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Microbiology > Parasitology Pt 1 > Flashcards

Parasitology Pt 1 Flashcards

(49 cards)

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1
Q

Characteristics of Protozoa

A

Unicellular eukaryotes
- Protists
- Bigger than bacteria (eat bacteria)

Usually motile
1. Cilia
2. Flagella
3. Pseudopodia
4. Polar filaments

Most often reproduce by asexual fission

Love wet environments

Essential decomposers
- NOT photosynthetic

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2
Q

Protozoa Habitats

A
  1. Marine
  2. Freshwater
  3. Terrestrial
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3
Q

Role of Protozoa in Food Chain

A
  1. Eat bacteria
  2. Food for larger species
  3. Maintain ecological balance in soil
  4. Decrease sewage solids
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4
Q

Protozoa Cell Structure

A

Membrane-bound nucleus & organelles

Specialized structures for movement

NO cell wall
- Food, water, O2 diffuse through membrane
- Pinocytosis & phagocytosis

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5
Q

Protozoa Reproduction

A

Complex life cycles
- Require more than 1 host/habitat

Polymorphic
(distinct morphological forms at different stages)
- Trophozoite = vegetative/feeding form
- Cyst = resting/infectious form (withstands)

Asexual &/or sexual reproduction
1. Binary fission
- DNA replication + division into 2 cells
- Longitudinal division = flagellates
- Transverse division = ciliates

  1. Multiple fissions (schizogony)
    - Multiple DNA divisions
    - Cell contains may single-celled infectious organisms
    - Parasite released at regular intervals
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6
Q

Protozoa Phyla

A
  1. Phylum Sarcomastigophora
    (Subphylums Mastigophora & Sarcodina)
  2. Phylum Ciliophora
  3. Phylum Apicomplexa
  4. Phylum Microspora
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7
Q

Subphylum Mastigophora

A

Flagella

  1. Giardia lamblia
  2. Leishmania species
  3. Trichomonas vaginalis
  4. Trypanosoma brucei rhodesiense
  5. Trypanosoma brucei gambiense
  6. Trypanosoma cruzi
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8
Q

Subphylum Sarcodina

A

Pseudopodia

Entamoeba histolytica (disease in humans)

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9
Q

Phylum Ciliphora

A

Cilia

Balantidium coli (ulcers in large intestine)

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10
Q

Phylum Apicomplexa (Sporozoa)

A

Flagella

  1. Plasmodium species (malaria)
  2. Toxoplasma gondii (toxoplasmosis)
  3. Cryptosporidium parvum (cryptosporidiosis)
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11
Q

Phylum Microspora

A

Polar filament

Microsporidium (diarrhea, immunocompromised)

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12
Q

Leishmaniasis

A

Zoonotic protozoa
Carried by: rodents, dogs, & foxes
Transmitted to humans by bite of sandfly

Promastigote
- Flagellated motile form
- Invades phagocytic cells & transforms into amastigote

Amastigote
- Nonmotile form
- Multiplies in phagocytic cells of reticuloendothelial system
(lymph node, spleen, liver, bone marrow)

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13
Q

Cutaneous Leishmaniasis

A

L. tropica & L. mexicana

Skin ulcer develops at site of bite

Nodular lesions diffuse across body (inactive CMI response)

Untreated infections can last for years
(NOT normally fatal)

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14
Q

Mucocutaneous Leishmaniasis

A

L. braziliensis

Initial dermal ulceration heals

Ulcers appear in mucous membranes of nose & mouth

May erode nasal septum, soft palate, & lips if left untreated
(NOT normally fatal)

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15
Q

Visceral Leishmaniasis

A

L. donovani

Common in young/malnourished children

Fever, anorexia, weight loss, & abdominal swelling (hepatomegaly & splenomegaly)

Often fatal

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16
Q

Leishmania:
Life Cycle

A
  1. Sandfly takes blood meal
    - Injects promastigote into human skin
  2. Macrophages phagocytose promastigotes
  3. Promastigotes transform into amastigotes
  4. Amastigotes multiply in cells of various tissues
  5. Sandfly takes blood meal
    - Ingests macrophages infected with amastigotes
  6. Amastigotes transform into promastigotes in midgut
  7. Promastigotes divide & migrate to proboscis
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17
Q

African Sleeping Sickness

A

Trypanosoma brucei

Tsetse fly bite spreads tryptomastigote via blood stream to CNS & lymph nodes

Initial painful skin ulcer heals within 2 weeks

Fever, headache, dizziness, lymph node swelling

CNS symptoms (daytime drowsiness, slurred speech, problems walking, coma, death)

