Disease (class 14)

Question 1

What increases the spread of disease-causing species?

Answer 1

Human activities, can lead to outbreaks

Question 2

Interactions with humans and domestic animals exposes wildlife to…

Answer 2

diseases they have not previously encountered

Question 3

Name an animal that was lost due to canines, human viruses, and diseases

Answer 3

the black-footed ferret in 1987

Question 4

What disease killed millions of bats in North America? How was it introduced?

Answer 4

White nose syndrome (powdery white funguses on snout- causes irritation and early waking causing starvation)
- possibly introduced by cave explorers or bat researchers in 2006

Question 5

What are the 3 implications of epidemiology that have practical implications for limiting disease in captive breeding and management of rare species?

Answer 5

1. High rate of contact between host and parasite encourages spread of disease
2. Indirect effects of habitat destruction increase susceptibility to disease
3. Species in conservation programs may contract diseases from related species, even humans

Question 6

4 ways to reduce spread of disease:

Answer 6

• inspection and quarantine at borders (domestic and wild species, clothing used by researchers)
• limit interaction between endangered species, humans, domestic species and closely related species
• endangered species should be monitored for disease outbreajs
• healthy living conditions for wild and captive populations

Question 7

What is an implication of invasive species and disease spread for human health? (and an example)

Answer 7

As humans move into wild areas through development and habitat fragmentation, there is greater potential for disease movement. Example: killer bees and fire ants

Question 8

Define zoonotic disease:

Answer 8

spread from wildlife to humans

Question 9

Give an example of zoonotic disease

Answer 9

Lyme disease, rocky mountain spotted fever spread by infected ticks.
West Nile virus by mosquitos
(also Ebola, HIV, bubonic plague, mad cow, bird flu)

Question 10

When was West Nile virus first detected in North America? In BC?

Answer 10

1999 and 2009

Question 11

How has climate change changed the transfer of disease?

Answer 11

It has allowed many disease-carrying insects and associated diseases to expand their ranges to higher elevations and farther from the equator

Question 12

What can help to reduce disease? (2 words)

Answer 12

species diversity

Question 13

What is the dilution effect?

Answer 13

greater species diversity reduces disease by diluting the number of suitable host species or by constraining the size of host populations through predation and competition

Question 14

Give an example of the dilution effect

Answer 14

Lyme disease has been linked to the local abundance of host rodent species and the overall LOSS of diversity

Question 15

Explain “traditional” vs “dilution effect” perspectives of biodiversity

Answer 15

Traditional: biodiversity amplifies disease risk
Dilution effect: biodiversity dilutes disease risk

• when compared to no forest and zero biodiversity

Question 16

Explain the life cycle of an infected tick

Answer 16

1) larval ticks go into rodents
2) grow into nymphs to go into larger animals
3) grow into full adults to infect deer and humans

Question 17

Human disease risk is related to the number of infected ticks in an area- how can we change this?

Answer 17

By changing the number of infected ticks in an area by:

-changing the total tick density or the prevalence of infected ticks

Question 18

Host species vary in their ability to…: (2 points)

Answer 18

1) provide blood meals to ticks and thus affect tick density

2) infect ticks with B. burgdorferi (host competency) and thus affect the prevalence of tick infection

Question 19

The density and prevalence of rick infection is related to what?

Answer 19

Which hosts are in a given area

Question 20

How do deer and opossums vary in their method of hosting ticks?

Answer 20

• deer provide blood meals to ticks, so high deer density increases tick densities
• opossums groom and eat their ticks, so they decrease total tick density
  (both are poor reservoir hosts compared to mice)

Question 21

What is meant when a host species has “high reservoir competence”?

Answer 21

this describes their ability to transmit B. burgdorferi to ticks (mice are most competent at this)

Question 22

Disease risk can be diluted by…?

Answer 22

Biodiveristy

Question 23

If 2 areas have the same tick density, but area 1 has higher host biodiversity, which would create a higher disease risk for humans?

Answer 23

Area 2- because ticks are feeding on other hosts in Area 1