Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Trinity Term 1 > Ecology of infectious diseases I > Flashcards

Ecology of infectious diseases I Flashcards

1
Q

Infectious disease is

A

the product of an interaction between two species; the pathogen and the host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The host is a

A

resource for the pathogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

y

A

proportion of the population that are infectious

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Give the equation for the tate of change of proportion of the population that are infectious

A

dy/dt = lambda(1-y) - mu x y
OR
dy/dt = By(1-y) - mu x y

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

lambda

A

force of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

force

A

per capita risk

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

B in equation

A

y / lambda

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

B in words

A

a combination of parameters relating risk of infection to prevalence of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Give the equation for B in directly transmitted pathogens

A

B = beta x N

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

N

A

population size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Beta

A

probability of transmission

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

For directly transmitted pathogens, lambda =

A

beta x Ny

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Give the equation for lambda for sexually transmitted infections

A

lambda = c x beta x y
where y = the probability a partner is infected
and beta is the per partnership probability of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

c

A

average no. of partners

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Give the equation for lambda for vector-borne pathogens

A

lambda = ma^2bcHy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

m =

A

number of vectors per host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

a =

A

biting rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

b =

A

proportion of infectious bites leading to infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

c =

A

proportion of bites on infectious hosts leading to infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

H =

A

average lifespan of vector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Give the equation for B for vector-borne pathogens

A

B = ma2bcH

22
Q

mu =

A

death rate of host

23
Q

What is the equation for the plateau in a graph that measures proportion infected against time in arbitrary units

A

1 - (mu/B)
Or
1 - (1/R0)

24
Q

Describe the pathogenesis of Herpes Simples Virus

A
  • subvirus enters peripheral sensory nerves
  • migrates along axons to sensory nerve ganglia in the CNS
  • allows virus to escape immune response, and become latent
25
Q

What happens post-latency

A

reactivation and spread to the surface for viral shedding

26
Q

Describe the VZV, EBV, CMV, HHV6 and HHV7 Herpesviruses

A

Primary infection generally occurs in a subclinical fashion in early childhood, with subsequent lifelong persistence of infection.

27
Q

Chickenpox

A

Varicella zoster virus

28
Q

A pathogen cannot invade a population unless

A
  • dy/dt > 0 when y = 0 (OR z=0)
  • hence (B/mu) > 1
29
Q

R0 =

A
  • B/mu
    OR
  • B/sigma
30
Q

R0

A
  • the basic reproduction number
  • the average number of secondary cases generated by a primary case in a totally susceptible population
  • a fundamental measure of the transmission potential of a pathogen in a given setting
31
Q

If you integrate out the dy/dt equation, what happens

A

you get a logistic

32
Q

What is the equation for intrinsic growth rate

A

r = B - mu

33
Q

What is the equation for carrying capacity

A

K = 1 - (1/R0)

34
Q

Describe the SIR model of pathogenesis

A
  • any individual in a population can be either Susceptible, Infected or Recovered (immune)
  • individuals that are born are fed into S (b)
  • individuals that die can leave at any stage (mu)
35
Q

Individuals that are Susceptible and Infected are related by

A

lambda - the risk of infection

36
Q

Those are Infected and Recovered are linked by

A

sigma - the rate of recovery

37
Q

Describe measles virus

A
  • hemagglutinin
  • fusion protein
  • SH protein
  • matrix protein
  • polymerase
  • nucleoprotein
  • phosphoprotein
38
Q

Describe the dy/dt equation in light of the SIR model

A

dy/dt = By(1-z) - (sigma + mu) y

39
Q

S

A

1 - z

40
Q

Give the equation for dz/dt

A

By(1-z) - (mu x z)

41
Q

Give the equation for dS/dt

A

bN - (lambda x S) - (mu x S)

42
Q

Give the equation for dI/dt

A

lambda x S - (sigma x I) - (mu x I)

43
Q

Give the equation for dR/dt

A

(sigma x I) - (mu x R)

44
Q

Describe the similarities between pathogen-host dynamics and predator – prey systems

A
  • cyclic (lag between consumption and resource renewal)
  • getting eaten = becoming immune
  • eating = infecting
  • transmission = predator reproduction
45
Q

Give some examples of viruses that broadly follow the SIR model (lifelong immunity with a short infectious period)

A
  • measles
  • mumps
  • rubella
46
Q

Give some examples of viruses that broadly follow the SI model (lifelong carriage)

A
  • HIV
  • herpesviruses
  • syphilis
47
Q

What is the aim of eradication?

A

reduce the average number of secondary cases generated by an index case to less than one

48
Q

How is eradication achieved?

A
  • p immunised must exceed the fraction immune at equilibrium (in the absence of vaccination)
  • p > 1 - (1/R0)
49
Q

p

A

proportion

50
Q

Why is malaria so deadly?

A

it demonstrates antigenic variation and co-circulating strains

Trinity Term 1 (38 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions