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Microbiology > Parasitology Exam 3: Malaria and Babesia > Flashcards

Parasitology Exam 3: Malaria and Babesia Flashcards

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Biology 101 flashcards
1
Q

What genus of organisms cause malaria?

A

Plasmodium sp.

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2
Q

What is the major species associated with the most deadly malarial infections worldwide?

A

Plasmodium falciparum

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3
Q

What are the most common malarial infections (95% of infections) ?

A

P. vivax and P. falciparum

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4
Q

When Plasmodium bites a human, what stage do they infect the human with? (i.e. what is the infective stage of Plasmodium in humans)

A

Sporozoites

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5
Q

After the injection of sporozoites in the human, what happens next in the malarial life cycle? (this happens in humans)

A

Sporozoites enter the blood and are carried to the liver where they grow in hepatocytes. This initiates the preerythrocytic or primary exoerythrocytic cycle.

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6
Q

What is schizogony?

A

Rapid division and multiplication of sporozoites

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7
Q

Intracellular sporozoites mature into _______. (this happens in humans)

A

Schizonts

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8
Q

After the schizont ruptures, what do they release? Where do these go? What cycle does this initiate? (this happens in humans)

A

Release merozoites; leave the liver to invade RBCs; this initiates the erythrocytic cycle

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9
Q

Merozoites feed on hemoglobin to become mature ___________. (this happens in humans)

A

Trophozoites

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10
Q

Tropozoites multiply and mature into _______. (this happens in humans)

A

Schizonts

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11
Q

Mature schizonts contain ________ which are released into the bloodstream and start a new cycle of ___________. (this happens in humans)

A

Merozoites; erythrocytic schizogony

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12
Q

Merozoites can begin to undergo development into male and female __________. These are then ingested by the mosquito when it takes a blood meal. (this happens in humans)

A

Gametocytes

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13
Q

Describe the malarial life cycle that occurs in MOSQUITOES.

A
  1. Mosquito takes a blood meal –> ingests gametocytes
  2. Male + female gametocytes generate zygotes
  3. Zygotes become motile and form ookinetes
  4. Ookinetes develop into oocyts
  5. Oocyts mature and release sporozoites
  6. Sporozoites are introduced into a new human host and cycle continues
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14
Q

Describe the malarial life cycle that occurs in HUMANS.

A
  1. Anopheles takes blood meal and releases sporozoites
  2. Sporozoites carried to the liver, enter hepatocytes –> initiation of preeythrocytic/primary exoerythrocytic cycle, schizogony occurs
  3. Sporozoites mature into schizonts
  4. Schizont ruptures and releases merozoites
  5. Merozoites leave the liver and invade RBC –> erythrocytic cycle
  6. Merozoites feed on Hgb and become mature trophozoites
  7. Trophozoites multiply and mature into schizonts
  8. Schizonts again rupture and release more merozoites initiating a new cycle of erythrocytic schizogony
  9. Some merozoites undergo development into gametocytes
  10. Gametocytes ingested by new mosquito
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15
Q

What are the possible diagnostic stages of malaria in humans?

A

Detection of immature trophozoites AKA merozoites (ring stage), mature trophozoites, schizonts, or gametocytes in the thick or thin blood smear.

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16
Q

Where do sporozoites invade? What cycle does this initiate?
Where do merozoites invade? What cycle does this initiate?

A

Sporozoites invade hepatocytes (liver) –> preerythrocytic cycle
Merozoites invade RBC –> erythrocytic cycle

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17
Q

What stage of malarial infection is the ring form we can see in blood smears?

A

Merozoites (immature trophozoites)

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18
Q

What is dormant schizogony and what organisms can exhibit this?

A

Organisms remaining quiescent in the liver –> hypnozoites
Can lead to relapse
P. vivax and P. ovale

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19
Q

What are hypnozoites and what organisms can display this?

A

Resting stage of malarial infection remaining quiescent in the liver
P. vivax and P. ovale

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20
Q

Microgametocytes vs Macrogametocytes

A

Microgametocytes = male sexual stage of malaria
Macrogametocytes = female sexual stage of malaria

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21
Q

Schizont

A

A multinucleated cell undergoing schizogony, contains merozoites

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22
Q

Exo-erythrocytic cycle vs erythrocytic cycle

A

Exoerythrocytic cycle = occurs in liver cells
Erythrocytic cycle = occurs in RBCs

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23
Q

Definitive vs intermediate host of malaria

A

Definitive = Anopheles mosquito (sexual stages found)
Intermediate = humans (asexual stages found)

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24
Q

What is the sexual stage of malaria?

A

Gametocytes

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25
Q

What are the 2 basic sign/symptoms of malarial infection? What stage causes these symptoms?

A

Fevers and rigor, all clinical symptoms caused by the asexual erythrocytic or blood stage parasites

26
Q

What 3 stages does a classical malarial attack consist of?

A
  1. A cold stage
  2. A hot stage
  3. A sweating stage
27
Q

Tertian parasites vs quartan parasites

A

Tertian = Symptoms/attacks occur every 2 days
Quartan = Symptoms/attacks occur every 3 days

28
Q

What is cerebral malaria and what Plasmodium species is associated with this?

A

Severe form of malaria where P. falciparum-infected RBCs adhere to the endothelium of blood vessels in the brain; associated with high mortality

29
Q

Hyperparasitemia

A

> 5% of RBCs are parasitized

30
Q

Describe STANDOUT features of P. vivax that help us identify it

A
  • ONLY infects reticulocytes
  • Dormant schizogony CAN occur –> hypnozoites, recrudescence
  • Contain Schuffner dots
  • Mature schizont contains 12-24 merozoites
  • Tertian
31
Q

Describe STANDOUT features of P. ovale that help us identify it

A
  • ONLY infects reticulocytes
  • Distinctive oval-shaped cells with ragged edges
  • Contain Schuffner dots
  • Dormant schizogony CAN occur –> hypnozoites, relapses
  • Mature schizont contains ~8 merozoites
  • Tertian
32
Q

How to differentiate P. ovale from P. vivax?

