Veterinary Epidemiology and Economics
Introduction to the course (lecture 1 Tuesday 28th oct)
Epidemiology of animal diseases
Reduce societal burden of animal diseases: negative impact of a disease on a community:
- Animal health
- Economics
- Animal welfare
- Public health (zoonosis + antimicrobial resistance)
- Environmental health (more GHG emissions due to a lower production – chemicals –
biodiversity)
- Amount of quality of animal products
- (satisfaction of animal owner)
Quiz
1. The status of an animal (diseased or healthy) can easily be determined by experts
(e.g. veterinarians). → incorrect
Health is a relative concept. There are many definitions. Even if it is not a relative concept, an expert
cannot indicate in all cases whether an animal is diseased or healthy. (e.g. a subclinical disease
cannot be observed with the naked eye (including those of an expert)).
Health is a dynamic balance.
,Homeostasis (adaptive capacity of an individual): temporary or permanent anatomical,
physiological or behavioural change of the organism to reduce or overcome health-threatening
influences.
- Specific: e.g. environmental temperature high: perspiration and vasodilation
- A specific: stress, non-specific reaction to a stimulus/stressor.
2. Stress reaction must be always avoided. → incorrect
Stress reaction is the body’s response to any stimulus (definition) and allows the animal to live with
suboptimal conditions.
If the stimulus persists for a long time, it can have negative consequences
Stress control is ‘symptom control’, it is better to remove the cause (the stimulus or stressor)
3. In general, the risk of diseases is highly productive animals higher → correct
High production affects the adaptive capacity in a negative way. It is not uncommon for a farmer to
complain that his best producing animal has fallen ill or died!
4. Subclinical disease is symptomless → correct
If symptoms were present, the disease would no longer be subclinical, but clinical. However,
expertise does play a role here: someone who specializes in a particular disease is more likely to
notice the symptoms than someone who comes across the disease sporadically (p. 97-101)
Also learn the clinical health characteristics and the deviations in case of clinical disease!
Clinical health characteristics:
- Body temperature - Body condition
- Digestion - Skin, hair and feathers
- Respiration - Circulation
- Behaviour - mucous membranes
- Gait and posture - production
,Each symptom is not specific to any one disease!
- E.g. fever can occur in several diseases.
- Sometimes a whole set of symptoms is more specific to a disease, but in almost all cases
even that is not specific.
Based on clinical symptoms, a probability or clinical diagnosis is made.
5. Serological tests are required to confirm a probability diagnosis → incorrect
Serological testing = blood testing
Research can also be carried out on:
- Secreta/excreta (faeces, urine, saliva): e.g. poison (toxins), pH, blood in urine etc.
- There may be an autopsy (post-mortem examination) to be carried out (evaluation of organs)
3 types of determinations (bepalingen):
- Products of pathogen (also called antigen) (best proof of current infection)
- Antibodies (evidence of current and previous infection)
- Blood composition (e.g. enzymes, leucocyte count, blood cell ratio, minerals, hormones,
enzymes)
Advantages: relatively fast and cheap.
Animals with detectable antibody titres are seropositive, else seronegative
Disadvantages: false-positive and false-negative results
- False+: vaccination, cross-reaction, infection gone but antibodies still present
- False-: latency time, tolerance
Who makes the diagnosis?
- Animal holder: inspects daily. In case of questions or problems, the vet is called
- Responsibility for animal health:
o Owner can usually cure a disease himself with medication with the help of a vet.
o The government if a disease is exceptionally infectious or dangerous.
Livestock owners must:
- Ensure adequate hygiene at their place of business
- Be alert to symptoms of disease
- Report (suspected) animal diseases to the Netherlands Food and Consumer Product Safety
Authority (NVWA)
- Comply with requirements when importing animals from countries outside the European
Union (EU)
- Vaccinate their animals if possible and necessary.
, Role of vets:
- Assist with prevention
- Diagnose animal diseases
- Treatment of diseased/infected animals (possibly whole herd)
- Monitoring and surveillance to prevent outbreaks of contagious animal diseases
- Safeguard public health.
The animal health service (Royal GD) in NL
- Collects signals of new signs of disease in animals
- Overall aim to detect and tackle new and existing animal infectious diseases quickly
Animal health monitoring is vital for animal health and welfare, food safety and the export
position of the Netherlands
These interests are translated into monitor goals:
- Detection of outbreaks of recognized pathogens, which are not known to be otherwise
present in the Netherlands
- Detection of unknown diseases or pathogens
- Description of trends and developments in animal health.
6. If a disease is of no economic importance, there is little point in paying much
attention to it. → incorrect
There are also non-monetary burdens:
- Public health
- Animal welfare
- Quality of animal products
- Environmental aspects (GHG emissions, chemicals, biodiversity)
Zoonosis: a zoonosis is an infectious disease that can be transmitted from animals to humans.
The word zoonosis is derived from the Greek words zoon (animal) and nosis (disease). About
60% of human disease originates from animals.
Learning objective: give an example for several animal species.
