Malaria Flashcards
What are the main reasons for the signifant reduction in malaria infection prevalence in Sub-Saharan Africa between 2000-2015?
Insecticide treated bednets
Effective chemotherapy
No vaccine as far
What are the ‘big three’ diseases that are important in World health?
HIV/AIDS
Malaria
Tuberculosis
These diseases receive the bulk of world funding for neglected diseases.
What control and treatment methods for malaria have become ineffective over time?
The widespread spraying of DDT, an insecticide, led to massive reduction in mosquito population. Over time mosquitoes developed resistance, health issues also arose.
Chloroquine (chemotherapy agent) effective treatment, mosquitoes now resistant.
What are artemisinins?
Artemisinins are a group of drugs that possess the most rapid action against Plasmodium falciparum malaria.
What does an infected mosquito inject into a human host?
The female mosquito injects sporozoites when it takes a blood meal.
These sporozoites infect liver cells and mature into schizonts.
What do sporozoites mature into?
Sporozoites, injected when a female Anopheles mosquito takes a blood meal, mature into schizonts in the liver cells they infect.
Briefly explain the malaria lifecycle stages that occur within the mosquito.
- A mosquito (female Anopheles) takes a blood meal from an infected human, ingesting gametocytes.
- In the mosquito midgut, the infected human RBCs burst, releasing the gametocytes.
- The gametocytes develop further into gametes.
- Male and female gametes fuse to form diploid zygotes which develop into actively moving ookinetes.
- The ookinetes burrow through the mosquito midgut wall and form oocysts on the other side.
- Growth and division of eeach oocyst produces thousands of active haploid forms, sporozoites.
- After 8-15 days. the oocyst bursts, releasing the sporozoites into the body cavity of the mosquito, from which they travel to, and invade the mosquito salivary glands.
- The cycle of reinfection starts when the mosquito takes a blood meal, inhecting the sporozoites from its salivary glands into the human blood stream.
How does a mosquito become infected with the Plasmodium falciparum parasite?
It takes a blood meal from an infected human host and ingests RBCs that contain gametocytes.
These gametocytes mature into gametes within the mosquito midgut.
What stage follows the fusing of the male and female gametes within the mosquito midgut?
The fused male and female gametes form diploid zygotes, these develop into actively moving ookinetes that burrow through the mosquito midgut and form oocysts on the other side.
What do ookinetes develop into?
Ookinetes develop into Oocysts when they burrow through the midgut wall.
What mosquito life cycle stage produces the sporozoites?
Sporozoites develop within the oocysts that are embedded in the midgut wall.
After 8-15 days the oocyst bursts, releasing sporozoites into the body cavity of the mosquito.
They travel to, and invade the mosquito salivary glands. The infection cycle restarts when a mosquito takes a blood meal. Injecting the sporozoites from its salivary glands into the bloodstream.
How long do the oocysts develop for before releasing sporozoites?
10-15 days.
When the sporozoites are released from the oocysts where do they travel to?
The sporozoites migrate to, and invade the mosquito salivary glands. The sporozoites are injected into a human host when the mosquito takes a blood meal.
What do sporozoites mature into?
Sporozoites travel to the liver and invade the hepatocytes. Over 5-16 days the sporozoites grow, divide and produce thousands of haploid forms, called merozoites
What are merozoites?
Sporozoites mature and develop into the haploid merozoites within the hepatocytes.
What do merzoites mature into?
Merozoites exit the liver cells and invade RBCs. Within the RBCs they mature into schizonts.
What happens to schizonts?
The mature schizonts rupture, releasing newly formed merozoites which can invade more RBCs.
If a merozoite infected RBC does not remain in the asexual cycle where does it go?
Some merozoite infected RBCs can leave the asexual cycle and the merozoites develop into male and female gametocytes.
How are the male and female malaria gametocytes produced?
Some merozoite infected RBCs leave the asexual cycle and instead develop into the sexual forms of the parasite, male and female gametocytes.
