Parasitology

Question 1

Life Cycle of Malaria: Asexual phase?

Answer 1

In man ( also called, vertebrate, intrinsic or endogenous phase)

Question 2

Life Cycle of Malaria: Sexual phase?

Answer 2

In Mosquito (also called invertebrate, extrinisc, or exogenous phase.

Question 3

What is the process of Parasite multiplication by division or splitting in the vertebrate host?

Answer 3

Schizogony

Question 4

Two forms of Schizogony?

Answer 4

• RBC - Erythrocytic schizogony.
• Liver Cells: Exo erythrocytic schizogony, or tissue phase, or pre-erythrocytic schizogony.

Question 5

What does the process of schizogony result in ?

Answer 5

Merozoites

Question 6

Describe the Pre-erythrocytic phase

Answer 6

• Pre-erythrocytic schizont or meront or cryptozoites.
  
  • Several daughter cells inside host cell
    
    • Hepatocyte becomes enlarged and the liver cell nucleus is pushed to the periphery.
    • No pigment observed in this stage.
• Within 5-15 days the schizont become mature and bursts, releasing thousands of merozoites. They enter red blood cells by invagination.

Question 7

What is the interval between the entry of the sporozoites into the body and the first appearance of the parasite in the blood called?

Answer 7

Pre-patent period.

Question 8

Merozoites use what receptor to invade RBC?

Answer 8

• Glycophorin, which is a major glycoprotein for RBCs.
  
  • Enter RBCs by Endocytosis.

Question 9

When stained with giemsa stain, what does the merozoite look like?

Answer 9

Red = nucleus

Blue = Cytoplasm

Central Vacuole = unstained.

Question 10

What is the parasite stage when in the erythrocyte called?

Answer 10

Ring form

Question 11

Vector for malaria?

Answer 11

Female Anopheles mosquito

Question 12

What is the infective form and where is it in the vector?

Answer 12

Sporozoites and are present in the salivary gland

Question 13

Malaria sexual multiplication is called ? and results in ?

Answer 13

Sporogony and sporozoites.

Question 14

Merozoites differentiate in the human host in what way?

Answer 14

Become male or female gametocytes

Question 15

When the mosquito takes up a blood meal containing the gametocytes what occurs next?

Answer 15

Oocysts are formed in the mosquitos gut, and sporozoites develop.

Question 16

Eruption of merozoites from RBC occurs in a synchronized fashion that causes severe symptoms, what is the name of this episode.

Answer 16

Short-term relapses or Recrudescence.

Question 17

In p. falciparum recrudescence are seen when?

Answer 17

for 1 to 2 years.

Question 18

In p. malariae recrudescence occurs for how long?

Answer 18

up to 30 years.

Question 19

Describe how the malaria pigment is formed?

Answer 19

Parasite feeds on hb of the rbc, and doesnt metabolize it completely leaving some behind.

Question 20

P. vivax pigment?

Answer 20

fine golden brown dust like particles

Question 21

P. falciparum pigment?

Answer 21

Few 1-3 solid blocks of black pigment

Question 22

P. malariae pigment?

Answer 22

numerous coarse, dark brown particles.

Question 23

P. ovale pigment?

Answer 23

Numerous blackish brown particles.

Question 24

P. falciparum unique traits

Answer 24

Most likely to become severe

Fatal forms with CNS involvement

Renal failure & anemia and acute respiratory distress.

Question 25

P. malariae unique traits?

Answer 25

Can last 30 years

Lead to nephrotic syndrome, and hypersplenism.

Question 26

P. vivax and p. ovale unique traits?

Answer 26

May relapse for 5 years.

P. Vivax includes splenomegaly.

Question 27

Incubation period for the 4 types of malaria?

Answer 27

• P. vivax and ovale - 14 days
• P. falciparum 9-12 days
• P. malariae - 30 days

Question 28

How does relapse occur after therapy has concluded?

Answer 28

Release of new brood of blood stage from parasites in a dormant liver stage termed (hypnozoite)

Question 29

Describe Black water fever?

Answer 29

• falciparum
• Patients with G6PD deficiency may develop this condition after taking oxidant drugs
• Bilious vomiting, prostration with the passage of dark red or blackish urine.
  
  • Massive haemolysis caused by anti-erythrocyte auto antibodies.

Question 30

Describe the two types of blood films done to test for malaria.

Answer 30

• Thick Film
  
  • Erythrocytes are lysed, releasing all blood stages of the parasite.
  • Allows diagnosis of low-level parasitaemias.
• Thin Film
  
  • Essential to confirm diagnosis
  • Id species of parasite
    
    • Quantify parasite load (counting percentage of infected RBCs)

Question 31

Prevention of malaria?

Answer 31

• Permethrin: treat clothing, netting, and gear. Lasts several washes and for several months.
• Mosquito netting: Bed nets

Question 32

Treatment options for malaria:

Answer 32

• Rehydration
• Monitor blood glucose and correct hypoglycemia
• Correcting severe anemia
• Correcting Acidosis
• Fever : Acetaminophen
• Monitor urine production.