VBDs

Question 1

What is a vector?What is a vector?

Answer 1

vector - an agent which carries an infectious agent between hosts

Question 2

Describe the impact of vector borne disease on plants?

Answer 2

• vector borne diseases profoundly affect agricultural productivity
• annual loses in crop quality and yield associated are measured in the billions of dollars
• threat to food security
• casava - 5th most common crop in the world - very good staple crop if your water supply is unsire
• Casava mosaic virus and casava brown streak virus threaten thee food seccurity of 135 mil people in ceentral and east africa

Question 3

describe the impact of vector borne disease on animals?

Answer 3

• sleeping disease carried by the tze-tze fly
• bluetongue virus affects sheep and costs around 3bil dollars per year
• vector-borne diseases can also affect wild populations -Rift valley fever is a viral zoonosis that can primarily affect animals but can also infect humans

Question 4

How many diseases in humans are vector borne?

Answer 4

> 17% of all infectious diseases in humans

Question 5

What are some neglected VBDs in humans and what is their impact?

Answer 5

• include negtected diseases
  
  • chagas disease causes greatest burden of any parasitic disease in the Americas
  • in 2017 Onchoceciasis caused vision loss in 1.15 million people

Question 6

What is mechanical transmission?

Answer 6

mechanical transmission - for example when a fly has a pathogen on it and then it sits on somebody’s food and mechanically implants the pathogen on the food; the flye never gets infected, the fly just moves the infections between hosts

Question 7

What is non-circulative transmission?

Answer 7

non-circulative - basically mechanical transmission but in plants

Question 8

What is biological transmission?

Answer 8

biological transmission - the vector actually is infected with the pathogen

Question 9

What is an extrinsic incubation period?

Answer 9

extrinsic incubation period - period in which the pathogen spends time in the vector either getting to the right places or completing the required developmental stages in given tissues

Question 10

What is an important thing about VBds?

Answer 10

TRUTH ABOUT VBD: only a small proportion of your susceptibles will be infected and even a smaller proportion will be infectious

Question 11

What is a gonotrophic cycle?

Answer 11

Gonotrophic cycle - thee mosquito eats blood and then they have to develop that blood meal into eggs aand lay those egss

Question 12

Why is malaria so complicated to study?

Answer 12

malaria gets very complicated because while the pathogen needs to undergo its own cycle the vector still continues with their own life cycle and laying eggs and stuff like that

Question 13

Draw out the model for vector borne diseases?

Answer 13

see notes

Question 14

What is the equation that describes R0 for VBDs?

Answer 14

see notes

Question 15

What is vector capacity?

Answer 15

vectorial capacity - estimation of a vector population’s potential to transmit

Question 16

Write out the equation for vector capacity

Answer 16

see notes

Question 16

How does temperature affect transmission in vVBDs?

Answer 16

• This framework is increasingly being adapted to incorporate environmental variation. For example, temperature can effect VBD transmission by altering vectors abundance, vector-pathogen interactions, and the timing of key events. Later in the course we will discuss some of these extensions as part of understanding how global and local climate can alter disease risk.
• it’s not always the caee that hotter = better; in some cases in might be too hot for transmission

Question 17

How are VBD models being improved?

Answer 17

factors influencing the vector density are increasingly being incorporated into the models as we realise that V is not static and a lot of vectors have very complicated life cycles which might influence vector density → stage specific modelling (takes into acocunt stages of life of the vecotr)