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Parasites and Disease > Intro and Immunology > Flashcards

Intro and Immunology Flashcards

1
Q

Distinguish between obligate and facultative parasitism

A

Obligate - must have association with host to live

Facultative - can be free living or parasitic

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2
Q

Over time, how may hosts/parasites evolve in relation to each other?

A

Obligate parasites die if their host dies, so they don’t want to be particularly virulent. It’s theorized that over time the tendency for virulence goes down.
However, it’s possible that causing damage to the host (including death) can be advantageous if the parasite is more likely to be preyed on by the definitive host (ex. infecting prey, causing it to be slow and sick, then infecting the predator).

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3
Q

Distinguish between permanent and temporary parasites

A

Permanent - Entire parasite life cycle is spent in association with host
Temporary - Have to occasionally find a host (usually ectoparasitic)

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4
Q

Describe a situation in which a host’s body may provide several different environments for parasites

A

Internal vs external environments. The environment in the small intestine of a human is different than the hair of a human. (Ex. tapeworm in gut and lice in hair)

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5
Q

Describe the different host types

A

Definitive - Host in which the parasite completes sexual reproduction
Intermediate - On the way to the definitive host, can allow changes in morphology or development
Paratenic - Allows organism to survive, but the parasite does not reproduce, develop, or change morphology
Phoretic - Temporary transfer host (ex. eggs need to be deposited on human skin but are transferred there by mosquitos)
Reservoir - Host that acts as a source of infection for another one (ex. humans are the reservoir for the influenze virus)

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6
Q

Alaria americana is a parasite of foxes/mink/other wild carnivores. How is it transported from the frog/tadpole hosts to something that doesn’t eat it?

A

Water snakes act as a paratenic host, eating infected tadpoles/frogs, and then eventually be eaten by a small carnivore

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7
Q

If parasite levels rapidly (exponentially) go up and then suddenly level off, what is that growth model called? What usually causes the population of parasites to level off

A

Asymptotic (Asymptote).

Immune system respomnse

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8
Q

What is it called when a parasite or virus is transmitted in high-population density environments?

A

Urban transmission

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9
Q

Why is transmission of Yellow Fever Virus unique?

A

It is transmitted two ways: Urban transmission and forest transmission (transmitted by other mammals in the forest)

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10
Q

Describe a direct/simple parasitic life cycle

A

Close proximity to the other host (same type of organism) gives host 2 the infection

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11
Q

Describe an indirect/complex parasite life cycle. Give an example.

A

Involves two hosts which must interact with each other. For example West Nile Virus must be transferred by mosquitos to birds

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12
Q

Why are humans not considered a part of the West Nile Virus cycle?

A

We do not act as a reservoir - we do not build up enough in our blood to pass it back to mosquitos.

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13
Q

What is referred to when a host cannot pass the parasite to the preferred host?

A

Dead end host

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14
Q

What is meant by the “host specificity” of a parasite?

A

The biochemical requirements confining a parasite to one group of organisms or even one species

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15
Q

Give an example of a general parasite (can survive in lots of hosts)

A

Trypanosoma cruzi - single celled parasite that can grow in >100 mammals species and some birds

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16
Q

A ______ cycle has at least one natural reservoir that is a non human animal

A

Zoonotic

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17
Q

Describe Enzootic transmission

A

Number of hosts infected remains relatively constant over time

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18
Q

Describe Epizootic transmission

A

Number of hosts fluctuates over time

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19
Q

Describe anthroponotic transmission

A

No non-human animals involved in the cycle (unless they are carriers - ex. malaria)

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20
Q

Which malaria species kills the most people worldwide?

A

Plasmodium falciparum

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21
Q

What is the difference between prevalence and incidence of an infection?

A

Prevalence - Percentage of hosts (carrying a single type of a parasite) in a given population at a given point in time

Incidence - number of newly infected hosts per population per unit time (ex. 25 cases/ 10 000 people/month)

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22
Q

Distinguish between density and intensity of an infection

A

Density - Average number of parasites per host (which includes non-infected hosts in a population)
Intensity - Absolute number of parasites in an INFECTED host (rules out those not infected)

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23
Q

How was “patient one” found during the AIDS epidemic of the 80s?

