Lecture Notes: Malaria
Introduction
- Malaria is one of six diseases being discussed.
- Caused by Plasmodium, a unicellular eukaryotic organism (it has a true nucleus, organelles).
- it is often referred to as a parasite because it benefits itself but it harms the host.
Causative Species
- Four primary species causing malaria in humans:
- Plasmodium falciparum (75% of cases)
- Plasmodium vivax (20% of cases)
- Plasmodium malariae
- Plasmodium ovale
- Note: the appearance of this plasmodium changes depending on life cycle stages
-Plasmodium is most motile during initial infective stages they have this slender shape here in order to move quickly through the bloodstream.
Transmission
-A vector is an organism that carries a disease from a person to another/from an animal to a human
- insect vector: Female Anopheles mosquitoes because only females take blood meals to supply eggs with nutrients
- Can also be transmitted through blood transfusions, use of unsterile needles, and although rarely from mother to child across the placenta.
- Malaria spreads because females takes a blood meal from infected person and then takes a blood meal from uninfected person.
Life Cycle Stages
- Different stages similar to a butterfly's life cycle.
-1. Plasmodium's gametes fuse, multiplies in and form infective stages in mosquitoes
When mos takes a blood meal, parasite enters host with mosquito's anticoagulant and saliva, through saliva the parasite will enter the host together with the survivor
- Infective stages of parasite enter bloodstream and then liver cells
- Parasite matures in liver cells, then leaves liver to enter RBCS
- Parasites multiply in RBCs, causing RBCs to lyse
- Parasites are released and infect other RBCs
- Parasites picked up by another mos in a blood meal
Symptoms
- Common symptoms include:
- Fever
- Anemia (due to lysing of red blood cells)
- Nausea, headaches, muscle pain, shivering, sweating, enlarged spleen.
Diagnosis
- Microscopic analysis of blood or rapid antigen dipstick test.
Treatment
- Use of anti-malarial drugs:
- Quinine, Chloroquine, Artemisinin (found through Chinese herbal medicine).•
- Proguanil inhibits sexual reproduction of Plasmodium in the mosquitoes
- Drugs prevent protein synthesis, replication, or reproduction in mosquitos.
- Combination therapy to prevent drug resistance.
Prevention
- No vaccine available.
- Prophylactic drugs (e.g., Chloroquine).
- Reduce mosquito population:
- Insecticides, breeding fish that eat larvae, etc.
- Prevent mosquito bites with nets, repellents.
Global Distribution
- Malaria mostly found near the equator (tropical and subtropical regions).
-WHY...
-The vector, the Anopheles mosquito, survives and breeds in hot and humid areas
• Needs still/stagnant water to reproduce
• Plasmodium reproduces within the mosquito at >20°C
• Eradicated outside tropics (e.g. USA, Italy)
Challenges
- **Other Problems:
• Drug-resistant Plasmodium (e.g. chloroquine)
• Insecticide-resistant mosquitoes (e.g. DDT)
– DDT is most common insecticide
– Insecticides used also killed other organisms
– Reduction in mos also caused lost in immunity to malaria in
local community, making them more vulnerable when the
diseased returned.
• Global warming has resulted in spread of mos
– More warm areas for mos to breed and survive
Conclusion
- Ongoing fight against malaria due to evolving challenges.
- Importance of education and