parisitology review Flashcards
what are parasites?
eukaryotic pathogens that lack a cell wall (unlike fungi)
what are single cell parasites?
protozoa
what are multi-cellular parasites?
helminths and arthropods
parasites are separated into what 2 groups?
GI and blood/tissue depending on the usual site of the pathology
what is a definitive host?
the site of sexual reproduction of a parasite
what is an intermediate host?
the site of non-sexual dvpmt of a parasite (ie it matures, but doesn’t reproduce)
what is a dead end host?
a host that doesn’t transmit the parasite– that said, the host can become sick and die from the parasite
can vectors be hosts?
yes
the human is a definitive host for which 3 parasites?
- Filaria
- GI Helminths
- Taenia Solium
Humans are intermediate hosts for which parasites?
Plasmodium species
Humans are a dead end host for which parasites
Echinococcus granulosus
Taenia Solium
which parasite can use the human as a definitive host or a dead end host depending on the route of ifxn?
Taenia Solium
what is a vector?
an arthropod that transmits an ifxn– it can double as a host (ie it is a definitive host for malaria)
anopheles mosquito is the vector for which parasite?
plasmodium species
plasmodium species are transmitted by what vector?
anopheles mosquito
triatomine bug is teh vector for which parasite?
trypanosoma cruzi
trypanosoma cruzi is transmitted by which vector?
Triatomine bug
Tsetse fly is the vector for which parasite?
Trypanosoma brucei
Trypanosoma brucei is transmitted by which vector?
Tsetse fly
the sandfly transmits which parasite?
Leishmania species
Leishmania species are transmitted by which vector?
the sandfly
Simulium blackflies transmit which parasite?
onchocerca volvulus
onchocerca volvulus are transmitted by which vector?
simulium blackflies
what is a reservoir?
a non-human site where a pathogen survives
reservoir control is critical for…
ifxn control
4 mechanisms of damage by parasites
1) mechanism impairment
2) kills cells (invasion or cytolysis)
3. competition for nutrients
4) inflammation —> tissue damage
which 3 parasites damage their hosts via mechanical damage? where is this damage?
- Echinococcus granulosus - liver
- Ascaris lumbricoides - intestine
- Plasmodium falciparum- capillaries, PCV
where does echniococcus granulosus cause mechanical damage, and how does it do it?
in the liver via the formation of hepatic cysts
where does ascaris lumbricoides cause mechanical damage and how does it do it?
intestine, via obstruction
where does plasmodium falciparum cause mechanical damage and how does it do it?
in the capillaries and PCV, via obstruction (by binding RBCs to the endothelium) which causes hypoxia (esp in the brain)
which 3 parasites kill host cells? and where do they do this?
- Entamoeba histolytica- liver
- trypanosoma cruzi - heart
- Leishmania species - macrophages (spleen/liver)
Where does Entamoeba histolytica kill host cells, and what is the resultant damage?
liver —> necrosis that’s like anchovy paste
Where does Trypanosoma cruzi kill host cells, and what is the resultant damage?
heart —> myocarditis, enlargement
Where do Leishmania species kill host cells, and what is the resultant damage?
macrophages (liver/spleen) —> splenomegaly and hepatic failure
what are two parasites that compete for nutrients, and where are they located?
- Hookworms in the GI tract
2. Diphyllobothrium latum in the GI tract
where do Hookworms compete for nutrients and what damage does it cause the host?
in the GI tract– the worm sucks out blood leading to blood loss —> anemia
where do Diphyllobothrium latum (tapeworms) compete for nutrients and what damage does it cause the host?
In the GI tract. They adsorb vitamin B12 through their skin —-> anemia
2 parasites that cause damage by inflammation, and where the inflammation is located
- Onchocerca volulus - in the eye
2. Trypasnosoma cruzi - nerves
Where does Onchocerca volvulus cause inflammation, and what damage results?
in the eye —> blindness
where does Trypanosoma cruzi cause inflammation and what damage results?
in the nerves —> megasophagus, megacolon, heart (arrhythmia)
how are protozoa classified?
by motility
3 groups of motility by which protozoa are classified
1) flagella – can swim
2) pseudopods
3) often non-motile
3 groups of protozoa and their motility
- flagellates- flagella
- amebas- pseudopods
- apicomplexans (coccida) - often non-motile
flagellates
motility:
other features (2):
flagellates
motility: flagella
other features (2): asexual, trophozoite and cyst
amebas
motility:
other features (1):
amebas motility: pseudopods other features (1): asexual
Apicomplexans (Coccidia)
motility:
other features (3):
Apicomplexans (Coccidia)
motility: often non-motile
other features (3): asexual and sexual. apical complex organelle, intracellular replication
which Apicomplexan protozoan parasites are GI parasites?
