chapter 8

Question 1

Emergence

Answer 1

The process of coming into being

Question 2

Epidemic

Answer 2

A widespread occurrence of an infectious disease in a community at a particular time

Question 3

Pandemic

Answer 3

An outbreak of a disease that affects a whole country or the world

Question 4

Emerging disease

Answer 4

A disease of infectious origin with an incidence that has increased within the last two decades or threatens to increase in the near future
-Virus can be new, well-established in the human population

Question 5

what are the 9 types of Types of Emergence we only focus on 5

Answer 5

Zoonosis
Geographical contact
Mutation
Deliberate Release
Accidental Release

Question 6

1. Zoonosis

Answer 6

• Usually asymptomatic in animal reservoir

- Jump to humans causes severe symptoms

Question 7

what are the three types of zoonosis

Answer 7

Direct zoonosis, cyclo and meta

Question 8

Direct zoonosis

Answer 8

transmitted from an infected vertebrate host to another host by direct contact, fomite or mechanical vector.
One example is rabies.
dog to humans

Question 9

Cyclozoonosis

Answer 9

requires more than one vertebrate host but no invertebrate host is needed.

Question 10

Metazoonosis

Answer 10

require an invertebrate host where the pathogen multiples or develops before it can infect a vertebrate host.
One example is yellow fever.
Mosquitoes to humans

Question 11

Zoonotic Examples

Answer 11

Ebola and HIV

Question 12

2. Geographical Contact

Answer 12

Increased travel causes emergence of virus pathogens in unprotected populations.

HIV thought to be present for ~ 50 yrs in isolated areas of central Africa

Question 13

3. Mutation Influencing Emergence

Answer 13

Mutation of an existing virus to create a new one

Most commonly be RNA viruses because of their low fidelity polymerase

Question 14

8. Deliberate Release

Answer 14

-Release of a pathogenic virus to control an animal (or human) population
international treaty to prevent stockpiling of biological weapons

Eg. rabbit hemorrhagic disease and Smallpox

Question 15

9. Accidental Release

Answer 15

• Release of the rabbit hemorrhagic virus from the testing grounds on Wardang Island (Australia)
• leakage of smallpox into the ventilation system at the University of Birmingham, England

Question 16

Arboviruses

Answer 16

Virus transmission via biting insects and ticks
Insects as vectors to transmit disease
Mosquitoes most common
Eg. West Nile virus

-Virus can be passed to subsequent generations in vector species’ eggs
-Can overwinter in the arthropod host
-Arthropod can sometimes act as a reservoir (ex. –Crimean-Congo hemorrhagic fever)
Arthropods can also be vectors for bacterial and protozoan infections [eg. bubonic plague (fleas) and malaria (mosquitoes)]

Question 17

Control of arboviruses

Answer 17

1. Mosquito nets impregnated with insecticide permiethrin
2. Removal of breeding habitats (stagnant water)
3. Chemical insecticides (temephos, DDT)
4. Larval growth inhibitors (methoprene)
5. Biological control agents (bacteria, predator fish, crustaceans)

Question 18

Extinction

Answer 18

The disappearance of a virus from the earth
99.9% of all species that ever existed are now extinct
High mutation rates in virus

eg, ebola or measles