

Parasites are of economic importance in the rearing of ruminant for production purpose.

Parasites can be internal or external but live on their host to survive by damaging the physiological conditions of the host.

The internal parasites includes worms, trypanosomiasis, liver flukes and coccidia.

Read Also : Impact of Agricultural Wastes on Human and Environment


Benadine Nonye is an agricultural consultant and a writer with several years of professional experience in the agriculture industry. - National Diploma in Agricultural Technology - Bachelor's Degree in Agricultural Science - Master's Degree in Science Education - PhD Student in Agricultural Economics and Environmental Policy... Visit My Websites On: 1. - Your Comprehensive Practical Agricultural Knowledge and Farmer’s Guide Website! 2. - For Effective Environmental Management through Proper Waste Management and Recycling Practices! Join Me On: Twitter: @benadinenonye - Instagram: benadinenonye - LinkedIn: benadinenonye - YouTube: Agric4Profits TV and WealthInWastes TV - Pinterest: BenadineNonye4u - Facebook: BenadineNonye

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