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Drug Action IV > Parasites (Patho) - Block 3 > Flashcards

Parasites (Patho) - Block 3 Flashcards

1
Q

What the of pathogens are parasites?

A

Eukaryotic that lack a cell wall

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2
Q

Differentiate the 2 groups of parasites?

A

Ectoparasite: lives on skin and hair (lice, mites)
Endoparasite: lives in host (parasitic protozoa, parasitic helminths)

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3
Q

Common mode of entry for parasites?

A
  1. Oral
  2. Direct penetration through skin or surfaces
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4
Q

How can parasites be transmitted?

A
  1. Environmental contamination with feces
  2. Vector
  3. Sex
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5
Q

What are the pathogenicity facotors of parasites?

A
  1. Infectious dose and exposure
  2. Penetration of anatomic barriers
  3. Attachment
  4. Replication
  5. Cell and tissue damage
  6. Disruption, envasion, and inactivation
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6
Q

What is a definitive host?

A

Parasite sexual reproduction occurs (source of mature, adult parasite)

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7
Q

What is an intermediate host?

A

Host in which eggs or larval forms develop into larval or intermediate stages

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8
Q

What is a reservoir?

A

Source of parasite in the environment

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9
Q

What is a vector?

A

Agent capable of transmitting the parasite from one host to another (mechanical, biological)

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10
Q

Describe the structure of ectoparasites?

A

Arthromods with hard exoskeleton with segmented bodies

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11
Q

What are the types of ectoparasites?

A
  1. Mites
  2. Bed bug
  3. Fleas
  4. Lice
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12
Q

Describe the activity of mites?

A

Causes scabies by burrowing into stratum corneum and lays eggs -> intense itching and spreads by direct skin-skin contact

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13
Q

Describe the activity of bed bugs?

A

Feed on blood of people and animals while asleep -> hides in fabrics and mattresses -> irritation and itching from saliva

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14
Q

Describe the activity of fleas?

A

Detect mammal’s movement, body heat, vibrations -> feeds on blood then lays eggs

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15
Q

Describe the activity of lice?

A

Feed off human blood and spreads by person to person:
* Body, pubic, head

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16
Q

What are the general protozoa pathogens?

A
  1. Parasitize intestinal and urogenital tract
  2. Parasitize blood or tissues
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17
Q

What are the types of protozoa classifications?

A
  1. Flagellates
  2. Amobaes
  3. Sporozoans
  4. Ciliates
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18
Q

What are the characteristics of protozoa?

A
  1. Inhabit in water and soil
  2. Trophozoite is the vegetative or feeding form
  3. Some produce cysts
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19
Q

Describe the protozoa life cycle?

A
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20
Q

Differentiate the trophozoite and cyst phase?

A

Trophozoite:
* metabolically active
* motile
* Multiplies by binary fission

Cyst:
* passed in feces
* non motile
* resistant to hostile environment
* doesn’t multiply

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21
Q

What is giardia? Taget?

A

Flagellated protozoan parasite that targets the duoenal and jejunal epithelium

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22
Q

What are the stage of the giardia life cycle?

A

Trophozoite: feeding and pathology-causing stage, flagellated with suckers

Cyst: highly resistant wall allowing for survival outside of host, infective form

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23
Q

How is Giardia transmitted?

A
  1. Fecal oral
  2. ZOonosis
  3. Sexual transmission
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24
Q

How does a Giardia trophozoite infect a host?

A
  1. Attach to intestinal mucosa and feed on nutrients -> detaches and moves further down -> malabsorption of protein and fat -> fatty diarrhea and flatulence
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25
Q

Lab test for Giardia?

A
  1. Presence of cysts/trophozoites in stool
  2. NAAT
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26
Q

What is plasmodium and how is it transmitted?

A

Infects erythrocytes, grows in liver and RBCs -> malaria

Transmitted: vector (femal anopheles mosquito), vertical transmission, direct transmission

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27
Q

What is the pathogen associated with malaria?

A

Plasmodium

28
Q

What is the infective form of plasmodium? How does it work?

A

Sporozoites are transmitted to human by mosquito saliva -> travels to liver and multipies -> liver cells rupture releasing merozoites

29
Q

What is the erythrocytic cycle of plasmodium?

A
  1. Occurs Q44-48H
  2. Induces periodic fevers
  3. May last months-yrs
30
Q

What happens once merozoites infect RBCs?

A
  1. Develop into trophozoites (ring)
  2. Develop into male and femal gametes to generate new sporozoites that will be taken up by mosquitos via blood
31
Q

Cyclical fevers are associated with what form of plasmodium?

32
Q

What is complicated malaria?

A

Occlusion and possible thrombosis of cerebral vessels due to increased RBC stickiness, cerebral malaria

33
Q

What is blackwater fever?

A

Plasmodium causes extensive hemolysis -> kidney damage (dark urine)

34
Q

What destruction of RBCs from plasmodium hemolysis can lead to?

A

Occlusion of capillaries -> hemorrhage and necrosis

35
Q

Lab tests for plasmodium?