none
which Apicomplexan protozoan parasites are Blood/Tissue parasites? (2)
- Plasmodium species
2. Toxoplasma gondii
which flagellate protozoan parasites are GI parasites? (1)
Giardia lamblia
which flagellate protozoan parasites are blood/tissue parasites? (2)
- Trypanosoma species
2. Leishmania species
Which ameba protozoan parasites are GI parasites? (1)
- Entamoeba histolytica (but it also spreads from there)
Which ameba protozoan parasites are blood/tissue parasites?
none– although entamoeba histolytica does spread from the GI to other areas
Giardia Lamblia spreads to the host from? via? in what form?
animals and people via fecal oral transmission in cyst form
Giardia Lamblia is what type of protozoa?
flagellate
pathogenesis of the flagellate Giardia Lamblia? (4)
- cyst consumed via fecal oral route from people or animals
- replication in GI tract
- Giardia adheres to the mucosa of the small intestine
- maladsorption
symptoms of giardia?
- asymptomatic
2. symptmatic: diarrhea, flatus (gas), cramping
entamoeba histolytica is what type of protazoa?
ameba
how is entamoeba histolytica spread?
fecal-oral consumption of cysts- spread from person to person
pathogenesis of entamoeba histolytica
- fecal-oral transmission of cysts
- replication in the GI tract
- adheres to colonic mucosa
- It kills cells with contact
- it invades and spreads locally
- causes colonic ulceration and hepatic abscesses (anchovy paste)
Plasmodium species and toxoplasma gondii are what type of protozoa and where do they attack?
they’re apicomplexans and they attack blood/tissue
how do you acquire Toxoplasma Gondii? (3)
- Primary route: ingestion of oocysts from rare meat
- ingestion of oocysts from cat feces
- vertical transmission (newly infected mother)
How does Adult (aka post natal) toxoplasmosis gondii spread in the the body?
through the blood
adult toxoplasmosis gondii spreads in the blood, encysts and…
is generally controlled by the immune response
manifestations of Primary infection with toxoplasmosis gondii
asymptomatic or mononucleosis like
what things have mononucleosis like symptoms?
EBV- mononucleosis
CMV- non-heterophile mono
Toxoplasmosis gondii
Acute HIV ifxn
when immunocompromised people with T cell defects (like HIV pts) get toxoplasmosis gondii, what happens?
reactivation/proliferation of toxoplasmosis —> severe ifxn with encephalitis
What is congenital toxoplasmosis?
when toxoplasmosis gondii spreads in the blood of the mother, crosses the placenta and infects the fetus
why are pregnant women instructed to avoid raw meats and cats?
to avoid Toxoplasmosis gondii
3 different outcomes of congenital toxoplasmosis gondii
- stillbirth/spontaneous abortion
- illness at birth with jaundice and hepatosplenamegaly
- unapparent ifxn at birth
babies with congenital toxoplasmosis who are ill at birth have…
jaundice and hepatosplenomegaly —> chorioretinitis and CNS abnormalities (calcifications, hydrocephalus and microcephaly)
babies with congenital toxoplasmosis that is unapparent at birth will still get (3)
- chorioretinitis
2, hearing loss - developmental delay
plasmodium species are transmitted by which vector?
anopheles mosquitos
3 modes of transmission of plasmodium species?
- anopheles mosquito
- vertical transmission
- transfusion
why do they ask you about travel when you’re giving blood
to screen you for malaria
pathogenesis of plasmodium species
- transmitted via anopheles mosquito, vertical transmission or blood tranfusion
- travels in the blood to the liver
- either becomes latent hynozoites (dormant protozoa) (P. vivax or P ovale) or go into RBCs
- Once in the RBCs they replicate and dvp gametocytes
- the gametocytes are picked up by mosquitoes where they sexually reproduce
- the mosquito bites a new host…
3 different malaria species. Which is the most severe?
Plasmodium ovale
plasmodium vivax
plasmodium falciparum – most severe!!
manifestations of all 3 malaria species (vivax, ovale and falciparum)
- constitutional symp: fever, headache nausea
- fever can become cyclical (every 2-3 days)
- anemia and splenomegaly is variable
severe manifestations of malaria caused by plasmodium falciparum
cerebral malaria: encephalopathy and coma
severe anemia, hypoglycemia, acidosis (bc of damage to kidneys/lysis of RBCs) and renal impairment (bc of damage to kidneys/lysis of RBCs)