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 hours for P. falciparum or almost continuously.

PATHOGENESIS of 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 merozoitesmerozoites 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.