Plasmodium

^[1]^[2]^[3]

Epidemiology

Plasmodia undergo a sexual phase (sporogony) in Anopheles mosquitoes & an asexual phase (schizogony) in humans
sporogony (in mosquitoes) results in formation of infectious sporozoites
schizogony within the vertebrate host results in formation of schizonts & merozoites
within female Anopheles mosquitoes
- gametocytes form macrogametes & microgametes within the stomach of the mosquito
- fusion of a microgamete with a macrogamete results in formation of a motile ookinete
- the ookinete migrates outside the stomach wall & forms an oocyst
- within the oocyst, numerous sporozoites are formed
- the mature oocyst ruptures into the body cavity releasing sporozoites
- sporozoites migrate throught the tissues to the salivary glands
- sporozoites are injected through the saliva into the vertebrate host
- development within the mosquito ranges from 8-21 days
within the vertebrate host
- sporozoites injected into the vertebrate host invade hepatocytes
- schizogony within hepatocytes begins within minutes
- release of merozoites from ruptured hepatic schizonts initiates bloodstream infection
- merozoites penetrate erythrocytes to form trophozoites (ring forms) which mature to form mature trophozoites (growing form)
- schizogony within erythrocytes occurs with schizont (dividing) forms & results in release of merozoites with rupture of the host erythrocyte to re-initiate the cycle
- some merozyoites eventually develop into gametocytes
- gametocytes are ingested by female Anopheles mosquitoes

↑ Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 1260-64
↑ Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 1180-89
↑ ^3.0 ^3.1 ARUP Consult: Plasmodium Species - Malaria The Physician's Guide to Laboratory Test Selection & Interpretation https://www.arupconsult.com/content/plasmodium-species