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MALARIA
• A vector-borne infectious disease
• Caused by protozoan parasites of the genus Plasmodium
• Plasmodium falciparum and Plasmodium vivax
• P.ovale, P.malariae and P.knowlesi
• Transmitted by female Anopheles mosquitoes
• Parasites multiply within RBCs• Transmission reduced by
– preventing mosquito bites with mosquito nets– insect repellents– spraying insecticides inside houses– draining standing water where mosquitoes lay
their eggs.
SYMPTOMS• Symptoms: Anemia, fever, chills &
shivering, joint pain, nausea & vomiting, hemoglobinuria.
• If severe, coma & death.• Classical symptom
– Cyclical occurrence of sudden coldness followed by rigor, fever and sweating lasting 4-6 hours, occurring
• every 2 days in P. vivax and P. ovale infections• every 3 days for P. malariae• every 36-48 hours for P. falciparum or almost
continuously.
PATHOGENESISof malaria in humans
• 2 phases– Exoerythrocytic (hepatic)– Erythrocytic phase (RBC)
• An infected mosquito pierces a person's skin to take a blood meal
• Sporozoites in mosquito's saliva enter the bloodstream and migrate to the liver.
• Within 30 min, they infect hepatocytes• Asexual multiplication • No symptoms for 6 – 15 days• Differentiate to yield thousands of merozoites• Rupture or burst of the host cells• Merozoites escape into bloodstream• Infection of RBCs
• Sporozoites are cells that develop in the mosquito's salivary glands and enter the liver where they multiply.
• Merozoites are daughter cells of a protozoan parasite, that result from asexual reproduction.
• Some P. vivax and P. ovale• No immediate conversion of sporozoites into
merozoites• Produces hypnozoites that remain dormant for
6–12 months to as long as 3 years• After dormancy, they reactivate and produce
merozoites. • Hypnozoites are responsible for late relapses of
malaria.
VACCINE
• No vaccine currently available for malaria
• Chloroquine
• Quinine
• Amodiaquine
• Artemisinin
• Propranolol: – Blocks both Plasmodium's ability to enter red
blood cell and establish an infection, as well as parasite replication.