Chapter 6 Flashcards
What disease does cryptosporidium cause
cryptosporidiosis- diarrheal
What type of organisms does cryptosporidium infect
humans-often children and AIDS patients
What was the worst cryptosporidiosis outbreak in the US
Milwaukee 1993- 400,000 people
What are the symptoms of cryptosporidiosis
watery diarrhea, dehydration, weight loss, abdominal pain, fever, nausea vomiting, severe to immunocompromised, mostly SI also other digestive organs and lungs
How are cryptosporidium diagnosed
acid fast staining, immunofluorescence microscopy
How is Cryptosporidiosis treated
electrolytes, nitazoxanide for immunocompetent, no guidance for immunocompromised
Explain the cryptosporidium life cycle
- thick walled oocyst (sporulated) exits host
- contaminated water and food with oocysts come into contact with humans, in drinking water
- thick walled oocyst ingested by human
How does cryptosporidium leave its host and what stage is it on when it does so
sporulated oocysts with 4 sporozoites leave through feces or possibly respiratory secretions
How is cryptosporidium transmitted to humans
contact with contaminated water, recreational or drinking, can be zoonotic when exposed to infected feces of animals
Once ingested by a human, what stage is cryptosporidium on and what does it do
after ingestion, excystation, where sporozoites are released and attack epithelial cells of GI tract or tissues in respiratory tract
Explain when and how cryptosporidium undergo asexual multiplication and sexual multiplication
In infected cells of the GI tract or respiratory sys. schizogony/merogony-asexual then
gametogony-sexual producing micro (M) and macro (F) gametes
What occurs in the cryptosporidium life cycle after asexual and sexual reproduction
once macrogamonts are fertilized, they develop into oocysts that sporulate in host
What types of oocysts are produced in cryptosporidium
thick walled- often excreted from host
thin walled- usually for autoinfection
what is special about oocysts of Cyclospora cayetanensis
they are unsporulated when excreted and do not become infected until sporulation is completed
What are the symptoms of cyclosporosis and what is the incubation period
incubation- 1 week
watery diarrhea, can be explosive, anorexia, weight loss, abdominal pain, nausea and vomiting, myalgias, fever, fatigue
or could be asymptomatic
How is cyclosporosis treated
antibiotics trimethoprim-sulfamethoxazole together called bactrim
sulf. . prevents growth of bacteria and
trimetho. .. is an antibiotic
What are the possible reactions to treatment for cyclosporosis
Stevens-Johnson syndrome-eruptions around mouth anus or eyes, disintegration of skin, liver damage, blood disorder, BM disorder
reactions to sulfonamide
Where in the world is cyclosporosis found
common in tropics, subtropics, outbreaks reported in US and Canada
Exlain the life cycle of cyclospora
- unsporulated oocysts are excreted in stool,
- environment is contaminated
- oocysts sporulate in environment
- sporulated oocysts enter food chain
- human ingests contaminated food/ water
- excystation in GI tract, asexual then sexual reproduction,
- unsporulated oocysts form, start over
What illness does cyclospora cause
cyclosporosis
What organism causes cyclosporosis
cyclospora
why is direct fecal-oral transmission not possible for cyclospora infection
because the oocyst is not infected at this stage
What environment does a cyclospora oocyst need to sporulate
days or weeks, temp 22-32,
Explain sporulation in cyclospora life cycle
sporont divides into 2 sporocysts, which each have 2 elongate sporozoites. result is sporulated oocyst
Explain excystation in cyclospora
oocyst excysts in GI tract of host, sporozoites are freed and invade epithelial cells of SI
What occurs in cells contaminated by cyclospora
schizogony-sexually mature into oocyst that shed in stool
How are cyclospora oocysts distinguished from cryptosporidium
mature oocysts have blue green fluorescence under UV light
cryptosporidium does not
What is different about isospora oocysts
each sporulated oocyst has 2 sporocysts
What kind of organism does isospora parasitize
mostly birds, sometimes mammals
Where in the world can isospora be found
all over, tropical and subtropical
What type of humans are often infected by isospora
immunodepressed and institutionalized groups
What symptoms does isosporosis have
acute nonbloody diarrhea, cramps in abs, lasts for weeks resulting in malabsorption and weight loss.
