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Microbiology - Parasites


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What are the four major protozoal groups classified by their mode of locomotion?
Amebas: extend cytoplasmic projections
Flagellates: rotate whip flagella
Ciliates: move by synchronous beating of hair like cilia
Sporozoa: Nonmotile adult forms
What are the clinically relevant Protozoan flagellates? (4 of them)
Giardia Lamblia
Trichomonas Vaginalis
Trypanosoma Species
Leishmania Species
What are the clinically relevant protozoan Ameba?
Entamoeba Histolytica
What are the clinically relevant protozoan Sporozoan?
Cryptosporidium Parvum
Plasmodium Species
Toxoplasma Gondii
What are 2 symptomatic characteristics of Entamoeba Histolytica infection?
Liver abscess
What protozoa can cause this clinical presentation: A patient presents with an enlarged, tender liver. Ultrasound analysis reveals a solitary cyst.
Entamoeba histolytica trophs can invade the liver and cause an abcess
What protozoa can cause this clinical presentation: A South African businessman presents with fever, chills and dark colored urine. A history reveals that the symptoms appear to be showing a periodicity of fever spikes approximately every 48 hours. A blo
Plasmodium falciparum
What protozoa would most likely cause a maternal infection leading to an undergrown fetus with a small head, purplish rash and enlarged liver
Toxoplasma is acquired by ingesting oocytes (often shed by cats) or transplacental transmission. Primary infection during pregnancy puts a patient at risk, especially during the first and second trimester
What flagellated protozoan associated with diarrhea?
Giardia lamblia
What sporozoan protozoan causes severe diarrhea in AIDS pts and watery diarrhea in non-HIV + ppl?
Cryptosporidium parvum
What organism causes this presentation: Your younger bro returned from summer camp in the Rockies. You notice that you can’t get into the broom at home bc he seems to spend all day there. When u ask him if he has any probs, he says he is having frequen
Giardia lamblia
What is the laboratory test confirm a diagnosis of Malaria?
Thick smear of the peripheral blood
What is the current drug of choice that is administered prophylatically to protect travelers when visiting areas in Africa in which malaria is endemic?
Mefloquine - As there is often chloroquine resistance in malarial areas
What dz does case describe: A 5-yr old, from Mexico is seen in ER bc of painless swelling around the rt eye. The lid and globe are mildly inflamed. The dad states daughter has had a low temp, headache, and does not feel well. Exam fails to reveal trauma,
Chagas disease
Why does Plasmodia cause fever that reoccurs with a periodicity of either three or four days?
Emergence of intra-erythrocytic parasites
Lysis of red cells causes release of pyrogens that cause fever. This lysis is synchronized in the infected person
What is the vector for Chagas Dz?
Reduviid insects: This "kissing" bug feeds at night, biting the lips or near the eyes
Sickle cell disease is associated with increased resistance to what disease
What protozoan parasites have arthropod vectors?
Trypanosoma Cruzi - Chagas' Disease: Reduviid bug
T. Gambiense/ Rhodesiense - African Sleeping Sickness: Tsetse fly
Leishmania donovani Kala-azar: Sandfly
Babesia - Babesiosis: Ixodes Tick
Plasmodium - Malaria: Female anopheles mosquito
What protozoan parasite can cause this presentation: A 32 year old male who has spent the summer in the Middle Atlantic States hiking the Appalachian Trail complains of fever, chills, arthralgia and malaise. Physical examination detects a palpable hepato
Babesia microti is passed to man via ticks which would be commonly encountered on a hike. The patient's symtpoms are very consistent with Babesia infection, a disease that's rather similar to Lyme disease
What Protozoans are treated with Metronidazole (FLAGYL)?
Entamoeba histolytica
Giardia Lamblia
Trichomonas Vaginalis
What is the feeding form of most protozoa?
What is the definitive host of Toxoplasma Gondii?
What is the treatment for Toxoplasma Gondii?
Pyrimethamine / sulfadiazine
What is the most pathogenic species of plasmodium?
Plasmodium falciparum
What forms of plasmodium can remain dormant in the liver?
Plasmodium Vivax
Plasmodium Ovale
What is the vector for Malaria (Plasmodium parasite)?
Female anonpheles mosquito
What is the mechanism of infection for plasmodium vivax?
Uses duffy bld group Ag to infect reticulocytes
What type of malaria does plasmodium ovale cause?
Benign Tertiary Malaria
What type of malaria does plasmodium malariae cause?
Quartan Malaria
What is the sexual and asexual phases of malaria caused?
Sexual: sporogony
Asexual: schizogony
What is the treatment for malaria?
Mefloquine: for resistant strains
Primaquine: prevent relapse pyrimethamine + sulfadoxine
What form of plasmodium is released in mosquito’s saliva?
What is the insect involved in the spread of Leishmaniasis ?
How is Entamoeba Histolytica (Amebiasis) transmitted?
Cysts in water
How is Giardia Lambia(Giardiasis) transmitted?
Cysts in water
How is Cryptosporidium transmitted?
Cysts in water
How is Toxoplasma Gondii transmitted?
Cysts in meat or cat feces
How is Trichomonas Vaginalis transmitted?
What is the vector for Babesia/
Ixodes Tick
How is African Sleeping Sickness
(T. gambiense/rhodiense) transmitted?
Tsetse Fly
What is the clinical picture of Babesiosis?
Mild Malaria like symptoms
What is the clinical picture of Toxoplasmosis in pregnancy?
Birth defects
What is the clinical picture of Toxoplasmosis in HIV + ppl?
Brain Abscess
What is the clinical picture of Malaria?
cyclic fever, headache, anemia, splenomegaly
P. Falciprum: cerebral malaria
What is the clinical picture of Vaginitis caused by Trichomonas vaginitis?
Foul-smelling, greenish discharge, itching, burning
What is the clinical picture of Chagas' Dz?
Swelling around eye and hrt dz
Which protozoans infect the intestines?
Entamoeba Histolytica
Giardia Lamblia
Cryptosporidium parvum
How do you diagnose the protozoans that infect the intestines?
Cysts in stool, must use acid-fast to see cryptosporidium parvum and trophozoites may be present for both Giardia Lamblia and Entamoeba Histolytica
How do you diagnose Trichomonas Vaginalis?
Trophozoites seen on a wet mount
Which protozoans infect the blood?
Babesia, Plasmodium, Toxoplasma gondii, Trypanosoma species and Leishmania species
How do you diagnose the protozoans that infect the blood?
Blood Smear, Babesia appears as Maltese cross w/ no RBC pigment and Toxoplasma: serology IgG/IgM

