Malaria

Question 1

What are the 4 major species of malaria?

Answer 1

Plasmodium falciparum, P. vivax, P. ovale, P. malariae

Question 2

What is the vector of malaria?

Answer 2

Female Anophales mosquito

Question 3

Describe the life cycle of malaria

Answer 3

• Sporozoites transmitted from anophales mosquito during blood meal
• Sporozoites invade hepatocytes and multiply into merozoites
• Merozoites invade erythrocytes and mature into trophozoite (ring form)
• Trophozoite divide into multi-nucleated shizont
• Shizont bursts releasing new merozoites, can either go through asexual cycle again or can differentiate into male and female gametocytes
• Gametocytes are taken up by mosquito and progress through stages to become sporozoites in the proboscis

Question 4

Which stages of the life cycle cause disease?

Answer 4

Asexual blood stages (destruction of erythrocytes)

Question 5

What makes P. falciprum more severe?

Answer 5

Var genes encode protein expressed on infected erythrocytes surface that causes endothelial adhesion and microvascular obstruction in brain and other organs (cerebral malaria)

Question 6

What species of malaria cause uncomplicated malarial disease?

Answer 6

Any four species

Question 7

What species of malaria cause the most severe malarial disease?

Answer 7

Plasmodium falciparum

Question 8

What is the clinical presentation of uncomplicated malaria?

Answer 8

• Periodic fever paroxysms every 48 hours
• Headache, myalgia, backache, cough, diarrhea, abdominal pain
• Anemia, hepatomegaly, jaundice

Question 9

What are lab signs of uncomplicated malaria?

Answer 9

Anemia, thrombocytopenia, normal to low white blood cell count

Question 10

What is the clinical presentation of severe malaria due to P. falciprum?

Answer 10

Cerebral malaria (altered consciousness, seizures common, rapid onset)
Severe anemia (hemoglobin <5 gm/dL)

Question 11

What is the clinical presentation of severe malaria due to P. vivax?

Answer 11

Splenic rupture, chronic anemia
Mostly SE Asia, West Pacific, and South America (African lack Duffy antigen to allow P. vivax invasion)
Ability to relapse, no sequestration

Question 12

What is the clinical presentation of severe malaria due to P. malariae?

Answer 12

Nephrotic syndrome in African children

Question 13

Which species of malaria remain dormant in the liver and can reactivate?

Answer 13

P. vivax and P. ovale (OVer and OVer)

Question 14

How is the diagnosis of malaria made?

Answer 14

• Giemsa stained blood smear

- Rapid antigen test

Question 15

What is the function of thin smear v. thick smear?

Answer 15

Thick smear - detects malaria

Thin smear - determines species based on morphology

Question 16

What are downsides to the rapid antigen tests?

Answer 16

• Sensitivity decreases with low parasitemia and non-falciparum infection
• Can’t differentiate P. falciparum from mixed infections
• May remain positive after treatment

Question 17

What are major clinical clues to suspect malaria?

Answer 17

Any fever in potentially exposed person (travel to malaria endemic country recently)
- Incubation usually 1-4 weeks

Question 18

Signs of severe malaria

Answer 18

Mental status altered
Acidotic breathing
Renal, hepatic, cardiac dysfunction, shock
Anemia
Hypoglycemia

Question 19

Treatment for uncomplicated P. falciparum malaria

Answer 19

Artemether-lumefantrine
Atovaquone-proguanil (Malarone)
Mefloquine
Chloroquine

Question 20

Treatment for P. vivax, ovale and malariae

Answer 20

Primaquine (make sure G6PD activity is good) to treat hypnozoites in liver
Chloroquine for shizonts in blood

Question 21

Treatment for severe malaria

Answer 21

IV quinine or quinidine
Supportive care
- Treat hypoglycemia
- Monitor anemia and cardiac-respiratory status
- Antipyretics
- Anticonvulsants if needed

Question 22

Is malarial anemia due to iron deficiency?

Answer 22

NO, do not give iron!

Due to peripheral hemolysis, bone marrow suppression, inflammation.