Malaria

Question 1

Classic morphological picture of malaria infected RBC?

Answer 1

ring form

Question 2

Four species of malaria causing parasites?

Answer 2

Plasmodium

• vivax
• ovale
• malariae
• falciparum

Question 3

Two most common species of Plasmodium?

Answer 3

vivax

falciparum

Question 4

Most deadly species of Plasmodium?

Answer 4

falciparum

Question 5

Two species of Plasmodium that can cause relapses:

Answer 5

vivax and ovale

**dormant in liver

Question 6

Lifecycle stage of P. falciparum that enters human from mosquito? What cells does it infect first?

Answer 6

Sporozoites

hepatocytes

Question 7

What stage of the parasite lifecycle is present in hepatocytes?

Answer 7

Hepatic schizonts

Question 8

After hepatic shizonts, what stage of the parasite infects RBCs?

Answer 8

Merozoites

Question 9

When a merozoite infects an RBC it undergoes three phase changes before becoming multiple merozoites able to infect more RBCs. What are the tree stages?

Answer 9

Ring form—> trophozoite—> schizont—> back to merozoites

Question 10

Characteristic of P. falciparum in trophozoite stage?

Answer 10

lots of rings

Question 11

shape of P. falciparum gametocytes?

Answer 11

crescent or banana

Question 12

Characteristic of P. malariae schizonts?

Answer 12

rosette arrangement of merozoites

**apparently falciparum also forms rossetes by binding uninfected RBCs

Question 13

Enlarged red cells in the trophozoite phase?

Answer 13

P. ovale

Question 14

Schuffner’s dots in the trophozoites?

Answer 14

P. ovale or vivax

Question 15

Enlarged red cells in the schizont phase?

Answer 15

P. vivax

Question 16

Key characteristic of why falciparum is so bad:

Answer 16

able to infect red cells of any age

Question 17

Red cell pathology from P. falciparum infx: (4 of them)

Answer 17

1. rosettes-caused by infected cell binding normal RBCs
2. abnormal RBC binding to epithilium
3. blood flow impedance
4. main cause of death in children: cerebral ischemia

Question 18

What’s a PFEMP?

Answer 18

knob on outside of infected RBC that binds vascular endothelial cells

Question 19

Clinical sx of falciparum infx?

Answer 19

Splenomegaly

• parasites in RBCs
• super-active macrophages
• if chronic: fibrosis, grayish color

Liver enlarged and pigmented

Brain vessels get plugged:

• red cell rosettes
• perivascular hypoxia
• ischemia

Heart and lungs may also be involved

Question 20

Incubation period?

Answer 20

1-2 weeks

Question 21

Prodrome sx?

Answer 21

Flu-like

Question 22

Fever comes and goes how often with each bug?

falciparum:

vivax/ovale:

malariae:

Answer 22

Quotidian (daily)

Tertian (every 48 hours)

Quartan (every 72 hours)

Question 23

Host resistance occurs in?

Answer 23

hemoglobinopathies

ie: sickle cell, G6PD def, thalassemias, ABO antigens

Question 24

How does falciparum evade partial host immune mediated resistance in endemic areas?

Answer 24

antigenic variation of PFEMS (the little bumps)

Question 25

Gold standard for dx:

Answer 25

blood smear

Question 26

other dx basis:

Answer 26

clinical sx + hx (travel, contact with infected blood)

rapid immunochromatographic tests