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VET YEAR ONE > DISEASE E&E (Transmission 1) > Flashcards

DISEASE E&E (Transmission 1) Flashcards

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1
Q

Taxonomic overview of pathogens and parasites

A

-viruses
-bacteria
Eukaryotes:
-protozoan
-fungi
-nematoda (roundworms)
-platyhelminthes (flatworms)
-arthropods

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2
Q

Helminths:

A

-nematoda
-platyhelminthes

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3
Q

Platyhelminthes:

A

-cestoda (tapeworms)
-trematoda (flukes)

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4
Q

Arthropods:

A

-mites
-ticks
-lice
-mosquitoes
-flies

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5
Q

Epidemiological models:

A

-distinguished between microparasites vs. microparasites

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6
Q

Microparasites:

A

-viruses, bacteria, protozoans
-acellular and unicellular
-small and replicate inside the host (numerous)
>don’t grow and develop

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7
Q

Macroparasites:

A

-multi-cellular
-helminths, arthropods
-grow and develop inside the host (don’t multiply)
*large and few

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8
Q

Microparasite models:

A

-modelled with SIR models
-model the dynamics by tracking NUMBER of susceptible, infected, and recovered HOSTS
-all infected individuals are the same (*percent of infected individuals is informative)

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9
Q

Probability of transmission (or recovery): microparasites

A

-does NOT depend on NUMBER of microparasites in host

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10
Q

Helminth worms: microparasitic models

A

-have different lifecycle stages: eggs, larvae, adults
-often aggregated in their hosts

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11
Q

Macroparasite models:

A

-must tack the developmental stages
*measure PARASITIC BURDEN
-percent of infected individuals is of limited value

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12
Q

Parasitic burden:

A

-the number of parasites per host
-influences transmission
Ex. host with 10 adult worms sheds more eggs than a host with 1 worm

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13
Q

Transmission: microparasite vs. macroparasite

A

-microparasite: direct, vector-borne
-macroparasite: direct, complex life cycles

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14
Q

Effect on host fitness: microparasite vs. macroparasite

A

-microparasite: mortality (IMMUNE system gets OVERWHELMED)
-macroparasite: morbidity

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15
Q

Steps in the parasite life-cycle:

A
  1. Finding a host
  2. Infection through the outer barrier and establishment in the host (Ex. skin)
  3. Growth or multiplication of the parasite inside the host
  4. Reproduction
  5. Development of transmission stages and transmission to the next host
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16
Q

Reproduction example:

A

-by exchange of genetic material between co-infecting strains

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17
Q

Lifecycle of rabies:

A
  1. Dog bit breaks the skin and dog saliva with virus contaminates the tissue
  2. Virus uses PNS as transport system to enter the CNS including the brain=preferred tissues
  3. Infection of CNS causes changes in behaviour that enhance virus transmission
  4. Rabies virus contaminates salivary glands
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18
Q

Rabies infection of CNS behaviour change:

A

-increased aggression and biting

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19
Q

Rabies contaminates salivary glands:

A

-so that the infected host will transmit the virus to a naïve host following a bite

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20
Q

Pathogen lifecycle determines:

A

-mode of transmission
-tissue tropism
-pathology
-disease symptoms

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21
Q

Respiratory pathogens:

A

-colonize the mucous membranes of the respiratory system
-cause symptoms like mucous production and coughing that facilitate pathogen transmission

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22
Q

GI pathogens:

A

-colonize the mucous membranes of the GI tract
-cause symptoms like diarrhea that facilitate pathogen transmission

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23
Q

Vector borne pathogens (VBPs):

A

-colonize the circulatory system to facilitate acquisition by blood-feeding arthropod vectors

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24
Q

Transmission definition:

Study These Flashcards
A

-process where a pathogen/parasite transits from an infected host to an uninfected host
-different pathogens/parasites are transmitted in different ways

