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MICR 121 > Parasites > Flashcards

Parasites Flashcards

(50 cards)

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1
Q

Parasitic organisms characteristics (2)

A

live on or in a host, and derive benefits or nutrients at expense of host

acquired from bites, contaminated water, contaminated environment, contaminated food

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2
Q

Main types of parasites (2)

A

1) Exoparasite

2) Endoparasite

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3
Q

Exoparasite

A

lives ON the host

causes an infestation

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4
Q

Examples of exoparasites (many)

A

scabies

public life (“crab” lice)

head lice

body louse

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5
Q

Endoparasite

A

lives IN the host

causes an infection

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6
Q

Global burden of parasitic diseases

A

incredibly high

morbidity and mortality

inadequate treatment

top death: malaria

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7
Q

Parasitic life cycles (2)

A

1) Direct

2) Indirect

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8
Q

Direct lifecycle

A

lifecycle completed in ONE host

self-limiting

eggs only viable for a short time in the environment

easier to treat

e.g. lice

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9
Q

Indirect lifecycle

A

lifecycle completed in MORE than one host

more difficult to treat

e.g. malaria, lyme disease, Toxoplasma gondii

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10
Q

Lyme disease lifecycle

A

typically a 3-host lifecycle

1st host: mouse/small rodent

2nd host: usually a rodent or rabbit

3rd host: human, dog, deer

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11
Q

Toxoplasma gondii lifecycle

A

causes the disease toxoplasmosis

humans and other mammals are DEAD END HOSTS (doesn’t get transmitted onwards)

starts out in mouse
-changes brain chemistry of mouse so that it loses fear of cats

cat: shed toxo eggs in their poop (80-90% affected)

most cat owners are infected

transmitted to humans through meat, food or water contaminated with cat feces or cat litter

not infected and then get PRIMARY infection with toxo

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12
Q

Main Classifications of Parasites

A

1) Protozoa
-single cell

2) Helminths
-multi cell

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13
Q

Protozoa (2)

A

1) Intestinal

2) Blood/tissue

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14
Q

T or F: All intestinal protozoa have a direct lifecycle

A

TRUE

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15
Q

Intestinal protozoa typical routes of transmission

A

Indirect:
-contaminated water
-food
-soil

Direct:
-zoonosis

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16
Q

Virulences factors produced by intestinal protozoa (2)

A

1) production of toxins (watery diarrhea)

2) ability to invade the GI epithelia (bloody diarrhea)

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17
Q

Intestinal protozoa (5)

A

1) Giardia lamblia

2) Entamoeba histolytica

3) Cyclospora cayetanensis

4) Dientamoeba fragilis

5) Cryptosporidium parvum

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18
Q

Most clinically significant intestinal protozoa

A

Giardia lamblia

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19
Q

Giardia lamblia

A

“Beaver Fever” - beavers are the natural hosts

associated
with contaminated H20

“rice water” stool, significant diarrhea

significant dehydration - cause of mortality in lower income countries

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20
Q

Entamoeba histolytica

A

major pathogen
associated with
poor sanitation

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21
Q

Cyclospora cayetanensis

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A

Contaminated water and produce exposed to contaminated water

including raspberries, lettuce, fresh fruit and vegetables

22
Q

Dientamoeba fragilis

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A

ubiquitous and
found in children
worldwide

transmitted person
to person

23
Q

Cryptosporidium parvum

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A

major outbreaks

carried in cattle and other zoonosis

can transmit human to human or from cattle

24
Q

Blood/tissue protozoa (3)

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A

1) Trichomonas vaginalis

2) Plasmodium spp.

