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54 Cards in this Set
- Front
- Back
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What is the definitive host and vector of Babesiosis?
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Ixodid ticks
same as lyme disease, etc. |
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What are the symptoms of babesiosis?
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asymptomatic OR malaria-like symptoms in immunosuppressed
fever, hemolytic anemia |
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What is the intermediate host of babesiosis-causing hemoprotozoans?
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White-footed mouse
asexual cycle, merogony |
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How is babesiosis diagnosed?
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thick/thin blood smear
Indirect Fluorescent Antibody if low parasitemia |
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What type of reproduction does Babesia undergo in humans?
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Humans = DEAD END HOST (except by blood transfusion)
--> Merogony, asexual reproduction in human. Noninfectious |
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What is the causative agent of Toxoplasmosis?
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Toxoplasma gondii
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Route of infection for Toxoplasmosis?
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ingestion or inhalation of mature oocysts
eating undercooked pork blood transfusions, organ transplants |
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What is the definitive host of Toxoplasma gondii?
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Domestic cats
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What is the intermediate host of Toxoplasma gondii?
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>200 mammals including man
self-limiting, acute disease via tachyzoites, or chronic infection via bradyzoites |
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How is toxoplasmosis diagnosed?
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SEROLOGY EXCLUSIVELY
look for increase in IgG titer newborns: IgM and IgA PCR of amniotic fluid (abort??) |
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Describe the general scheme of coccidial infections in humans.
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infection via oral-fecal ingestion of mature, infectious oocysts
obligately intracellular! sexual AND asexual stages in epithelium of small intestine --> heavy diarrhea |
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What are the names for the sexual and asexual cycles of coccidia in humans?
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sexual = gametogony
asexual = merogony |
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Which coccidial oocysts are immediately infective?
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Cryptosporidium parvum
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Which coccidial oocysts require maturation in soil?
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Cyclospora, Isospora belli,
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Recommendations for prevention of babesiosis?
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remove ticks ASAP!
infection only occurs after tick has been feeding after a while |
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What is babesiosis similar to under the microscope? How to differentiate?
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looks like ring form of malaria-causing plasmodium spp.
babesiosis: wispier rings than malaria, TETRAD FORM (4x infect same RBC) |
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What are the end products of a cycle of sexual reproduction?
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Sporozoites
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What are the end products of a cycle of asexual reproduction?
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Merozoites
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What is the unifying characteristic structure of members of phylum Apicomplexa?
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Apical Complex: enzymes at tip of organism that lyse a hole in host cell so parasite can infiltrate
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When is Toxoplasmosis most severe?
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1st trimester of pregnancy
Immunocompromised patients: AIDS, organ transplant pts |
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Route of infection for Toxoplasma?
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eat undercooked meat w/tissue cysts containing tachyzoites
inhale oocysts (old cat litter) garden work: oocysts in soil |
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How does Toxoplasma affect the developing fetus?
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hydrocephalus: inhibit circulation of CSF
enlarged skull brain inflammation meningoencephalitis |
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Describe symptoms of acute toxoplasmosis.
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intracellular TACHYZOITES (like malarial merozoites)
tachyzoites excyst and spread to BRAIN (!!) and liver may affect Chorioretina --> wooly infiltrate in eye |
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Describe symptoms of chronic toxoplasmosis.
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dormant infection--harmless!
tissue cysts containing slow-dividing BRADYZOITES but may RELAPSE to acute toxo if immune system becomes compromised! |
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Where is toxoplasmosis most common?
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France, Austria (eating undercooked meat: beefsteak tartar )
S. America (lots of stray cats) |
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What form of toxoplasmosis affects newborns?
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acute form!
may have a low level infection and then deteriorate after birth |
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Prophylactic recommendations for toxoplasmosis?
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cook meat well
clean cat box daily wear gloves during garden work |
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Describe life cycle of cryptosporidium parvum.
