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The desire to prevent the spread of infectious diseases has long existed. However, with the realization in the 19th century that such diseases were caused by microorganisms, which can be transmitted from one person to another through direct or indirect contact, health officials became increasingly resolute in their efforts to prevent disease introduction and spread.
1. Identify the common diseases in the various types of farm animals. 2. State their symptoms, the methods of control and prevention of the diseases 3. Identify common livestock parasites and give their effects on, farm animals. 4. Outline the control measures for each parasite.

What is a disease?

A disease may be defined as an abnormality in health. the diseases of animal lead a deviation in the normal performance of the organism. 11.2 Types of disease of farm animals Diseases can be classified according to their causes into: (a) Pathogenic diseases: These are caused by living organisms, These organisms include: (i) Viruses (ii) Bacteria (iii) Fungi (iv) Protozoan (v) Larger organisms such as ticks, lice, worms(ecto-parasites), etc. (b) Nutritional deficiency diseases such as rickets, ketosis. (c) Diseases caused by inanimate objects such as environment and chemicals. for more study on disease organisms read here


Parasitology, the study of animal and plant parasitism as a biological phenomenon. Parasites occur in virtually all major animal groups and in many plant groups, with hosts as varied as the parasites themselves. Many parasitologists are concerned primarily with particular taxonomic groups and should perhaps be considered students of those…

How does disease get to animals?

This is through: 1. Droppings or faeces of infected animals
2. Contaminated feeds and water as water borne diseases
3. Contact with infected animals
4. Air
5. Insects, feed or water troughs, etc.

How to identify a diseased/sick animal

The following signs help in identifying a sick or diseased animal:
1. Loss of appetite
2. Persistent coughing
3. Fever (high temperature)
4. Watery, bad smelling or blood stained faeces.

5. Inability to rise and sluggishness.
6. Rough skin/coat, and drooping of tail or wings in case of birds,
7. Discharges from the

eyes, nostrils, mouth, or anus.
8. Emaciation
9. Death

Summary of some common diseases of farm animals

The table below shows a summary of common diseases of animals:

Name of disease.
Causative agent.
Animal affected .
Symptoms Mode of transmission.

Control measures .

Foot and Mouth disease.


Cattle Sores on feet, lips, tongue, cheek, salivation and foaming, inability to eat, weakness, lameness and death Transmitted by contact with infected animals or by contact with contaminated feed materials from diseased herd. Serious loss of animals through death. Vaccination. Isolation

of diseased animals from healthy ones. Bury dead animals deeply. No treatment. Rinderpest, Virus Cattle, High fever, blood stained shooting diarrhea. Difficult breathing and animals grind their teeth. Death rate is very high Through contamination with infected animal and eating contaminated food. Death of animals.


Myiasis, infestation of the body with the larvae (maggots) of certain species of flies. Intestinal myiasis results from ingestion of food contaminated with eggs or larvae and may produce cramps, nausea, vomiting, and diarrhea. Within a short time, however, the organisms are destroyed by gastrointestinal juices and passed in the…

how to Vaccinate farm animals.

Isolation of diseased animals.
Kill and bury deeply infected animals. No treatment of Newcastle disease (NCD) Virus Poultry Drop in feed intake, severe respiratory difficulties. Neck twisting and paralysis of the legs or wings. Laying of soft shelled eggs, water greenish diarrhea Through contact with faeces of infected birds, nasal and oral discharge from diseased birds and materials, contaminated by the virus. Low egg production in layers. High mortality rate resulting in loss of birds. Routine vaccination using freeze dried NCD vaccine given either intra-occular in young birds or inter-muscular in older birds. Good sanitary practices. No treatment.

BRUCELLOSIS (Contagious abortion) Bacteria (Brucclla Abortus)

Cattle Irritation and catarrhal conditions in the womb of the pregnant cow. This results in the expulsion of foetues at about the 5th – 7th month of pregnancy as still birth Contacted when animals feed on contaminated pasture or other feed. Also servicing by infected bull and flies that have rested on the foetus of affected animals can transmit the disease Loss of foetus. Reduction in the level of an animal’s production. The disease is zoonotic. That is can affect human beings. Vaccination. Report any occurrence to the nearest veterinary officer.

ANTHRAX Bacteria (Baccilus anthracis)

Cattle, sheep and goat In acute cases, the first sign is death. In less acute cases, there may be blood stained discharges from nostrils and mouth and swelling in the neck, genitals and lower abdomen. Through contact with infected animals/man and their products Loss of animals. Note: Do not open carcass of infected animals as the disease is also zoonotic. Vaccination. Burn or bury deeply any diseased animal. Disinfect properly after disease has occurred in a herd.

