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Microbiology Part 2 > Lec42 Malaria and Babesia > Flashcards

Lec42 Malaria and Babesia Flashcards

1
Q

What are helminths?

A

multicellular worms

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2
Q

What are protozoa?

A

unicellular parasites

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3
Q

What is main target of plasmodia?

A

red blood cells

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4
Q

What are symptoms of malaria?

A 
initially symptoms of flu:
- fever
- shivering
- pain in joints
- headache
- vomiting
rapidly progresses:
--> anemia, hemoglobinuria [black water fever], organ failure [kidney/liver/brain], death
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5
Q

Where are most of malaria cases?

A

more than 90% in Africa

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6
Q

What are signs of plasmodium falciparum?

A
  • most pathogenic
  • see ring forms on peripheral sphere, may see banana gametocytes
  • multiply infected red cells
  • rapidly progresses to heavy paraistemia
  • infected cells same size as non-infected
  • get endorgan damage [esp. cerebral]
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7
Q

How is plasmodium falciparum transmitted?

A

via anopheles mosquito

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8
Q

What are schizonts?

A

bag of parasites ready to rupture open

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9
Q

Which two malaria species have a hypnozoite stage? what does that mean?

A
  • hypnozoite stage = a dormant stage where it hangs around in liver
  • plasmodium ovale and plasmodium vivax
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10
Q

What additional treatment do you need to give for malaria with hynozoite stage?

A

need to give primaquine

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11
Q

What is life cycle of plasmodium?

A
  • mosquito injects gametocytes
  • mosquito injects sporozoites
  • sporozoites go to liver and form tissue schizont = replicating parasite
  • schizont ruptures and gives off sporozoites = when it becomes diagnostic
  • sporozoites infect RBCs, mature and form more erythrocytic schizonts and rupture to continue cycle
  • ## some sporozoites mature into gametocytes and can then be infective
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12
Q

What is major preventitive measure against malaria

A
  • use bed nets
  • use repellent especially at night
    major time of mosquito activity = night
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13
Q

Where do most malarial agents work?

A

in blood phase at level of erythrocytic schizont

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14
Q

How much time between mosquito bite and symptoms?

A
  • about 8 days incubation period when it may not be detectable
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15
Q

What is a hypnozoite?

A

resting stage of malaria wks/months later

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16
Q

What is rapid malaria test?

A
  • strip with test and control bands
  • parasite Ag captured by a labeled Ab then the labeled Ab-Ag complex will be captured by bound Ab of test band
  • labeled Ab captured by bound Ab of control band
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17
Q

What is the most lethal cause of malaria?

A
  • plasmodium falciparum
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18
Q

What are the four causes of malaria?

A
  • plasmodium falciparum
  • plasmodium vivax
  • plasmodium ovale
  • plasmodium malariae
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19
Q

What drug is plasmodium falciparum resistant to in most parts of the world?

A

chloroquine

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20
Q

What is cause/effect of cerebral malaria?

A
  • usually due to falciparum infection
  • 20% mortality
  • cerebral ischemia secondary to sequestration of parasitized RB or cytokines
  • get seizure, altered mental status, hypoglycemia/lactic acidosis
  • normal CSF but high ICP [intracranial pressure
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21
Q

What cells does falciprum infect vs ovale/vivax?

A

falciprum can infect RBCs of any age

ovale/vivax primarily infect young reticulocytes

22
Q

What do you normally see in plasmodium faliparum blood smear?

A
  • only see early trophocytes [rings] and [banana shaped] gametocytes
  • common to see multiple infections of single red cell
  • infected cells are same size as uninfected
  • small trophozoites = 2 chromatin dots in cell
  • do not usually see schizonts
  • may see parasitized RBC and schizonts in brain capillaries
23
Q

How do merozoites enter erythrocyte?

A

via parasitopherous vacuole

24
Q

What is PfEMP1 protein?

A
  • parasite protein that gets expressed on infected cells
  • forms knobs that allow cell to attach capillary endothelium
  • undergoes antigenic variation so immunity difficult
25
Q

What are challenges of malaria vaccine?

A

spends most of time as intracellular pathogen

26
Q

What are ring hemorrhages?

A

accumulation of parasites in brain capillaries leads to ischemia surrounding capillary in ring shape

27
Q

What is hemozoin?

