Parasites

Question 1

In a protozoa what is the name of the replicating form and the inactive form?

Answer 1

Replicating form is trophozoite

Inactive is cyst

Question 2

What are the four types of protozoa? How are they classified?

Answer 2

Amoebas, Flagellates, Ciliates, Sporozoans

Classified by locomotion

Question 3

What parasites covered in class are amoebas?

Answer 3

E. histolytica

Question 4

What parasites covered in class are flagellates?

Answer 4

Giardia, Trichomonas vaginalis, T. cruzi, Leishmania

Question 5

What parasites covered in class are sporozoans?

Answer 5

Plasmodium

Question 6

How are protozoa and helminthes different?

Answer 6

Protozoa are single celled, microscopic, eukaryotes

Helminthes are multicellular, macroscopic and have organ systems and reproductive systems

Question 7

What are the classes of helminthes? How are they classified?

Answer 7

Cestodes (tapeworms), Nematodes (roundworms),

Classified according to structure

Question 8

What kind of genetic traits give someone protection from P. falciparum?

Answer 8

HbS and HbC (in heterozygous and homozygous state)

Question 9

What kind of genetic trait gives some protection to P. vivex? What has this resulted in with the predominant form of malaria?

Answer 9

Lacking a Duffy RBC antigen is resistant to P. vivex infection
Shift to P. falciparum being the predominant form f malaria

Question 10

What is the vector for plasmodium? What cells are the first to be infected? What happens when these first cells to be infected burst? What cells are infected second?

Answer 10

Mosquito- injects sporozoites when bite

Infect hepatocytes first then burst and release merozoites into the bloodstream. Infect RBC second

Question 11

What is the malaria paraoxysm? How long does it typically last?

Answer 11

Cold stage, Hot stage, Sweating stage, followed by fatigue- typically lasts 6-10 hours but timing differs by species

Question 12

What makes P. falciparum more fatal than the other plasmodium?

Answer 12

Can infect RBC of all ages, leads to expression of PfEMP-1 on infected RBC which allows it to bind to endothelium causing blockage and ischemia

Question 13

During pregnancy what do RBC infected with P. falciparum bind to?

Answer 13

Chondroitin sulfate A (CSA) on the placenta

Question 14

What is the vector for leishmanias?

Answer 14

Sand fly

Question 15

What are the three different forms of leishmanias? How long after bite do they appear?

Answer 15

Cutaneous: skin sores, weeks afer bite
Visceral: internal organs, potentially life-threatening, months after bite
Mucosal: less common- can be from same species causing cutaneous

Question 16

What parasite causes American trypanosomaiasis?

Answer 16

T. cruzi

Question 17

What vector transmits T. cruzi? What is the mechanism?

Answer 17

Triatomine insects (aka kissing bugs)- get the parasite when mucus membrane, conjunctiva, or breaks in skin get infected with bug poop

Question 18

What are the symptoms of Chagas disease? What parasite causes Chagas?

Answer 18

Acute: fever/swelling around the site of inoculation- usually eye
Can develop heart problems leading to sudden death, or an enlarged esophagus and colon leading to problems eating; T. cruzi

Question 19

How are babesia transmitted to humans? Is it direct transmission?

Answer 19

Zoonotic disease- reservoir in one vertebrate that is then transferred to a invertebrate vector before infecting humans
Indirect transmission

Question 20

What is the vector for babesia? What cells are infected?

Answer 20

Ticks; RBC

Question 21

What are the symptoms of babesia?

Answer 21

Non-specific, flu-like; if symptomatic

Question 22

What is the most commonly diagnosed enteric parasite in the US?

Answer 22

Giardia

Question 23

How is giardia transmitted?

Answer 23

Direct ingestion of giardia cysts in contaminated water, person-to-person, or foodborne transmisison

Question 24

What the stages and symptoms following giardia infection?

Answer 24

Asymptomatic cyst infection, acute self-limited diarrhea, and chronic diarrhea, malabsorption and weightloss

Question 25

How is giardia diagnosed?

Answer 25

Express cysts in stool; detection of giardia antigen in stool

Question 26

What is the second most common parasitic infection in the US?

Answer 26

Cryptosporidium

Question 27

How is cryptosporidium transmitted? Where is it found?

Answer 27

Ingestion of oocysts- found in contaminated water

Question 28

Where do outbreaks of cryptosporidium arise? Why?

