Prof. Dr. Mansur-ud-Din Ahmad

Part-II

The universe of natural lawGreeks thought-disease was the result of derangement of four humours of the body

Four humours were associated with four properties (heat,moisture, dryness and cold) and with four elements (air, earth, water and fire)

The universe of natural lawDiseases were considered to be caused by external forces, including climatic and geological changes

The word 'malaria' literally means 'bad air' and hints at the 19th century belief that the disease was caused by stale air.

The Greek idea of disease was susceptible to scientific investigation

ContagionIdea-diseases can be transmitted from one animal to another has its ubiquitous origins

The Romans believed that disease could be spread by airborne seeds

The primitive Hindus associated sick rats with human plague, the first suggestion of a zoonosis.

Germ Theory of Diseases

Main advances-identification of microbes as causes of infectious diseases (19th century)

Louis Pasteur's investigation of anthrax & rabies

Robert Koch's discovery of bacteria causing TB & cholera firmly established microbiology (downfall-miasmatic theory)

Miasmatic Theory Of DiseaseMiasmatic theory of disease-such as cholera were caused by a miasma (ancient Greek:"pollution"), a noxious form of "bad air"

Microbes as cause of infectionThe set of postulates formulated by Koch to define causal agents-used to identify many microbial diseases since those early days of bacteriology

Viruses discovered in late 19th century (1892) Iwanowsky demonstrated that tobacco mosaic disease could be transmitted by sap (filterable agent)

Movement for changeVeterinary medicine has experienced five stable periods and revolutions up to the middle of the 20th century relating to disease control

The first period: until the first century ADInitial domestication of animals brought man into close contact with animals and therefore with their diseases

Humoral pathology developed and the miasmatic theory of cause evolved.

Slaughter became preventive strategies

The second period: the first century AD until 1762Veterinarians specialized in equine medicine and surgery, reflecting the importance and value of horses

The third period: 1762-1884The animal plagues, especially those of

cattle, became particularly common in Europe with the introduction of rinderpest from Asia

Public concern, highlighted by the rinderpest outbreak of 1865 was responsible for the establishment of the British State Veterinary Service

By the mid-19th century, disinfection was also being applied to control the disease

The fourth period: 1884-1960Treatment of disease was based on

laboratory diagnosis involving isolation of agents and identification of lesions followed by Therapy

The discovery of disease vectors facilitated prevention by vector control

The fourth period: 1884-1960Many infectious diseases were either effectively controlled /eradicated using new techniques of the microbial revolution and older techniques including quarantine, importation restrictions, slaughter and hygiene

The fifth periodThe animal-health problems and anomalies

stimulated a change in attitude towards disease causality and control

The fifth periodVeterinary services Veterinarians practicing in the livestock sector continue to control and treat disease in individual animals.

Developments in molecular biology are improving diagnostic procedures

New control strategies Two major strategies: the structured recording of information on disease Analysis of dis. in populationsSurveillance & monitoring: intensive investigation of particular diseases

Recent trends Veterinary services : Control and treat disease

individual animal Improving diagnostic proceduresNew opportunities for vaccine production systemsMultification nature of many disease necessitates

modification of the environment of the animal and management practices.

Food animals-reduced levels of productionDiseases assessed in terms of suboptimal health,

manifested by decreased herd performanceSelect suitable ‘performance indicators’ (e.g., ‘calving

to conception interval’) herd that miss the targets.Performance-related diagnosis.Veterinarian, involved in husbandry, management and

nutrition. Veterinarian’s evolving role in animal production.

Investigations of specific animal health problems of complex cause, such as mastitis.

Food Quality Area of concern (Vet. public health) is food qualityGuaranteeing wholesomeness of food at the

abattoir, and addresses all levels of the production chain.

Establishment of quality assurance programs on the farm, using techniques such as HACCP (Hazard Analysis Critical Control Points), in focus from quality control of food throughout the production.

Quantitative evaluation of the risk of transmission of infection throughout the chain

Animal welfare Obvious aspects of animal welfare are

deliberate physical abuse (non-accidental injury) and neglect; surgical mutilation (tail docking of dogs)

Welfare in livestock production systems is often evaluated in the context of the ‘five freedoms’ freedom from hunger and thirst;freedom from discomfort; freedom from pain, injury and disease; freedom from fear and distress.

National & international disease reporting Improved disease reporting systems at the national &

international level in the prevention of spread of infectious agents form one country to another.

Residues need to be identified and eliminated-pesticides and hormones, antibiotic residues

Free internal market in the European Union, and global goals to liberalize international trade through the World Trade Organization (WTO)

highlighting the requirement for comprehensive disease reporting

Established organizations, such as the Office International des Epizooties (OIE), are modifying their goals and reporting techniques, taking account of these new requirements.

What Is a "Herd Health"Herd health plans are designed by herd

veterinarian and producer to reduce disease incidence, provide effective diagnosis and treatment protocols, and improve productivity

Herd health Includes:Routine visits by veterinarian at specific

times of yearTraining of employeesHealth and production recordsEconomic analysis of decisions

Herd healthHerd health is a key driver of profitability in

today’s production environment. Maintaining health is extremely challenging,

particularly as management systems become more intensive and profit margins are squeezed.

Disease robs profits and productivity by reducing growth, increasing deads, lightweights and culls, and adding drug and vaccine costs.

A healthy and robust immune system protects profits and animal welfare by minimizing the incidence and effects of disease