Block E Lecture 3: Protozoan Cell Biology and Disease Part B: Blood and Tissue Parasitic Infections

Question 1

What is naegleria fowleri?

Answer 1

A free-living amoeba found in soil and water
(Slide 23)

Question 2

How do infections with naegleria fowleri usually result?

Answer 2

From swimming in warm, soil-contaminated water sources (such as hot springs or lakes)
(Slide 23)

Question 3

How does naegleria fowleri cause extensive haemorrhaging and brain damage?

Answer 3

It enters the human body through the nose and burrows directly into the brain
(Slide 23)

Question 4

How are naegleria fowleri infections diagnosed?

Answer 4

From cerebrospinal fluid
(Slide 23)

Question 5

How are naegleria fowleri and Acanthamoeba infections treated?

Answer 5

Drug treatment, but it’s only effective if infections are identified early. Azoles, amphotericin B, rifampicin and miltefosine can be used
(Slides 23 and 24)

Question 6

What are Acanthamoeba?

Answer 6

A eukaryotic genus containing many species found in fest and salt water throughout the world
(Slide 24)

Question 7

What are 3 ways Acanthamoeba eukaryotes can cause infection?

Answer 7

Through contaminated contact lenses / contact lens cases
Through broken skin causing cutaneous disease and even spread to the brain through blood
Can infect the mucosa and then the brain like naegleria
(Slide 24)

Question 8

What are 3 examples of diseases which Acanthamoeba eukaryotes can cause?

Answer 8

Acanthamoeba keratitis (AK) - an eye disease
Cutaneous Amoebiasis - a skin disease
Granulomatous Amoebic Encephalitis (GAE)
(Slide 24)

Question 9

How are Acanthamoeba infections diagnosed?

Answer 9

By microscopic examination of tissue samples
(Slide 24)

Question 10

What is Acanthamoeba keratitis (AK)?

Answer 10

A progressive sight-threatening corneal disease
(Slide 26)

Question 11

What is the leading risk factor of acanthamoeba keratitis?

Answer 11

Contact lens wear
(Slide 26)

Question 12

What is often required in acanthamoeba keratitis if treatment fails?

Answer 12

A corneal transplant
(Slide 26)

Question 13

What often happens after someone gets a corneal transplant after acanthamoeba keratitis?

Answer 13

Reactivation of the disease
(Slide 26)

Question 14

What parasite causes malaria?

Answer 14

Plasmodium
(Slide 27)

Question 15

What phylum is the plasmodium parasite a part of?

Answer 15

The Apicomplexa phylum
(Slide 27)

Question 16

Where is the plasmodium parasite generally found?

Answer 16

In tropical and subtropical regions
(Slide 27)

Question 17

What occurs in the human stage of the life cycle of plasmodium?

Answer 17

When a infected female mosquito feeds on human blood, it transfers sporozoites into the human host. These infect liver cells and then mature into schizonts which then rupture and release merozoites which then invade and undergo asexual multiplication in red blood cells. This involves ring stage trophozoites maturing in schizonts which rupture, releasing merozoites. Some parasites differentiate into gametocytes; microgametocytes (male) and macrogametocytes (female) which are then ingested by a mosquito feeding on human blood
(Slide 29)

Question 18

What occurs in the mosquito stage of the life cycle of plasmodium?

Answer 18

Gametocytes are ingested by a mosquito when it feeds on human blood. When in the mosquito’s stomach the microgametes (male) penetrate the macrogametes (female) generating zygotes. These zygotes then become motile and elongated (becoming ookinetes) which invade the midgut wall of the mosquito where they develop into oocysts. The oocysts then grow, rupture and then release sporozoites which make their way to the mosquito’s salivary glands, which get transferred to a human host when the mosquito feeds on human blood
(Slide 29)

Question 19

How is malaria diagnosed?

Answer 19

By identifying plasmodium-infected erythrocytes in blood smears via microscopy
(Slide 30)

Question 20

What are 3 examples of drugs used to prevent / treat malaria infections?

Answer 20

Chloroquine
Mefloquine (Lariam)
Pyrimethamine
Doxycycline
Clindamycin
(Slide 30)

Question 21

On top of some drugs, what else is being develop to help combat malaria?

Answer 21

Vaccines
(Slide 30)

Question 22

What may occur several years after the primary malaria infection?

Answer 22

Another malaria infection due to some species having a dormant phase
(Slide 30)

Question 23

What 2 ways can malaria be controlled?

Answer 23

By draining swamp or eliminating mosquitoes
(Slide 30)

Question 24

Give 3 examples of malaria species.

Answer 24

Answers Include:
P. malariae
P. vivax
P. ovale
P. falciparum
P. knowlesi
(Slide 31)

Question 25

What does paroxysm mean in the context of disease?

Answer 25

A sudden attack or reoccurrence of symptoms
(Slide 31)

Question 26

What are 3 forms of malaria?

Answer 26

Malaria quartana
Malaria teritana
Malaria tropica
(Slide 31)

Question 27

Compare malaria quartana, teritana and tropica, mention what specific species of plasmodium cause each type and how often their paroxysms occur.

Answer 27

Malaria quartana; Caused by P. malariae and paroxysms occur every 72 hours.
Malaria teritana: Caused by P. vivax and P. ovale and paroxysms occur every 48 hours
Malaria tropicana: Cause by P. falciparum and it has irregular paroxysms which occur roughly every 48 hours
(Slide 31)