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118 Cards in this Set

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What kind of life cycle do Plasmodium have?
heteroxenous life cycle involving a vertebrate host and an arthropod vector
What type of vector transmits Plasmodium?
anopheline mosquitoes
Describe the generalized life cycle of plasmodium
parasite is injectedby mosquito undergoes a round of merogony in the liver followed by multiple rounds of merogony in the erythrocytes. Gametogony begins in erythrocytes of the host and is completed within the mosquito where sporogony takes place.
What is the prepatent period for falciparum?
6-9 days
What is the prepatent period for vivax?
8-12 days
What is the prepatent period for ovale?
10-14
What is the prepatent period for malariae?
15-18
What is the incubation period for falciparum?
7-14
What is the incubation period for vivax?
12-17
What is the incubation period for ovale?
16-18
What is the incubation period for malariae?
18-40
What indicates the prepatent period in Plasmodium?
time between sporozoite inoculation and appearance in the blood
What is meant by the incubation period for Plasmodium?
period btw inoculation of sporozoites and onset of symptoms
Which Plasmodium spp can enter a hypnozoite?
Ovale and vivax
What does recrudescence mean?
parasitemia drops below detectable levels then resurges
How long after initial infection can there be a ovale relapse?
less than one year
How long after initial infection can there be a vivax relapse?
several years
What is the by product of hemoglobin?
hemozon, malaria pigment
Which stage of falciparum adhere to endothelium?
schizont and trophozoite
What is an alternative to schizongony in Plasmodium?
gametocyte production
Where does gametogenesis (formation of micro- macro gametes) happen?
in the mosquito
What induces exflagellation in Plasmodium?
exposure to air
decrease in temp (2-3C)
increase to pH above 8
Xanthurenic Acid (mosquito metabolite)
What is the average parasitemia for vivax?
20 000
What is the ave parasitemia for ovale?
9000
what is the ave parasitemia for malariae?
6000
what is the ave parasitemia for falciparum?
50 000-500 000
What is the maximum parasitemia for Pv?
50 000
What is the maximum parasitemia for Po?
30 000
What is the maximum parasitemia for Pm?
20 000
What is the maximum parasitemia for Pf?
2 500 000
which plasmodium can have renal complications?
malariae
what is the advantage for Pf in sequestration?
avoidance of spleen
what are the molecular mechanisms for cytoadherance in Pf?
knobs -expressed in schizont and trophozoite stages. PfEMP1 is implicated parasite protein
Stable malaria
endemic. measurable incidence of transmission
Unstable malaria
epidemic. increase in malaria in low endemnicity areas. outbreaks in areas without malaria or among non immune persons
Premunition
refers to an immunity that is contingent upon the pathogen being present
What does duffy negative protect from
Plasmodium vivax
How does ovalcytosis protect from malaria?
in SE Asia, mutation in erythrocyte membrane causes it to become rigid and does not allow parasite in
How do sickle cell, thalassemia and G6PD protect from malaria?
oxidative stress causes the erythrocyte to burst before merocytes are mature
Which drug combo is called the radical cure?
chloroquine and primaquine
What are the 3 invasive stages in Plasmodium?
sporozoites, merozoites and ookinete
does cryptosporidium have an intracellular stage?
no, it creates a host membrane by fusing microvilli
What is TRAP?
thrombospondin relted anonymous protein. micronemal protein implicated in adhesion of apicomplexa parasites.
what are the intestinal coccidia?
cryptosporidium, cyclospora, isospora
what are the tissue coccidia?
toxoplasma and sarcocytis
What are the 2 spp of crytposporidum that infect humans?
C parvum: can infect cattle and other mammals
C hominis: infects only humans
what is the extracytoplasmic location?
cryptosporidium. microvilli extend and enclose zoite. creates adhesive xone, feeder organelle
what is cryptosporidum more closely related to?
gregarines
What is the pathogenesis of cryptosporidian diarrhea?
enterocytes killed/damaged (decrease Na absorption); crypt cell hyperplasia (increased Cl secretion); lamina propia inflammation
How long does it take for the isospora belli oocyst to sporulate?
<24 hrs
What is the pathology of Isospora belli?
villous blunting and crypt cell hyperplasia
What was cyclospora cayetanensis originally called
cyano-bacteria like body or big cryptosporidium
How is cyclospora cayetanensis often transmitted?
food borne (imported fruit)
how many sporocysts do you cryptosporidium, cyclospora and isospora have?
crypto: non (4 sporozoites)
cyclo: 2 (2 sporozoites each)
iso: 2 (4 sporozoites each)
which coccidia exhibit soil transmission?
Cyclospora cayetanensis
Isospora belli
what is the estimate for Toxoplasma gondii infection worldwide?
~1/3 world’s population infected
What is the definitive host for Toxoplasma gondii
cats
What is endodyogeny?
type of cell division in the toxoplasma life cycle in which two daughter cells form within the mother. These are tachyzoites
What kind of zoites are in the tissue cyst of toxo?
bradyzoites
how long after initial infection do bradyzoites appear in toxo?
10 days
How many bradyzoites are in cyst?
