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Microbiology > Parasitology Pt 1 > Flashcards

Parasitology Pt 1 Flashcards

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Biology 101 flashcards
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

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

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

A

Resolves in ~month

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

23
Q

Chaga’s disease: Intermediate Phase

A

Low levels of parasites in blood

Positive antibody response against T. cruzi

NO symptoms

24
Q

Chaga’s disease: Chronic Phase

A

Organs primarily affected:
- Heart
- Colon
- Esophagus

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

25
Q

Trypanosoma cruzi:
Life Cycle

A
  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
Q

Plasmodium species

A

Malaria

Periodic episodes of high fever & shaking chills (paroxysms)

Followed by periods of profuse sweating

RBCs burst & release merozoites

27
Q

Tertian malaria

A

P. vivax & P.ovale

Every 48 hours

28
Q

Quartan malaria

A

P. malaria

Every 72 hours

29
Q

P. falciparum

A

Most common & deadly malaria

Irregular episodes

Short liver stage

30
Q

Plasmodium species:
Life Cycle

A
  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
Q

Toxoplasmosis

A

Toxoplasma gondii

Transmission via oocysts (cat feces) or bradyzoites (raw/undercooked meals)

Transplacental transmission possible

Problems in immunocompromised individuals (toxoplasma encephalitis)

32
Q

Toxoplasma gondii:
Life Cycle

A
  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
Q

Blood & Tissue Protozoa

A
  1. Leishmania
  2. Trypanosoma brucei
  3. Trypanosoma cruzi
  4. Plasmodium species
  5. Toxoplasma gondii
34
Q

Intestinal & Luminal Protozoa

A
  1. Giardia lamblia
  2. Cryptosporidium parvum/hominis
  3. Entamoeba histolytica
35
Q

Giardiasis

A

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
Q

Cryptosporidium parvum/hominis

A

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
Q

Entamoeba histolytica

A

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
Q

Entamoeba histolytica:
Life Cycle

A
  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
  5. Extra-intestinal amoebiasis
    - Trophozoites invade blood vessels of large intestines
    - Transported to other organs (brain, liver, lungs)
39
Q

Trichomaniasis

A

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
Q

Free-living Meningitis-causing Amoebas

A
  1. Naegleria fowleri
  2. Acanthamoeba
41
Q

Naegleria fowleri

A

“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
Q

Acanthamoeba

A

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
Q

Mechanical vector

A

Mechanically transporting microbe from 1 place to another

Ex: microbe carried on fly’s leg

44
Q

Biological vector

A

Essential part of life cycle

Pathogen multiplies with vector

Ex: growth of Leishmania & Plasmodium inside sandfly & anopheles mosquito (respectively)

45
Q

Mosquitoes as vectors

A

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
Q

Fleas as vectors

A

Yersinia pestis
- Causes plague
- Picks up when biting host
- Bacterium multiplies/blocks digestive tract
- Starving fleas repeatedly bite & pass bacteria

47
Q

Lice as vectors

A

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
Q

Ticks as vectors

A

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
Q

Mites

A

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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