Improved Animal Health
Environmental Issues

Animal diseases cause heavy economic losses both for individual farmers and at national or regional levels. The prevention and control of diseases aims to permanently or temporarily reduce these losses and, as far as the major animal epidemics are concerned, to prevent the economic and social catastrophes which accompany them.

The control of animal health presents three categories of possible repercussions on the environment :

  • Some ecological, biological and mechanical methods replace the use of pesticides, particularly against external parasites. Environmental effects of non-chemical control methods are generally considered to be much lower.
  • Reduction of livestock morbidity and mortality promotes increase in human and animal populations and consequently pressure on the environment. These indirect consequences are shown on the page Environmental issues of livestock protection.
Environmental Impact: 
  • Using Chemicals and Medicines in Animal Health Control    
  • Non-Chemical Methods of Combating External Parasites of Livestock
  • Animal Health Care: Summary
  • Female deer tick. Ixodes scapularis


    Disease can be defined as a disturbance of all or part of the biological functioning of the animal. Factors causing disease can be grouped into two large categories:

    Diseases can be: However, it should not be forgotten that there are many more useful microbes than pathogenic microbes. For example, in ruminants, microbes living in the rumen enable the digestion of cellulose. Micro-organisms contribute to soil fertility, fermentation of waste, purification of water, etc. The maintenance of microbial activity in the environment is therefore essential.


    Eradication of disease normally uses one or more of the following methods.

    To reduce the prevalence of animal diseases, two main types of action are implemented :

    a) Preventive and therapeutic measures:

    b) Sanitary measures: To fight against external parasites, two types of methods are used :

    c) Chemical methods (e.g. insecticides, acaricides).

    d) Non-chemical methods.
    These include:
  • Ecological approaches (biotope modification of the vectors or of the intermediates hosts).
  • Biological control measures (predators, parasites, growth regulators).
  • Genetic measures (release of sterile males).
  • Mechanical measures (trapping and repelling techniques.  See Non-Chemical Methods for methods of trapping tsetse flies).

  • The Pan African Rinderpest Campaign is an example of a large scale vaccination campaign to control rinderpest in Africa. The campaign has succeeded in eradicating the disease from most countries and rinderpest remains present only in a few areas. The second step in diseases-free countries consists of sero-surveillance and more globally in an epidemic-surveillance activity.

    Total eradication can be both very expensive and almost impossible. Therefore, in such cases, the aim is not eradication, but diminution of infection to a reasonable level at which economic and/or social consequences are minimal. Hence, the acaricid treatments now aim at maintaining a minimum load for ticks on cattle. In this case, a minimum load is necessary to keep a natural immunity, which is useful in cases where cessation of treatment occurs. For these control programs to be optimised, an acceptable maximum load must also be determined, above which the negative effects on animal production are considered too heavy.


    Evaluating the costs of animal health control has to take into account the methods and the technologies applied, the strategy of prevention or treatment, as well as the country where the progrmmme is to be implemented (cost of services, of salary, cost of products etc).

    The costs include equipment, products, transport, infrastructures and labour.

    Targeted Livestock Systems

    The control of animal health is relevant to all animal production systems.

    Consequences for Livestock Production and Human Welfare

    The control of zoonoses in animals has a positive impact on human health because animals can be a source of infection for human: for instance the control of rabies, of anthrax, of tuberculosis, of Rift Valley Fever, etc.

    Diseases are a major constraint to livestock development. Alleviating disease impacts on livestock is an important condition for increasing animal population; productivity and animal production (milk, meat, energy..).


    Monitoring: EIA, Indicators

    References / Further Reading

    FAO, 1984. Ticks and tick-borne disease control. A practical field manual. Rome, FAO, pp. 621.

    Bussieras, J., Chermette, R. 1991. Abrégé de Parasitologie vétérinaire- Fascicule 4- Entomologie. Ecole Nationale Vétérinaire, Maisons Alfort, pp. 163.

    Douthwaite, R.J. 1992. Non targets effects of insecticides used in tsetse control operations. FAO World Animal Review.  70-71: 8-14.

    Koeman, J.H. 1979. Chemicals in the environment and their effects on ecosystems. In: GEISSBÜHLER H. Edit.; Advances in Pesticide Science. Part 1. World Food Production- Environment- Pesticides, Pergamon Press, Oxford, 25-38.

    Müller P. 1988. Effects of pesticides on fauna and flora. In: IAEA ed.: Pesticides: Food and Environmental Implications. IAEA-SM-297-40, 11-27.