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18
Q

West African Sleeping Sickness

A

Trypanosoma brucei gambiense

Slowly progressing symptoms

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19
Q

East African Sleeping Sickness

A

Trypanosoma brucei rhodesiense

More severe
Death occurs within weeks

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20
Q

Trypanosoma brucei:
Life Cycle

Study These Flashcards
A
  1. Tsetse fly takes blood meal
    - Injects metacyclic tryptomastigotes
  2. Metacyclic tryptomastigotes transform into bloodstream tryptomastigotes
  3. Tryptomastigotes multiply by binary fission in bodily fluids
    - Blood, lymph, spinal fluid
  4. Tsetse fly takes blood meal
    - Ingests tryptomastigotes
  5. Bloodstream tryptomastigotes transform into procyclic tryptomastigotes in midgut
    - Multiply by binary fission
  6. Procyclic tryptomastigotes leave midguit & transform into epimastigotes
  7. Epimastigotes multiply in salivary gland
    - Transform into metacyclic tryptomastigotes
21
Q

Chaga’s Disease

Study These Flashcards
A

Trypanosoma cruzi

Spread by triatomine bug feces (travels through blood to distant organs)

Tryptomastigotes tunnel into human host & transform into amastigote

Amastigote invades:
- skin
- macrophages
- lymph nodes

Hard/red area develops at entry site

Systemic spread: fever, malaise, & swollen lymph nodes

Infects heart & CNS

22
Q

Chaga’s disease: Acute Phase

Study These Flashcards
A

Resolves in ~month

Symptoms:
- Fever
- Malaise
- Swollen lymph nodes
- Meningoencephalitis
- Acute myocarditis