Answer 28

Swimming pools because resistant to chlorination and tied to fecal contamination

Question 29

What are the symptoms associated with cryptosporidium? When do they begin?

Answer 29

``` Watery diarrhea (avg 7 days after infection) Diarrhea lasts for 1-2 weeks and then if healthy gets cleared ```

Question 30

How is E. histolytica transmitted? What is the disease is causes?

Answer 30

Ingestion of cysts from contaminated water (contaminated with human fecal matter) Causes amebiasis

Question 31

How is E. histolytica severe/life-threatening?

Answer 31

Can cause liver abscess- manifesting either acutely (with severe pain) or subacutely (with weight loss and abdominal pain)

Question 32

What is the most common manifestation of E.histolytica?

Answer 32

Diarrhea without dysentery (inflammation)

Question 33

How is Trichomonas vaginalis transmitted? Who is the natural host?

Answer 33

STD, humans are the natural host (direct transmission)

Question 34

When symptomatic, what symptoms do women infected with Trichomonas vaginalis express? What other infections have similar symptoms?

Answer 34

Vaginal discharge and irritation; discharge has an odor and there's edema/erythema; candidiasis and bacterial vaginosis have similar symptoms

Question 35

What is the most common helminth infection worldwide?

Answer 35

Ascariasis

Question 36

Where do ascariasis worms mate?

Answer 36

Lumen of the small intestine

Question 37

How is ascariasis transmitted? What is it's life cycle?

Answer 37

Eggs are ingested/inhaled and hatch in the small intestine, releasing larvae, larvae penetrate intestinal wall, travel to lungs, heart and then lungs, break into alveoli, coughed out and then swallowed, to return to the intestines where mature

Question 38

What are the symptoms of Ascariasis?

Answer 38

Most are asymptomatic; some people get pulmonary involvement, others can cause obstruction of bowel

Question 39

What are the other names for hookworm?

Answer 39

Ancylostoma dudodenale or Necator americanus

Question 40

In what areas do hookworm infections normally occur?

Answer 40

Areas where human feces are used as fertilizer

Question 41

How is hookworm transmitted? What is it's life cycle?

Answer 41

Eggs are passed in stool and into soil, under favorable conditions hatch releasing rhabditiform larvae,which mature in soil; on contact penetrate human skin and carried through blood vessels to heart and lungs, penetrate alveoli, coughed and swallowed, go to intestine for maturation

Question 42

What is another name for pin worm?

Answer 42

Enterobiasis or Enterobiasis vermicularis

Question 43

How is someone infected with pinworms?

Answer 43

Ingest pinworms either directly or indirectly

Question 44

What is the main cause of tapeworm infection in humans?

Answer 44

Eating undercooked or raw meat from animals with tapeworm

Question 45

What are the three most common tapeworms? Which animals do they come from?

Answer 45

Taenia saginata (beef), Taenia solium (pork), diphyllobothrium latum (fish)

Question 46

How do cows/pigs become infected with tapeworm?

Answer 46

Ingesting food that has been grown in areas that are contaminated with Taenia eggs from human feces

Question 47

Once in the cow/pig where do taenia eggs go?

Answer 47

The eggs hatch in the intestine and go to the muscle where they become cysticerci

Question 48

When do humans become infected with taenia?

Answer 48

Ingestion of raw/undercooked meat that contains infective cysticerci

Question 49

Where do taenia go once in the human?

Answer 49

Travel to intestine where mature into adult tapeworms and produce segments and eggs that pass in feces

Question 50

How can a human get cysticercosis?

Answer 50

Ingestion of T. solium; or when a person who has tapeworm infects themself

Question 51

What is cysticercosis?

Answer 51

Eggs that are ingested hatch in the intestine and then pass through the intestinal wall and go to striated muscle as well as brain, liver, and other tissue where develop cysticeri

Question 52

What is neurocysticerocosis?

Answer 52

Cysticeri (from tapeworm) localizes to the brain; serious

Question 53

What produces the largest tapeworms that can infect people?

Answer 53

Diphyllobothrium latum

Question 54

How are cryptococcosis and cryptosporidium different?

Answer 54

cryptococcosis is an opportunistic mycoses resulting from environmental yeasts; yeasts are inhaled and then lead to lung infection and either pneumonia/disseminated disease and meningitis if compromised cryptosporidium is ingested as an oocyst and leads to watery diarrhea; from ingesting contaminated water; usually if healthy cleared in 1-2 weeks