Plasmodium sp. Flashcards
What are the strains of Plasmodium which affect humans?
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium malariae
- Plasmodium ovale
What is the first step in the plasmodium life cycle?
Sporozoites from salivary gland of female anopheles mosquito are inoculated during a blood meal into blood stream.
What happens once Sporozoites from Anopheles enter the blood stream?
Rapidly invade hepatic parenchymal cells
What happens to sporozoites once they invade liver parenchymal cells?
2 alternative pathways of differentiation are possible:
1) Sporozoites mature into shizont, which contains many merozoites
- or-
2) Goes into a dormant phase (Ovale and vivax only) which is then called a hypnozoite
What happens once merozoites formed in the liver cells are released into the bloodstream in Plasmodium spp?
-They attach to and invade circulating erythrocytes
Over what time frames do the various species of Plasmodium take to develop once inside the RBC?
- 48 hrs: P. falciparum, P. vivax, P. ovale
- 72 hrs: P. malariae
Regarding the Plasmodium lifecylce, describe the general morphological changes that occur within an RBC.
- Changes from ‘ring form’ to trophozoite and finally to shizonts containing daughter erythrozoite merozoites.
- Liberated by red cell lysis and immediately invade uninfected RBC’s. producing repetitive cycle.
In regards to the Plasmodium lifecycle, how is the P. vivax and P. ovale erythrocytic cycles different from the other plasmodium species?
Both of their erythrocytic cycles are synchronous and erythrozoite lysis and merozoite release occurs at the same time of day for the duration of the infection.
In regards to the developmental cycle of plasmodium spp, besides continuing the cycle by attacking other RBC’s, Merozoites released from the Erythrocytic shizont may also what?
-Undergo a different developmental pathway and develop into male and female gametocytes. (development and morphology changes between species)
Regarding the life cycle of Plasmodium, what is taken up by a new feeding mosquito to continue the cycle?
Gametocytes
Regarding the plasmodium life cycle, what happens after a mosquito takes in gametocyte?
- Mosquito midgut -> male & female gametocytes liberated and fused to form zygote
(male gametocyte = microgamete; female gametocyte = macrogamete)
Regarding the plasmodium life cycle, what happens to the zygote inside the mosquito’s midgut?
-Develops into an ookinete which is able to penetrate the gut wall and form an oocyst.
Regarding the plasmodium life cycle, what happens after the oocyst is formed?
-Asexual multiplication occurs and sporozoites are formed which migrate to the salivary gland and complete the life cycle.
How many days does it take for sexual reproduction to occur while in the gut of the vector for Plasmodium falciparum?
5 days (faster in heat)
How long does the exoerythrotic shizont cycle last in the liver for Plasmodium falciparum?
8 days
