Protozoans and Biting Insects Flashcards
Describe the life cycle of leishmania
sand fly life cycle:
o Sand fly takes meal of blood cells with amastigotes (no flagella)
o Amastigotes transform into promastigotes in fly’s midgut
o Promastigotes multiply by binary fission in midgut and are then injected into new host during next blood meal
o Human macrophage ingests the parasites
o Promastigotes transform into amastigotes and multiply in macrophage
o Macrophage ruptures and amastigotes are released into the blood stream where they can infect more macrophages
promastigote
has a flagella, seen in the sand fly
amastigote
has no flagella- seen in mammalian host of leishmania
leishmania tropica
causes oriental sore - ulcer, can be immune following innoculation
leishmania donovani
causes Kala-azar (visceral leishmania)- amastigote goes to any organ/skin and kills it, usually leads to death in a few years because person has no macrophages to protect them
Post-Kala-azar dermal leishmanoid- if not treated a disfigurement of the lesion occur
What is T. brucei?
tsetse fly, African sleeping sickness, organisms replicate in blood and get into the organs, cause lymph node swelling and massive immune stimulation. Undergoes lots of antigenic variation via transposons
Which T. brucei is chronic? Which is acute?
Chronic- T.b. gambiense
Acute- T.b. rhodensiense
Stercoraria
complete development in the hindgut (people scratch the feces from parasite into the opening in their skin
T. cruzi
kissing bug, t. cruzi related to CHAGAS disease
Life cycle of T. cruzi
o Kissing bug ingests trypomastigoes during blood meal
o Trypomastigotes form epimastigotes by binary fission in midgut of kissing bug, and they transform into more trypmastigotes in the hindgut of kissing bug
o Trypomastigotes deposited in feces of kissing bug at wound site, scratched into the blood
o Trypomastigotes travel in blood and penetrate cells, transform ito amastigotes
o Amastigtes multiply in cells and infected tissues
Can infect other cells
Can transform into trypomastigotes in blood
ramona’s sign
lymph node swelling associated with t.cruzi (kissing bug)- CHAGAS DISEASE
T. cruzi is ____cellular
intracellular, organism replicates in phagocytes.
describe t. cruzi pathology
forms a pseudocyst (pocket of parasites in muscle or brain or heart tissue) causing inflammation that can lead to death, Chagas disease (megaesophagus and megacolon)
what does entamoeba histolytica cause?
amoebic dysentery- organism ingests RBCs and eats into intestinal mucos (causes erosions) and can spread to liver and lungs and CNS
How many nuclei does entaoeba histolytica have?
4 nuclei in cyst form, one nuclei as trophozoite (central endosome in nucleus)
What does giardia lamblia cause?
diarrhea (like campers/ traveler’s disease), pear-shaped trophozooite with 2 nuclei (look like eyes), causes fat-laden smelly stool with no blood
What is trichomonas vaginalis associated with?
STD, associated with vaginitis in women
undulating membrane on trophozoite
What is associated with Balantidium coli?
ciliar dysentery, get this from pig feces, stays in intestine
What is associated with cryptosporidium parvum?
diarrhea in immunocompromised, outbreak in Milwaukee; acid fast stain used for diagnosis
Which state is motile and inactive? Which state is infective?
o Trophozoite stage- motile form, inactive
o Cyst stage- Infective stage, spherical shape
How do you distinguish cyst vs. trophozoite in entamoeba histolytica?
4 nuclei in cyst form, 1 nucleus in troph form (central endosome in nucleus)
Which intestinal protozoa has a kidney shaped macronucleus with cilia around it?
balantidium coli
name the three stages of the plasmodium life cycle and where each stage occurs
pre-erythrocytic cycle (exo-erythrocytic cycle)- in liver erythrocytic cycle (in RBCs) sporogonic cycle (in mosquito)
What is the most significant disease transmitted by fleas?
plague
protozoans are ___cellular
unicellular, but multicolonial
Where is P. vivax common? Why?
