Infection control (SA5)

Question 1

What are the stages of the chain of infection?

Answer 1

• Pathogen
• Reservoir
• Portal of exit
• Mode of transmission
• Portal of entry
• Susceptible host

Question 2

What is a convalescent carrier?

Answer 2

• Recovered from disease but still sheds into environment

Question 3

What is a healthy carrier?

Answer 3

• Exposed to organism but doesn’t become ill
• Usually because immune system has fought disease previously

Question 4

What is an open carrier?

Answer 4

• Continuously shed organism
• Usually weeks-months
• Can be life long

Question 5

What is a closed carrier?

Answer 5

• Doesn’t normally shed disease
• Shedding triggered by stress or steroids

Question 6

Where is MRSA found?

Answer 6

• Within naso-oral cavity

Question 7

What is an infectious disease?

Answer 7

Caused by microorganism capable of invading and replicating within a host

Question 8

What is a contagious disease?

Answer 8

• Can be passed from one animal to another
• Via direct or indirect contact
• Spread through contagions

Question 9

What is a zoonotic disease?

Answer 9

• Can be passed from vertebrate animals to humans
• immunosuppressed, young, old and pregnant most at risk

Question 10

What is contamination?

Answer 10

• Presence of microorganisms on body surface or inanimate object

Question 11

What is colonisation?

Answer 11

• Presence of microorganisms with no clinical signs

Question 12

What are pathogens?

Answer 12

• Disease producing microorganisms
• May live in or on the host
• Disrupts normal physiological function

Question 13

What is a facultative anaerobe?

Answer 13

• Will grow whether oxygen is present or not

Question 14

What is an epidemic?

Answer 14

• Increase in number of cases of a disease
• Above what is normally expected in that population

Question 15

What is a pandemic?

Answer 15

• Epidemic of worldwide proportions
• Increase in number of cases of a disease worldwide above normal expectations

Question 16

What is an endemic?

Answer 16

• Disease that permanently exists is particular populations
• At normal levels and is predictable

Question 17

• What is an epizootic?

Answer 17

• Epidemic of an animal disease
• Increase in number of cases of an animal population above normal levels

Question 18

What are the causal agents of infectious diseases?

Answer 18

• Bacterium
• Virus
• Protozoan
• Fungus
• Prions
• Ecto/endo-parasites

Question 19

What are viruses?

Answer 19

• Tiny intracellular parasites
• Can only replicate within a host cell
• Can only attach to compatible cells

Question 20

What is the structure of a virus?

Answer 20

• Each virus particle
• Core of nucleic acid (RNA or DNA)
• Surrounded by protein coat (Capsid)
• Together known as nucleocapsid
• Some viruses are enclosed in an envelope

Question 21

What are virus envelopes made from?

Answer 21

• Lipoprotein and glycoprotein
• Some have glycoprotein spikes to help them attach to host cells

Question 22

What is the name for spherical viruses?

Answer 22

Icosahedral

Question 23

What is meant by an icosahedral virus?

Answer 23

• Spherical in shape

Question 24

What makes enveloped viruses easier to kill?

Answer 24

• Envelopes are fragile
• Readily absorb disinfectants

Question 25

How do viruses replicate?

Answer 25

- Attach to host cell and penetrate membrane - OR being taken into cell by endocytosis - Takes control of cell, instructs to produce more virus particles - Released by rupture or no harm to the cell

Question 26

How can viruses be diagnosed?

Answer 26

- Serology detects antibodies - Antigens (Viral proteins) detected in serum - PCR detects viral DNA/RNA but expensive

Question 27

What are bacteria?

Answer 27

Single cell organism, vary in size and shape

Question 28

What are the 3 basic shapes of bacteria?

Answer 28

- Bacilli (Ovals) - Cocci (Circles) - Spirochaetes (Spirals)

Question 29

Bacteria cell walls

Answer 29

- Can be inhibited by Cephalosporins - Some have slimy coat for protection and to enable them to attach to cells - Some have pili/fimbriae to stick to host

Question 30

What are the different arrangements of cocci?