TUBERCULOSIS Bacteria (Mycobacterium spp)

Occurs in most animals Infects lungs resulting in persistent cough, emaciation, loss of condition and finally death Contact with infect animal. It can also be through contact with discharge or sputum from cough. Milk infected with the bacterium can equally transmit the disease. read how diseases are transfered here. Lowers productivity and also results in loss of animals. The disease is also zoonotic. No treatment. Kill and bury deeply infected animal. Routine checking by a veterinary doctor is important. Good hygiene. Vaccination.


Poultry Birds become dull and pass out yellowish diarrhea Contact with the dropping from infected bird or contaminated food, water or soil. Loss of birds Proper sanitation. Vaccination. Contact a veterinary doctor CHRONIC RESPIRATORY DISEASE (CRD) Not yet identified. Could be bacteria or virus Poultry Nasal discharges rattling sound during breathing, loss in weight. Through contact with infected birds and their nasal discharges Lowers production in birds (read about poultry management here) and also results in loss of birds Good sanitation. Avoid use of saw dust as litter. Use antibiotics. Consult a veterinary doctor or officer RINGWORM (Favus in Poultry) Fungus

All animals and birds Lesions or scab on the skin of the animals, usually irritating and causing the falling off of the animal’s hair. In Poultry, the disease is common on the combs and wattles producing grey patches The fungus is usually spread from infected to healthy one through contact Results in loss of hair in animals resulting in low market value due to poor appearance of the animal Maintain clean conditions. Isolate infected animals and treat with iodine as surface dressing TRYPANOSOMIASIS Protozoa (Trypanosoma spp) Mainly Cattle. Also attacks goat and sheep Intermittent fever. General weakness. Hair on tail often pull out. General loss of condition and finally death.

Transmitted by tse-tse flies (Glossina spp) by biting infected animal, sucking(and piercing insect) the protozoan and injecting it into the blood of a healthy animal. Drop in level of animal production death Use drugs e.g. trypanosomide. Rear resistant breeds. Also use chemical to kill the flies and clear bushes around animals pens to ward off the flies

COCCIDIOSIS Protozoa (Coccidia Parasite-E imeria spp)

Poultry Blood stained watery droppings. Ruffled feathers. Loss of weight due to fall in feed intake. Death of birds. By taking contaminated food and water from the droppings of infected birds Drop in egg production. Death of birds Maintain high hygienic conditions. Disinfect poultry house before stokcing. Use cocci-diostats e.g. Sulphamethazone added to drinking water. SCABIES Fungus Cattle, Goat, Sheep It causes very itchy little lumps that can appear all over the body of the animal. It is very common on the udder of female animals and the genitals of the male. Scratching can cause infection, producing sores with pus and some times swollen lymph nodes or fever. Spreads by touching the affected parts of animals or by beddings. Causes loss of animal hair and destruction of skin. Could affect level of production. Maintain high level of cleanliness in the animal houses. Dip animals in solution lindane.

Other diseases include (a) Rabbit coccidiosis: This is caused by a protozoan. The signs of the disease include blood-stained faeces and diarrhea. Prevention is by separating young animals from old ones. Diseased rabbits should also be separated. Rabbit hutches should be cleared always. Treatment is by the use of sulphonamide drugs. (b) Swine fever or hog cholera: This affects pig(common diseases of pigs read here) and is caused by virus. The virus is usually present in faeces and blood. The signs are shivering, loss of appetite, vomiting, fever and diarrhoea. 11.6 Animal Parasites A parasite is a living organism which establishes itself on or in another organism called host(read more here), from which it gets its food. parasites are found inside the host.

These are called Endo-Parasites,

e.g. Tape Worm, Round Worm, Liver Fluke and Trypanosome. Those found on the body of animals are called Ecto-Parasites. e.g. Ticks, Lice, Mites. Some parasites of farm animals include:



(a) Ticks: These are eight-legged organisms belonging to the group arachnids. They feed on farm animals by sucking blood from them. Animals mostly affected by ticks are cattle, sheep, goats and dogs. The effects of ticks on the farm animals include (a) Anaemia (b) Irritation leading to sore formation on the skin (c) Destruction of skin (d) Transmission of diseases such as red water, etc. Ticks, Lice DIAGRAM Figure 2.11.c Tsetsefly (transmits typanesomes by biting) Ticks can be conlrolled by: (i) using clean environment for animals (ii) practising rotational grazing (iii) spraying pens and animals with chemicals such as malathion. (b) Lice: These are small wingless insects which live under the hair of animals or feathers of birds. They also feed by sucking blood from animals, just like the ticks. Lice cause irritation which results in sore formation and creates avenues for disease agents. They also cause anaemia. Lice can be controlled by: (i) maintaining clean environment (ii) avoiding over crowding (iii) dipping animals in water containing chemicals such, as lindane and DOT.



