Lecture 1: Intro to Disease

Question 1

What is Health (Reference to livestock)?

Answer 1

Welfare, Production, and Reproduction

Question 2

What is the traditional definition of Disease?

Answer 2

A finite abnormality of structure or function with an identifiable pathological basis and recognizable clinical signs

Question 3

What are clinical signs? What is an example?

Answer 3

Direct observation of the patient (objective). Ex. laboured breathing, limping

Question 4

What is the now broadened definition of Disease?

Answer 4

Now includes subclinical disease, suboptimal production and welfare

Question 5

Define: Subclinical disease, Clinical disease and sub-optimal production.

Answer 5

Subclinical disease: Not visible but measurable in some way. EX somatic cell count
Clinical Disease: Overt visible signs EX. Diarrhea
Sub-optimal production: Below what is expected for the breed, industry or genetic line

Question 6

What is the acronym for the classification of Disease?

Answer 6

D- Degenerative
A- Anomalous
M-Metabolic
N-Neoplasm/Neoplastic
I-Infectious
T-Traumatic or Toxic

Question 7

What does degenerative mean in terms of the classification of disease?

Answer 7

Structure is altered by age, use or disuse, or biochemical changes. Ex Arthritis

Question 8

What does Anomalous mean in terms of the classification of disease?

Answer 8

Abnormal structure or function that is congenital and may be genetic. E Cleft palate, atresia ani (lacking a rectum)

Question 9

What does metabolic mean in terms of the classification of disease?

Answer 9

Due to nutrition, toxins or hormonal activity that alters normal metabolism. EX Milk fever, ketosis HINT: THINK DAIRY

Question 10

What does Neoplasm/neoplastic mean in terms of the classification of disease?

Answer 10

Abnormal growth of cells at the expense of normal tissue structure and function. EX lymphosarcoma and eye cancer

Question 11

What does infectious mean in terms of the classification of disease?

Answer 11

Microorganisms invade the body and damage normal structure and function. EX Mycoplasma hyopnemonia causing pneumonia in pigs.

Question 12

What does trauma and toxic mean in terms of the classification of disease?

Answer 12

Mechanical injury EX broken bones
exogenous substance gains access to the system which causes damage to structure leading dysfunction.

Question 13

What is a pathogen and what part of DAMNIT is it considered?

Answer 13

Any disease-producing (or infectious) microorganism or material ie virus, bacteria and fungus.
A pathogen is considered infectious.

Question 14

What is Etiology?

Answer 14

Study of the causes of disease. An Etiologic agent = causative agent of disease but NOT= “the cause”

Question 15

What is the Koch’s Postulates process?

Answer 15

Sick animal –> Isolate a Pathogen –> Infect healthy animal –> Cause same disease –> Re-isolate same pathogen

Question 16

What is pathogenesis?

Answer 16

The development or process of a disease OR The process by which a pathogen produces a disease

HINT: Pathogenesis: Path: pathogen genesis: formation

Question 17

What are the infectious causes/agents of disease? Examples?

Answer 17

Bacteria
Viruses
Prions (cause BSE AKA mad cow)
Mycotic (fungal ringworm)
Parasites (3 types Intracellular, Internal, external)

Question 18

What are 2 ways disease transmission can be described?

Answer 18

1. How the pathogen is exchanged between hosts
2. Populations the pathogen is exchanged between

Question 19

What is the difference between horizontal and vertical disease transmission?

Answer 19

Horizontal is between the same generation ex the same pen and vertical is between animal of a different generation ex mother to offspring.

Question 20

What are the modes of disease transmission?

Answer 20

Direct
Fomites-Inanimate objects, does not infect-passive carrier
Vector-Invertebrate animal required for agent lifecycle and transmission
Infectious secretions or excretions- Resp droplets, saliva, put exudate, faces and urine

Question 21

What is the Epidemiological Triad? Does an infectious agent present mean that a disease is also present?

Answer 21

Host

                                          Agent                                    Environment 

No.

Question 22

What are the 2 different concepts related to Triad?

Answer 22

1. Tipping point- Health with protective factors balancing with disease risk factors
   2.The iceberg concept- clinical perception is less then the actual herd problem