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Faith's Multisystems module > Malaria > Flashcards

Malaria Flashcards

0
Q

What type of pathogen is malaria? What cells does it infect?

A

Protozoan paracyte that infects RBC and hepatocytes

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1
Q

What are the two key clues that highly indicate malaria?

A

Fever + travel

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2
Q

What are the major risk factors for severe malarial disease?

A

Non immune pts: children < 5 OR pregnant woman

Asplenic pts

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3
Q

How long does one have to be in a malaria endemic area to acquire disease?

A

All it takes is one bite

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4
Q

What are the five different malaria species?

A 
Plasmodium falciparum
P. vivax
P. ovale
P. malarial
P. knowlesi
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5
Q

What is the vector for malaria?

A

Anophelene mosquito

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6
Q

What is the non human reservoir for malaria? Which one?

A

Macaques- P. Knowlesi

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7
Q

Where is P. Knowlesi located?

A

Borneo

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8
Q

What is the maturation pathway of malaria?

A

Enters as a sporozoite=> liver schizont => burst release merozoites (infect RBC) => ring, trophozoites => schizonts (then burst) OR gametocytes

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9
Q

What is the dormant form of malaria? Which specific malaria paracite has it?

A

Hypnozoite? Only seen in P. Ovale and P. Vivax. Releases parasites weeks to months after primary infection

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10
Q

What is the typical time frame between initial infection and symptoms?

A

Coincides with start of erythrocytes cycle 1-2 weeks after infection.

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11
Q

What are three possible evolutionary defenses against malaria?

A
  1. Duffy antigen negative: P. Vivax requires Duffy to enter RBC
  2. Sickle cell trait: selective suckling of p. Falciparum infected RBC cells
  3. Glucose-6-phosphate dehydrogenase deficiency- malaria grows poorly in G6PD deficient RBC
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12
Q

What are the classical symptoms of malaria?

A 
Fever 
Chills
Headache
Fever
Splenomegaly
Abdominal pain
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13
Q

What are some clinical laboratory signs seen with malaria?

A 
Low platelets (<12)
High total bili (1.95)
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14
Q

What are the different clinical types of malaria?

A

Acute uncomplicated malaria
Severe malaria
Hyper reactive malarial syndrome (tropical splenomegaly)

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15
Q

What causes mild uncomplicated malaria? What are the key symptoms? How do the periodicity change with each type of malaria?

A

All plasmodium can cause uncomplicated malaria
Classic paroxysms: first cold stage then hot stage then sweat with reduction of fever

Episodes last 6-10 hrs
P. Vivax/ovale: every 2 days (tertian fever) and P. Falciparum
P. Malaria: every 3 days (quartan fever)

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16
Q

What is so bad about P. Falciparum that makes it have such a bad disease?

A

It infects RBC at any stage of the RBC life cycle

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17
Q

Complicated malaria (P. Falciparum high parasitemia)

A

Cerebral malaria
Respiratory distress
Severe anemia
Renal failure

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18
Q

What are the two main prognostic factors in a patient with malaria?

A

Degree of acidosis

Degree of parasitemia

19
Q

What is the major cause of tissue hypoxia and lactic acidosis in malaria?

A

SEQUESTRATION. Parasites creates knobs on RBC => RBC stuck in capillaries => blockage of tissue

20
Q

Cerebral malarial- causes?

A

Acute encephalopathy not attributable to other causes in pt with malaria

SEQUESTRATION hypothesis

  • obstructed vessels => hetergeneous (some blocked some not)
  • sequestered RBC => mass effect => swollen (not from cerebral edema)

INFLAMMATION hypothesis
- malaria toxin => cytokines storm but anti inflammatories do not help

HEMOSTASIS DYSFUNCTION hypothesis
- Coagulation dysfunction

21
Q

Malaria dx

A

Blood smear (thick/thin)
Antigen testing: binax
CPR

22
Q

What is the key morphology of P. Vivax and P. Ovale?

A
  • Schuffners dots
  • enlarge cells

P. Vivax: Lots of merozoites compared to P. Ovale

23
Q

Key morphology of P. Malariae on microscope?

A
  • band form
  • owl eye teophozoite
  • smaller infected cells (does not get bigger)
24
Q

Key morphological features of p. Falciparum?

A

Multiple ring shaped tropozoites

Banana shape gametocyte

25
Q

Key prevention of malaria?

