Malaria II

Question 1

History of Fever & Travel

Answer 1

Malaria

Question 2

What are the different spp. of malaria?

Answer 2

P. ovale
P. vivax
P. falciparum
P. malariae
P. knowlesi

Question 3

What is malaria’s vector?

Reservior?

Answer 3

Anophelene mosquito

Humans (macaques for knowlesi)

Question 4

What is a hypnozoite and what spp. form them?

Answer 4

Dormant liver stage in vivax and ovale

releases blood stage wks to mos. after primary infection

Question 5

How long after infection do Sx develop?

Answer 5

falciparum- 8-11 days
ovale and vivax- 10-17 days
malariae 18-40 days (<20 years due to subclinical erythrocytic stage)
corresponds to beginning of erythrocytic cycle

Question 6

What is the infective stage of malaria?

Answer 6

Sporozoites enter host from mosquito salivary glands and migrate to infect liver cells.

Question 7

What is the erythrocytic cycle?

Answer 7

Merozoites burst from liver schizonts and infect RBCs

Ring stage–>trophozoite–>early/late schizont–>lysis and reinfection of RBCs

Question 8

What is Duffy Antigen?

Answer 8

P. vivax uses it to enter RBCs

Question 9

Classical symptoms of malaria?

Answer 9

Fever
Chills
Headache

Question 10

What are the three clinical types of malaria?

Answer 10

Acute uncomplicated (mild)
Severe malaria
Hyperreactive Malarial Syndrome (tropical splenomegaly)

Question 11

What are the classic malarial paroxysms?

Answer 11

1. Cold stage with shaking
2. Hot stage with fever (>104)
3. Sweating stage with fever resolution
   each lasts 6-10 hrs then recur

Question 12

How frequently do fevers relapse in chronic uncomplicated malaria?

Answer 12

Every 2 days P. vivax, ovale, falciparum

Every 3 days P. malariae (quartan fever)

Question 13

Why is P. falciparum infection more severe?

Answer 13

more protozoa
infect all ages of RBCs
emergency in non-immune patients!

Question 14

What are important prognostic factors in patients with malaria?

Answer 14

Degree of acidosis

Degree of parasitemia

Question 15

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

Answer 15

Sequestration!
RBCs with mature parasites develop knobs that cause them to adhere to endothelial cells
Decreased deformability of infected and non-infected RBCs contributed to sludging, rosetting, and aggregation

Question 16

What is cerebral malaria?

Answer 16

Acute encephalopathy not attributable to other causes
Sequestration and coagulation dysfunction plus inflammation hypothesized as cause.
100% mortality without treatment, 20% w/tx

Question 17

How do you diagnose malaria?

Answer 17

Blood smear (thick and thin)
Antigen testing
PCR

Question 18

What is the mechanism of severe malaria?

Answer 18

Lactic acidosis due to hypo perfusion from sequestration
Hypoglycemia due to increased demand
Renal failure due to filtered hemolysis products
Anemia due to hemolysis
Pulmonary edema–unknown

Question 19

Which Plasmodium species cause schuffner’s dots and enlarged infected cells?

Answer 19

P. vivax

P. ovale

Question 20

What indicates vivax on a smear?

Answer 20

schuffner’s dots and enlarged infected cells

mature schizont with 12-24 merozoites

Question 21

What indicates P. oval on a smear?

Answer 21

schuffner’s dots and enlarged infected cells

mature schizont with 6-12 merozoites is elongated or oval

Question 22

What indicates P. malariae on a smear?

Answer 22

Band form
Owl eye trophozoite
Smaller infected cells
yellow/brown pigment

Question 23

What indicates P. falciparum on a smear?

Answer 23

Multiple ring-shaped trophozoites

Banana-shaped gametocyte

Question 24

How do you prevent malaria?

Answer 24

PPE
Chemoprophylaxis
-doxy
-atovaquone/proguanil
-mefloquine
-primaquine
-chloroquine

Question 25

What are the classes of antimalarials?

Answer 25

Quinolines-inhibits parasitic heme polymerization
Antifolates/Sulfa-DHPR DHFR inhibition
Artemisinins-endoperoxidase–> free radicals
Antibiotics-ribosomal function in apicoplast

Question 26

What are blood schizonticides?

Answer 26

Primaquine, doxycycline, Mefloquine, chloraquine, quinine, Artemisinins, Atovoquone-Proguanil

Question 27

What are tissue schizonticides?

Answer 27

Primaquine

Atovoquone-Proguanil (some activity)

Question 28

What are malaria gametocides?

Answer 28

Primaquine

Artemisinins

Question 29

What is presumptive anti-relapse therapy (PART)?

Answer 29

for people who have prolonged exposure to malaria endemic areas
30mg Primaquine for 14 days

Question 30

What is the mechanism of Atovaquone?

Answer 30

Inhibits parasite mitochondrial electron transport
Effect potentiated when combined with proguanil
(Malarone)

Question 31

What are the two types of malaria prophylaxis?

Answer 31

Causal-kills in primary liver stage and blood stage, Continue one week after departure, Atovaquone-proguanil
Suppressive-kills in erythrocytic stage only, mefloquine, doxy, chloroquine. Continue 4 weeks after departure.

Question 32

What are the side effects of primaquine?

Answer 32

G6PD-hemolysis

Question 33

What are the side effects of mefloquine?

Answer 33

Vivid dreams
Nausea
Dizziness/syncope
Neuropsychiatric complications <1%
Cardiotoxic if combined with quinine/quinidine

First line in pregnancy (cat. B drug)

Question 34

When would you use chloroquine as a malaria prophylactic?

Answer 34

travel to Haiti or central america

pregnancy

Question 35

When would you use atovaquone/proquanil as a malaria prophylactic?

Answer 35

In resistant areas

If you have a lot of money (expensive drug)