Disease Ecology and Emerging Diseases

Question 1

Ecology

Answer 1

study of factors influencing the abundance and distribution of organisms

Question 2

Disease Dynamics

Answer 2

Changes in rates over time and location

Question 3

Micro scale

Answer 3

interactions within cells and organs in the host

Question 4

Macro Scale

Answer 4

Within the broader population

Question 5

Competition

Answer 5

the driving force of natural selection. Pathogens compete with each other for resources, whether they are viruses competing within the same cell, or bacteria competing in the soil. Within a cell, viral competition works via a system of RNAs that can cause another virus’ RNA to be degraded. Parasites compete for resources within hosts as well.

Question 6

Cooperations

Answer 6

mutual benefit to the different species involved. For example, your microbiome is a cooperation between the many bacteria that compose it and you. Bacteria can also cooperate in ways that do not help you

Question 7

Biofilms

Answer 7

groups

Question 8

Quorum Sensing

Answer 8

cell to cell communication that regulates the density of bacteria growth so they can share resources

Question 9

Habitat

Answer 9

The physical area in which a species inhabits. Habitats can be a small area next to a magma vent in the floor of the ocean, or it can be all of the rainforest of Brazil.

Question 10

Ecological Niche

Answer 10

the sum total of the habitat and all of the behaviors of a particular organism. For example, a raccoon’s niche might include: “temperate forests and suburban areas of the northeast/likes to scavenge for food/ is nocturnal.” No two species can occupy the exact same niche. Either one species will evolve to separate the niches, or one will out-compete the other, resulting in its extinction.

Question 11

Ecological Niche Models

Answer 11

Mathematical models to try and determine where and when pathogens are likely to be most prevalent, and therefore where and when to target prevention strategies.

Question 12

How climate change can impact infectious disease distribution

Answer 12

1) Warming can cause a shift in timing, where epidemic peak may occur at a different time of year than it did in the past
2) Warming can cause more epidemic “cycles”, meaning that there may be two epidemic peaks in the same year
3) Warming can cause overall epidemic intensity to either increase or decrease, depending on whether the pathogen can well-tolerate the new climate.

Question 13

Zoonotic Diseases

Answer 13

a disease that has its origins in a species other than humans. They include vector-borne diseases and diseases that are transmitted directly from other animals to humans. Most human diseases, including new, emerging diseases, are zoonotic.

Question 14

Density dependent

Answer 14

transmission rates increase with population density of the host. This is true of most respiratory and water-borne diseases.

Question 15

Frequency dependent

Answer 15

transmission rates increase with the number of people infectious, but it doesn’t matter how geographically dense they are. Most mosquito-carried diseases fall into this category, as do sexually-transmitted infections.

Question 16

Silent zone

Answer 16

everything necessary for a disease to spread is present in an area (pathogen is there, right climate, etc.) but there are no humans to infect.

Question 17

The fundamental modes of disease transmission

Answer 17

airborne (respiratory droplets), water-borne, fecal-oral (ingesting microscopic amounts of contaminated fecal matter), vector-borne (carried by non-host species to host), fomite (touching surface, object or person), perinatal (mother to child), food-borne, animal bites and sexual

Question 18

Direct human to human transmission

Answer 18

the disease emerges in humans, having originated in another animal species, and then is only transmitted person to person.

Question 19

Direct Zoonosis

Answer 19

the disease is transmitted from an animal to a person, but then people do not transmit it to each other (like rabies)

Question 20

Vector borne

Answer 20

a disease is transmitted from human to human only via another species

Question 21

Vectored Zoonosis

Answer 21

If the disease is transmitted between members of another animal species and can infect a person, but the person cannot spread the disease to another vector or animal

Question 22

Anthropo-zoonosis

Answer 22

Finally, if the situation is the same as for a vectored zoonosis (the disease is transmitted between members of another animal species and can infect a person, but the person cannot spread the disease to another vector or animal), except that infected humans can spread it further

Question 23

Reservoirs

Answer 23

the primary host species for an infectious disease. The reservoir species does not typically become seriously ill from the pathogen, though it sometimes can.

Question 24

Spillover event

Answer 24

the moment in time where a disease moves from one host species to another. Bats, mice and birds are very common reservoirs.

Question 25

Biodiversity

Answer 25

the number of species present in a given area

Question 26

Dilution effect

Answer 26

the more species are in an area, the lower the number of contacts between disease-carrying species and non-disease carrying species

Question 27

Disease emergence

Answer 27

the process by which an infectious disease takes hold and spreads in a new host species after a spillover event