Parasitology Flashcards
Life Cycle of Malaria: Asexual phase?
In man ( also called, vertebrate, intrinsic or endogenous phase)
Life Cycle of Malaria: Sexual phase?
In Mosquito (also called invertebrate, extrinisc, or exogenous phase.
What is the process of Parasite multiplication by division or splitting in the vertebrate host?
Schizogony
Two forms of Schizogony?
- RBC - Erythrocytic schizogony.
- Liver Cells: Exo erythrocytic schizogony, or tissue phase, or pre-erythrocytic schizogony.
What does the process of schizogony result in ?
Merozoites
Describe the Pre-erythrocytic phase
- 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.
- Several daughter cells inside host cell
- Within 5-15 days the schizont become mature and bursts, releasing thousands of merozoites. They enter red blood cells by invagination.
What is the interval between the entry of the sporozoites into the body and the first appearance of the parasite in the blood called?
Pre-patent period.
Merozoites use what receptor to invade RBC?
-
Glycophorin, which is a major glycoprotein for RBCs.
- Enter RBCs by Endocytosis.
When stained with giemsa stain, what does the merozoite look like?
Red = nucleus
Blue = Cytoplasm
Central Vacuole = unstained.
What is the parasite stage when in the erythrocyte called?
Ring form
Vector for malaria?
Female Anopheles mosquito
What is the infective form and where is it in the vector?
Sporozoites and are present in the salivary gland
Malaria sexual multiplication is called ? and results in ?
Sporogony and sporozoites.
Merozoites differentiate in the human host in what way?
Become male or female gametocytes
When the mosquito takes up a blood meal containing the gametocytes what occurs next?
Oocysts are formed in the mosquitos gut, and sporozoites develop.
Eruption of merozoites from RBC occurs in a synchronized fashion that causes severe symptoms, what is the name of this episode.
Short-term relapses or Recrudescence.
In p. falciparum recrudescence are seen when?
for 1 to 2 years.
In p. malariae recrudescence occurs for how long?
up to 30 years.
Describe how the malaria pigment is formed?
Parasite feeds on hb of the rbc, and doesnt metabolize it completely leaving some behind.
P. vivax pigment?
fine golden brown dust like particles
P. falciparum pigment?
Few 1-3 solid blocks of black pigment
P. malariae pigment?
numerous coarse, dark brown particles.
P. ovale pigment?
Numerous blackish brown particles.
P. falciparum unique traits
Most likely to become severe
Fatal forms with CNS involvement
Renal failure & anemia and acute respiratory distress.
P. malariae unique traits?
Can last 30 years
Lead to nephrotic syndrome, and hypersplenism.
P. vivax and p. ovale unique traits?
May relapse for 5 years.
P. Vivax includes splenomegaly.
Incubation period for the 4 types of malaria?
- P. vivax and ovale - 14 days
- P. falciparum 9-12 days
- P. malariae - 30 days
How does relapse occur after therapy has concluded?
Release of new brood of blood stage from parasites in a dormant liver stage termed (hypnozoite)
Describe Black water fever?
- 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.
Describe the two types of blood films done to test for malaria.
-
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)
Prevention of malaria?
- Permethrin: treat clothing, netting, and gear. Lasts several washes and for several months.
- Mosquito netting: Bed nets
Treatment options for malaria:
- Rehydration
- Monitor blood glucose and correct hypoglycemia
- Correcting severe anemia
- Correcting Acidosis
- Fever : Acetaminophen
- Monitor urine production.