1000-2000
describe the tachyzoites stage in toxo
acute infection stage
rapid replication
reticuloendothelium system
is followed by bradyzoite stage
describe the bradyzoite stage in toxo
slow replication
muscle CNS
encapsulated (chilin wall)
highly infectious
What immune response is implicted in the change from tachyzoite (acute) to bradyzoite (chronic) stage?
strong Th1 response
At what stage can congenital transmission of toxo occur?
only the acute stage
Congenital Toxoplasmosis
when is it most serious, when is it most common
serious if infection occurs early, most infection happen late in preg
Ocular Toxoplasmosis
rarely from primary infection. 20% congenital exhibit at birth, 82% by adolescense
what fraction of mothers who get toxo during preg pass this on to fetus
1/3
What happens to IgM levels in preg with toxo?
IgM rises the first 8 months following infection and persists for 18 months
What happens to IgG levels in preg with toxo?
IgG first appears 1-2 weeks after infection, peaks at 6-8 wks and last for lifetime
Using IgM and IgG, what are indications of acute toxo infection?
high IgM and rising total antibody titers along with sympoms
Using IgM and IgG, what are indications of Chronic toxo infection?
low or no IgM and stable IgG levers
What are the rapidly replicating parasites in Sarcocycstis called?
metrozoites
What are the slowly replicating parasites in Sarcocycstis called?
sarcocysts
Which one is a tick borne parasite?
babesia
What are the babesia spp infective to humans?
B. microti (US)
B. divergens (europe)
In which parasite is the tetrad seen?
babesia, this is called the Maltese cross
Which one has Strahlenkoerper (ray bodies)?
babesia
In which parasite does lack of spleen make infection dangerous?
Babesia
What are the piroplasms
babesia
What does Naegleria fowleri
cause?
primary amebic meningoencephalitis (PAM)
what does Acanthamoeba spp.
cause?
granulomatous amebic encephalitis (GAE)
granulomatous skin and lung lesions (primarily immunocompromised)
amebic keratitis
What does Balamuthia mandrillaris
cause?
GAE + granulomatous skin and lung lesions (primarily healthy)
Where is Naegleria fowleri found?
fresh water lakes and ponds
What are the apical organelles in apicomplexa called?
polar ring, micronemes, rhoptries
What are the induction factors for Gametocytogenesis?
not known, but drug treatment increases numbers, so does immune response
Where does Gametocytogenesis happen?
in human host
Where does Gametogenesis occur?
mosquito gut
What factors are involved in the Gametogenesis of plasmodium?
decrease in temp (2-3 C), decrease in dissolved CO2, increase in pH (8-8.3), MEF (xanthurenic acid)
IN mosquito, how many days from gametes to sporozoites?
9-21 days
What are the invasive stages of Plasmodium and what do they invade?
merozoites (erythrocytes)
Sporozoites (salivary glands, hepatocytes)
ookinete (epithelium [mosquito])
What % of worlds pop lives in endemic malaria zone?
40%
How many deaths attributed to malaria per year?
1.5-2.7 mil
what are the Prodromal Symptoms of malaria?
flu-like symptoms. end of incubation period, 2-3 days before 1st paroxysm
Cold stage of plasmodium
shivering, cold feeling, last 15-60 min
Hot stage of plasmodium
intense heat, throbbing headache, dry burning skin. last 2-6 hours
Sweating stage of plasmodium
declining temp, profuse sweating, lasts 2-4 hours.
sleep follows
does falciparum exhibit paroxysms?
not always, can be febrile entire time
quartan malaria
febrile paroxysms occur every 72 hours, or every fourth day counting the day of occurrence as the first day of each cycle; due to Plasmodium malariae.
tertian malaria
vivax malaria in which the febrile paroxysms occur every 42 to 47 hours, or every third day counting the day of occurrence as the first day of the cycle.
TNF-α in malaria
P. vivax: correlation btw fever & serum TNF-α levels. antigens or toxins are released when the infected erythrocyte ruptures and lead to the production of TNF-α and the febrile attacks.
if someone gets vivax or ovale thru blood transfusion, can there be relapses?
no, because hypnozoites are produced in the liver stage
how many merozoites in falciparum?
up to 36
Why is parasitemia much higher in falciparum?
will invade all types of erythrocytes, up to 36 mreozoites, evades immune response in spleen via sequestration
What type of cells do Pv/Po prefer?
reticulocytes (young RBC)
What type of cells do Pm prefer?
senescent RBC (older)
What is the molecular mechanism of knobs and cytoadherence in Pf?
PfEMP1 crosses the erythrocyte membrane and is exposed on the surface
What may be the 5th human spp of malaria?
P. knowlesi (malaysia) A. latens could be vector
Hypoendemic
areas with low transmission (P=<10%)
Mesoendemic
Usually small rural communities with varying intensity of malaria.
P=11-50%
hyperendemic
areas with intense. but seasonal, transmission of malaria
P=51-75%
holoendemic
areas with high degree of year long malaria transmission
P>75%
malaia vaccine that targets sporozoite
anti-infection, prevent liver stage
malaria vaccine that targets merozoite
anti-parasite, decrease efficiency of malaria parasite
malaria vaccine that targets infected erythrocytes
increase clearance of infected erythrocytes
malaria vaccine that targets the sexual stages
anti-transmission, eliminates gametes or prevent infection of mosquitos
What do you do if malaria blood smear is negative?
repeat every 12 hours for 48 hours
How is parasitemia calculated?
% of infected erythrocytes