Protozoan and Helminth Infections Flashcards
Nematodes are:
Roundworms.
How to DX protozoan infection?
Transmission?
Where do they usually live in humans?
Blood smears or lesions.
By insects or F-O route.
Blood or GI.
3 major intestinal protozoan infections
Entamoeba histolytica
Giardia lamblia
Cryptosporidium
Entamoeba histolytica morphology:
Clinical findings:
Amoeba, oocyst, trophozoite (motile)
- Asymptomatic carriage - 90% are asx.
- Bloody diarrhea - trophozoites invade GI mucosa.
- Liver abscess.
Giardia lamblia morphology:
Clinical findings:
Oocyst, flagellated trophozoite (motile)
Foul smelling, greasy diarrhea ad abdominal distension.
Cryptosporidium morphology:
Clinical findings:
Oocyst, life cycle occurs in infected epithelial cells.
Watery diarrhea, vomiting, abdominal pain. Usually slef limiting, but can be very serious in immunocompromised pts.
Trichomonas vaginalis is the…
Morphology:
Clinical findings:
STD protozoan infection.
No cyst stage, but a flagellated trophozoie.
Men usually asymptomatic.
Women have a vaginitis, burning urination and a yello-green odorous discharge.
3 free-living/meningitis causing protozoa
Naegleria
Acanthamoeba
Balamuthia
Naegleria morphology:
Transmission:
Clinical findings:
Amoeba
Freshwater lakes
Acute meningitis, usually fatal within one week
Acathamoeba morphology:
Transmission:
Clinical findings:
Amoeba stage, cyst stage in brain.
Freshwater lakes, eye infections from dirty contact lenses.
Chronic granulomatous brain infection that is fatal within 1 year.
Corneal infection.
Balamuthia morphology:
Transmission:
Clinical findings:
Amoeba stage, cyst stage in brain.
Freshwater and soil.
Chronic granulomatous brain infection - poor prognosis.
Granulomatous skin infection.
Malaria w/ severe cerebral malaria is caused by:
Plasmodium falciparum
Malaria is most common COD in what population?
What transmits it?
Kids younger that 5 y/o. 90% of deaths come from sub-Saharan Africa. 500K deaths/year.
FM Anopheles mosquitos
3 things allowing for P. falciparum’s greater pathogenicity
Able to infect RBCs of any age.
Causes RBCs to clump together (rosette) and stick to endothelial cells (sequestration) via PfEMP1 protein leading to ischemia and manifestations of cerebral malaria.
GPI-linked proteins are released from infected RBCs and cause increased cytokine production (TNF, IFN-y, IL-1).
Red cell parasites (2)
Malaria
Babesiosis
Blood-borne flagellates (3)
Leishmaniasis
African Trypanosomiasis
Chagas disease
Babesia morphology:
Transmission:
Clinical:
Sporozoites from tick, then becomes trophozoite in humans and infects RBCs.
Ticks (ixodes).
Asymptomatic in healthy.
Causes anemia due to hemolysis in immunocompromised.
Leishmania morphology:
Transmission:
Clinical:
Flagellated.
Sandfly, contaminated blood transfusion, zoonotic.
Cutaneous - single ulcer at site of sandfly bite.
Diffuse cutaneous - nodules at bite (do not ulcer) and all over body (nose mostly). Can last 20 yrs w/o TX.
African Trypanosome morphology? Where does it live in humans? (3)
Transmission:
Clinical:
Flagellated. In blood, LNs and CNS.
Tsetse fly bite, contaminated transfusion.
African sleeping sickness: hard ulcer at bite site.
- fever, HA, LN swelling.
- CNS sx: drowsiness, sleepiness, trouble walking, etc.
American Trypanosome morphology (2)? Where does it live?
Transfusion:
Clinical types (3)
Flagellated form is EC and lives in blood.
Non-motile and IC is present in Mo and LNs, heart and brain.
Kissing bite defecation, blood transfusion.
Chagas disease: hardened red area at site of bite.
Acute Chagas disease: fever, malaise, LN swelling. Meningocephalitis, acute myocarditis.
Chronic Chagas has significan heart problems associated.
Helminths are…
How are they contracted?
Where do they live?
DX?
Multicellular euks.
By consuming parasite, often in undercooked meat or direct invasion.
GI, skin, lung, liver, muscle, BVs and lymphatics.
Microscopic eval of larvae or ova in excretions or tissues.
Life cycle of Acaris
Eggs -> swallowed -> GI tract/develop -> penetrate gut wall and travel to lungs -> larvae develop in lungs, then coughed up (pneumonia phase) -> GI tract again -> excreted -> eggs
Blood and tissue nematodes (3)
Onchocerca volvulus - “river blindness”
Wucheria boncroft - impaired lymph drainage.
Dracunculus medinesis - infect mediastinum. “Guinea worm”. Found in water.
Flatworms (platyhelminthes) types (2)
Trematomes: flukes.
Schistosomes: blood flukes.
