Epidemiology and Intro to Protozoa Flashcards
Name some common parasites with high mortality rates
Helminths: Ascaris lumbricoides, hookworms, filarial worms, schistosomes, Trichuris trichura
Malaria
Entamoeba histolytica
Why is the anti-malaria vaccine not super effective?
It really only induces an immune response comparable to that of the natural immunity developed after 1 malaria infection
“Schizonticides” are what kind of medication?
Attack malaria schizonts.
What is the Extrinsic Incubation Period and how does it relate to malaria control?
Time it takes for a parasite to develop fully in a host (transmission). This is important because if we can kill the transmission host before the parasite can develop, it will dramatically decrease transmission potential
What was the name of the doctor who did the first major epidemiological study? Where was this and how did he do his work?
John Snow.
In London, Cholera broke out and he recognized that most of the cases started around one specific water pump. He then assumed that maybe the poop in the water was causing the problem. People obviously didn’t agree.
Why was London such a disaster during the Cholera epidemic?
One private company hauled water to people, but also hauled waste away. THEY USED THE SAME TRUCKS. THEN DUMPED THE WASTE IN THE THAMES. WHERE THEY WOULD ALSO TAKE THE WATER OUT AGAIN
How did the earthquake in Haiti affect public health?
Water could accumulate in weird areas - so Dengue broke out.
Flooding occurred, so feces was swept up and people drank the water, resulting in diseases such as Cholera.
Name some protozoan-caused diseases
Malaria, sleeping sickness, beaver fever, dysentery
How is widespread desertification in Africa related to parasites?
More grazing animals are present because of control of Trypanosoma brucii
What is the “parasitologist’s dilemma”?
The idea that a parasitologist must choose which is more moral: saving humans that will destroy the environment, or simply studying parasites. Basically, who lives and who dies?
What are examples of Phytoflagellate protozoans?
Dinoflagellates, Euglena, Volvox
What are two parasitic examples of Zooflagellate protozoans?
Trypanosoma, Giardia (causes Beaver fever)
How do dinoflagellates affect public health?
Their toxins can accumulate in filter-feeding organisms. (neurotoxins)
Beaver fever is caused by _______. Describe this organism and how it infects humans
Giardia. It is a cyst-forming protozoan parasite that is passed through Beaver feces into water. It infects the duodenum and causes diarrhea
How do single celled parasites often protect themselves from the immune system?
Forming a cyst where they can reproduce freely without interference
What is symmetrogenic asexual reproduction?
Single celled organism divides bilaterally
Multiple fission is otherwise known as _____. How is it performed?
Schizogony. Nucleus divides several times within one cell, and then membranes are created between nuclei. The daughter cells then all break free of each other.
Distinguish between endodiogeny and endopolyogeny
Endodiogeny - 2 daughter cells
Endopolyogeny - more than 2 daughter cells
Are the amoebae a phylum?
No, they used to be but now we know they have different evolutionary origins. Basically it is considered a body plan.
Briefly describe the genus Entamoeba
Lack mitochondria and golgi bodies. Very few have a flagellated stage. Reproduce asexually. Parasitize intestinal tracts of animals. Have a vesicular nucleus
Why are amoebae important on a global health scale?
Amoebic dysentery is one of the most common diarrhoeal diseases. 3rd most common cause of parasitic death in the world.
What happens during amoebic dysentery?
Trophozoite (feeding) stage amoebas crawl around the intestine and invade mucosa where they consume host tissue and cause lesions
How do Entamoebae often infect humans?
OFten they attack the crypts in the submucosa of the intestine. They feed off of bacteria and carbohydrates produced by said bacteria
Which Entamoeba species is the only one that causes disease? Why are the others important?
Entamoeba histolytica.
Others are important because they are often confused with Entamoeba histolytica.
How can one identify an Entamoeba histolytica trophozoite?
Have a large nucleus with a “nucleosome”, which is concentrated chromosomes in the center.
At what point do Entamoeba histolytica trophozoites turn into cysts?
As the stool in the intestine becomes less watery (basically as it enters the colon)
What do Entamoeba histolytica cysts look like?
Thick cyst wall, smaller than trophozoites, have 4 nuclei.
What triggers ingested Entamoeba histolytica cysts to undergo “excystation”? Where do they go after that?
Ingested cysts undergo excystation (Stop being cysts) when they hit the small intestine. As they travel the small intestine, they either attach to the wall of the caecum and start eating, or they continue to pass with the feces and become cysts once more.
If Entamoeba histolytica parasites penetrate into the intestine, what happens?
Firstly, you can get a bacterial infection and subsequent tissue degeneration. The trophozoites can get into the blood vessels and start to migrate to places such as the lungs, liver, and brain (extra intestinal disease).
IF someone is infected with an amoeba it is referred to as ____
Amebiasis
What part of an Entamoeba histolytica infection causes diarrhea?
Necrosis of gut tissue can cause feces production to speed up significantly.
Distinguish between E. histolytica and Entamoeba coli
E. coli cyst is larger, has 4-8 nuclei
Why is Entamoeba histolytica sometimes considered an STI?
IT can be transferred through mouth-anal sexual contact
When an intestinal pathogen finds its way to another organ, what is it referred to as?
Extra-intestinal infection