A

Doctors painstakingly interviewed the infected people, looking for a common sexual partner to explain how HIV became such a huge deal in New York City. Turns out many of their interviews traced back to a gay Air Canada flight attendant with frequent flights to France

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24
Q

What is Ecological Epidemiology?

A

The study of the weak points in transmission events over the life cycle of an infection, developing interventions to prevent infection (Ex. killing mosquitos to prevent spreading of malaria). Basically making the environment less receptive to transmission

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25
How is the Dengue fever carrier "Aedes aegypti" adapted for life with humans?
Preferentially feed on humans (like our scent), can lay eggs in super small quantities of water. Generally just meant to live in human houses.
26
Distinguish between urban and periurban transmission
Urban - Transmission occurs in city centers with dense population Periurban - Transmission occurs in the outskirts of cities (usually slums, poorer sanitation, more wild animals)
27
______ parasites live in human homes
Domestic
28
_______ parasites live immediately around human homes (ex. backyards)
Peridomestic
29
_____ infections are acquired in wild or non-populated areas
Sylvatic
30
What does it mean if a parasite is "infectious"?
They are not always able to infect another host in the chain of transmission, there may be a lag time
31
____ means one is capable of becoming infected, and the parasite can grow and develop. ____ means that the parasite may still infect someone, but not reach high enough numbers to establish itself
Susceptible, Resistant
32
How does nutrition affect resistance?
Well balanced diets, low stress levels, and healthy bodies can provide a manageable level of resistance to certain parasites (ex. malnutrition affects malaria susceptibility)
33
What occurs when someone has an autoimmune disease?
The immune system fails to recognize self vs non self
34
A _____ is a large, relatively solid tissue that forms around a parasite
Granula
35
Describe the contents of a granuloma. Why do they form?
Comprised primarily of immune system components (ex. macrophage and other immune cells that surround a parasite). They form to wall the parasite off from the rest of the body
36
When a granuloma forms a permanent lump it is referred to as a _____
Tubercle
37
What is an ulcer?
A perforation of a living layer of tissue
38
A _____ is an enclosed, fluid-filled cavity that develops around a sight of infection. It is filled with a combination of lymph, pus, cytokines
Abscess
39
Why is the study of parasitic routes of transmission important for human health?
Gives insight into ways of acquiring disease
40
Describe the mechanical mode of transmission
Transported on surfaces such as medical tools or animals (the animal is not infected by it)
41
Describe the biological mode of transmission
Host to host
42
How does horizontal biological transmission differ from vertical?
The vertical transmission the pathogen is passed from parent-child through reproductive tissues (ex. ovarian infection)
43
What are the varying routes of infection used by pathogens?
Mouth, skin, venereal, lungs, through water, food, predator-prey
44
Most pathogens infect the areas lined by ________, such as ______
Mucous membranes, | such as eyes, mouth, nose, lungs
45
How do worms of the genus Schistosoma enter the skin?
Have enzymes secreted near the mouth to dig into the skin of humans
46
Pathogens often get into the lungs through _______, which are thin mists of water given off when we breathe
Aerosols
47
What does Trichonella do?
It infects the muscles of pigs, and humans used to acquire Trichonella sporalis from eating undercooked pork
48
Anything that can stimulate an immune response is referred to as a _______
antigen
49
How did edward Jenner contribute to the development of vaccines?
He noticed that milk maids almost never got smallpox (which is highly related to a cow-nipple disease: cowpox), which was basically like little vaccinations. Then he injected the material from cowpox blisters into young children, then took material from human smallpox blisters and injected it as well
50
A ______ is a graft from another person
Xenograft
51
In what situations are people immunosuppressed?
AIDS cases, pregnancy
52
What is the "Hygiene Hypothesis"?
The idea that excessive cleanliness (ex. not exposing children to pets, soil, other "scary" things) has caused our immune systems to not function as well (less exposure) and therefore we have less asthma
53