    Nagel, P. 1995. Environmental monitoring handbook for tsetse control operations. CTA/RTTCP, Scientific Environmental Monitoring Group, pp. 323.

    Nagel, P. 1994. The effects of tsetse control on natural resources. FAO Animal Production and Health paper , 121:104-119

    OIE. 1994. Ectoparasites des animaux et méthodes de lutte. Revue scientifique et technique de l'OIE, 13(4), pp. 1430.

    Reid R., Wilson C.J., Kruska R.L., Mulatu W. 1997. Impacts of tsetse control and land-use on vegetative structure and tree species composition in south-western Ethiopia. Journal of Applied Ecology, 34: 731-747.

    Rodhain et Perez C. 1985. Précis d'entomologie médicale et vétérinaire,.Maloine S.A. pp. 458.

    Uilenberg G., 1998. A field guidefor the diagnosis, treatment and prevention of African animal trypanosomosis. Rome, FAO, pp. 158.

    Wilson C.J., Reid R., Stanton N.L., Perry B.D. 1997. Effects of land use and tsetse fly control on bird species richness in southwestern Ethiopia. Conservation Biology, 11(2): 435-447.

    WHO. 1984. Chemical methods for the control of arthropod vectors and pests of public health importance. WHO, Geneva, pp. 108.

    WHO. Safe use of pesticides. Ninth report of the WHO expert Committee on vector biology and control. WHO Technical Report Series 720, 60 pages.

    WHO. 1989. DDT and its derivatives. Environmental aspects. International Programme on Chemical Safety (IPCS), Environmental Health criteria, N° 83,  pp. 98.

    WHO. 1989. Deltamethrin health and safety guide. International Programme on Chemical Safety (IPCS), N° 30, 31 pages.

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    Environmental Impact:
    Using Chemicals and Medicines in Animal Health Control


    Medical and chemical treatments should strictly follow the instructions for use: quantity of product, frequency of application, duration of treatment, as well as delay before eating meat or milk. People who apply the treatment should be specially trained in those aspects and in the correct use of the medicines.Incorrect usage may lead to ticks resistant to acaricides, and diseases resistant to treatment.

    To control ticks, acaricides are regularly applied also, weekly, fortnightly or monthly, according to tick species and tick infestation rate. The use of organophosphates as acaricides requires a delay before consuming the meat. Other acaricides, e.g. pyrethroids need a shorter delay but are more toxic for fish.

    Positive Environmental Impact

    Negative Environmental Impact Environmental Impact:
    Non-Chemical Methods of Combating External Parasites of Livestock
    Main Techniques Used
    • Intensive land clearing to modify the vegetation hosting insects vector of parasites (for instance tsetse fly).
    • Land use planning adapted to isolate or to protect vector-free areas of new infestation, and helping chemical treatment of certain areas.
    • Rotational grazing systems on pastures to break down the natural cycle of ticks.
    • Techniques to deter flies: cleaning stables, broadcasting regularly the manure, covering the manure with a plastic film (increase of temperature), stirring liquid manure.
    • Treatment of surface water with Bacillus thuringensis, limiting mosquito development.
    • Removal of wild mammals as a reservoir of diseases.
    • Separation of wild and domestic animals to avoid cross contamination (foot and mouth disease, tuberculosis, rabies).
    • Use of specific artificial traps for insects (for instance tsetse fly). These traps are impregnated with insecticide (pyréthrinoid), particularly useful in sedentary agropastoral system. But the traps are exposed to damage and stealing. The method requires active participation from rural communities.
    • Use of "living traps" against biting insects and other arthropods: tsetse fly, Haematobia sp., Stomoxys sp.), ticks. Animals are impregnated with insecticide by manual spray, dipping, pour on application, or endectocide injection. This method is very efficient. Number of treatment is becoming lower with the increasing remanence of the product. When animals are reservoir of pathogenic agent for humans, the use of living traps (animals mpregnated or receiving chemotherapy) can reduce the epidemiologic cycle.
    Positive Environmental Impact Negative Environmental Impact Conditions of Application Animal Health Care: Summary

    Health care and disease prevention for livestock has a positive effect on the animal populations. Basically they allow other livestock improvement technologies as :

    They also cause a potential for a livestock population increase, with both positive and negative consequences on environment: The major campaigns limiting incidence of disease or parasites have stimulated livestock production, human occupation and grazing pressure on natural resources. The progress resulting of animal health protection must be managed to a proper use of resources avoiding degradation and environmental damage. Development planning must encourage awareness of farmers on environmental opportunities and issues involving population in the resource management.