Protozoa II

Question 1

Give the Sketchy rundown on Trypanosoma cruzi.

Answer 1

• Transmitted by the reduviid bug, which bites people and then defecates on the wound. People then scratch the wound and rub it in.
• Causes Chagas disease (CHe’s GAS)
• Causes megacolon (large gas line with haustra), dilated cardiomyopathy (saggy heart bag on motorcycle), and achalasia (snake with large throat)

Question 2

Sketchy forgot to mention that Trypanosoma cruzi is _____________.

Answer 2

extracellular and intracellular (recall the mole burrowing up from the ground)

Question 3

Chagas’ disease is becoming more common because ________________.

Answer 3

the parasite that causes it has spread to dogs

Question 4

What famous person died of Chagas’ disease?

Answer 4

Charles Darwin

Question 5

There are three kinds of Leishmaniasis: _________________.

Answer 5

1) Cutaneous
2) Mucocutaneous
3) Visceral

Question 6

Leishmania can be transmitted by _______________.

Answer 6

insects (sandflies) or direct contact of cutaneous lesions

Question 7

Which protozoa lives inside macrophages?

Answer 7

Leishmania (like the goats in the desert cages)

Question 8

Visceral Leishmaniasis presents with ___________________.

Answer 8

hepatosplenomegaly (cow with liver and spleen spots), fever (guy sweating), and pancytopenia (empty pan

Question 9

Public health experts try to prevent African sleeping sickness by limiting fly bites. What time of day does the Tse tse fly bite?

Answer 9

Daytime

Question 10

Advanced _______________ can lead to severe wasting and skin irritation from itching.

Answer 10

Trypanosomiasis

Question 11

Because of its antigenic variation, T. brucei presents with ______________.

Answer 11

undulating waves of parasitemia with varying fevers

Question 12

Give some numbers for the incidence of malaria per year.

Answer 12

• 400 million infections per year

* 0.5 million deaths

Question 13

What is the incubation period of malaria?

Answer 13

Up to two weeks

Question 14

The febrile cycle of malaria coordinates with ________________.

Answer 14

how long it takes for the RBCs to lyse

Question 15

Mosquitoes transmit the ____________ form of malaria.

Answer 15

sporozoite

Question 16

What three stages does malaria go through within RBCs?

Answer 16

Trophozoite, schizont, gametocyte

Question 17

Describe the most common way by which Plasmodium falciparum causes mortality.

Answer 17

P. falciparum infects RBCs and makes them express a membrane protein that increases their adherence. This can lead to stroke.

Question 18

How is malaria diagnosed?

Answer 18

• Patient symptoms: fever, chills, headache, myalgia
• Travel to endemic area
• Blood smear looking for microbes

Question 19

Why is the prophylactic treatment for malaria controversial?

Answer 19

Resistance rapidly develops (which has already happened with chloroquine)

Question 20

How do rodents and birds contract Toxoplasmosis?

Answer 20

From eating plant material with cysts on it.

Question 21

True or false: immunocompromised people only develop symptomatic Toxoplasmosis from acute infection.

Answer 21

False. It can reactivate.

Question 22

Toxoplasma infection during the third trimester leads to high chance of infection of the fetus, but _______________.

Answer 22

symptoms will be more mild

Question 23

Describe the differences in where T. cruzi and T. brucei replicate.

Answer 23

T. cruzi replicates inside the gut. T. brucei replicates in the blood.

Question 24

Describe the lifecycle of T. cruzi.

Answer 24

• Infection with amastigotes from Reduviid bug
• Amastigotes divide by fission
• Trypomastigotes enter blood and other tissues
• Reduviid bug ingests more from infected animal
• Trypomastigotes replicate in bug

Question 25

The mortality of Chagas’ disease is _____%.

Answer 25

10

Question 26

How is chronic Chagas detected?

Answer 26

Often tissue biopsies are needed because the trypomastigote form of T. cruzi will not present in many chronic Chagas cases.

Question 27

The amastigotes of Leishmania transform into promastigotes in ______________.

Answer 27

the midgut of sandflies

Question 28

Describe the life cycle of Trypanosoma brucei.

Answer 28

T. brucei does not form amastigote or promastigote forms, so it is always a trypomastigote. When it divides it does so by binary fission.

Question 29

All forms of trypanosomiasis present with _____________ at the site of entry.

Answer 29

chancres

Question 30

The merozoites of Plasmodium mature inside RBCs to trophozoites (which look like rings) and then ____________.

Answer 30

the trophozoites evolve back into merozoites to rupture the RBCs and infect more RBCs

Question 31

True or false: P. falciparum and P. malariae do not infect the liver.

Answer 31

False. All Plasmodia infect the liver initially, but only P. vivax and P. ovale can create dormant hypnozoites in the liver.

Question 32

What form of Babesia makes the Maltese cross?

Answer 32

Merozoite (dividing in RBCs)

Question 33

The Ixodes tick introduces the ____________ form of Babesia into humans.

Answer 33

sporozoite

Question 34

How many Toxoplasma infections occur in the U.S. each year?

Answer 34

• 4,000 symptomatic congenital cases

* 4,800 adults losing vision due to chorioretinitis

Question 35

Those negative for the Duffy blood group cannot be infected with ___________.

Answer 35

P. vivax