A

Personal protection

Chemotherapy

26
Q

What are the classes of anti-malarials?

A
  1. Quinolone
  2. Artemisin.
  3. Antifolates
  4. Other- tetracyclines, atovaquone/proquanil
27
Q

What are a few key things to do when treating a malaria pt?

A

1 admit all pts with p. Falciparum

  1. Watch them take the meds
  2. Watch for respiratory compromise, hypoglycemia, neurological change
  3. Depressed sensorium? Vomiting? Organ problems or high paracitemia (>5%) =need I’ve tx
  4. Pts with p.vivax or p. Ovale: need primaquine to eradicate hypnozoites
28
Q

A 3 yr old in Ghana presents with fever headache cough for 3 days and positive for P. Falciparum. He is tolerating PO. What is the recommended medication?

A

Artemeter-lumefantrine (coartem)

29
Q

A 25 yo AD female plans a two week safari in western Kenya. What is the most appropriate chemo prophylactic?

A

Atovaquone-proguanil

30
Q

How do quinolone and quinolone-like drugs work?

A

Impairs intra-parasitic heme polymerization into hemozoin (parasites die on their own poop)

31
Q

What is the resistance mechanism against quinolones?

A

Efflux pump: P. Falciparum chloroquine resistance transporter (PfCRT)

32
Q

When are quinolone used?

A

Therapy (use with other agents as well)
PART/radical cure: Primaquine
Primary prophylaxis: chloroquine/mefloquine
* mefloquine can cause crazy dreams

33
Q

What is cinchonism?

A

Overdose of quinine- causes tinnitus, headache, nausea, bitter taste, dysphoria

34
Q

What is a side effect of quinine to watch out for?

A

Hypoglycemia

35
Q

How do you treat severe p. Falciparum? Uncomplicated?

A

Severe- quinine/quinidine
Uncomplicated- oral quinine and doxy/clindamycin

**resistance to quinine in SE Asia

36
Q

Where can you use chloroquine?

A

Only for p. Falciparum in Central America, Haiti, Dominican Republic.

Good for P. Vivax, p. Ovale, p. Malariae in most locations

37
Q

Mefloquine- indications? Side effects? Contraindications? Who is best to use this?

A

Use in locations of chloroquine resistant P. Falciparum. Weekly chemo - due to 3 wk half life. Use for long term travelers/children/ preggers

Neuropsychiatric side effects -crazy dreams
Cardio toxic if used with quinine, quinidine, halofantidine

38
Q

Mefloquine resistance?

A

Plasmodium falciparum multidrug resistance protein 1 (PfMDR1)

  • ATP cassette
  • effluent pump
  • polymorphisms
  • primarily in SE Asia.
39
Q

Primaquine- use? Things to worry about?

A

Radical cure of P vivax, or P. Ovale
PART
- print relapse in ppl who have had long exposure

test for G6PD deficiency: especially for preggers as we don’t know if fetus is g6pd.

Recommended for artemisinin resistance or elimination areas

40
Q

How are preggers with p. Vivax or p. Ovale treated?

A

Chloroquine

41
Q

Antifolate/sulfa derivatives

  • pro guano
  • prime thiamine

Resistance?

A

Dihydroperase synthase or dihydrfolate reductase point mutations

42
Q

Atovaquone - mechanism of action? Resistance?

A
  • inhibits mitochondrial electron transport (even better potentiated when paired with proguanil (Malarone)
  • use as therapy and prophylaxis
  • resistance- single point resistance in parasite cytochrome b gene
43
Q

Antibiotics for malaria: which ones? Target? Things to consider?

A

Doxycycline, tetracycline, clindamycin, azithromycin, fluoroquinolones

  • all target ribosomal functioning
  • if these drugs are used for other purposes, it may mask or change the typical presenting signs of malaria.
44
Q

Artemisinins- how do they work, where?

Used in what clinical setting?

A

Effective against wide range of stages of parasite
Mechanism: endoperoxide => free radicals
Use in artemisinin combined therapy
- artemisinin-lumefantrinev(coartem). First line tax of uncomplicated p. F

IV form: artesunate

45
Q

Tx of severe malaria

A

IV quinidine

IV artesunate

46
Q

Oral tax of uncomplicated malaria

A

Atovaquone-proquanil (Malarone)
Artemether-lumefantrune (coartem)

Quinine+ doxy or clindamycin
If pregnant, malarone and coartem become second line

Faith's Multisystems module (12 decks)

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