23
Q

Chaga’s disease: Intermediate Phase

Study These Flashcards
A

Low levels of parasites in blood

Positive antibody response against T. cruzi

NO symptoms

24
Q

Chaga’s disease: Chronic Phase

Study These Flashcards
A

Organs primarily affected:
- Heart
- Colon
- Esophagus

Symptoms:
- Dementia
- Megaesophagus
- Heart damage
- Heart failure

25
Trypanosoma cruzi: Life Cycle
1. Triatomine bug takes blood meal - Passes metacyclic tryptomastigotes in feces - Enter bite wound or mucous membranes 2. Metacyclic tryptomastigotes penetrate cells at wound site - Transform into amastigotes 3. Amastigotes multiply by binary fission (in cells of infected tissue) 4. Intracellular amastigotes transform into tryptomastigotes - Burst out of cells & enter bloodstream - Infect other cells 5. Triatomine bug takes blood meal - Ingests tryptomastigotes 6. Tryptomastigotes transform into epimastigotes in midgut 7. Epimastigotes multiply in midgut 8. Epimastigotes transform into metacyclic tryptomastigotes in hindgut
26
Plasmodium species
Malaria Periodic episodes of high fever & shaking chills (paroxysms) Followed by periods of profuse sweating RBCs burst & release merozoites
27
Tertian malaria
P. vivax & P.ovale Every 48 hours
28
Quartan malaria
P. malaria Every 72 hours
29
P. falciparum
Most common & deadly malaria Irregular episodes Short liver stage
30
Plasmodium species: Life Cycle
1. Mosquito takes blood meal - Injects sporozoites 2. Sporozoites travel to liver & multiply (schizogony) 3. Merozoites released from liver cells & invade RBCs - Erythrocytic cycle (immature - mature trophozoite - schizont) 4. Gametocytes differentiate from some merozoites 5. Mosquito takes blood meal - Ingests gametocytes 6. Gametocytes multiply (sporogonic cycle) - Microgametocytes (male) - Macrogamtocytes (female) 7. Zygote 8. Ookinete 9. Oocyst - Ruptures & releases sporozoites 10. Sporozoites travel to salivary glands
31
Toxoplasmosis
Toxoplasma gondii Transmission via oocysts (cat feces) or bradyzoites (raw/undercooked meals) Transplacental transmission possible Problems in immunocompromised individuals (toxoplasma encephalitis)
32
Toxoplasma gondii: Life Cycle
1. Human ingests oocysts or bradyzoites - Cat = fecal oocysts (intestinal phase) - Other animals = tissue cysts (extraintestinal phase) 2. Transform into tachyzoites 3. Tachyzoites localize in neural & muscle tissue - Develop into cyst bradyzoites - Tachyzoites can infect fetus via bloodstream (pregnant)
33
Blood & Tissue Protozoa
1. Leishmania 2. Trypanosoma brucei 3. Trypanosoma cruzi 4. Plasmodium species 5. Toxoplasma gondii
34
Intestinal & Luminal Protozoa
1. Giardia lamblia 2. Cryptosporidium parvum/hominis 3. Entamoeba histolytica
35
Giardiasis
Giardia lamblia (Mastigora) Tranmitted via ingestion of cyst (fecally contaminated food/water, streams, day cares, mental hospitals) Chlorination doesn't kill cysts (boiling & filtration works) Trophozoite adheres to small intestinal wall (sucking disk) & interferes with fat absorption Non-bloody, foul-smelling diarrhea
36
Cryptosporidium parvum/hominis
Transmitted via ingestion of oocysts (fecally contaminated water, agricultural runoff - zoonosis) Short-term/mild diarrhea Chronic/watery diarrhea in immunocompromised Opportunistic infection Common in US
37
Entamoeba histolytica
Amoebiasis (amoebic dysentery) - Diarrhea (mild asymptomatic disease to severe dysentery) May invade intestinal mucosa (causing erosions) May penetrate portal blood circulation (forming abscesses in liver & lung; often resulting in death)
38
Entamoeba histolytica: Life Cycle
1. Human ingests fecal cyst 2. Cyst transforms into trophozoites in small intestine 3. Trophozoites reproduce by simple division - May invade lining of large intestine 4. Cysts passed in feces 4. Extra-intestinal amoebiasis - Trophozoites invade blood vessels of large intestines - Transported to other organs (brain, liver, lungs)
39
Trichomaniasis
Trichomonas vaginalis Sexually transmitted via trophozite (NO cyst stages) Most males asymptomatic Often asymptomatic in women Heavy infection symptoms: - Itching - Burning on urination - White/frothy/malodorous discharge from genital tract (trophozoites visible) Treat males to prevent re-infection of female partner
40
Free-living Meningitis-causing Amoebas
1. Naegleria fowleri 2. Acanthamoeba
41
Naegleria fowleri
"Brain-eating" amoeba Enters body through nose - Contaminated water gets high up in nasal passages Travels to brain & spinal cord (destroys tissue) Primary amebic meningoencephalitis (PAM) - Brain inflammation (fatal within week) Symptoms: - Fever - Headache - Stiff neck - Nausea & vom
42
Acanthamoeba
Humans acquire from: - Swimming in contaminated water - HVAC systems - Shower heads - Taps Acanthamoeba keratinitis - Local infection of eye (healthy individuals) - Can lead to permanent visual impairment/blindness Granulomatous Amebic Encephalitis (GAE) - Serious infection of brain & spinal cord (immunocompromised individuals) Disseminated infection - Widespread infection (immunocompromised individuals) - Can affect: skin, sinuses, lungs, & other organs
43
Mechanical vector
Mechanically transporting microbe from 1 place to another Ex: microbe carried on fly's leg
44
Biological vector
Essential part of life cycle Pathogen multiplies with vector Ex: growth of Leishmania & Plasmodium inside sandfly & anopheles mosquito (respectively)
45
Mosquitoes as vectors
Insert feeding tube into host skin - Ingests blood (can pick up infectious agent & transfer to next host) Transmit: 1. Malaria 2. Yellow fever 3. Dengue fever 4. West Nile encephalitis
46
Fleas as vectors
Yersinia pestis - Causes plague - Picks up when biting host - Bacterium multiplies/blocks digestive tract - Starving fleas repeatedly bite & pass bacteria
47
Lice as vectors
Suck blood through skin - Appendages adapted for attachment Spread by direct contact with person or personal items Head lice does NOT transmit disease Body lice transmits bacterial diseases: 1. Trench fever (Bartonella quintana) 2. Epidemic typhus (Rickettsia prowazekki) 3. Relapsing fever (Borrelia recurrentis)
48
Ticks as vectors
Arachnids - NO wings or antennae - 4 pairs legs - fused thorax & abdomen Live in low vegetation Burrow into skin with mouthparts - Feed continually Wood tick (Dermacentor anderson) - Rocky Mountain spotted fever (Rickettsia rickettsii) Ixodes scapularis - Lymes disease (Borrelia burgdorferi)
49
Mites
Live on outer surfaces of plants/animals Microscopic Demodoex mites - Hair follicles/oil-producing glands Do NOT transmit disease Chiggers (larvae) - Attach/feed on fluid within skin cells - Intense itching Sarcoptes scabei mites - Transmitted via personal contact - Cause scabies (itchy skin rash)

Microbiology (15 decks)

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