Epidemiology and Transmission Ecology

Question 1

What does a complete understanding of disease transmission require the study of (both)

Answer 1

Macroepidemiology and microepidemiology

Question 2

• large-scale problems of disease distribution
• demographic and cultural factors affecting transmission
• illness and death rates
• economic impacts
• requires substantial funding, institutions, trained personnel, and government policies allowing for data collection

Answer 2

macroepidemiology

Question 3

• small-scale problems
• looks at how disease distribution affects individual host-parasite interactions, parasite strains, host genetic variation, immunity

Answer 3

microepidemiology

Question 4

Which institution monitors national health statistics, issues weekly morbidity and mortality reports, responds to situations to learn more about origin/transmission dynamics, and provides electronic health statistics?

Answer 4

The Centers for Disease Control and Prevention (CDC)

Question 5

What organization is global in scale and provides information about many health issues?

Answer 5

The World Health Organization (WHO)

Question 6

Name four things the distribution of a parasite is influenced by WITHIN POPULATIONS:

Answer 6

1) host age
2) sex
3) social and economic status
4) diet and ecological conditions that factor completion of life cycles

Question 7

How are pinworms an example of how a parasite is distributed?

Answer 7

Influenced by age – children are a source of parasites for the entire family

Question 8

How is leishmania an example of how parasites are distributed?

Answer 8

Infections often occur in agricultural workers (shows how occupation plays a role in health)

Question 9

Vehicles by which infections are transmitted from one host to another – provide two examples

Answer 9

Vectors; snails and blood-sucking arthropods

Question 10

What are the two most medically important vectors and what do they carry?

Answer 10

• mosquitos (malaria)

- snails (blood flukes/schistosomes)

Question 11

How does malaria illustrate the need to understand vector biology as a means of control?

Answer 11

Standing water is a good breeding ground for mosquitos – difficult to eliminate as this may be the only available source of water for drinking/bathing

Question 12

How does Egyptian agricultural practices illustrate the need to understand vector biology?

Answer 12

Irrigation ditches are the ideal environments for snails, which are intermediate hosts for schistosomes

Question 13

• a natural set of conditions under which it is predicted for a disease to occur
• a landmark of parasitology (scientists could recognize and predict where diseases could occur and could thus be controlled)

Answer 13

A natural “nidus” or focus (part of landscape epidemiology)

Question 14

Name four knowledge factors influencing landscape epidemiology within the nidus:

Answer 14

• Climate
• Plant and animal population densities
• Geological conditions
• Human activities

Question 15

What type of mapping can be used to reveal vegetation and land-use patterns?

Answer 15

Geographic information systems

Question 16

Name two diagnostic groups that have been helpful

Answer 16

• IsoCode STIX (allows samples to be collected and transported for processing)
• Human Genome Project (opened opportunities for epidemiologists to address public health problems)

Question 17

What type of descriptors are the the following

• numbers of parasites
• reproductive success/fitness

Answer 17

quantitative descriptors

Question 18

when talking about parasite communities, what two terms are used?

Answer 18

mean intensity and prevalence (can also include density, abundance, etc.)

Question 19

large parasites that do not multiply in or on a host, occur in aggregated populations, most hosts uninfected or lightly infected

provide examples

Answer 19

macroparasites; adult tapeworms, trematodes, nematodes, arthropods

Question 20

small parasites that do multiply within a host

provide examples

Answer 20

microparasites; trypanosomes, apicomplexans, amoebas

Question 21

List four things a complete quantitative description of parasitic populations might include

Answer 21

• counts
• measurements
• determination of sexes
• determination of maturity

Question 22

when a single host can harbor many species

Answer 22

parasite community

Question 23

are parasites autotrophic or heterotrophic and what does this mean?

Answer 23

heterotrophic; they can only obtain energy from other sources (existing organic mcs, nitrogen, and amino acids)

Question 24

how to tapeworms and acanthocephalans feed without a digestive tract?

Answer 24

they absorb sugars and amino acids across their surface/through uptake sites on their plasma membrane

Question 25

what does tick saliva contain?

Answer 25

an anticoagulant

Question 26

True or false: parasites always live at higher trophic levels than their hosts

Answer 26

False; parasites make up a substantial fraction of biomass/can be important indicators of biodiversity bc tells which intermediate hosts are present and larval stages indicate habitat

Question 27

In terms of parental care and reproductive success, how do parasites function?

Answer 27

- little parental care - low reproductive success leads to high reproductive potential --> heavy energy investment to counteract low probability of offspring success

Question 28

how can parasites increase their reproductive potential?

Answer 28

- asexual reproduction/hermaphroditism - helpful because they do not have to find another member of their species to reproduce - high egg production

Question 29

- the nucleus divides multiple times before cytokinesis - simultaneous production of multiple daughter cells - leads to millions of offspring in very few days

Answer 29

schizogony/multiple fission

Question 30

what is the life cycle of coccidia

Answer 30

schizogony (asexual) --> gametes --> cyst form outside of host

Question 31

what is binary fission most common among?

Answer 31

free-living protozoa

Question 32

provide examples of asexual reproduction during immature stages

Answer 32

- metacestodes of tapeworms - cysticerci of taenia - hydatid cysts of echinococcus

Question 33

- when embryo generations are produced within the body of prior generations - many embryos develop from a single zygote who is this exhibited by

Answer 33

polyembryony; flukes/trematodes

Question 34

life cycle of a fluke/trematode

Answer 34

eggs --> miracidia --> sporocysts give rise to daughter sporocysts that each produce rediae --> cercariae

Question 35

when a parasite can fertilize its own eggs, does not produce unusual genetic recombinations (does guarantee offspring)

Answer 35

hermaphroditism

Question 36

what is the continual asexual reproduction in tapeworms known as (leads to the production of proglottids)

Answer 36

strobilization

Question 37

how do leucochloridium change their behavior to enhance the likelihood of a host encounter

Answer 37

- pigement in sporocysts move into snail tentacles and pulsate to look like caterpillars - goal to get land snails eaten by insectivorous birds

Question 38

how to acanthacephalans alter their behavior?

Answer 38

change the color of amphipod, leads to photactic behavior where the IH swims to the water's surface

Question 39

the study of relationships between organisms and their environments

Answer 39

ecology

Question 40

when the host is the parasite's environment, what four things need to be considered

Answer 40

- taxonomy - transmission - population dynamics - evolutionary history

Question 41

what two things make the host as an environment ideal?

Answer 41

- hosts are nutrient dense | - they can regulate body temperature

Question 42

why do adaptation often come about?

Answer 42

- so the life stage can better survive the abiotic conditions existing between hosts - because hosts can defend themselves (immune response)

Question 43

which step do parasite control strategies often target

Answer 43

reducing probability of host-parasite encounter

Question 44

what is niche often determined by?

Answer 44

host diet, physiological condition, and the presence of other parasites

Question 45

how do nematodes in testudo graeca demonstrate how parasites occupy different niches?

Answer 45

they live in the large intestine but are restricted radially from the center to the mucosa

Question 46

when an organism inhabits a cavity of an animal's body; when an organism lives in the tissues of a host

Answer 46

coelozoic; histozoic

Question 47

where do most endoparasites live?

Answer 47

in the GI tract

Question 48

what provides evidence of parasite adaptation to a habitat within a host

Answer 48

site specificity

Question 49

what is an example of site specificity

Answer 49

toxoplasma gondii in the retina vs. taenia in the chamber

Question 50

there is evidence for many --------- within a host

Answer 50

microenvironments

Question 51

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Answer 51

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