severe in immunodepressed and children, eosinophilia
how is isoporosis treated
trimethoprim-sulfamethoxazole,
Describe the life cycle of isospora
- oocyts released in feces, become immature oocysts with sporoblasts then sporocysts inside
- mature oocysts with sporozoites are ingested
- mature oocysts become sporozoites when excystation occurs
- asexual reproduction creates merozoites
- sexual reproduction results in oocysts released in feces, start over
Explain how isospora goes from an immatura oocyst to become sporozoites
immatura oocysts contains 1 sporoblast, sporoblast divides into 2 and secretes a cysts wall becoming a sporocyst, sporocyst divides twice producing 4 sporozoites
where and how does excystation occur in the isospora life cycle
in the SI , sporocysts excyst and release sporozoites which invade epithelial cells and start schizogony
Explain schizogony in isospora life cycle
schizonts rupture and release merozoites, invade epithelial cell, asexual reproduction
Map out stages of isospora, DRAW IT
OOCYST in feces-> meiosis, mitosis becomes INFECTIVE OOCYST->ingested becomes SPOROZOITE in SI->invades cell becomes TROPHOZOITE->becomes MERONT in enterocyte->merogony becomes MEROZOITE in lumen->can go back to troph/ MACRO and MICRO sexually reproduce becomes GAMETE-> fertilization becomes ZYGOTE->forms cyst wall becomes OOCYST.
Where are isospora trophozoites and what do they become
in invaded cell, become schizonts containing merozoites
What organisms do Eimeria infect
fowls-chickens, turkey
What organism is eimeria confused with
coccidiosis
why is eimeria significant
results in 7-9% of poultry industry loss
What conditions does eimeria live under
unsanitary, does well in summer
Why are fresh feces with eimeria non infective
sporogony from oocyst is exogenous
How long does sporogony in eimeria take
2 days in summer
what treatment is used to combat coccidiosis
no medication cures chicken once infected, prophylactic treatment is used-2 coccidiostat used in conjunction
Explain the life cycle of Eimeria
- Sporozoite enters
epithelial cell - Grows as trophozoite
- Schizogony producing many merozoites
- Schizont ruptures
- Merozoites invade new epithelial cells
6.-10. Schizogony again, some merozoites loop here - & 15. 2nd and 3rd generation merozoites enter epithelial cells and take a different path (to 16 or 19).
16.-18. Many
microgametes are
produced & released
19.-20.
Macrogametes are produced and stay in cell - Microgametes fertilize macrogametes in host epithelial cell and produce wall
- Erupt from cell
- These sporulate
- Infective oocysts
What type of organisms does toxoplasma gondii infect
most warm blooded animals, definitive hosts are cats
How are cats infected with T gondii
ingesting oocysts from environment or from tissue of prey
what happens after a cat ingests a tissue cyst of T gondii
bradyzoites are released and move to SI epithelial cells and go through endodyogony
Explain endodyogony in T. gondii
2 daughters form in parent without nuclear conjugation, parent dissolves and 2 daughters form
How long does T gondii need to become infective
oocysts need 1-5 days to sporulate, can survive for months, resistant to drying and freezing.
How does T gondii go from a sporulated oocysts when ingested by a cat to a bradyzoite in a tissue
sporulated oocyst releases sporozoites and penetrates epithelial cells, sporozoites become tachyzoites and infect tissue, tachyzoites spread to other cells and become bradyzoites in a tissue cyst.
How can pregnant women avoid T gondii infection
no changing litter box, no uncooked meat, no mammal or bird meat
What are the infection rates of T gondii in humans, is it alarming?
16-40% of humans, cosmopolitan, few actual symptoms, only concerning with pregnancy
What are the symptoms of T gondii infection
swollen lymph nodes, muscle pain, fatigue, fever, sore throat, headaches.
What are the symptoms of congenital T gondii infection
causes congenital toxoplasmosis- tachyzoites cross placenta, later in life infants show vision loss, mental disability and seizures, retinochoroiditis-eye pain, light sensitivity, blurred vision, damage to retina
How severe is congenital toxoplasmosis
only possible during pregnancy, mother shows no signs, infection more severe during 1st than 2nd and 3rd trimester,
Congenital toxoplasmosis if early in pregnancy there is __ transmission but __ pathology.
If late in pregnancy there is __ transmission but ___ pathology
low, high
high, low
How does toxoplasmosis affect the immunocompromised
worse symptoms, at risk of relapse, HIV+ more likely to develop severe infection
What organisms does Neospora caninum infect, which is the definitive host
dogs (definitive) and cattle, can cause neosporosis
What are the symptoms of neosporosis
continuous abortion in cattle, in puppies- 7 weeks old muscle atrophy, heart failure, jaw and hind leg paralysis
explain the life cycle of neospora caninum
oocysts excreted in dog feces, sporulate in environment, cattle graze and ingest it, in infected meat bradyzoites are in tissue cysts can cross placenta, passed in feces
