Malaria

Question 1

5 spp of Plasmodium

Answer 1

Plasmodium falciparum

malariae

ovale

vivax

knowlsei - this is not typically a human pathogen but a monkey one that then infects humans

Question 2

Which Plasmodium spp causes most malaria cases?

Answer 2

P falciparum

Question 3

Which spp of Plasmodium cause recurrent malaria?

Answer 3

Vivax and ovale can hide out in the liver and cause recurrence of malaria

Question 4

Outline the malaria lifecycle

Which stage of the cycle contributes to symptoms?

Answer 4

sporozoites in mosq salivary gland >> hypnozoites (in hepatocytes) >> schizonts >> merozoites >> ring/troph/schizont >> gametocyte >> gametes >> oocyts >> sporozoites

Symptomatic stage: blood stages

**hypnozoites are only with Vivax and Ovale

Question 5

Reason why there’s increased malaria burden in sub-saharan Africa

Answer 5

Anopheles gambiae mosquito

(likes to feed at night, lives long, feeds only on humans)

Question 6

___ can adhere to vascular endothelium (mediated by var genes) and lead to end organ damage

Answer 6

Plasmodium falciparum can adhere to vascular endothelium (mediated by knobs that form thanks to var genes) and lead to end organ damage

Question 7

The two clinical forms of malaria are ___

Answer 7

The two clinical forms of malaria are uncomplicated and severe malaria

Question 8

Presentation of uncomplicated malaria + Rx

Answer 8

Uncomplicated malaria: presents with non-specific symptoms (fever w/ shaking chills, headache, myalgias etc);

Rx: oral antimalarials

Question 9

Presentation of severe malaria

Answer 9

Severe malaria (only w/ P falciparum): presents with severe anemia or cerebral malaria

Rx: IV antimalarials

Question 10

Presentation and course of cerebral malaria

Answer 10

Flattening of the cerebral sulci

Kids staring off to one side

Seizures

Comatose

Infecting RBCs adhere to vasculature and rosette (basically attach to other uninfected RBCs and that impedes blood flow)

Causes host inflammatory response that results in cerebral edema >> death

Question 11

Why wouldn’t you find Plasmodium vivax in Africa?

Answer 11

Africans lack Duffy antigen to allow P. vivax invasion

Mostly SE Asia, W. Pacific and S. America

Question 12

How long is the malaria incubation period (before you become symptomatic)?

Answer 12

Malaria incubation period: 10-14 days

Question 13

Dx of malaria

Answer 13

Finger prick and blood smear microscopy

Rapid diagnostic (first line, smear takes a while)

Question 14

Which smear (thick/thin) is diagnostic vs good for speciation?

Answer 14

Thick smear = diagnostic

Thin smear = speciation

Question 15

What are the signs to look for severe malaria (based on the following):

mental status

respiratory status

prostration (sitting/standing)

vomiting

shock

Answer 15

Mental status: Altered consciousness; Seizures

Respiratory status: Acidotic breathing

Prostration: Unable to sit or stand

Vomiting: Unable to eat or drink

Shock

Question 16

What 3 other things do you need to look for with severe malaria?

Answer 16

Low glucose

Low Hb (less than 5)

High parasite density

Question 17

Rx for uncomplicated falciparum malaria

Answer 17

First line treatment in US for uncomplicated malaria: artemisinin-combination therapies (ACTs) >> artemether – lumefantrine

2nd line treatment: atovaquone-proguanil (Malarone)

Question 18

Rx for uncomplicated vivax and ovale malaria

Answer 18

Must treat blood stage AND liver stage

Rx: artemether-lumefantrine + primaquine (after testing normal G6PD activity. patients with deficiency will have hemolytic crisis)

Question 19

Rx for severe malaria

Answer 19

Quinine/quinidine: Can give IM, IV or oral

Use with doxycycline or clindamycin (if <8 years old)

2nd line treatment: IV artesunate (but not approved IV here in the US)

**in both cases, finish therapy with oral treatment - artemether/lumefantrine**

Question 20

Types of supportive care given to pts with severe malaria in addition to IV drugs

Answer 20

Address hypoglycemia

Cardiac monitoring (quinidine can cause arrythmias)

Question 21

How would you treat malaria anemia?

Answer 21

treat with iron after malaria therapy

Question 22

How would you treat severe malaria due to vivax?

Answer 22

Same treatment you would give for uncomplicated malaria due to vivax

(Chloroquine/ACTs + primaquine after testing G6PD deficiency)

Question 23

What’s the primary stage targeted by malaria vaccines being developed and is there one out there yet?

Answer 23

The sporozoite stage

Yup. RTS,S