Introduction

What is a parasite? A Parasite is an organism which obtains its livelihood from another organism (host) which suffers damage. Parasitism is the association between a parasite and a host.

The effects of parasite on the host animal are:

• Depriving the host of its food.
• Sucking blood.
• Damaging the organs of the host.
• Cause irritation on the skin of the host.
• Destruction of hides and skins.
• Transmission of diseases.
• Cause obstruction in body passages.

 

General Symptoms of Parasites infestation:

• Potbellied condition.
• Swellings in the jaw or other areas.
• Rough hair or rough coat.
• Presence of worm segments and blood stains in the defecation.

 

Types of Parasites

There are two types of parasites: (1) External (ecto-parasites) (2) Internal(endo-parasites)

External parasites are;

• ticks,
• tsetse flies,
• mites,
• lice,
• fleas
• keds

Life Cycle of ticks

• Eggs are laid in cracks on the ground.
• They hatch in 4-6 weeks into larvae which climb on the grass waiting for a passing animal.

One-Host Tick

• This requires one host to complete its life cycle.
• Example: blue tick (Boophilus decoloratus).
• Preferred sites: face, neck, dewlap and side of the body.
• Disease transmitted: Redwater and anaplasmosis.

Two-Host Tick

• This requires two different hosts to complete its life cycle.
• Example: The red legged tick (Rhipicephalus everts)
• Preferred sites: Ears, anus, udder and the tail.
• Disease transmitted: Redwater and east coast fever.
• Example: Bont legged tick (amblyomma spp.)
• Preferred sites: Udder, scrotum and tail switch.
• Disease transmitted: Sweating sickness.

Three-Host Tick

• This requires three hosts to complete its life cycle.
• Example: The brown ear tick (Rhipicephalus appendiculatus)
• Preferred sites: Ears, tail switch and around the eyes.
• Disease transmitted: East coast fever and redwater.
• Bont tick transmit heartwater (amblyomma spp.)

Control of Ticks

• Dipping/spraying/hand dressing with acaricides.
• Rotational grazing.
• Ploughing the land to break the life cycle.
• Hand picking and killing.
• Fencing of the grazing fields to keep off other animals including wild game.
• Burning of grass to kill them in various stages.

 

Endo-parasites ( internal Parasites)

Endoparasites are helminths.

They can be divided into:

Platyhelminthes/flatworms which include;

– Trematodes (flukes)

– Cestodes (tapeworms).

– Nemato-helminthes/nematodes. E.g Roundworms.

 

General Symptoms of Helminthiasis

• Diarrhoea which foul the anal and tail region.
• Big stomach (pot bellied condition).
• Presence of worm segments in faeces.

 

Trematodes (Liver Fluke)

There are two species of flukes:

• Fasciola gigantica
• Fasciola hepatica.

Fasciola hepatica is more common.

It is commonly found in the liver and bile duct of cattle, sheep and goats.

Liver fluke is a problem in marshy and low lying wet areas.

 

Life Cycle of the Liver Fluke

• Adult fluke in the liver of the primary host lays eggs.
• Eggs pass through the bile duct into the small intestines and are passed out in faeces onto the pasture.
• Under moist conditions, they hatch into a miracidium larva which swims about in search of a secondary host (fresh water snails).
• In the snail, it develops through sporocyst, redia and cercaria.
• When it leaves the snail, the cercaria gets encysted on vegetation and becomes metacercaria.
• This is swallowed by the primary host with grass.
• The young fluke migrates into the liver through blood vessels when it matures.

 

Control of Liver Fluke

• Keep livestock off marshy areas near the rivers/streams/lakes and dams.
• Drench af-fected animals.
• Drainage of swampy areas.
• Eradicate the intermediate host by use of molluscicides.
• Provide water to livestock in elevated troughs.

 

Tapeworms

There are many species of tapeworms

Example:

Taenia solium

Taenia saginata.

• The adults live in the small intestines of man (the primary host).
• The intermediate host of Taenia solium is pig .
• The intermediate host of Taenia saginata is cattle.

Life Cycle of Tapeworm

• Adult tapeworms live in man’s intestines where it lays eggs.
• Eggs are passed out with faeces,
• Then they develop an outer covering known as onchosphere.
• The eggs are swallowed by intermediate host.
• The outer covering is digested and the young worm emerges.
• This bores into the blood vessels and is carried to specific muscles such as the tongue, heart, thigh muscles.
• It develops into an encysted form called bladder-worm.
• When the animal is killed and meat is eaten raw or in an inadequately cooked form, man gets infected by the bladder-worm.
• In man, the bladder-worm evaginates and attaches itself onto the intestinal wall where it develops into an adult.

Control of Tapeworms

• Meat should be well cooked before eating.
• Use of drugs in primary host.
• Meat inspection by meat inspectors] veterinary officers.
• Use of pit latrines by man.

 

Nematodes (Roundworms)

Common ones are:

• Ascaris suum (pig roundworms),
• Ascaris lumbricoides found in man and sheep
• Haemonchus contortus found in sheep, cattle and goats.
• Roundworms are common in warm areas especially in areas where the standards of hygiene and sanitation are low.

Nature of Damage

• Damage is done to the liver and lung tissues as they migrate in the body.
• Suck out blood.
• Deprive the host of food.

Control of Roundworms

• Use of drugs.
• Rotational grazing.
• Use of proper stocking rates to avoid overgrazing.

Practicing high standards of cleanliness and hygiene such as use of latrines

 

scheme of work

vegetation

Propagation

STOCK EXCHANGE

CLASSIFICATION OF ANIMAL FEEDS