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Protozoans Flashcards

1
Q

What are the 2 divisions of the parasites?

A

Protozoa- single celled

Metazoa- multicellular, made of helminths and arthropods

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2
Q

What are the different families of protozoa?

A 
Amoebae have pseudopodia for locomotion
Flagellates have flagella for locomotion
Ciliates have cilia for locomotion 
All 3 undergo asexual reproduction
Coccidia or sporozoans
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3
Q

What are the characteristics of coccidia or sporozoans?

A 
Amebic or flagellated forms
Asexual cycle- Schizogony
Sexual cycles-Sporogony or gametogony
Have alternative hosts
Typical cycle goes from oocyst to sporozoite to gametocyte to oocyst
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4
Q

What groups form the helminths?

A

Platyhelminths or flatworms

Nematodes or roundworms

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5
Q

What are the characteristics of the flatworms?

A

Composed of cestodes or tapeworms and trematodes or flukes
Hermaphroditic except schistosomes
Snail is first intermediate host
Eosinophilia is common, IgE
Have mouth with no anus
Cause cercarial itch especially schistosomes

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6
Q

What are the characteristics of cestodes ot tapeworms?

A

Ribbon like segmented and cause mild diarrhea

Diphyllobothrium latum causes pernicious anemia due to vitamin B12 deficiency

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7
Q

What are the different names for the tapeworms segments?

A

Proglottid= single segment
Gravid proglottid=proglottid containing eggs
Strobila= chain of proglottids
Scolex= head with suckers and/or hooklets

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8
Q

What are the characteristics of roundworms?

A

Have separate sexes
Have a mouth and anus
Pathology due to worm movement causing irritation and blockage

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9
Q

What are the characteristics of arthropods?

A

Ectoparasites- feed and live on host exterior without transmit microorganisms
Vectors can be biological or mechanical and transmit disease causing microorganisms

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10
Q

What are some common parasites?

A

Ascaris- most common in the world
Plasmodium- Most deadly
Trichomonas vaginalis- most common in the US

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11
Q

What are some ameboid protozoans?

A

Entamoeba histolytica
Acanthamoeba c encephalitis
Naegleria

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12
Q

what are the characteristics of entamoeba histolytica

A

Fecal- oral transmission
Infective stage is a cyst
Cyst is resistant to environmental conditions
Trophozoite form is the motile from in intestinal mucosa
Patients can be symptomatic or chronic carriers

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13
Q

What are the virulence factors of entamoeba histolytica?

A

Cytotoxins/proteases degrade basement membranes
Galactose inhibitable adherence lectin attach to host
Phospholipase and ionophore like protein kill neutrophils
Cell surface necrosis factors

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14
Q

What are the diseases caused by entamoeba histolytica?

A

Intestinal amebiasis/amebic dysentery( abdominal pain, flask shaped ulcers in colon, bloody stools)
Invasion of intestinal mucosa
Liver abscess fairly common
Ameboma=tumor like mass

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15
Q

how to ID entamoeba histolytica?

A

Trophozoites with ingested RBC help differentiate between pathogen and normal flora (E. Dispar, Ent. coli)
Cysts with 1-4 nuclei

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16
Q

What are the characteristics of Naegleria and acanthamoeba?

A

Free living amebae in soil and contaminated warm water
Naegleria has a flagellate and non flagellate stage
Both may be contracted by swimming or inhalation of dust
Acanthamoeba contracted from non sterile contact lens solutions (85% of cases in the US)
Infectious forms are cysts or trrophozoites depending on the route

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17
Q

What are the routes of infection for Naegleria and acanthamoeba?

A

Naegleria enter through the olfactory and migrate to the brain along the olfactory nerve
Acanthamoeba enters through the lower respiratory tract or broken skin in IC patients

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18
Q

What are the diseases of Naegleria and acanthamoeba?

A 
Naegleria fowleri (brain eating ameoba) causes acute primary encephalitis (PAM) fatal in 7-10 days
Acanthamoeba causes granulomatous amebic encephalitis (GAE) chronic in IC patients
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19
Q

How to ID Naegeria and Acnthamoeba?

A

Trophozoites in sterile fluid such as CSF
Culture amebae on E. Coli lawns and look for trails
Acanthamoeba trophozoites and/or cysts seen in corneal scrapings in keratitis patients
No cysts of Naegleria in the human patient

20
Q

What are the flagellated protozoans?

A

Giardia lamblia
Dientamoeba fragilis
Trichomonas vaginalis

21
Q

What are the characteristics of giardia lamblia?

A

1 cause of water borne diarrhea in the US
Fecal contamination of food or water
Cyst is infective stage
Cyst excyst in small intestine releasing 2 trophozoites
Virulence-adhesins taglin, GLAM-1

22
Q

What are the diseases caused by Giardia Lamblia?

A

Asymptomatic carriage 50% of the time

Mild diarrhea to malabsorption syndrome with foul smelling , greasy and fatty stools

23
Q

How to ID Giardia Lamblia?

A

Trophozoites with face like appearance
String test
Cysts and trophs in feces

24
Q

What are the characteristics of Dientamoeba fragilis?