3) Toxoplasma gondii

25
Trichomonas vaginalis
common STI increases risk of other STIs most common complaint: vaginal discharge other: -urinary frequency -dysuria -cystitis diagnosis: wet-prep and antigen detection -doesn't stain -have to look for motion and stops moving 1 hour after collection difficult to diagnose, no PCR yet
26
Plasmodium spp.
agents that lead to malaria transmission via anopheles mosquitoes (vector) indirect lifecycle bite dusk to dawn so mosquito nets and other control measures work quite well high pathogenicity
27
Species of Plasmodium (5)
1) Plasmodium faliciparum 2) Plasmodium malariae 3) Plasmodium knowlesi 4) Plasmodium vivax 5) Plasmodium ovale
28
Which species of Plasmodium is a medical emergency?
Plasmodium faliciparum synchronize their replication/blowing up symptoms can be timed infect RBC and blow them up blood count drops, oxygen drops - how they kill you, high pathogenicity
29
Countries/areas of the world where malaria is most common
South East Asia -India, Malaysia, Laos, Cambodia Africa
30
Plasmodium spp. lifecycle
indirect mosquito bites human saliva with sporozoites injected into human blow RBCs up sexually mature in the mosquito, asexual state in human RBCs can stay dormant in liver and reactivate
31
Laboratory Diagnosis of Malaria (3)
1) Protein Detection -PCR* -Malaria +/- -Faliciparum +/- -won't tell you species 2) Microscopy -put on slide and look for parasites 3) Molecular detection
32
Toxoplasma gondii
complex life cycle with multiple hosts and environmental maturation asymptomatic infections in immune-competent hosts serious clinical manifestations if acute infection during pregnancy (infects the baby in utero and lead to significant morbidity to the baby including deafness, microcephaly, meningitis, encephalitis, hydrocephalus, retinitis and even death, development issues, premature abortions) also bad if older, immunocompromised goes into muscle tissue and brain - if you take steroids for something, can reactivate and cause issues
33
Helminths (3)
1) Cestodes (tapeworms) 2) Nematodes (round worms) 3) Trematodes (flukes)
34
Parasites are common where ________________________
human waste is accessible by intermediate animal hosts
35
Cestodes (3)
1) Diphyllobothrium latum 2) Tinea solium 3) Tinea saginata
36
Diphyllobothrium latum
mostly in fresh water fish grows up to 40 feet in gut fish sold in Ontario for consumption has to be FLASH FROZEN to kills eggs of parasite complex life cycles with multiple hosts crustaceans, fish and humans
37
Tinea solium
pork multiple hosts eggs in feces are ingested by humans they can migrate to different tissues including the eye, brain (Neurocysticercosis), muscle and bones why you need to cook your meat -why some cultures don’t eat pork we think
38
Tinea saginata
does not develop tissue phase disease
39
taeniasis
disease caused by: tinea solium -contaminated meat tinea saginata -contaminated meat or cattle fecal matter
40
Nematodes (3)
1) Ascaris lumbricoides 2) Enterobius vermacularis 3) Strongyloides stercoralaris
41
Ascaris lumbricoides
contaminated food / water ingestion of eggs one of the largest roundworms lifecycle: goes into gut, goes into lungs and tries to go back into gut when you swallow eggs have to mature in the environment for several days life of the worm is between 10 months and 2 years
42
Enterobius vermacularis
pin worm most common worm infection in North America* the butt one transmission from person to person via contaminated surfaces often in day care centres, primary schools leads to intense anal itching and often is passed on person to person via faecal matter (after they itch their bum) hangs out on anal verge -females inside of anus -at night, travel out in the perianal area and lay eggs there -causes itching
43
How to get sample for Enterobius vermacularis
“Scotch tape method” have to get a sample early morning, get tape, go into anus, put on slide
44
Strongyloides stercoralaris
contact with the environment free larval forms found in contaminated soil (can get from walking on beach) can also get from feces worms that are able to burrow in skin simple cycle with only ONE host symptoms: dermatitis, swelling, itching, larva currens immunocompromised individuals - can develop a hyper-infective syndrome - associated with 90% mortality
45
What is unique about Strongyloides stercoralaris?
auto-infection has ability to continually infect you for over 30 years can stay dormant most other parasites have a lifecycle and then die
46
Trematodes (2)
Flukes 1) Shistosoma species (blood flukes) 2) Clonorchis sinensis (chinese liver fluke)
47
Shistosoma species
blood flukes risk factor: swimming in contaminated water found in tropical to semi tropical waters primary host: snails burrows into skin of humans swimmer’s itch, UTIs complex life cycle with > 1 host includes an environmental stage with an intermediate host
48
Clonorchis sinensis
chinese liver fluke includes an environmental stage with an intermediate host found in tropical to semi tropical waters result of ingestion of contaminated or infected fish (sushi!) cause liver absences and infection
49
Lab detection of intestinal parasites
STOOL SPECIMEN in preservatives to maintain the parasite structure put on slide and look at eggs
50
Lab detection of blood/tissue parasites
antibody detection and biopsy PCR - more sensitive, quicker to diagnose

MICR 121 (15 decks)

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