A

The main difference between them is P. ovale has oval-shaped cells with ragged edges and schizont contains less merozoites (~8). P. vivax schizont can contain 12-24 merozoites.

They both only infect reticulocytes, can cause hypnozoites, are Tertian, and contain Schuffner dots.

33
Q

Describe STANDOUT features of P. malariae that help us identify it

A
  • Infects OLD RBCs
  • Quartan (infects every 72 hours)
  • May enter a period of recrudescence
  • Developing rings may exhibit band forms
  • Mature schizont contains 6-12 merozoites
  • Can cause kidney problems
34
Q

What is recrudescence?

A

Recurrence of symptoms; repeated malarial attack due to survival of parasites in RBCs

35
Q

Relapse vs recrudescence

A

Relapse = recurrence of disease after it has been cured
Recrudescence = repeated malarial attack due to survival of parasites

36
Q

Describe STANDOUT features of P. falciparum that help us identify it

A
  • Infects All ages of RBCs
  • Schizogony occurs in liver, BM, and spleen rather than circulating blood
  • Exhibit cytoadherence
  • Tertian
  • Multiple parasite infections per cell
  • Rings have 2 dots of chromatin
  • Maurer dots
  • Gametocytes are crescent/banana shaped
  • Can be associated with Blackwater fever, cerebral malaria, and DIC
37
Q

Which Plasmodium sp exhibit Schuffner dots?

A

P. vivax, P. ovale

38
Q

Which Plasmodium sp. only infect old RBCs?

A

P. malariae

39
Q

Which Plasmodium sp. can infect any age RBCs?

A

P. falciparum, P. knowlesi

40
Q

Which Plasmodium sp. can only infect reticuloctes?

A

P. vivax, P. ovale

41
Q

What are Maurer dots and which Plasmodium sp. are they associated with?

A

Coarse granulation in the RBC cytoplasm, blue in color
Associated with P. falciparum

42
Q

What are applique or accole ring forms? What Plasmodium sp. are they associated with?

A

Delicate ring forms with 2 dots of chromatin located on the surface of the RBC
Associated with P. falciparum

43
Q

Cytoadherence

A

Parasite binds to the surface of RBCs and to vascular endothelial cells, associated with severe malaria (P. falciparum)

44
Q

What is Blackwater fever?

A

Result of RBC lysis, release of HGB into bloodstream and urine causing discoloration
Associated with P. falciparum

45
Q

What is the major cause of death in P. falciparum infections?

A

Cerebral malaria

46
Q

Name 2 features of P. falciparum that allow infection to become very serious.

A

DIC, Cerebral malaria, Blackwater fever

47
Q

Describe STANDOUT features of P. knowlesi that help us identify it

A
  • Invades all ages of RBCs
  • AKA The Fifth Human Malaria/Simian Malaria
  • Associated with Southeast Asia
  • Early blood stages resemble P. falciparum infections
  • Late blood stages resemble P. malariae infections
48
Q

What test is used to diagnose Malaria and Babesia parasites?

A

Thick and thin blood smear, 200-300 oil immersion fields examined

49
Q

Why is it important to speciate Malarial infections?

A

P. falciparum and P. knowlesi can be fatal and need treated ASAP
The other species are not as serious

50
Q

What is Acridine orange stain used for?

A

Quantitative buffy coat method

51
Q

How do we report the presence/absence of malarial/babesia parasites?

A

Absence = NPF
Presence = speciate and quantify % parasitemia

52
Q

How is % parasitemia reported?

A

% of cells counted that contain parasites
Extracellular forms NOT counted, Gametocytes NOT included b/c they are not the infectious form

53
Q

What is the current suggested therapy for P. falciparum infections?

A

ACT: Artemisinin combination therapy

54
Q

What is the vector of Babesia spp.?

A

Ixodes (deer tick)

55
Q

What Babesia spp. is the most common cause of infection in the US?

A

B. microti

56
Q

How is the Babesia life cycle different from the malarial life cycle?

A
  • No exoerythrocytic stage –> Sporozoites invade RBCs directly
  • Trophozoites reproduce by binary fission instead of schizogony
57
Q

What is the definitive, intermediate, and Incidental/dead-end host of Babesia?

A

Definitive = Ixodes tick
Intermediate = Rodents (white-footed mouse)
Incidental = humans

58
Q

Describe the life cycle of Babesia spp.

A
  1. Infected tick introduces sporozoites into mouse host
  2. Sporozoites enter RBCs and undergo asexual reproduction
  3. Some parasites differentiate into male/female gametes in the blood
  4. Gametes ingested by another tick, undergo sporogenic cycle resulting in sporozoites
  5. Tick introduces sporozoites into human
  6. Sporozoites enter human RBCs and undergo asexual reproduction
    Humans = dead end host, cannot spread any further
59
Q

Babesia microscopic morphology (Standout features)

A
  • Ring forms OUTSIDE of red cells
  • 2-3 rings INSIDE red cells
  • Maltese cross forms, diagnostic for Babesia infection
60
Q

What are the infective and diagnostic stages of Babesia sp.?

A

Infective: Sporozoites introduced into mouse or human
Diagnostic: Trophozoite or merozoite

Microbiology (24 decks)

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