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Multisystem Part 2 > Malaria > Flashcards

Malaria Flashcards

1
Q

what is the most common cause of fever in a returned traveler?

A

malaria

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2
Q

how do many docs misdiagnose malaria?

A

forget to get a travel history!

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3
Q

mosquitoes carry malaria- where do they store it?

A

salivary gland

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4
Q

vector for malaria?

A

anopheles mosquito

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5
Q

non human reservoir for malaria?

A

none except for macaques with P. knowlesi

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6
Q

“hidden plasmodia” dilemma

A

after infection, the sporozoites circulated free for only about half an hour, and then vanished for several days they hide/go to liver cells!!!

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7
Q

sporozoites

A

come from mosquito

tiny thread like

short lived in the blood –> travel to the hepatocytes

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8
Q

schizont

A

in liver

asymptomatic

contains merozoites (the merozoites are infective for RBCs)

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9
Q

merozoites

how many in Pv? Pf?

A

merozoites are infective daughter cells that invade RBCs

10,000 in Pv

30,000 in Pf

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10
Q

what form is transmitted by mosquito saliva?

A

sporozoites

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11
Q

after merozoites infect the RBCs, what do they form?

A

ring-stage trophozoites

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12
Q

ring stage trophozoites turn into …

which do what?

A

schizonts

schizonts rupture and release merozoites which infect more RBCs

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13
Q

hypnozoite

A
  • Dormant liver stage in P. vivax and P. ovale -> can have recurrent infxns
  • Release blood stage parasites weeks to months after primary infection
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14
Q

which two malaria types can have recurrent infections due to a dormant stage?

A

P vivax and P ovale

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15
Q
A

1 - mosquito bites and injects sporozoites

2 - sporozoites go to liver and form schizonts which rupture and release merozoites (exo-erythrocytc cycle)

3 - merozoites go to blood and for primary ringed trophozoites

–they can either become gametocyte or mature trohpzoite

4 - mature trophozoite becomes schizont which ruptures and releases more merozoites into blood (erythrocytic cycle)

5 - gametocytes form new gametocytes which can infect new mosquito if an uninfected mosquito bites person

6) sporogenic cycle = gametocytes inside new mosquito create macrogametocyte and then an oocyst which creates new sporozoites

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16
Q

how long does it take for malaria symptoms to appear?

P falciparum

P ovale

P vivax

P malariae

A

Pf 8-11 days

Po/Pv 10-17

Pm 18-40

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17
Q

onset of symptoms of malaria coincides with….

A

the start of the erythrocytic cycle

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18
Q

incubation with ______can be up to 20 years due to chronic subclinical erythrocytic stage

A

P. malariae

19
Q

3 evolutionary defenses against malaria

A

Duffy antigen negative (P viva uses duffy agent to enter RBCs)

sickle cell trait (selective sickling of falciparum infected RBCs)

G6PD deficiency (malaria parasites grow poorly in G6PD deficient rbcs d/t increased ROS in rbcs)

20
Q

classic triad of symptoms for malaria

A

fever, chills, headache

21
Q

three clinical types of malaria

A

acute uncomplicated

severe malaria

hyperreactive malarial syndrome (tropical splenomegaly)

22
Q

uncomplicated (mild) malaria

A

Occurs with all Plasmodium species

—–sudden episodes of: fevers, chills, and sweats

  1. cold stage with shaking – 2. hot stage with high temperature (>104°F) – 3. sweating stage with resolution of fever

episodes last 6-10 hours, and then recur

every 2 days with P. vivax and P. ovale (tertian fever)

and for P. falciparum (malignant tertian fever)

every 3 days with P. malariae (quartan fever)

23
Q

complicated/severe malaria

A

Can cause any of these:

• Cerebral malaria (change in mental status, coma)

• Respiratory distress

• Severe anemia (hct <15%)

• Renal failure

• Hypoglycemia

  • Circulatory collapse (shock) and lactic acidosis
  • Bleeding disorder (spontaneous bleeding or evidence of DIC)

******complications primarily occur with P falciparum, usually when parasitemia >2% (% of rbcs infected).

24
Q

complicated malaria is usually with what species?

A

falciparum

25
Q

why are falciparum infections the most severe?

A

because it will infect ANY rbcs

asexual blood stage parasites of P. falcip. can develop in erythrocytes of all ages there is

NO LIMIT ON THE DEGREE OF PARASITEMIA

26
Q

What is the mechanism for tissue harm in malaria?

A

tissue hypoxia and lactic acidosis

RBCs become “sticky” and clog up vasculature

SEQUESTRATION! –> Erythrocytes containing mature P. falcip. parasites develop “knobs” and express adhesion molecules that bind to endothelium of capillaries/venules.

Also there is decreased deformability of infected AND non-infected RBCs, contributing to sludging, aggregation, and blockage of vessels.

This causes tissue hypoxia and organ failure.

27
Q

cerebral malaria

A

•acute encephalopathy not attributable to other causes in a patient with malaria

decreased consciousness + delirium + seizures

brain has increased mass (swollen)

cerebral malaria is driven by sequestered RBC in brain blood vessels

28
Q

cerebral malaria untreated Px and treated Px

A

untreated - 100% die

treated - 20% die

29
Q

cerebral malaria is diven by what process?

A

RBCs accumulation in brain parenchyma

30
Q

malaria diagnosis - 3 methods

A

blood smear - thick and thin

antigen testing

PCR

31
Q

BinaxNow

A

malaria card test - antigen capture

Control line + T1 and T2

  • all three lines Pf or combined
  • just C and T1 –> Pf
  • C and T2 –> Px, Pm, Po
32
Q

enlarged cells + schuffners dots

which species?

A

vivax or ovale

33
Q
A

vivax or ovale

enlarged infected RBCs and schuffners dots

34
Q
A

TOP vivax - schizont with 12-24 merozoites

BOTTOM ovale - schizont that is oval and fewer merozoites (6-12)

35
Q

what species makes band forms?

A

malariae

36
Q
A

P malariae

37
Q
A

P malariae

owl eye trophozoite, infected cells are smaller, has yellow/brown pigment

38
Q

features of P malariae

A

owl eye trohpozoites

smaller infected cells

yellow/brown pigment

39
Q
A

P falciparum

multiple ringed trophozoites and banana shaped gametocyte

40
Q

multiple ringed trophozoites and banana gametocyte?

A

p falciparum

41
Q

if malaria smear is negative, keep what?

A

repeating smears/Ag tests every so often until better

42
Q

prevention of malaria

A

PPE

chemotherapy =

–doxycycline

–atovaquone/proguanil

–mefloquine

–Primaquine

–Chloroquine (in chloroquine-sensitive areas)

43
Q

admit all patients with ___

A

falciparum

44
Q

Patients with P. vivax and P. ovale should receive therapy (primaquine) to

A

eradicate any remaining hypnozoites after treatment for intraerythrocytic stage.

Multisystem Part 2 (20 decks)

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