What are the two arms of the immune system? BRiefly describe them
Humoral system - antibodies | Cell system - cells like neutrophils, lymphocytes, etc
54
Blood clotting is achieved by the ______/_____ pathway
Thrombin/prothrombin
55
_____ cells are those that can become many types of cells
Pluripotent
56
T-lymphocytes maturate in the _____. What do they do?
Thymus. | They recognize the difference between parasite tissue and self tissue
57
Natural Killer lymphocytes and B lymphocytes form from _____ stem cells
Lymphoid stem cells
58
________ are the cells that produce antibodies
B Lymphocytes
59
Which immune cells can be produced from Myeloid stem cells?
Erythrocytes (red blood cells), megakaryocyte (blood clotting), monocytes (and therefore macrophage), and granulocytes
60
What are the primary parts of the innate immune system and what type of cells do they each include?
Antigen presenters (monocytes/macrophages, dendritic cells). Natural Killer cells Granulocytes (basophils, eosinophils, neutrophils)
61
What purpose do Dendritic cells serve?
Dendritic cells recognize an antigen, carry it to the liver, and activate the production of cells which can react to that antigen
62
What purpose do Natural Killer cells serve?
they release cytokines to kill invading pathogens`
63
The granulocytes release "proinflammatory cytokines", what does this mean?
They cause inflammation to aid in curbing infection
64
What are the primary parts of the adaptive immune system?
``` B lymphocytes T lymphocytes (includes CD4+ and CD8+) ```
65
The innate immune system is most effective against....
Bacterial and viral infections
66
What are the physical parts of the innate immune system?
Skin, mucous production, cilia
67
What purpose do interferons serve?
Aid in inflammation and inactivation of immune cells
68
What does the "Ig" in IgG stand for?
Immunoglobulin
69
Genes in what complex code for the "V" regions possible within antibodies in your body?
Major Histocompatability complex
70
the "V" or variable regions of antibodies are responsible for what?
Being able to recognize an invading pathogen
71
What purpose do IgG antibodies serve?
Long lasting, basic immune response antibodies
72
What purpose do IgM antibodies serve?
Come up within a few days, recognize foreign organisms, help trigger cellular components of the immune system
73
What purpose do IgA antibodies serve?
Hang out around mucous membranes, can activate immune response in places like mouth and gut
74
What purpose do IgD antibodies serve?
Helper antibodies on the outside of B lymphocytes (may be associated with the production of IgM)
75
What purpose do IgE antibodies serve?
Largely present in lungs and skin, cause allergic responses. Trigger mast cells and histamine (which causes inflammation)
76
The primary lymphoid organs are ____ and ____. What are the secondary ones?
Thymus, bone marrow. | Secondary ones are the lymph nodes in the gut, skin, and other parts of the body, as well as the spleen
77
Describe the malaria life cycle starting with sporozoite injection into human blood
Sporozoites transfer via mosquito saliva into human blood. The sporozoites travel to the liver, use their recognition proteins to get inside the hepatocytes. They feed on the cytoplasm and start to divide asexually in a process called schizogony. Cell lysis occurs and many parasites are released into the blood stream. The parasites move into the red blood cells (typically 1 per cell), it feeds on the cytoplasm, now called a trophozoite. Schizogony occurs again. Parasites differentiate into male or female gametocytes and as long as the mosquito (of the correct genus) picks up one of each sex, sexual reproduction will occur. The fertilized "ookinate" undergoes sporogony in the gut wall of the mosquito. This begins asexual mass "sporogony"
78
What are ways in which parasites can evade the human immune system?
Decrease expression of recognition/presenting cells (or antibodies) Induce apoptosis - may inhibit apoptosis in cells they infect Change surface of parasite (especially if intercellular) to make it harder to access Interfere with MHC (major histo-compatibility) expression - can stop host from initially recognizing foreign invader Molecular mimicry - change surface of parasite to biochemically resemble host tissue
79
What are different ways in which parasites induce pathogenesis?
Physical damage to host tissue (ex. damage to epithelium, consumption of tissue) Competition with host for nutrients Autoimmunity/misdirected immunity Toxins (ex. Cholera toxin) - unrelated to immune response

Parasites and Disease (11 decks)

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