Topic 4 - Prevention and control of infectious diseases.

Question 1

What is the aim of preventing or controlling an infectious disease?

Answer 1

To prevent introduction of the disease, and to prevent spread.

If the disease is introduced, the aims is to localize and eliminate the epidemy.

Question 2

Which methods are used in prevention and control of infectious diseases?

Answer 2

1. Veterinary administration methods
2. Immune prophylaxis
3. Chemo prophylaxis

Question 3

What is meant by “veterinary administration methods”?

Answer 3

there are administration rules, general epidemiological rules and specific measures which are variable for each disease.

Question 4

Name “veterinary administration rules”:

Answer 4

1. We have notifiable disease
2. rules for international transport
3. Import restrictions
4. Identification of animals
5. Certificates
6. Traceability of the animal

Question 5

Name the general epidemiology rules:

VERY IMPORTANT FOR THE EXAM

Answer 5

1. All-in-all out, WITH disinfection
2. Isolated keeping of different animal species and age groups
3. Closed keeping, limited traffic (personal, vehicles)
4. Introduction of animals: diagnostic tests, quarantine
5. Isolation from wild living animals, rodents, birds
6. Rendering dead animals, waste
7. Rules of hatching, transport of day-old chicken
8. Excluding carrier people

Question 6

Name some specific epidemiologic measures:

Answer 6

This is specific for each disease, we have two different method:

1. Great economic impact
2. Smaller economic impact

Question 7

Specific epidemiological measures for diseases of GREAT economic impact:

Answer 7

1. Strict rules
2. Closed herd
3. protection zone
4. observation zone
5. stamping out

Question 8

Specific epidemiological measures for diseases of SMALLER economic impact:

Answer 8

1. Movement restriction
2. Closed herd
3. Diagnostic examination
4. Treatment + vaccination

Question 9

What is immune prophylaxis?

Answer 9

We have two types:

1. Passive immunisation
2. Active immunisation

Question 10

What is passive immunisation under immune prophylaxis treatment?

Answer 10

We have:
1. Hyperimmune serum
2. Maternal immunity

Question 11

What is hyperimmune serum of passive immunisation under immune prophylaxis treatment?

Answer 11

the animal is given a high level of antibodies through a vaccine.

Homologous half-life = 2-3 weeks

Heterologous half-life = 7-10 days

Question 12

What is maternal immunity of passive immunisation under immune prophylaxis treatment?

Answer 12

It is a passive immunity. Depending on the type of placenta, the significant of the colostrum is varying. Also the colostrum quantity and quality changes over time

good colostrum immunity = the mother is vaccinated

Question 13

Significance of colostrum with Epitheliochorial:

Answer 13

colostrum

horses, pigs

Question 14

Significance of colostrum with Syndesmochorial:

Answer 14

mainly colostrum

ruminant ungulates

Question 15

Significance of colostrum with Endotheliochorial:

Answer 15

diaplacental + colostrum

cat and dog

Question 16

The number of maternal antibodies depends on?

Answer 16

1. The antigen
2. Nutrition of the dam
3. General state of the dam

Question 17

Why is it important to measure the colostrum level before vaccinating?

Answer 17

If the animal have high colostrum immunity level, the vaccination efficiency can be decreased, because the antibodies bind the antigens of the vaccine

Question 18

What is active immunisation?

Answer 18

Immunisation provided by the veterinarian, such as the vaccine

Question 19

Factors influencing the efficacy of the active immunisation:

Answer 19

1. the agent
2. Vaccine type
3. Amount of antigen
4. Method of vaccination
5. age of animal
6. health of animal

Question 20

Different types of vaccine, name them and the subunits of them.

Answer 20

1. Live vaccines
   a. Avirulent
   b. Attenuated - natural and artificially
2. Inactivated vaccines
3. Polyvalent vaccines

Question 21

What helps the efficiency of the vaccine?

Answer 21

the adjuvant, they have a longer antigen release

Question 22

What is a live vaccine?

Answer 22

Fast effect and more effective, they induce a faster immune reaction

Question 23

What is an AVIRULENT live vaccine?

Answer 23

there are no pathogenic opportunity, they can be used in vaccines

Question 24

What is an ATTENUATED live vaccine?

Answer 24

virulent, but after passaging they can be attenuated artificially

Question 25

What is inactivated vaccine?

Answer 25

They contain viruses whose genetic material has been destroyed by heat, chemicals or radiation so they cannot infect cells and replicate, but can still trigger an immune response

Question 26

What types can the inactivated vaccine be?

Answer 26

1. Complete agent 2. Partial antigen extract 3. Subunit 4. Toxoid = inactivated toxin

Question 27

What is a polyvalent vaccine?

Answer 27

more than one agent is present in the vaccine

Question 28

What does the DIVA principle stand for?

Answer 28

DIVA = Differentiation Infected and Vaccinated Animals. Also called marker vaccine

Question 29

What is the DIVA principle?

Answer 29

= induce an immune response which is different from that induced by natural infection. Difference between the field and the vaccine strains

Question 30

Name different marker vaccines:

Answer 30

1. Deletion markers 2. Subunit markers 3. Non-structural marker

Question 31

What is a deletion marker vaccine?

Answer 31

Gene-deletion-lack of certain non-important protein

Question 32

What is a subunit marker vaccine?

Answer 32

Vector-produced, different structure

Question 33

What is a non-structural marker vaccine?

Answer 33

Viral enzymes, no-replication, no immune answer

Question 34

What is Chemo prophylaxis?

Answer 34

refers to the administration of a medication for the purpose of preventing disease or infection. Antibiotics, for example, may be administered to patients with disorders of immune system function to prevent bacterial infections.

Question 35

Which methods are used for control and eradication of an infectious disease?

Answer 35

1. Selection 2. Generation shift 3. Herd replacement 4. SPF method 5. Embryo transfer 6. Eradication with antibodies 7. Eradication of infectious disease of animals

Question 36

What is selection as a control and eradication method?

Answer 36

In small herds we can select the animals, selection test and removal of the infected animal and we have a high chance of removing the disease. To test we a useful tool, the DIVA marker vaccine

Question 37

What is generation shift as a control and eradication method?

Answer 37

Generation shift is a method where we isolate the keeping of new-born animals, and then we replace the infected parent stock with the new-born when they are old enough. In optimal conditions we will then have a new herd without the disease.

Question 38

What is herd replacement as a control and eradication method?

Answer 38

This is a VERY expensive method, we eliminate the herd, disinfect the area and buy new livestock.

Question 39

What is SPF method as a control and eradication method?

Answer 39

SPF = Specific Pathogen Free It is a health state, there is a risk of pathogens – that is why it is specific.

Question 40

What is embryo transfer as a control and eradication method?

Answer 40

Embryo transfer can be used, but with the restriction that deep frozen embryos can harbour infections as well. In some diseases this will work

Question 41

What is eradication with antibodies as a control and eradication method?

Answer 41

Is not preferred, because of the resistance issues. In case of leptospirosis it can work

Question 42

How was Rinderpest eradicated?

Answer 42

Rinderpest was the only disease with sterile immunity, so if the animals was vaccinated the immunity would cause sterility so the virus couldn’t cause infection anymore – this is why it was possible to eradicate the disease