BIO220H1 Lecture Notes - Lecture 24: Avian Malaria, Drug Resistance, Antimicrobial Resistance
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March 26th 2020
BIO220 LEC0101
BIO220 Lecture 24: Drug and Insecticide Resistance
Malaria
- Caused by protozoan parasite Plasmodium sp.
- Transmits by mosquitoes
- Fever, chills, anemia (loss of red blood cells)
Control
- Kill the parasite within us – drug treatments
- Kill the vector – mosquito control/eradications
- Decrease contact between humans and vector – bed nets
- Drug treatment
- First drug used to treat malaria is Chloroquine – 1930s
- Resistance then was detected in this drug use, the drug was not immediately
abandoned, when resistance is too wide spread, it stop becoming effective
- Many drugs in the past decades were used to treat malaria, but all of those drugs had
shown drug resistance
- What we use now is artemisinin – it is showing resistance in Cambodia
Why?
- Genetic variation in parasite
- Under drug treatment – they become more resistance and less sensitive to the drug, that
way they can better survive and compete better as other strains are killed by the drug
(taking advantage)
2) Eradicate mosquitoes I – larval stage
- When mosquitoes lay their eggs on the water – remove areas where mosquitoes can lay
their eggs
3) Eradicate mosquitoes II – Adult stage
- Reduce vector density and longevity
- Rapid killing with insecticide spray, and bed nets
Evolution of insecticides resistance in mosquitoes
- Avian malaria in France (Plasmodium relictum)
- Treatment with an organophosphate insecticide in 1968
- Not a major vector to humans, but it is to birds
- Treatment ended in 1990 because by 1978 resistance allele was common near the sea.
When the selection pressure was removed, the frequency of allele declined rapidly
Antibiotics and bacterial pathogens
- Antibiotic penicillin – discovered in 1929
- Antibiotics target biochemical process of bacteria
- Susceptible genotype is killed with antibiotics, but antibiotic resistance can emerge.
- If we increase the selection pressure, we should see an increase in response.
- Resistance increases with drug use