Dogs → Rabies (transmitted through bites); leptospirosis (spread through urine-contamined
water); birds → Avian influenza (close contact with birds); goats → Q-fever (dust)
7. The proportion of replacement for sows is approximately 45% per year. The most
important cause for the culling of sows is a health disorder. → correct
A sow has an average lifespan of 2 to 2,5 years and in 70% of all cases the reason for culling is a
health disorder. (if not in a farm 15-20 years)
Introduction to the course (lecture 1 Tuesday 28th oct)
Epidemiology of animal diseases
Reduce societal burden of animal diseases: negative impact of a disease on a community:
- Animal health
- Economics
- Animal welfare
- Public health (zoonosis + antimicrobial resistance)
- Environmental health (more GHG emissions due to a lower production – chemicals –
biodiversity)
- Amount of quality of animal products
- (satisfaction of animal owner)
Quiz
1. The status of an animal (diseased or healthy) can easily be determined by experts
(e.g. veterinarians). → incorrect
Health is a relative concept. There are many definitions. Even if it is not a relative concept, an expert
cannot indicate in all cases whether an animal is diseased or healthy. (e.g. a subclinical disease
cannot be observed with the naked eye (including those of an expert)).
Health is a dynamic balance.
,Homeostasis (adaptive capacity of an individual): temporary or permanent anatomical,
physiological or behavioural change of the organism to reduce or overcome health-threatening
influences.
- Specific: e.g. environmental temperature high: perspiration and vasodilation
- A specific: stress, non-specific reaction to a stimulus/stressor.
2. Stress reaction must be always avoided. → incorrect
Stress reaction is the body’s response to any stimulus (definition) and allows the animal to live with
suboptimal conditions.
If the stimulus persists for a long time, it can have negative consequences
Stress control is ‘symptom control’, it is better to remove the cause (the stimulus or stressor)
3. In general, the risk of diseases is highly productive animals higher → correct
High production affects the adaptive capacity in a negative way. It is not uncommon for a farmer to
complain that his best producing animal has fallen ill or died!
4. Subclinical disease is symptomless → correct
If symptoms were present, the disease would no longer be subclinical, but clinical. However,
expertise does play a role here: someone who specializes in a particular disease is more likely to
notice the symptoms than someone who comes across the disease sporadically (p. 97-101)
Also learn the clinical health characteristics and the deviations in case of clinical disease!
Clinical health characteristics:
- Body temperature - Body condition
- Digestion - Skin, hair and feathers
- Respiration - Circulation
- Behaviour - mucous membranes
- Gait and posture - production
,Each symptom is not specific to any one disease!
- E.g. fever can occur in several diseases.
- Sometimes a whole set of symptoms is more specific to a disease, but in almost all cases
even that is not specific.
Based on clinical symptoms, a probability or clinical diagnosis is made.
5. Serological tests are required to confirm a probability diagnosis → incorrect
Serological testing = blood testing
Research can also be carried out on:
- Secreta/excreta (faeces, urine, saliva): e.g. poison (toxins), pH, blood in urine etc.
- There may be an autopsy (post-mortem examination) to be carried out (evaluation of organs)
3 types of determinations (bepalingen):
- Products of pathogen (also called antigen) (best proof of current infection)
- Antibodies (evidence of current and previous infection)
- Blood composition (e.g. enzymes, leucocyte count, blood cell ratio, minerals, hormones,
enzymes)
Advantages: relatively fast and cheap.
Animals with detectable antibody titres are seropositive, else seronegative
Disadvantages: false-positive and false-negative results
- False+: vaccination, cross-reaction, infection gone but antibodies still present
- False-: latency time, tolerance
Who makes the diagnosis?
- Animal holder: inspects daily. In case of questions or problems, the vet is called
- Responsibility for animal health:
o Owner can usually cure a disease himself with medication with the help of a vet.
o The government if a disease is exceptionally infectious or dangerous.
Livestock owners must:
- Ensure adequate hygiene at their place of business
- Be alert to symptoms of disease
- Report (suspected) animal diseases to the Netherlands Food and Consumer Product Safety
Authority (NVWA)
- Comply with requirements when importing animals from countries outside the European
Union (EU)
- Vaccinate their animals if possible and necessary.
, Role of vets:
- Assist with prevention
- Diagnose animal diseases
- Treatment of diseased/infected animals (possibly whole herd)
- Monitoring and surveillance to prevent outbreaks of contagious animal diseases
- Safeguard public health.
The animal health service (Royal GD) in NL
- Collects signals of new signs of disease in animals
- Overall aim to detect and tackle new and existing animal infectious diseases quickly
Animal health monitoring is vital for animal health and welfare, food safety and the export
position of the Netherlands
These interests are translated into monitor goals:
- Detection of outbreaks of recognized pathogens, which are not known to be otherwise
present in the Netherlands
- Detection of unknown diseases or pathogens
- Description of trends and developments in animal health.
6. If a disease is of no economic importance, there is little point in paying much
attention to it. → incorrect
There are also non-monetary burdens:
- Public health
- Animal welfare
- Quality of animal products
- Environmental aspects (GHG emissions, chemicals, biodiversity)
Zoonosis: a zoonosis is an infectious disease that can be transmitted from animals to humans.
The word zoonosis is derived from the Greek words zoon (animal) and nosis (disease). About
60% of human disease originates from animals.
Learning objective: give an example for several animal species.
Dogs → Rabies (transmitted through bites); leptospirosis (spread through urine-contamined
water); birds → Avian influenza (close contact with birds); goats → Q-fever (dust)
7. The proportion of replacement for sows is approximately 45% per year. The most
important cause for the culling of sows is a health disorder. → correct
A sow has an average lifespan of 2 to 2,5 years and in 70% of all cases the reason for culling is a
health disorder. (if not in a farm 15-20 years)