What organism causes this presentation in RBCs?
What is the treatment for African trypanosomes causing African Sleeping Sickness?
Diamidines, arsenicals; DFMO at later stages
What are the clinical differences between the 2 organisms that cause African Sleeping Sickness ?
Trypanosoma brucei gambiense – SLOW CNS involvement
Trypanosoma brucei rhodiense – QUICK CNS involvement
What is a trypomastigote?
Hemoflagellate form found in man and animals
What is a epimastigote
Hemoflagellate form found in insect vector, is infectious
What is a promastigote
Hemoflagellate form found in found in insect vector and easiest to culture
What is a amastigote?
Hemoflagellate form intracellular form found in man. Only African trypanosomes do not have this stage.
What cell type does Leishmania infect?
How do you diagnose Leishmania?
Tissue biopsy of macrophages
How does Leishmania evade the host immune system?
superoxidase dismutase to resist killing by lysosomal enzymes
How does host cell immunity exacerbate Leishmania (braziliensis, major, tropica) lesions?
Immunity associated with production of IFN Gamma and TNF by CD4+ cells-
exacerbation of lesions associated with high levels of IL-4 which inhibits activation of
macrophages by TNF; blocked production of cytokines
What is the clinical picture of kala-azar caused by Leisshmania donovani?
fever, wt loss, hepatosplenomegaly, anemia, death.

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