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Intracellular trophs --> schizonts --> release of merozoites or gametocytes --> ookinetes --> oocysts --> sporozoites
same as malaria but all in same host. |
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What is the major reservoir of Cryptosporidium Parvum?
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cattle!
H2O contaminated w/oocysts |
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Which stains are most often used for detecting oocysts in stool specimens?
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**acid fast stain
also auramin fluorescent stains |
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What is the only coccidium with an animal reservoir?
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Cryptosporidium parvum
cattle reservoir |
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What are the reservoirs of Cyclosporidium?
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man ONLY (as far as we know)
even oocysts must mature in humans |
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Why do we not usually observe outbreaks of coccidial infections?
What is the exception to this rule? |
oocysts require maturation periods in soil
exception = Cryptosporidium b/c oocysts immediately infectious |
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What are the symptoms of Cyclospora infections?
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heavy diarrhea
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Which stain is best to detect oocysts of Cyclosporidium?
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Auramine stain
oocysts ~12um diameter, about size of granulocyte |
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What is the reservoir of Isospora belli?
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man only, as far as we know
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Describe the life cycle of Isospora belli.
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fecal-oral contamination
ingest mature oocyst --> merogony + sporogony in human host intestine --> excrete oocyst into soil --> maturation of oocyst --> reinfection |
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How do Microsporidia invade host cells?
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latch on and puncture cell with harpoon-like device (POLAR FILAMENT)
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Describe the life cycle of Microsporidia.
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only sporogony--asexual reproduction within host cells
grows intracellularly until it ruptures host cell |
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What are the infectious agents of Microsporidiasis?
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spores of Enerozoon bieneusi and Encephalitozoon intestinalis
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Microsporidia are important intracellular pathogens of what patient population?
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AIDS patients especially.
rapidly disseminating infection. |
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What are the symptoms of Microsporidiasis?
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diarrhea!! due to small intestine infections
ocular, urinary tract, respiratory tract infections |
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What is the approximate size range of intracellular Enterozytoon bieneusi? Where are they located?
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intestine
0.8-1.4 um |
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What is the approximate size range of intracellular Encephalitozoon intestinalis? Where are they located?
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intestines but tends to spread to distant areas of body.
1.4-4 um |
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How does Toxoplasmosis usually manifest itself in immunocompetent people?
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harmless disease!
maybe flulike symptoms usually lifelong infection controlled by immune system (bradyzoites in brain, etc.) bradyzoite stage does not spread transplacentally. |
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How does toxoplasmosis manifest itself in immunocompromised people?
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encephalopathy
chorioretina inflammation --> blindness, wooly-looking infiltrates in retina |
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Why are humans considered a dead end host?
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though infected, humans are typically not ingested by domestic cats and thus cannot infect cats.
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What are the chances that a baby will contract acute toxoplasmosis from its mother? What two forms are present?
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25%
1. general reticuloendothelial infection 2. acute CNS infection/encephalitis (brain immune system develops slower) |
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What percentage of congenital toxoplasmosis cases are asymptomatic at birth?
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~60%
child usually deteriorates rapidly thereafter |
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How is it possible for chronic toxoplasmosis to relapse into the acute phase?
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loss of immune system function: AIDS, HIV, organ transplant-related immunosuppressive drugs
reactivation of bradyzoite cysts --> tachyzoites, especially in the brain. |
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Where are bradyzoite cysts most often found?
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skeletal muscle
myocardium brain |
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Morphology of Cryptosporidium parvum under the microscope?
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RED under acid-fast stain of stool sample, irregularly pigmented sphere surrounded by zone of clearing
yellow under auramin stain ~4um, smaller than RBC |
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How to differentiate between a sporulated and unsporulated coccidial oocyst?
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unsporulated: only one cell inside
sporulated: usually 2 cells inside. gives rise to 2 sporozoites. |
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What is the typical route of infection for Cyclospora cayetanensis?
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sporulated oocysts ingested (contaminated produce/water: raspberries, basil)
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