Parasitology Lecture 9 Flashcards
coccidia are _____ ________ parasites
obligate intracellular
the ________ (infectious form) have a similar mechanism of cell attachment & penetration
sporozoites
coccidia are major pathogens in people who have ______
HIV/AIDS
which intestinal coccidia is known to be the most notorious & why?
cryptosporidium because its oocysts are immediately infectious
true or false: the oocytes of cyclospora and cystoisospora are not immediately infectious
true
cryptosporidium _____/_____ cause gastroenteritis with _______
parvum/hominis
________ is the most commonly isolated organism in people who have _____ and are infected with ____
crypto, diarrhea, HIV
crypto typically causes ____ and ____ term infection - but it can be serious in ____ or ______ people
acute, short, kids, immunocompromised
crypto is shed as ______
oocysts
true or false: the oocysts of cryptosporidium are not resistant to chlorination
false - they are very resistant (use iodination or boiling)
what encourages the sporozoites to pop out of the oocysts?
a drop in pH
the oocyst contains baby _________
sporozoites
the progeny of the zygote is the _____
oocyst
______ orient their _____ end toward ____ epithelial cells where they invade, but just hang around near the membrane
sporozoites, apical, GI
what are the clinical symptoms that crypto causes?
- mild to profuse watery diarrhea
- cramps, nausea, vomiting, weight loss, etc.
true or false: crypto is usually self-limiting but can go longer than 30 days if the individual is HIV+
true
true or false: recrudescence with crypto is very uncommon
false - it is common
the ______ and ______ are common places for crypto to reside in, but there can be widespread disease in patients with _____
jejunum, ileum
HIV/AIDS
true or false: outbreaks of crypto have been found in hospitals, institutions, and day care centers
true
typically, children who are infected with crypto are ________
asymptomatic
transmission of crypto between humans is through the _______ route
fecal-oral
c. hominis is found in _____ only, however, c. parvum is found in ____, _____, _____ and can infect mice & calves
humans
sheep, cows, humans
traditional stains (Giemsa) do not differentiate between _____ and similarly sized _____ or other debris
oocysts, yeasts
what stain should be used to look for cryptosporidium?
modified acid fast stain
what is the size of crypto?
4.2-5.4 microns in diameter
an ______ stain can also be used to identify crypto, but you do need a special microscope
auramine
an _________ assay can also be used to identify crypto, where antibodies are fluorescently tagged against crypto
immunofluorescence
true or false: multiplex PCR has replaced ELISA
true
true or false - the infectious dose is very low for crypto
true
how can crypto be prevented?
- treatment of water facilities
- animal waste management
- boil water (or iodinate, but do not chlorinate - it will not kill crypto!)
what is the treatment for crypto?
fluids, electrolytes (for loss of water in profuse watery diarrhea), also Nitazoxanide (antiprotozoal), and ART (if HIV+)
cyclospora cayetanensis causes all ___ cases
human
cyclospora is associated with ________ outbreaks or _______ diarrhea
foodborne, traveler’s
true or false: oocysts from cyclospora are not immediately infectious, they need to progress in the environment for days to weeks
true (these are known as unsporulated oocysts)
cyclospora typically infects __________ foods like raspberries or basil
non-processed
cyclospora is often ______
asymptomatic
the symptoms of cyclospora?
- mild to severe watery diarrhea
- weight loss, abdominal pain, N/V, tiredness, fever, fatigue
if untreated, cyclospora can last ____ weeks
10-12
cyclospora should be treated with _____ if infection persists
bactrim
true or false: a single negative stool result is enough to diagnose cyclospora
false
for cyclospora diagnosis, more than __ specimens may be needed at ___ day intervals
3, 2-3
cyclospora can also be diagnosed via a modified ____ ____ stain or an _____ stain
acid fast, auramine
similar to cyclospora cayetanensis, cystoisospora ___ only infects humans, and the oocysts are NOT _____ _____
belli, immediately infectious
from the human coccidian infections, which one is least common?
cystoisospora belli
symptoms of cystoisospora belli?
diarrhea, steatorrhea (fatty stools), headache, fever, nausea, dehydration, water loss,
similar to cyclospora, cysto can be treated with ______
bactrim
t or f: cystoisospora can lead to occasional eosinophilia
true (eosinophilia is an increase in disease fighting white blood)
t or f: the lifecycle of cystoisospora is very similar to cyclospora
true
what is the size of cystoisospora?
25-30 microns (largest of the coccidia)
what stains can be used for cystoisospora?
iodine stain, modified acid fast
t or f: cystoisospora has a typical ellipsoidal shape
true
toxoplasmosis is usually self-limiting in the ________, but severe complications can arise in ____ or __________
immunocompetent, fetus, immunocompromised
are the oocysts for toxoplasma immediately infectious?
NO (they mature in the soil)
what is the route of entry for toxo? (2)
- undercooked meat or ingesting contaminated soil
2. gardening, handling cat litter
t or f: toxo has a high rate of seroprevalence
true (22.5% of Americans have antibodies to toxo!)
where does the sexual cycle for toxo occur?
in cats
cats excrete ____, and they sporulate in soil for a few days, then become fecal oocysts..where can they go from here?
- cat eats soil and the cycle continues in them
- or birds/mouse eat contaminated soil or water (where they eventually forms cysts, and then the cat may eat the infected bird or mouse)
both _____ ___ and ____ _____ transform to ______ after ingestion
tissue cysts, fecal oocysts, tachyzoites
if a pregnant women becomes infected w toxo, then ______ can infect the fetus via the ______
tachyzoites
bloodstream
most people who get toxo are asymptomatic, but some people get a ____-like disease
flu-like
people who get toxo but are immunocompromised may get ____-enhancing ______ or _______ inflammation
ring, lesions, retinal
if the fetus becomes infected w/ plasmo, it may lead to _______ or _______
malformations, hydrocephalus (water in brain)
chronic toxoplasmosis occurs when a cyst is filled with ______
bradyzoites
bradyzoites are metabolically ______ and are therefore very ___ dividing
inert, slow
congenital toxo has the most risk during the ___ trimester because key developmental processes take place at this time
1st
acute toxo can lead to…(3)
- hydrocephalus
- meningoencephalitis
- chorioretinitis
t or f: ring-enhancing lesions are not pathognomonic
true
what does igG+ mean? igM-? igM+?
igG+ = previous infection at some time igM- = no recent infection igM = hard to interpret, b/c toxo gondii igM is present 1.5 yr after infx)
what does it mean if the newborn is igM+?
new infection in baby and not from mom because only igG can pass the placenta
name ways of diagnosing toxo (4)
- look for tissue cysts (BAL, lymph node, etc)
- X-ray for hydrocephalus (in new born affected)
- head CT (for HIV patients)
- amniotic fluid PCR
how to prevent toxo?
- cook meat well
- clean cat litter daily
- wear gloves doing garden work
what’s unique about sarcocystis?
heteroxenous lifecycle
for sarco, merogony occurs in the ____ host while gametogony occurs in the _____ host
intermediate, definitive
how many species of microspora can infect humans?
at least 15
what is unique about the structure of microspora?
polar filaments (tubule)
what do polar filaments inject?
sporoplasm
microspora causes _____ in immunocompromised people
diarrhea
how is microspora diagnosed?
stains, histology, EM (best)
enterocytozoon bieneusi and encephalitozoon intestinalis are names of ….?
microspora
drug used to decrease microspora severity
albendazole
a _____ stain can be performed with microsporidia
chitin