25
Mode of transmission is a critical factor for
-understanding biology of an infectious disease -control of infectious diseases
26
Types of transmission:
-horizontal -vertical *in most vertebrate pathogens: HT is more important than V
27
Vertical transmission:
-mother transmits pathogen to her offspring -vertebrate pathogens with VT also have HT >pathogens with only VT are rare
28
Horizontal transmission:
-pathogen transmission between unrelated individuals -can occur between individuals of same or different generations
29
Salmonella in chickens:
-causes GI disease in many vertebrate species -colonize GI tract and cause diarrhea -HT occurs via fecal-oral route -persist in environment form long periods of time (weeks to years)
30
VT of Salmonella Enteritidis and food poisoning:
-colonizes ovaries and oviduct of the chicken reproductive tract -yolk, albumen (egg white) and eggshell can all be contaminated -VT: infected hens lays infected eggs that produce infected chicks=produce infected eggs >humans get food poisoning when they consume contaminated eggs
31
Pestiviruses in livestock examples:
-bovine viral diarrhea (BVDV) in cattle -classical swine fever in pigs -Border disease in sheep
32
Pestiviruses in livestock:
-shed in fecal material, urine, and nasal secretions (HT) -immunocompetent animals infected via direct transmission clear the infection -viruses commonly cross the placenta and infect the fetus (VT)
33
Outcome of pestviruses VT:
-abortion -persistently infected offspring that are super spreaders
34
BVDV:
-infection of dam during gestation causes immunotolerance and birth persistently infected (PI) calves >PI don’t have a competent immune system at the time of infection >viral cells were accepted as self during immune system development
35
PI individuals:
-shed high numbers of virus over their lifetime=highly effective horizontal transmission
36
Horizontal transmission types:
1. Direct -Close contact -Contaminative (distant) 2. Indirect -Arthropod vector -Intermediate host -*anytime when multiple species are involved
37
Close contact:
-skin-skin -sexual -aerosol -secretions/excretions -carcasses
38
Contaminative (distant):
-air-borne -water-borne -soil-borne -fomites
39
Skin to skin: ex. cattle ringworm
-fungal skin disease -causative agent: cattle ringworm fungus -skin-to-skin contact between sick and healthy animals
40
Cattle ringworm: symptoms
-patches of hair loss -desquamation -formation of thick crusts
41
Cattle ringworm: economics
-spoils milk -meat -leather quality
42
Sexual transmission: brucellosis in dogs
-affects many animals including dogs, cattle, swine and goats -causative agent: brucella canis -infected dogs have bacteria in their genital secretions -oral and sexual transmission -reproductive problems and other symptoms
43
Biting: FIV in cats
Biting: FIV in cats -feline immunodeficiency virus -affects cats world wide -causes AID-like syndrome but not typically fatal -compromises the immune system of cats by infecting WBC
44
FIV transmitted:
-mostly through deep wounds >only a problem if the cats fight -low risk of transmission via sharing water bowls, food bowls and litter box *males more likely to be infected than males
45
Pathogens can be spread through:
-air -soil -water
46
Foot-and-mouth disease (FMD):
-example of direct airborne transmission -highly infectious viral disease -causation: FMD virus (picornavirus) -affects ungulates, humans are rarely infected -affects young animals more
47
FMD hosts:
-cattle -water buffalo -sheep -goats -pigs -antelope -deer -bison
48
FMD symptoms:
-blisters inside mouth, foamy salvia and drooling -blisters on feet that can rupture and cause lameness
49
FMD transmission:
-close-contact animal-to-animal spread -fomites (inanimate objects) -food (eg. Dried hay) -motor vehicles -long-distance aerosol spread
50
Optimal conditions for long-range air-borne transmission of FMDV:
1. High virus emission: pigs in acute state sheds lots of virus 2. Low dispersal rate: gentle winds and a stable atmosphere 3. High virus survival: relative humidity (more than 55%) *RESULTS IN: large numbers of susceptible livestock exposed to virus plume for many hours *cattle have low infectivity threshold
51
Giardiasis: direct waterborne transmission
-caused by protozoan parasite: Giardia duodenalis -hosts: humans, beavers, cows, rodents and sheep -common parasitic disease of humans around the world
52
Giardiasis infection occurs by:
-ingestion of contaminated food or water -animal-to-animal contact *cysts can survive for 3 months in cold water
53
Giardiasis symptoms:
-diarrhea: facilitates transmission
54
Anthrax: direct soilborne transmission:
-causes severe illness in both humans and animals -cause: Gram-positive bacterium (Bacillus anthracis) -found in soil -affects domestic and wild animals world-wide -endemic in Latin America, parts of Africa and Asia -rare in North America
55
Anthrax North America:
-people can get sick if they contact infected animals or contaminated animal products
56
Where anthrax is endemic:
-bacterium infects grass-eating animals, which encounters spores in the environment as they graze
57
Anthrax spores:
-can persist in environment for a long time (decades) -infection happens when animals breath in or ingest spores in soil, plants, or water -activated when ingested and turn into active growing cells
58
Active anthrax:
-bacteria multiply inside host and disseminate using circulatory system -bacteria produce endotoxins that cause severe illness in host and ultimately death *carcass contains millions of spores that contaminate the soil for the next victim
59
Gruinard Island and anthrax:
-UK studied anthrax as a bioweapon -exploded bombs with anthrax on an island -all 80 test sheep died within days of exposure -decontaminated the island >tons of formaldehyde >removed topsoil -test sheep remained healthy -humans could go back on (48 years later)

VET YEAR ONE (108 decks)

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