Epidemiology and Intro to Protozoa

Question 1

Name some common parasites with high mortality rates

Answer 1

Helminths: Ascaris lumbricoides, hookworms, filarial worms, schistosomes, Trichuris trichura
Malaria
Entamoeba histolytica

Question 2

Why is the anti-malaria vaccine not super effective?

Answer 2

It really only induces an immune response comparable to that of the natural immunity developed after 1 malaria infection

Question 3

“Schizonticides” are what kind of medication?

Answer 3

Attack malaria schizonts.

Question 4

What is the Extrinsic Incubation Period and how does it relate to malaria control?

Answer 4

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

Question 5

What was the name of the doctor who did the first major epidemiological study? Where was this and how did he do his work?

Answer 5

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.

Question 6

Why was London such a disaster during the Cholera epidemic?

Answer 6

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

Question 7

How did the earthquake in Haiti affect public health?

Answer 7

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.

Question 8

Name some protozoan-caused diseases

Answer 8

Malaria, sleeping sickness, beaver fever, dysentery

Question 9

How is widespread desertification in Africa related to parasites?

Answer 9

More grazing animals are present because of control of Trypanosoma brucii

Question 10

What is the “parasitologist’s dilemma”?

Answer 10

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?

Question 11

What are examples of Phytoflagellate protozoans?

Answer 11

Dinoflagellates, Euglena, Volvox

Question 12

What are two parasitic examples of Zooflagellate protozoans?

Answer 12

Trypanosoma, Giardia (causes Beaver fever)

Question 13

How do dinoflagellates affect public health?

Answer 13

Their toxins can accumulate in filter-feeding organisms. (neurotoxins)

Question 14

Beaver fever is caused by _______. Describe this organism and how it infects humans

Answer 14

Giardia. It is a cyst-forming protozoan parasite that is passed through Beaver feces into water. It infects the duodenum and causes diarrhea

Question 15

How do single celled parasites often protect themselves from the immune system?

Answer 15

Forming a cyst where they can reproduce freely without interference

Question 16

What is symmetrogenic asexual reproduction?

Answer 16

Single celled organism divides bilaterally

Question 17

Multiple fission is otherwise known as _____. How is it performed?

Answer 17

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.

Question 18

Distinguish between endodiogeny and endopolyogeny

Answer 18

Endodiogeny - 2 daughter cells

Endopolyogeny - more than 2 daughter cells

Question 19

Are the amoebae a phylum?

Answer 19

No, they used to be but now we know they have different evolutionary origins. Basically it is considered a body plan.

Question 20

Briefly describe the genus Entamoeba

Answer 20

Lack mitochondria and golgi bodies. Very few have a flagellated stage. Reproduce asexually. Parasitize intestinal tracts of animals. Have a vesicular nucleus

Question 21

Why are amoebae important on a global health scale?

Answer 21

Amoebic dysentery is one of the most common diarrhoeal diseases. 3rd most common cause of parasitic death in the world.

Question 22

What happens during amoebic dysentery?

Answer 22

Trophozoite (feeding) stage amoebas crawl around the intestine and invade mucosa where they consume host tissue and cause lesions

Question 23

How do Entamoebae often infect humans?

Answer 23

OFten they attack the crypts in the submucosa of the intestine. They feed off of bacteria and carbohydrates produced by said bacteria

Question 24

Which Entamoeba species is the only one that causes disease? Why are the others important?

Answer 24

Entamoeba histolytica.

Others are important because they are often confused with Entamoeba histolytica.

Question 25

How can one identify an Entamoeba histolytica trophozoite?

Answer 25

Have a large nucleus with a “nucleosome”, which is concentrated chromosomes in the center.

Question 26

At what point do Entamoeba histolytica trophozoites turn into cysts?

Answer 26

As the stool in the intestine becomes less watery (basically as it enters the colon)

Question 27

What do Entamoeba histolytica cysts look like?

Answer 27

Thick cyst wall, smaller than trophozoites, have 4 nuclei.

Question 28

What triggers ingested Entamoeba histolytica cysts to undergo “excystation”? Where do they go after that?

Answer 28

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.

Question 29

If Entamoeba histolytica parasites penetrate into the intestine, what happens?

Answer 29

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).

Question 30

IF someone is infected with an amoeba it is referred to as ____

Answer 30

Amebiasis

Question 31

What part of an Entamoeba histolytica infection causes diarrhea?

Answer 31

Necrosis of gut tissue can cause feces production to speed up significantly.

Question 32

Distinguish between E. histolytica and Entamoeba coli

Answer 32

E. coli cyst is larger, has 4-8 nuclei

Question 33

Why is Entamoeba histolytica sometimes considered an STI?

Answer 33

IT can be transferred through mouth-anal sexual contact

Question 34

When an intestinal pathogen finds its way to another organ, what is it referred to as?

Answer 34

Extra-intestinal infection