Malariais a protozoan disease caused by of Plasmodium. The female anophelesmosquito is the vector. Plasmodiumvivax, Plasmodium ovale, Plasmodium malariae,and Plasmodiumfalciparum. P. vivaxand P.falciparumare more common causes of malaria than are P.ovaleand P.malariae.Co-infection, which is the invasion of the body with a primarydisease, which is accompanied by another disease, is rare withmalaria.
Thereare two phases in the life cycle in the process of transmission ofmalaria. The sexual cycle in humans causes malaria transmission. Thesexual cycle, also called sporogonyresults in production of sporozoites. Introduction of sporozites fromthe mosquito saliva in humans is followed by their uptake byerythrocytes. P.vivaxand P.ovalehave a latent stage called hypnozites in the liver, responsible forrelapse of malaria. Other species do not cause relapse. Merozoitesare released from the liver cells and infect red blood cells wherethey develop to trophozoites. The ring form grows into an ameboidform and then differentiates into a schizont filled with merozoites,which infect erythrocytes. Release of merozoites causes malarialsymptoms of chills, fever, and sweats.
Malariais a big problem accounting for more than one million deaths annuallyworldwide. Malaria cases are increasing in the tropical andsubtropical Africa, Asia, South and Central America. Treatmentantimalarials like chloroquine, primaquine and artemisinins is themost effective way of fighting malaria. Newer drugs like Halofentrineare available. Malaria prophylactics do not mask the symptoms buthelp to prevent malaria contact. There is no malaria vaccine.Treatment is important for pregnant women to avoid transmission tofetuses. Sickle cell anemics confers immunity to malaria since thePlasmodia cannot survive in the sickle cells.
Levinson,Warren, and Ernest Jawetz. MedicalMicrobiology and Immunology: Examination and Board Review.Appleton & Lange, 1996.