11.11 Emerging Infectious Diseases

Question 1

Give two overarching reasons why we’re seeing an increase in emerging viruses

Answer 1

1. Expansion of humans (more population, more travel)
2. We are better at detecting the viruses

Question 2

Cross species infection is a common mechanism of emerging viruses. What is it called when an infection spreads from animals to humans?

Answer 2

Zoonosis (zoonotic infection)

Question 3

Are all emerging viruses sustained from human-to-human transmission? Provide an example

Answer 3

• No, not all are.
• For instance, Ebola is not sustained from human-to-human transmission

Question 4

Are emerging viruses typically new or pre-existing?

Answer 4

• Pre-existing; there are basically no new viruses
• Viruses have co-evolved with us for millenia, and will continue to do so

Question 5

Give an example of three different viruses that can be carried by animals, and state which animals carry them

Answer 5

• Rabies: dog and bat
• Arbovirus: mosquitos
• Foot and mouth Disease: sheep

Question 6

What is the most deadly animal in the world?

Answer 6

Mosquito (at least, in regards to infectious diseases)

Question 7

Give an example of when human encroachment on natural habitats has led to virus introduction

Answer 7

• Zika virus
• Encroaching on natural sylvatic cycle led to establishment of ‘urban cycle’ within immunologically-naive Brazilian population

Question 8

Give some examples of changes in human demographics and behaviour that have influenced the emergence of new viruses

Answer 8

• Population increase
• Urbanization
• Increase in elderly population
• Increases in children in daycare
• Fast-paced life (more stress)
• High -risk behaviours

Question 9

How can increased rain increase the vulnerability of a population to mosquito-borne infections?

Answer 9

• More mosquito breeding
• Waterbirds migrate, and can be vectors as well

Question 10

Is transportation of people the only reason why transport is causing increased virus spread?

Answer 10

No:
- It’s also got to do with transportation of goods
- Speed is also a big factor; people get to their destination while asymptomatic but still infectious

Question 11

Using Sars-CoV-1 and Sars-CoV-2 as an example, explain how symptoms can contribute to outbreak control

Answer 11

When a disease causes a person to show symptoms as soon as they become infectious (CoV-1) it is much easier to control than when people may remain asymptomatic or become infectious before symptoms arise (CoV-2)