Microbiology of disease

Question 1

Infection

Answer 1

the invasion and/or colonisation by and subsequent multiplication of pathogenic organisms in a body part or tissue which can produce subsequent tissue injury and progression to overt disease through a variety of cellular/toxic mechanisms

Question 2

Enzootic

Answer 2

a disease regularly affects animals in a particular district/season.

Question 3

Endemic

Answer 3

(for humans but used anyway)

regularly found in a particular group or in a particular area.

Question 4

Latency

Answer 4

the pathogen goes inert in animals; reactivation may occur if the pathogen is switched back on.

Often relates to viruses.

Question 5

Carriage

Answer 5

the animal tolerates the pathogen without disease. The carrier animal is a reservoir for infection as it may shed pathogens.

Question 6

Reservoir of infection

Answer 6

any animal/human/environment in which an infectious agent normally lives and mutliplies.

Question 7

Acute infection

Answer 7

pathogen is cleared shortly after infection

Question 8

Chronic infection

Answer 8

pathogen is detectable for the lifetime of the host

Question 9

Latent infection

Answer 9

Infectious agents disappears within the animal but can be reactivated by a number of factors.

Question 10

What descriptive term for disease does this graph show?

Answer 10

Acute infection

Question 11

What descriptive term for disease does this graph show?

Answer 11

Chronic infection

Question 12

What descriptive term for disease does this graph show?

Answer 12

Latent infection

Question 13

Endogenous pathogen

Answer 13

already on the animal; may suddenly cause disease due to changes in the organism/host or opportunity arising.

Question 14

Exogenous pathogens

Answer 14

transferred to the animal from another source; not already present on the animal.

Question 15

Method of transmission of pathogens

Answer 15

• Vertical transmission
• Horizontal transmission
• Sexual transmission
• Food-borne
• Vector-borne
• Iatrogenic

Question 16

Vertical transmission

Answer 16

transmission of pathogen/disease from parent to offspring

Question 17

Horizontal transmission

Answer 17

transmission of a pathogen within a group

Question 18

Commensals

Answer 18

bacteria or fungi that exist on or in hosts without causing disease. Some are very important to the animal’s health (e.g. gut bacteria of ruminants)

Question 19

Commensalism

Answer 19

the relationship between two species whereby one benefits from the association, whereas the other neither benefits nor suffers.

Includes bacteria, fungi and protozoa.

Question 20

Opportunistic pathogen

Answer 20

normally benign organism which causes infections when given the chance

–> a commensal in the wrong place

–> when host defences are compromised