High-Yield Levinson Microbiology: Blood & Tissue Protozoa (Plasmodium)

Important properties of plasmodium

Diseases:

1. P. vivax
2. P. ovale
3. P. malariae
4. P. falciparum

Host and transmission:

 Definitive host  female anopheles mosquito
 Intermediate host  humans
Life cycle:
1. Sexual cycle or sporogony in mosquito
2. Asexual cycle, schizogony in humans
3. First sporozoites inject from mosquito to human and invade hepatocyte
(exoerythrocytic phase)
4. Multiply and form merozoites
5. Merozoites are released in blood and infect RBCs (erythrocytic phase)
6. Ring shaped trophozoites develop to schizonts that rupture and
destroy RBCs.
Pathogenesis and clinical features:
 Periodic synchronized release of merozoites from RBCs  recurrent
symptoms of fever, chills, sweats.
 P. vivax and ovale produce a latent form in liver, hypnozoite
 Hypnozoite is responsible for relapses of malaria

p. falciparum severity:
 Cause most severe and life threatening malaria
 This is because RBCs of all ages are infected
 Parasitized RBCs aggregate adnd occlude capillaries  cerebral edema
 Kidney damage with hemoglobinuria  blackwater fever
 P. falciparum gametocytes are crescent or banana shaped.

Human resistance against malaria if:
 Sickle cell trait
 G6PD deficiency
 Lack of duffy blood group antigen

Toxoplasma:
1. Disease caused