(a) Roundworms: These are elongated, cylindrical, smooth-skinned, whitish worms, which are pointed at both ends. They are common parasites of cattle, pigs, and poultry. Roundworm is found in the animal's intestine where it gets its food. This parasite deprives the animals of their food thereby reducing their weight. It can also result in slow growth and loss of appetite. The parasite could cause stomach disorders such as diarrhoea, vomitting, etc. Control is by: (i) maintaining good hygienic conditions in animal environment, and (ii) use of dewormers such as piperazine. (b) Liver fluke: This is a short flatworm which attacks mainly cattle and sjheep". It sucks blood from the animal thereby causing emaciation and reducing productivity. It may lead to the death of the animal. Control can be achieved by: (i) the use of appropriate drugs (ii) supplying clean drinking water, and (iii) destruction of snails on grazing land because they helo to harbor the pest Roundworms Liver Fluke Tapeworm: This is a long segmented flat worm which looks like the tape of the tailor. The parasite mainly affects pigs and cattle. The tapeworm possesses hooks and suckers in the scolex and these help to attach the parasite to its host while the suckers assist in feeding. In animals, the presence of tapeworm in tissues or organs could cause some physiological disorders, such as anaemia, abdominal pains, weakness and loss of weight.

how to control the spread of bacteria

The parasite can be controlled by: (i) maintaining good hygienic conditions (ii) use of drugs (iii) proper cooking of meat before eating by man which serves as primary host. General methods of controlling animal diseases Diseases can be: (i) Prevented, and (ii) Controlled. (a) Prevention: This involves the following practices: (a) Good sanitation/hygiene (b) Good feeding . (c) Vaccination (d) Quarantine (e) Breeding (f) Separation (g) Rotational grazing. (b) Control: This involves; (i) Treatments The use of drugs which may be in the form ot powder, liquid or solids, given in ` water, feeds or as injections. (ii) Destruction of diseased animals. They arc either burnt or buried. STUDY QUESTIONS 1. Explain the meaning of: (a) Disease (b) Parasite 2. Differentiate between endo and ectoparasites. Give two examples of each. 3. List five methods of preventing animals diseases. 4. How would you control tapeworm as a parasite in your animals. 5. List eight common diseases that may affect farm animals in your country. 6. Enumerate the effects of ticks on farm animals.

Stages of Diseases Development and Transmission

There are four major stages of disease development and transmission in crops.
These are:

1. Invasion: This is the stage where 'the disease causing agent comes in contact with the host plant.
2. Establishment
At this stage the disease causing agent enters and establishes llfe in the crop tissues.
3. Injury
This is the stage where the disease pathogen multiplies itself leading to the actual attack of the host.
4. Mission/Spread
This is the stage where the disease organism spreads from one plant to a healthy one. The process is aided by wind-air borne diseases, water-water borne diseases, insects-insect borne diseases contact and others.

Prevention and Control of Crop Diseases

It is better and more economical to prevent a disease from, crops than to control it when it has occurred. The sure way luting diseases, in farms is to prevent the disease causing organism from reaching the crops. This is possible through regular removal of rotten materials from the farm, routine spraying of crops planting resistant varieties and so on.

However, crop diseases can be controlled in the following ways:


Cultural Control

The techniques adopted in this control measure include:
(i) Proper care for plants such as regular weeding. This practice reduces the amount of disease attack on the crops.
(ii) Burning, of farmland: This involves setting farmland on fire before cultivation. The fire helps to kill disease causing agent such as bacteria, fungi, virus and others in the soil.
(iii) early Planting: Early planting enables the crops to escape the outbreak of some crop diseases.
(iv) Practicing Crop Rotation: This practice, ensures that crop which suffer from similar diseases do not follow each other in the same rotation of crops. This is to make sure that the cycle of the disease development is disturbed.
(v) Removal of dead plants and other disease harbouring agents from the farm. The source of the disease is removed when this is done.


Biological Control

This involves the use of good resistant crops varieties to plant. It is a very successful method of controlling most serious plant diseases. Over the years, scientists have developed crop types which have great resistance to some deadly crop diseases. The use of which helps to control most diseases of crops.


Chemical Control

This involves the use of chemicals to kill the disease organism affecting the crops. For example: (i) Fungicides such as perenox. Bordeaux mixture, and copper sulphate are used in the
control of fungus diseases.
(ii) Virus diseases can be controlled by using appropriate chemicals such as vetox 85 to kill the vectors e.g. aphids. mealy-bugs white flies, etc. that transmit the virus diseases.
(iii) Most bacterial diseases can now be treated using appropriatle chemicals (bacteriacides) such as Agrosan 5W mercurial duss and acid.
(iv) Nematodes can be controlled by using nematicides such a nemagoiu and DDT.