Veterinary Epidemiology (QVE)
- rinderpest
- cowpox
- foot-and-mouth disease
- rabies
- tuberculosis
- canine ascarid infections
- anthrax
- avian influenza
- leptospirosis
Chapter 1 - The development of veterinary medicine
Dogs domesticated ~ 14,000 years ago. Sheep and goats ~9,000 B.C.
Greece ~6 B.C. → disease due to derangement of the four humours, associated
with four properties (heat, moisture, dryness and cold) and with four elements
(air, earth, water, and fire). Diseases were believed to be caused by external
forces.
20th century Europe → microbial theory of infectious disease
5 periods of veterinary medicine:
1. until 1st century AD: demonic theory and miasmatic theory of cause →
quarantine and slaughter as preventive strategies
2. first century AD until 1762: interest in equine matters → military healers
3. 1762 - 1884: improvement of farm hygiene, slaughter and treatment as control
techniques. Disinfection.
4. 1884-1960: microbial theory → vaccination
1
, 5. 1960s- : disease causality and control. Multifactorial theory of disease which is
equally applicable to infectious and noninfectious diseases.
Major strategies:
1) structured recording of information on disease: surveillance and monitoring
2) the analysis of disease in populations
Disease is defined as the unacceptable performance of groups of animals (decreased herd
performance).
Performance-related diagnosis: includes performance indicators, and estimation of covert
biochemical values (metabolite levels in serum).
Subclinical diseases do not produce overt clinical signs, although often affect production.
Non-infectious diseases can be predominantly genetic, metabolic and neoplastic.
Clinical disease, subclinical disease and production need to be monitored in the context of
anticipated levels for a particular production system.
Food quality is an area of concern in veterinary public health (salmonella, E.coli, legionella
etc.).
The focus on the individual animal has shifted to focus on herd or flock to a focus on the
food production chain.
Animal welfare is important for the general public as well as the scientific community.
The five freedoms:
1. freedom from hunger and thirst
2. freedom from discomfort
3. freedom from pain, injury and disease
4. freedom to express normal behaviors
5. freedom from fear and distress
An important component of free trade is the assessment of the risk of disease and related
events.
Chapter 2 - The scope of epidemiology
The investigation of disease in populations is the basis of epidemiology. Epidemiology is
the study of disease in populations and of factors that determine its occurence. It includes
the investigation and assessment of other health-related events, notably productivity. The
investigations involve observing animal populations and making inferences from them.
Epidemiology is the study of human populations. epizootiology is the observation of animal
populations.
Zoonoses are transferred from animals to humans.
The five objectives of epidemiology:
1. determination of the origin of a disease whose cause is known
a. can be diagnosed precisely by the signs exhibited by the affected animal,
laboratory tests and other clinical procedures.
2. investigation and control of a disease whose cause is either unknown or poorly
understood
3. acquisition of information on the ecology and natural history of a disease
a. more knowledge about the natural history of a disease can be obtained by
studying the host’s ecosystem.
4. planning, monitoring and assessment of disease control programmes
2
, 5. assessment of the economic effects of a disease, and analysis of the costs and
economic benefits of alternative control programmes.
Types of epidemiological investigation:
1. Descriptive: observing and recording diseases and possible causal factors.
2. Analytical: analysis of observations using diagnostic and statistical procedures.
3. Experimental: control of the test subjects, allowing the alteration of factors.
4. Theoretical: representation of the disease using mathematical models to attempt to
simulate natural patterns of disease occurrence.
Epidemiological subdisciplines:
● clinical epidemiology: concerned with frequency and cause of disease, the factors
that affect prognosis, the validity of diagnostic tests and effectiveness of therapeutic
and preventive techniques. evidence-based medicine
● computational epidemiology: application of computer science to epidemiological
studies, e.g. mathematical models and expert systems.
● genetic epidemiology: the study of cause, distribution and control of disease in
related individuals, and of inherited defects in populations. Many diseases involve
both genetic and non-genetic factors, thus geneticists are also concerned with
interactions between the two.
● field epidemiology: for rapid or immediate action; timely and judgemental process
based on description, analysis and common sense.
● participatory epidemiology: the use of local knowledge to gain information, with the
main goal to improve animal health.
● molecular epidemiology: the study of small genetic and antigenetic differences
between viruses and other microorganisms at a higher level of discrimination. e.g.
peptide mapping, nucleic acid fingerprinting and hybridization, restriction enzyme
analysis, monoclonal antibodies and the polymerase chain reaction.
○ part of the wider use of biological markers; cellular, biochemical and
molecular alterations that are measurable in biological media such as tissues,
cells or fluids.
● other subdisciplines: chronic disease epidemiology, environmental epidemiology,
micro-epidemiology, comparative epidemiology, macro-epidemiology, nutritional
epidemiology, subclinical epidemiology, social epidemiology, psychosocial
epidemiology.
Components of epidemiology:
● Qualitative investigations:
○ natural history of a disease: the ecology of diseases, incl. distribution, mode
of transmission and maintenance of infectious disease, investigated by field
observation.
○ causal hypothesis testing
● Quantitative investigations: involve measurement and therefore expression and
analysis of numerical values.
○ surveys, monitoring, surveillance, studies, modelling, and the biological and
economic evaluation of disease control.
○ screening: the identification of undiagnosed cases of disease using rapid
tests or examinations. The aim is to separate the healthy individuals from
affected animals.
