Parasites Flashcards
What are the two categories of parasites?
Protozoa & Helminths.
Is absolute immunity to parasites common?
No, parasitic disease confers a low level of immunity compared to bacterial or viral infection.
What is a mechanical vector?
An invertebrate in which the parasite does not develop or reproduce as it is being moved.
What is a biological vector?
An invertebrate in which the parasite is able to develop and reproduce.
What is an intermediate host?
A host which supports the asexual stage of the parasitic life cycle.
What is a definitive host?
A host which supports the sexual stage of the parasitic life cycle.
What does Giardia lamblia cause? How is it transmitted?
Beaver fever or travellers diarrhea. Giardia causes malabsorption syndrome and diarrhea. Fat deposits in the feces and villus shortening in the intestines is also seen.
Giardia is spread by a fecal-oral root with parasitic maturation in the host small intestine.
What does Cryptosporidium cause? How is it transmitted?
Watery diarrhea. Can be found anywhere in the GIT from anus to mouth but prefers the villi and crypts of the small intestine. Transmission is oral-fecal via cysts.
What is the difference in cryptosporidium infection between immunocompetent and immunocompromised hosts?
Watery diarrhea is usually mild and lasts only a few days in immunocompetent hosts. In immunocompromised hosts it can be severe and last months to years.
What can Amoebiasis cause and how is it transmitted?
If in the intestines it will cause diarrhea and lesions. If it is found extracellularly it will cause abscesses. Transmission is fecal-oral via cysts and is aided by asymptomatic carriers including flies and cockroaches.
What is the difference between E. histolytic and E. dispar?
Both are Amoebiasis. However, E. histolytic is pathogenic while E. dispar is not.
What does Ascaris Lumbricoides cause? How is it transmitted?
Can cause pulmonary issues from worms hatching in your lungs after travelling through the blood. Adult worm is often asymptomatic with the exception of a nutritional deficit in the host. Transmitted by fecal-oral route; the host swallows eggs which hatch into worms in the gut.
What do cestodes cause? What are they? How are they transmitted?
Cestodes are tapeworms. They can cause many problems including host nutrient deficiency and cysticercosis (Taenia Solium). They are transmitted through undercooked beef (Taenia Saginata) or pork (Taenia Solium). They live in the small intestine.
What is an important pathological difference between Taenia Solium and Taenia Saginata? (pork and Beef tapeworms)
If we ingest the eggs of either species we will have an adult tapeworm watch in us. The difference between the two is that the eggs of Taenia Solium (pork) tape worms are also contagious in us. So, a human cannot get a Taenia Saginata tape worm from a human but humans can get Taenia Solium (pork) tape worms from fecal-oral transmission from other humans (transmission of eggs).
What disease does the protozoan Plasmodium give you?
Malaria
Name the two significant species of Plasmodium for malaria.
Vivax & Falciparun
If you do not know what species or parasite is causing malaria in your patient which one should you treat for? Why?
P. falciparum. It results in severe illness and has the highest mortality of all the Plasmodium. It can infect all stages of RBCs and can cause them to stick to endothelial cells. This leads to obstruction of small vessels, organ damage, and possible anemia. Can be lethal.
P. Vivax has a hypnozoite liver phase. What does this mean?
P. Vivax infects young RBCs. Because it has this hypnozoite liver stage relapses are possible after weeks to months. P. falciparum does not have this stage.
What should you treat uncomplicated malaria (caused by unknown species) with?
Malarone
What is the common name of Enterobius Vermicularis? How does it differ from Ascaris?
Pin worm. Its adult form is smaller.
Why is it important for pregnant women to avoid infection with toxoplasma gondii?
Infection is much more severe in pregnant women and can be transmitted vertically to the fetus resulting in toxoplasmosis.
Why are cats evil?
We can catch a lot of things from them, including toxoplasma gondii.
How do humans acquire a schistosomes (flatworms) infection?
Skin contacted with contaminated water.
What are “nits”?
Lice eggs.
What are the usual hosts of Echinococcus Granulosus (Dog tapeworm or Hydatid tapeworm) and how is it similar to an infection with taenia solium?
Sheep, dogs, and arctic animals.
Both involve ingestion of an egg and are cestodes.
What is “night soil”?
The term used for human feces being used as fertilizer. Can cause the spread of parasites including Ascaris lumbricoides.
What parasites life cycle includes a cyst with a germinal cell line?
Echinococcus Granulosus.
The cyst will grow 1-4cm per year.
Which parasite has a conjugal groove on the male in which the female lives for life?
Schistosomes
Name three ectoparasites.
Head lice, Public lice, and Scabies.