A
  1. Blood smear
  2. Rapid antigen/antibody test
  3. NAAT
36
Q

What is toxoplasma gondii?

A

Intracellular coccidian protozoan parasite

37
Q

What is the definitive host for toxoplasmosis?

38
Q

What is the intermediate host for toxoplasmosis?

A

Other mammals (rodents, cattle, sheep, pigs)

39
Q

How is toxoplasma transmissed?

A

Fecal-oral, eating meats contaminatesd with cysts, transplacental

39
Q

Describe how toxoplasma migrates from felines to intermediate host?

A
  1. Oocysts are shed in cat feces
  2. Oocysts are ingested by intermedite host
  3. Oocysts release sporozoites that invade the intestines and multiple and form tachzoites
  4. Tochyzoites spread to and infect local cells and through lymph
40
Q

What do you prevent toxoplasma gondii prevention?

A

Properly cooking meats and washing or veggie/fruits and washing hands after changing litter box

41
Q

How do you test for toxoplasma?

A

anti-Toxoplasma IgG and IgM, NAAT, histology

42
Q

Describe the characterisitcs of helminth?

A
  1. Eukaryotic worm
  2. Multicellular
  3. Contains functional organ systems
  4. Multiple hosts -> invade and live in tissues:
    * Intermediate host: asexual stages
    * Definitive host: adult form develops, sexual reproduction
43
Q

What are monoecious helminths? Examples?

A

Hermaphroditic: male and femal reproductive systems in one
Ex: trematodes (flukes), cestodes (tapeworms)

44
Q

What are dioecious helminths? Examples?

A

Separate male and female
Nematodes (roundworms)

45
Q

Describe the life cycle of helminths?

A

Egg -> larva -> adults

  • Eggs have tough resistant walls
46
Q

Describe the activity of trematodes

A
  1. Adults produce eggs in human host and relesed in feces
  2. eggs develop into larva that move into snails for asexual reproduction
  3. Released from intermediate hosts as late larval stage (cercaria) that leave snail and infect crabs or fish (secondary intermediate hosts) and forms cysts
47
Q

Diagnostic for flukes?

A

Eggs in stool

48
Q

Presentation of fluke?

A
  1. Fever
  2. chills
  3. Eosinophilia
49
Q

What are cestodes?

A

Adult ribbon-like segmented tapeworms that inhabit small intestine of definitive host

50
Q

What are the parts of a cestodes?

A

Scolex: suckers and hooks for adhesion to GI mucosa
Neck: produces the segments of the worm
Proglottid: hermaphroditic reproductive organs that produces eggs that are released in stool

51
Q

Increased tapeworm number can cause what kind of complication?

A

Blockage of intestine

52
Q

Describe the life cycle of tapeworms?

A
  1. Eggs/proglottids are released in feces
  2. In the animal’s intestines, eggs hatch form oncospheres that invade intestinal wall and move to the muscles
  3. In muscles, oncospheres develop into cysticerci
  4. Humans ingest infected meat and become infected and cysticersi develop into adult tapeworm and attach to intestinal wall
  5. Cysticerci can move to other tissues or brain and cause more severe disease
53
Q

Sx of tapeworm infection?

A
  1. Abdominal pain
  2. Diarrhea
  3. Anemia
54
Q

Difinitive hosts of tapeworms?

A

Pork: Taenia solium
Beef: Taenia saginata

55
Q

Describe the structure of nematodes?

A

Elongated, nonsegmented roundworm with tapered ends that is covered by a tough with a complete digestive system

56
Q

How are nematodes transmitted?

A
  1. Ingestion of eggs
  2. Ingestion of larvae
  3. Direct invasion of skin by larval form in soil contaminated by feces
  4. Larvae transmission by insect bite
57
Q

Dx of nematodes infestation?

A
  1. Ab pain
  2. Weight loss
  3. Weakness
  4. Fatigue
58
Q

Where are pinworms found?

A

Perianal folds or vagina of infected children

59
Q

What is the pinworm dx?

A

Enterobiasis

60
Q

Definitive host of pinworms?

61
Q

How are pinworms transmitted?

A

Person-person

62
Q

Describe the cycle of pinworm infestation?

A
  1. Eggs are ingested and hatch into larvae in small intestine then migrate to the large intestine and mature into adult worm
  2. Sexual reproduction produces new eggs (>20,000)that are laid in perianal folds by migrating female worm
  3. Eggs rapidly mature and are infectious within hours
63
Q

Presentation of pinworms?

A

Eggs in perianal region swab

64
Q

How to control pinworms?

A
  1. Personal hygiene
  2. Clipping of fingernails
  3. Washing sheets
  4. Prompt treatment of infected individuals
65
Q

What are the methods the immune system responds to parasitic infection?

A

Alarmins (cytokines) stimulate TH2 cells, mast cells, basophils and eosinophils
Mucus production is increased to bind and trap parasite
IgE induced immune responses cause mast cell degranulation
IgE induced activation of eosinophils to release enzymes to kill parasite
Mucus production and smooth muscle contraction and influx of other immune cells causes smooth muscle spasms that eject the pathogen

Drug Action IV (28 decks)

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