3
- rinderpest
- cowpox
- foot-and-mouth disease
- rabies
- tuberculosis
- canine ascarid infections
- anthrax
- avian influenza
- leptospirosis
Chapter 1 - The development of veterinary medicine
Dogs domesticated ~ 14,000 years ago. Sheep and goats ~9,000 B.C.
Greece ~6 B.C. → disease due to derangement of the four humours, associated
with four properties (heat, moisture, dryness and cold) and with four elements
(air, earth, water, and fire). Diseases were believed to be caused by external
forces.
20th century Europe → microbial theory of infectious disease
5 periods of veterinary medicine:
1. until 1st century AD: demonic theory and miasmatic theory of cause →
quarantine and slaughter as preventive strategies
2. first century AD until 1762: interest in equine matters → military healers
3. 1762 - 1884: improvement of farm hygiene, slaughter and treatment as control
techniques. Disinfection.
4. 1884-1960: microbial theory → vaccination
1
, 5. 1960s- : disease causality and control. Multifactorial theory of disease which is
equally applicable to infectious and noninfectious diseases.
Major strategies:
1) structured recording of information on disease: surveillance and monitoring
2) the analysis of disease in populations
Disease is defined as the unacceptable performance of groups of animals (decreased herd
performance).
Performance-related diagnosis: includes performance indicators, and estimation of covert
biochemical values (metabolite levels in serum).
Subclinical diseases do not produce overt clinical signs, although often affect production.
Non-infectious diseases can be predominantly genetic, metabolic and neoplastic.
Clinical disease, subclinical disease and production need to be monitored in the context of
anticipated levels for a particular production system.
Food quality is an area of concern in veterinary public health (salmonella, E.coli, legionella
etc.).
The focus on the individual animal has shifted to focus on herd or flock to a focus on the
food production chain.
Animal welfare is important for the general public as well as the scientific community.
The five freedoms:
1. freedom from hunger and thirst
2. freedom from discomfort
3. freedom from pain, injury and disease
4. freedom to express normal behaviors
5. freedom from fear and distress
An important component of free trade is the assessment of the risk of disease and related
events.
Chapter 2 - The scope of epidemiology
The investigation of disease in populations is the basis of epidemiology. Epidemiology is
the study of disease in populations and of factors that determine its occurence. It includes
the investigation and assessment of other health-related events, notably productivity. The
investigations involve observing animal populations and making inferences from them.
Epidemiology is the study of human populations. epizootiology is the observation of animal
populations.
Zoonoses are transferred from animals to humans.
The five objectives of epidemiology:
1. determination of the origin of a disease whose cause is known
a. can be diagnosed precisely by the signs exhibited by the affected animal,
laboratory tests and other clinical procedures.
2. investigation and control of a disease whose cause is either unknown or poorly
understood
3. acquisition of information on the ecology and natural history of a disease
a. more knowledge about the natural history of a disease can be obtained by
studying the host’s ecosystem.
4. planning, monitoring and assessment of disease control programmes
2
, 5. assessment of the economic effects of a disease, and analysis of the costs and
economic benefits of alternative control programmes.
Types of epidemiological investigation:
1. Descriptive: observing and recording diseases and possible causal factors.
2. Analytical: analysis of observations using diagnostic and statistical procedures.
3. Experimental: control of the test subjects, allowing the alteration of factors.
4. Theoretical: representation of the disease using mathematical models to attempt to
simulate natural patterns of disease occurrence.
Epidemiological subdisciplines:
● clinical epidemiology: concerned with frequency and cause of disease, the factors
that affect prognosis, the validity of diagnostic tests and effectiveness of therapeutic
and preventive techniques. evidence-based medicine
● computational epidemiology: application of computer science to epidemiological
studies, e.g. mathematical models and expert systems.
● genetic epidemiology: the study of cause, distribution and control of disease in
related individuals, and of inherited defects in populations. Many diseases involve
both genetic and non-genetic factors, thus geneticists are also concerned with
interactions between the two.
● field epidemiology: for rapid or immediate action; timely and judgemental process
based on description, analysis and common sense.
● participatory epidemiology: the use of local knowledge to gain information, with the
main goal to improve animal health.
● molecular epidemiology: the study of small genetic and antigenetic differences
between viruses and other microorganisms at a higher level of discrimination. e.g.
peptide mapping, nucleic acid fingerprinting and hybridization, restriction enzyme
analysis, monoclonal antibodies and the polymerase chain reaction.
○ part of the wider use of biological markers; cellular, biochemical and
molecular alterations that are measurable in biological media such as tissues,
cells or fluids.
● other subdisciplines: chronic disease epidemiology, environmental epidemiology,
micro-epidemiology, comparative epidemiology, macro-epidemiology, nutritional
epidemiology, subclinical epidemiology, social epidemiology, psychosocial
epidemiology.
Components of epidemiology:
● Qualitative investigations:
○ natural history of a disease: the ecology of diseases, incl. distribution, mode
of transmission and maintenance of infectious disease, investigated by field
observation.
○ causal hypothesis testing
● Quantitative investigations: involve measurement and therefore expression and
analysis of numerical values.
○ surveys, monitoring, surveillance, studies, modelling, and the biological and
economic evaluation of disease control.
○ screening: the identification of undiagnosed cases of disease using rapid
tests or examinations. The aim is to separate the healthy individuals from
affected animals.
3