A
  • malaria pigment that can be seen deposited in infected organs
28
Q

What are characteristics of plasmodium vivax?

A
  • can relapse months or yrs later via hypnozoites
  • duffy blood group antigen needed for attachment to RBC
  • only infects reticulocytes [so lower parasitemia]
  • synhronous schizogony so get fever every 48 hrs
29
Q

Can chloroquine treat plasmodium vivax?

A
  • usually but some resistance reported in papua new guinea
30
Q

What do you see with plasmodium vivax on blood smear?

A
  • infected RBCs are enlarged
  • see all stages in peripheral blood [ring form, ameboid trophozoites, schizonts, gametocytes]
  • multiple infections in RBC common
31
Q

What do you see in plasmodium ovale on blood smear

A
  • all stages in peripheral blood [ring form, ameboid trophozoites, schizonts, gametocytes]
  • rarely see multiple infections
  • infected RBCs are slightly enlarged and oval shape
32
Q

How do you tell difference between ovale and vivax?

A
  • ovale = oval shaped infected cells

- ovale you never see multiple infections of same cell

33
Q

What are signs of plasmodium ovale?

A
  • fever every 48 hrs [same as vivax]

- possible relapses

34
Q

What is primaquine?

A
  • tissue schozontocide –> treats liver phase of malaria

- use to treat p vivax or p ovale

35
Q

When is primaquine contraindicated?

A

in G6PD deficiency –> can cause hemolytic anemia

36
Q

what are evolutionary adaptations related to malaria?

A
  • G6PD deficiency –> more oxygen radicals –> survival advantage, might destroy parasite
  • sickle cell –> malaria can’t infect sickle RBCs
  • thalassemia –>
  • duffy antigen
37
Q

how long can ovale/vivax persist vs malariae?

A

ovale/vivax persist for 5 yrs

malariae persist for 20-30 yrs

38
Q

What are characteristics of plasmodium malariae?

A
  • may persist in blood 20-30 yrs after infection
  • no hypnozoite liver stage just delayed onset in humans
  • infects only aging RBCs [lower parasitemia]
  • 72 hr schizogony so longer duration between fevers than vivax/ovale
39
Q

What do you see with plasmodium malariae smear?

A
  • all stages in peripheral blood
  • multiple infections rare
  • infected erythrocytes not enlarged
  • can see band form
40
Q

What is p knowelsii?

A
  • looks identical to p. malariae, originally a primate pathogen recently reported in humans in SE Asia
41
Q

How is quinine administered? what can it treat?

A
  • good agent against all 4 species

- not available in US as IV –> give quinidine

42
Q

What is possible side effect of quinidine?

A

cardiotoxicity

43
Q

What are breeding sites for malaria vector?

A
  • rice field
  • marsh/swamp
  • open water storage tank
  • urban area construction site with open water storage
44
Q

What are the antimalarial drugs?

A
  • quinine/quinidine
  • chloroquine
  • mefloquine
  • primaquine
  • atovaquone/proguanil
  • doxycycline
  • sulfadoxine-pyrimethamine
  • artemesinin derivatives
45
Q

what are preventitive malarial meds?

A
  • malarone
  • doxycycline
  • mefloquine
46
Q

What do you use to treat severe malaria?

A

IV quinidine in combo with doxy or clindomycin

47
Q

What is babesia microti

A
  • intra-erythrocytic parasite very difficult to distinguish from plasmodium
48
Q

How is babesia microti transmitted? vector? reservoir?

A
  • by ixodes scapularis tick [same as lyme disease]

- reservoir = white footed mice and other small rodents

49
Q

What do you use to treat babesia microti?

A
  • first choice: atovaquone + azithromycin

- 2nd choice: clindamycin + quinine

50
Q

Where are most cases of babesia in US?

A
  • nantucket, marthas vineyard, cape cod, block island, eastern long island, shelter island, fire island
51
Q

What are clinical signs of babesiosis?

A

can be asymptomatic: incubation for wks to months
mild: viral like disease after 1-6 wks, malaise/fever/fatigue/anemia, less common: ab pain/ nausea/ vomitting/sore throat/depression

severe: in pts who are asplenic or immunosuppressed –> acute resp failure, DIC, CHF, liver/renal failure

52
Q

how is babesia transmitted?

A

tick, blood transfusion

Microbiology Part 2 (30 decks)

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