Asia, Africans have anti-Duffy blood type so not affected by this form of plasmodium
Which plasmodium types cause tertian malaria? Which plasmodium types are quartan?
P. vivax, P. ovale are tertian.
P. malariae is quartan
P. falciparum has no tertian pattern in symptoms (incessant)- malignant tertian)
What is different about P. malariae?
quartan malaria, enters aging RBCs, has recrudescence
Which forms of malaria have relapses from the liver?
P. vivax and P. ovale
T. gondii
causes toxoplasmosis (myalgias, rash), cats are definitive host, intracellular parasite (in cat); pregnant women should stay away from litter boxes
Acanthamoeba
get infected when contacts are washed with water, can cause keratitis in eyes and can invade CNS causing granulomatous ameobic encephalitis
naegleria
infected water gets into nose, and the trophozoites migrate to the brain causing primary ameobic meningoencephalitis (trophozoites found in CSF)
How can protozoans reproduce?
Asexually or sexually
asexual- schizogony (multiple fission –> schizont–> merozoite)
sexual- makes gametocytes
True or false: P. falciparum releases more merozoites/RBC than other species, making it more virulent than other forms of malaria
TRUE
T/F: there are continuous symptoms during p. falciparum infection
TRUE; no spontaneous recovery in p. falciparum.
Describe recrudescence. What parasite causes this?
In recrudescence the parasite is present in low levels and replicatimg slowly, so many years later you are symptomatic.
Occurs in plasmodium malariae since it only enters aging red blood cells.
What is the diagnostic stage of plasmodium?
Trophozoite (ring stage) in erythrocytic cycle (in RBC)
clinical manifestations of malaria are due to…
the erythrocytic stage of the life cycle (merozoites infect RBCs, replicate, and burst the cells)
What is infectious stage of plasmodium?
release of sporozoites in the anopholes mosquito to the salivary glands, for entrance into host via mosquito bite
Where does sexual division occur in plasmodia? Where does asexual division occur?
sexual - in anopheles mosquito
asexual- in liver cell and RBC of host (human)
Who is resistant to p. falciparum?
sickle cell patients
Who has milder p. falciparum symptoms?
G6P dehydrogenase deficiency patients
Why is p. vivax seen more in Asia than Africa?
Some Africans lack Duffy antigen, which is needed for plasmodium to get into the cell
What are the three main symptoms of malaria?
- chills and rigors
- fever spikes
- sweating
tertian malaria means…
1 day of symptoms every 48 hours (3 days total for cycle)
P. vivax only affects ____ cells
affects young cells
hypnozoites are ____ and are associated with ____
liver cell dormant phase
p. vivax and p. ovale
hypnozoites can cause a relapse when they become active again.
describe quartan malaria
24 hours of feer, 72 hours of feeling well (4 days total); typical of p. malariae which infects older RBCs
which malarial forms have spontaneous recovery?
p. vivax and p. ovale
however, these have hypnozoites which can be dormant and cause a relapse
paroxysm means…
sudden appearance of symptoms
malaria is treated with:
quinine
Why is it hard to make a vaccine for malaria?
- organism continuously changes protein coat
2. each reproductive stage has different antigens
How are humans infected by toxoplasma gondii?
Remember, this is transmitted by cats
- eating undercooked meat of animals harboring tissue cysts.
- consuming food or water contaminated with cat feces (fecal-contaminated soil or changing the litter box of a pet cat).
- blood transfusion or organ transplantation.
- transplacentally from mother to fetus.
What is infective phase of leishmania?
sandfly takes a bloodmeal and injects promastigotes into host
What is the diagnostic phase of leishmania?
amastigotes in macrophages and tissues
What does heteroxenous mean?
requiring more than one host to complete the life cycle (example: leishmania, plasmodium, trypanosomes)
