Animal Diseases & TREATMENT OF INFECTED ANIMALS AND BUILDINGS

  

Losses in animal husbandry in most tropical areas, including West Africa, are due mainly to diseases.

Parasites such as the trypanosomes which cause sleeping sickness in many animals are still widespread in many areas, despite the measures which have been taken to control them. Many diseases,however, are no longer as serious as they were, due to the improved level of livestock management, higher standards of hygiene, the more effective use of preventive measures and the greater use of the government veterinary services. Better animal diets have also contributed to a reduction in deficiency diseases caused by a lack of essential Clements, More livestock farmers have also become aware of the need to isolate sick animals and thus prevent the spread of contagious diseases. Prompt attention by veterinary officers and the increased use of vaccines and other types of treatment have also considerably reduced the number of animal deaths.

CAUSES OF DISEASE IN ANIMALS

Viruses, bacteria and other micro-organisms enter into the bloodstream of animals where they can multiply rapidly by division. Most of these organisms can only be seen under the microscope but some of the larger parasites can be seen under fairly low magnification. Entry of some of these micro-organisms into the body of the animal is often through the mouth or nose or through wounds such as cuts and abrasions. Others may be transmitted by ticks or other insects such as biting flies which carry infection from one animal to another.

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PREVENTION OF CROP PESTS & CONTROL MEASURES

PREVENTION OF DISEASE

The segregation of stock so that animals which are healthy do not come into contact with stock which may be infected is a basic principle to be followed in protecting animals from disease. Grazing, feeding and watering facilities should not be used by animals from other herds or groups and no new animals should be included in a healthy unit until they have been kept in quarantine and observed long enough for any disease symptoms to have appeared.

  Accommodation in which disease has occurred should not be re used until all possible precautions have been taken to ensure that there is no longer a danger of re-infection.

  Overcrowding of animals should be avoided and units should be small enough to allow for rapid and effective separation from other units if an outbreak of disease occurs. This is often more expensive than maintaining large units, with a corresponding reduction in management and labour costs, but can result, in the long term, in the maintenance of a more productive and efficient enterprise.

The early detection of any disease is essential if severe losses are to be avoided and workers in charge of livestock units should always be alert to observe any symptoms of sickness, reporting them promptly to the veterinary authorities if there is a possibility that a disease may be contagious.

DEVELOPMENT OF IMMUNITY

The natural defences which are present in the blood of most animals are the antibodies. These may be inherited from the mother or may develop as a result of an initial, usually mild, infection by micro-organisms. This infection stimulates the production of antibodies at a rapid rate and, if this takes place more quickly than the multiplication of the micro-organism, the animal will not only recover from the infection but will retain immunity to the specific disease organism which caused the initial production of the antibodies. Many indigenous breeds of animals have inherited immunity to local diseases and rarely suffer serious effects when exposed to infection; this is not the case with exotic breeds which have not acquired immunity in this way.

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VACCINATION AND INOCULATION

The production of antibodies in the blood is used also as a protection through the processes of vaccination and inoculation. Extracts of the disease organism are diluted to a low concentration and, when these are introduced into the blood, the required antibodies are produced and afford protection against future infections. Another means of stimulating the production of antibodies is the use of dead extracts of the micro organism; a third approach is to keep the required antibodies alive in laboratory conditions so that they can be injected directly into the bloodstream of young animals. This method has the advantage of becoming effective immediately in resisting an infection which may have already taken place. The first two methods rely on the production of antibodies in the treated animal; where infection has already occurred, this procedure may be too late to prevent the spread of the disease.

  Where the possibility of infection occurs, therefore, it is always an advantage to treat an animal before it actually becomes infected. The state of health of an animal when it becomes infected by disease is of particular importance since animals which are in a poor state of health due to inadequate feeding, a low level of accommodation or recent illness have little natural resistance to disease.

  The immunity developed in animals against virus diseases may last for a considerable time but the antibodies produced in response to bacterial infections are usually of short duration and the treatment has to be repeated fairly often if it is to remain effective. Both viral and bacterial diseases are spread rapidly by contact, often through food and water, and the symptoms are often difficult to detect. Some animals may be 'carriers', that is, they will pass on the infection without showing symptoms of the disease themselves.

  

TREATMENT OF INFECTED ANIMALS AND BUILDINGS

Insect-Borne Diseases

If an animal is showing symptoms which indicate that it may be suffering from a disease transmitted by an insect, such as trypanosomiasis, it should be separated from other animals and kept in quarantine until a veterinary officer can examine it and identify the nature of the disease.

 

Bacterial Diseases

When a disease appears likely to be of bacterial origin, animals which appear to be uninfected should be moved to alternative accommodation, leaving the sick animals in the area where the disease was first observed until they can be properly treated. The premises should be thoroughly disinfected and all bedding or contaminated material burned.

  Disinfection is most effectively brought about by exposure to strong sunlight so that the organism responsible for the disease become dried and desiccated. Utensils should be kept in boiling water for several minutes to sterilise them.

  Chemicals such as chlorinated lime, carbolic acid (5% solution) and formalin (2.5% solution) should be used to soak concrete floors, which should be thoroughly scrubbed to ensure complete penetration of the chemical. Carcasses of dead animals should be burned or buried to a depth of 2 metres.

Viral Diseases

Owing to the rapid rate of infection, no attempt should be made to separate animals suffering from viral diseases from apparently healthy stock, all animals being treated together as one unit.