A

No cysts known
Fecal oral
Associated with pinworm infections
Asymptomatic to intermediate diarrhea

25
What are the characteristics of trichomonas vaginalis?
``` Worlwide-49% in STD clinc Trophozoite only ,no cyst Undulating membrane Cell detaching membrane Also transmitted through fomites Diagnose through wet mount and culture ```
26
What are the diseases caused by trichomonas vaginalis?
Men are usually asymptomatic but can develop urethritis, epididymitis and prostatitis Women can be symptomatic or asymptomatic Vaginitis Burning, pruritus, foul smelling watery discharge green and frothy
27
What are the hemoflagellates?
Leishmania donovani-visceral leishmaniasis Leishmania tropica-cutaneous leishmaniasis Leishmania brasiliensis-mucocutaneous leishmaniasis Trypanosoma brucei complex Trypanosoma cruzi
28
What are the characteristics of leishmaniasis?
Caused by all 3 families of leishmania Vector is the sandfly Promastigote is infective stage Amastigote causes tissues damages
29
What are the characteristics of Leishmania donovani?
Caused visceralleishmaniasis also called Kala-azar or dum-dum fever Characterized with fever, diarrhea and anemia Lethal destruction of major organs (liver, spleen, kidneys) Hepatosplenomegaly Pancytopenia= reduced RBC and WBC
30
What are the characteristics of Leishmania braziliensis?
Causes mucocutaneous or american leishmaniasis also called chiclero Death by asphyxiation
31
What are the characteristics of trypanosoma brucei complex?
Composed of 2 differents species= T.b. Gambiense (West Africa), T.b.Rhodesiense (East Africa) Causes African trypanosomiasis- sleeping sickness Vector is the Tsetse fly that has a painful bite Evades immunity by antigenic variation (1000 genes) Trypomastigote is infective stage
32
What are the characteristics of the African Trypanosomiasis?
Neurological damage with somnolence leading to coma Recurring fevers Fatal without treatment Winterbottom’s sign= enlargement of posterior cervical lymph nodes ID: thick and thin blood smears stained with Giemsa show trypomastigotes
33
what are the characteristics of T. Cruzi?
Causes American trypanosmiasis or chagas disease Vector is the Reduviid bug vector (kissing bug) which has a painless bite Bite around mouth inoculate trypomastigotes into wound Trypomastigotes become intracellular amastigotes
34
what are the characteristics of Chagas disease?
Often fatal through heart damage Pediatric cases are usually acute Adult cases are usually chronic Romana’s sign/chagoma= allergic reaction to reduviid bug Granulomas in brain cause meningoencephalitis Hyperplasia of organs (cardiomegaly, megacolon, megaesophagus)
35
What are the characteristics of Balantidium coli?
Ciliated protozoan Fecal oral transmission from handling swine ad monkeys or contaminated water Cysts are infective stage Cysts excyst in small intestine release trophozoites Trophozoites replicate by binary fission and colonize large intestine Troph encyst and pass out with feces, some invade colon
36
what are the diseases cause by Balantidium coli?
Asymptomatic carriage-pig handlers Diarrhea-watery stools Tenesmus- straining Blood and pus;intestinal ulceration
37
What are the coccidians/sporozoans (epicomplexans)?
Plasmodium species-malaria Babesia microti-babesiosis Toxoplasma gondii-toxoplasmosis Cryptosporidium parvum-cryptosporidiosis
38
What are the different plasmodium species?
P.falciparum P.vivax P.ovale P.malariae-fever periodicity of 72 hours-attacks mature erythrocytes- recrudescence P.knowlesi-monkey malaria may be transmitted to man Plasmodium has a sexual cycle in mosquito=gametogony and an asexual cycle in human= sporogony
39
What are the characteristics of plasmodium falciparum?
Most often fatal and causes cerebral malaria Sausage shaped gametocytes Delicate ring stages-multiple trophs per cell Attacks all stages of erythrocytes Fulminating disease with parasite knobs sticking to RBC,clog capillaries, blackwater fever- kidney damage, liver damage
40
what are the characteristics of Plasmodium vivax and ovale?
P. Vivax has the widest geographic range Both attack immature RBC Cause begning tertian malaria Fever periodicity of 48 hours Hypnozoite found in liver Cause relapsing malaria= symptoms appear after a complete absence Recrudescence= low level parasitemia converts to high level parasitemia
41
What are the characteristics of malaria?
Spread by bite of female anopheles mosquitoes found in tropical and subtropical climates Prevented by mosquito netting and drugs (chloroquine, doxycycline) Paroxysms of fever, chills or rigors Headaches, muscle aches, tiredness Jaundice, anemia Vomiting, diarrhea, organ damage (brain, liver, kidney)
42
What are the characteristics of Babesia microti?
Causes babesiosis Vector is Ixodes tick Co infections with lyme disease and ehrlichiosis is common Symptoms of babesiosis: commonly asymptomatic Mild malaria without periodicity (fever, anemia) Severe malaria in asplenic or IC patients ID: Maltese cross=pathognomic
43
What are the characteristics of toxoplasma gondii
Causes toxoplasmosis Vector is cat feces Most of the time asymptomatic Reactivation in AIDS with encephalitis, retinitis Congenital triad (hydrocephalus, chorioretinitis, intracranial calcifications) Cysts release tachyzoites Tachyzoites cross placenta and infect muscle and brain become tissue bradyzoites ID: high titer anti toxoplasmosis IgM in mom
44
What are the characteristics of cryptosporidium parvum?
``` Causes cryptosporidiosis Fecal oral, water borne outbreaks Asymptomatic to mild diarrhea AIDS associated severe diarrhea ID: acid fast (stain red), oocysts in feces ```
45
What are the characteristics of cyclospora cayetanensis?
Similar to cruptosporodium parvum disease and etiology ID: variable acid fast staining oocysts, unstained mottled pink to deep red Cysts autofluoresce

Microbiology (8 decks)

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