Source and transmission of infection

Question 1

Infection

Answer 1

Presence of micro-org in or on host tissues

Question 2

Disease

Answer 2

Pathological and clinical conseq of infection

Question 3

Opportunistic pathogens

Answer 3

Some commensal or enviro micro-orgs

Question 4

True pathogens

Answer 4

Initiate disease as a conseq of their presence on tissues

Question 5

Fx of commensals

Answer 5

Metabolism
Dev of imm syst
Colonisation resis

Question 6

Virulence or pathogenicity

Answer 6

Capacity of a particular org to cause dis assessed by Koch’s postulates

Question 7

Koch’s postulates

Answer 7

Org must be recovered from all cases of the disease
Must be cultures in vitro
Reinoc must reproduce dis
Same org must be reisolated from lesions of induced dis

Question 8

Issues with kochs postulates

Answer 8

Ignores host factors
Some are non-culturable
Poly microbial infections not accounted for
Strain difference not accounted for

Question 9

Pathogenesis

Answer 9

Mech by which an agent induces symptoms or pathology

Question 10

What can understanding of the pathogenic process lead to

Answer 10

Dev of appropriate methods for diagnosis, prevention, control and or therapy

Question 11

Sources of infection and disease

Answer 11

Endogenous
Animals within group
Other species of animals
Enviro

Question 12

Endogenous sources of disease

Answer 12

Commensal can become opportunistic with right conditions eg antibio misuse, stress, imm compromised

Question 13

Animals within grp as source of disease

Answer 13

Most important source
Can produce epizootic/epidemic - outbreak
Or enzootic/endemic - continuous
Most pathogens multiply best in natural host

Question 14

Other species as source of disease

Answer 14

Some microorgs can infect a variety of hosts but charcteristics of infection may differ
Zoonoses (vet has spec responsibility to control risk and report)

Question 15

Enviro as source of infection

Answer 15

Some pathogens or oppotunists can survive in enviro or grow on plant or organic material. Usually ltd direct animal-animal transmission

Question 16

Direct transmission

Answer 16

Animal-animal

Oral, resp,cutaneous, urogenital, bidy fluid trasmission

Question 17

Indirect transmission

Answer 17

Food and water supply (could be contam by faeces)
Fomites
Arthropod vectors
Iatrogenic
Nosocomial infections

Question 18

Fomites

Answer 18

Inanimate object that can transfer infection

Question 19

Iatrogenic infection

Answer 19

Result of himan interference eg introduced by vet in surgery

Question 20

Nosocomial infection

Answer 20

Acquired during hospitalisation
Congregation of diseased animals and vet interference
Anti-infective agent use can cause drug res prevalence

Question 21

Horizontal transmission

Answer 21

Between animals within a group

Question 22

Vertical transmission

Answer 22

Parent to offspring via germ line, in utero or milk or colostrum

Question 23

Vector borne bact pathogen examples

Answer 23

Borrelia, coxiella and tularemia

Question 24

How does Borrelia (burgdorferi) move

Answer 24

A spirochete, motile via endoflagella cont within periplasmic space between semirigid peptidoglycan layer and multi-layer flexible outer mem sheath
Filaments rotate in this space and cause corkscrew fashion bact movement (may be adaptation to viscous enviro eg aquatic sediments, mucosal tissue)

Question 25

Outer surf pro of Borrelia burgdorferi

Answer 25

Various unique Osps (Osp A - F) presumed to play role in virulence
A & B most abundant
Small, Linear chromosome

Question 26

Borellia transfer and reservoir hosts

Answer 26

Ixodes Ticks transfer from natural reservoir of white footed mouse to other warm blooded animals. Bact invades blood and tissues. In humans dogs and others it can cause lyme disease
(On pacific coast western black legged tick)

Question 27

Borrelia can persist by

Answer 27

Immune suppression and or evasion

Question 28

How does borrelia control its own virulence

Answer 28

Bu regulating virulence gene expression in resp to enviro (diff hosts)

Question 29

Lyme disease distrib

Answer 29

Wide distrib in N temperate regions
(US: NE and NC states)
UK incr prevelence or better awareness and diagnostics

Question 30

Canine lyme disease manifestation

Answer 30

Doesnt manifest for weeks or months, arthritis sign noticed and neurological issues rare
Most serious long term potential is glomerular dis

Question 31

Glomerular dis

Answer 31

Kidney dam where imm syst stim for long time lead to circulating imm complexes get stuck in filtration mem of glomerulus causing inflam and eventually a small hole
Can be Caused by canine lyme dis

Question 32

Canine lyme dis treatment

Answer 32

Respond rapidly to inexpensive antibio course
Goal to bring patient into premunitive state (state of dogs infected that never get ill) so organism in bodies latently but not cause infection

Question 33

Coxiella transmission, manifest in diff species, spore or nonspore?

Answer 33

Produce spores C. Burnetti cause Q fever in man
Ruminant often asymptomatic
Cattle excrete in milk and there is placental colonisation
Ovine similar but can cause the odd abortion
Not just tick transmission

Question 34

Tularemia

Answer 34

Bact septicaemia affecting domestic mammals birds reptiles fish people

Question 35

Tularemia cause

Answer 35

F tularensis
highly virulent facultative IC pathogen
Inoc/inhal 10 organism can cause severe dis so is a category A agent (likely bio weapon)