2. 40% of the world’s population lives in
endemic areas
3-500 million clinical cases per year
1.5-2.7 million deaths (90% Africa)
increasing problem (re-emerging
disease)
• resurgence in some areas
• drug resistance ( mortality)
• causative agent = Plasmodium species
• protozoan parasite
• member of Apicomplexa
• 4 species infecting humans
transmitted by anopholine mosquitoes
• P. falciparum
• P. vivax
• P. malariae
• P. ovale
3. It is minute, slightly curved, sickle
shaped, uninucleated organism 11 to 12
U length and 0.5 to 1 u in width.
Motile, vibratory movement, it is
covered with firm, elastic, thin cuticle
called pellicle.
Body is elongated slightly swollen in
the centre and tapering towards the
both ends.
Accessory organelles.
Structure of Sporozoite of P. vivax
Fig 1: Structure of Sporozoite of P. vivax
4. Bird and Backer (1963).
Pellicle with 3 layers containing longitudinally
arranged contractile microtubules are in 11.
Responsible for wriggling movement of the body.
Anterior Cup like depression called apical cap
having 3 contractile ring .
A pair of long narrow, secretary, organelles open
into apical cap.
They secrets proteolytic enzymes which facilitate
entry of sporozoites in to liver cell
Many convoluted tubules are present but
unknown function
Micropyle contain the malarial parasites
containing organelles
5.
6.
7. Life Cycle
sporozoites injected during mosquito
feeding
invade liver cells
exoerythrocytic schizogony (merozoites)
merozoites invade RBCs
repeated erythrocytic schizogony cycles
gametocytes infective for mosquito
fusion of gametes in gut
sporogony on gut wall in hemocoel
sporozoites invade salivary glands
Transmission
sporozoites injected with saliva
enter circulation
trapped by liver (receptor-ligand)
Female Anopheles mosquito
10. Gametocytogenesis
• alternative to asexual replication
• induction factors not known
• ring gametocyte
• sexual dimorphism
• microgametocytes
• macrogametocytes
• no pathology
• infective stage for mosquito
• occurs in mosquito gut
• exposure to air induces
• gametoctye activating factor in mosquito
11. Sporogony
occurs in mosquito (9-21 d)
fusion of micro- and macrogametes
zygote ookinete (~24 hr)
ookinete transverses gut epithelium ('trans-invasion’)
ookinete oocyst
between epithelium and basal lamina
asexual replication sporozoites
sporozoites released
sporozoites migrate through hemocoel
sporozoites 'invade' salivary glands