Answer 30

- Diplococcus (2 cocci) - Streptococcus (Chains of cocci) - Staphlococcus (Bundles of cocci - grapes)

Question 31

What is the name for curved Bacilli?

Answer 31

Vibrios

Question 32

What is the optimum temperature for bacteria to replicate?

Answer 32

37 degrees

Question 33

What are the 2 ways bacteria can replicate?

Answer 33

Binary fission - Asexual - Creates 2 identical cells Conjugation - Sexual - Sharing of DNA only - No new cell

Question 34

How does antibiotic resistance come about?

Answer 34

Conjugation

Question 35

Commensals

Answer 35

Bacteria living on animals and not causing harm

Question 36

Facultative

Answer 36

- Opportunistic bacteria - Will cause harm in immunosuppressed

Question 37

Obligate

Answer 37

Bacteria that always causes disease

Question 38

Saphrophytic

Answer 38

- Replicate on dead tissue - Responsible for decay

Question 39

Symbiotic and mutualistic bacteria

Answer 39

benefits both parties

Question 40

How are bacteria diagnosed?

Answer 40

- Bacterial smears - Grams stains - Culture on nutrient medium - Sensitivity testing

Question 41

Examples of viral infections

Answer 41

- Parvo - Lepto - Distemper - Myxo - RHD - FELV - FIV - Parainfluenza

Question 42

Examples of bacterial infections

Answer 42

- Bordetella bronchiseptica - Leptospira canicola - Chlamydophila felis

Question 43

What are fungi?

Answer 43

- Large group of organisms - Ranging from micro to macroscopic - Moulds, yeasts

Question 44

What are the 3 fungi of veterinary importance?

Answer 44

- Dermatophytes (Ringworm) - Yeasts (e.g Malassezia) - Mould (Aspergillus)

Question 45

Is ringworm a multicellular fungus?

Answer 45

Yes

Question 46

What is Dermatophytes?

Answer 46

Ringworm

Question 47

What are the 2 types of dematophytes?

Answer 47

Trichophyton mentagrophytes - Dogs, cats, rabbits, guinea pigs Microsporum canis - Dogs and cats

Question 48

What are the clinical signs of ringworm and how is it diagnosed?

Answer 48

- Circular hair loss, may be inflamed - Some long hair cats are asymptomatic - Hair plucks for staining or culture - Some species fluoresce with woods lamp - 50% of Microsporum canis apple green - Spores can live on fomites for long periods

Question 49

Are yeasts unicellular?

Answer 49

Yes

Question 50

What is Malassezia pachydermatis?

Answer 50

- Yeast - Found on skin normally - Dematitis/otitis externa on susceptible pets - Often during summer - Can be greasy, has distinct odour

Question 51

How is Malassezia pachydermatis diagnosed?

Answer 51

- Tape strips stained with methylene blue - appears as bottle shapes under the microscope

Question 52

What is Candida Albicans?

Answer 52

- Yeast - Present in normal animals - May cause clinical signs in young, old, immuno - Thrush

Question 53

What are the clinical signs of Candida Albicans?

Answer 53

- White plaques in mouth - Ulcers - In birds sour crop

Question 54

What is a protozoa?

Answer 54

- Single cell organisms - Many capable of independent movement - Many survive outside body in moisture films

Question 55

How are protozoa diagnosed?

Answer 55

- Cysts in faeces - Pooled samples required - Results may be unreliable - ELISA or PCR tests are more expensive

Question 56

Is toxoplasma zoonotic?

Answer 56

- Yes - Can cause spontaneous abortion

Question 57

What are prions?

Answer 57

- Mutated proteins leading to serious neurological disease - Spread by ingestion of infected tissue, especially brain and spinal cord - Genetic predisposition may be required, proven in sheep - Prions are always fatal