Malaria: Life Cycle of Plasmodium vivax

1. Infected mosquito with sporozoites bites an uninfected human:

   • The infected female mosquito carries sporozoites in her salivary glands

   • Sporozoites enter the human’s bloodstream and travel to the liver

2. Asexual reproduction = Schizogony (in the liver):

   • 1 sporozoite divides into 8 merozoites in liver cells

   • Human = intermediate host (asexual part)
      

3. Merozoites leave the liver:

   • Released into the bloodstream, where they can infect RBCs
      

4. Merozoites in RBCs develop into the “ring form” 

   • Diagnosis of malaria = ring-formed merozoites in RBCs on a blood smear
      

5. More division → more merozoites:

   • The ring stage grows and divides inside the RBC

6. RBC ruptures → merozoites released:

• Causes symptoms: paroxysms (intermittent fever and chills)

• Released merozoites either infect new RBCs or become male and female gametocytes
   

7. Uninfected mosquito takes a blood meal from the infected human:

   • It takes in the gametocytes, which go to the mosquito’s GI tract
      

8. Male and female gametocytes unite in the GI tract → zygote:

   • Sexual reproduction: mosquito = definitive host

9. Zygote becomes sporozoites → travel to the mosquito’s salivary gland:

   • This lets them get passed to the next human at the next blood meal (they’d be useless if they stayed in the GI tract)