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Download Plasmodium spp.
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Malaria • Caused by Plasmodium spp. – Protist • Female Anopheles mosquito feed on human blood and acts as a ‘vector’ for the parasite – Transfers it between humans • May also be transferred by: – Blood transfusions – Unsterile needles – Across the placenta from mother to a foetus Plasmodium life cycle • Mosquito takes up some of the parasite’s gametes from an infected person • Pass into the next human with anti-coagulant in saliva of mosquito • Enters red blood cells of human • Multiplies in human and in mosquito Life Cycle Plasmodium Infected Red Blood Cells Features of Malaria Occurence Immunity • May become immune if continually reinfected – Have to survive first five years of infection • Epidemics where malaria is not endemic are very dangerous – And where outbreaks after the rainy season Controlling Malaria 1. Reduce number of mosquitoes 2. Avoid being bitten 3. Drugs to prevent the parasite infecting people Kill Mosquitoes • Spread oil on water which mosquitoes breed in – Prevents larvae from getting oxygen from the surface • Drain marshes • Add fish which eat mosquito larvae to ponds etc. • Spray with bacterium which kills mosquito larvae Avoid being bitten • Nets • Insect repellent • Soak nets in insecticide • Cover skin at dusk • Sleep with a dog or a pig! Drugs • Treat infected people and as prophylactic (preventative) • Quinine • Chloroquine – Prevents parasite spreading by inhibiting protein synthesis • Plasmodium may develop resistance – Eg widespread chloroquine resistance – Use Mefloquine instead, but: • Expensive & side effects: dizziness, vomiting, disturbed sleep At Risk • Visitors to countries • Misdiagnosed in other countries (‘flu) • Immigrants who visit relatives – Immunity is lost Eradication Attempt • 1950’s, World Health Organisation • Unsuccessful, because: – Resistance by Plasmodium – Resistance by mosquitoes (eg to DDT) • Immunity lost and resulted in deaths when the disease returned • Expensive • Insecticides killed wasps which ate caterpillars which eat thatched roofs • Programme did not involve indigenous people Concern • • • • • • Increase in resistance of Plasmodium Increase in worst species, P. falciparum Climate change favours outbreaks Increased migration (due to wars) No vaccine available One of world’s biggest health threats Progress…. • Improve diagnosis eg ‘dipstick’ test • Supply effective drugs – Eg Genome sequencing of plasmodium to find vaccine • Use drug combos to reduce resistance • Prevent transmission
