Lecture 16 Flashcards
What is relapse in Malaria?
Seen in P. vivax and P. ovale
Caused by hypnozoites (dormant liver stage)
Can happen weeks or years after first infection
Prevented with liver-stage treatment (e.g. primaquine)
What is recrudescence in Malaria?
Seen in P. falciparum and P. malariae
No hypnozoites
Caused by low-level parasites remaining in blood
Can return if immune system weakens, even after treatment
Factors influencing severity of Malaria
- age
- absence of spleen
- previous exposure
- genetic characteristics
give 2 genetic characteristics influencing the severity of malaria
- sickle cell anemia: resistant to p. falciparum
- Duffy antigen mutations: immunity to p. vivax
How does Plasmodium avoid being eliminated by the immune system?
Plasmodium species express variant surface antigens
These change over time, helping them evade immune detection
How long does it take to build immunity to different Plasmodium species?
falciparum: ~2 years
P. vivax: ~5 years
P. malariae: up to 30 years
Which species cause relapse or recrudescence?
Relapse: P. vivax and P. ovale (due to dormant hypnozoites in liver)
Recrudescence: P. falciparum and P. malariae (due to persistent low-level infection in blood)
Diagnosis of Malaria
- Clinical diagnosis of symptoms in endemic areas
- stained blood smear
- antigen detection - rapid diagnostic test
- PCR: detects parasite DNA
- Serology (ELISA): antibody detection
Old treatments of Malaria
Quinine
Chloronine
Current treatments of malaria depend on what factors?
- availability
- severity
- age
- required speed of treatment
Treatment for p. falciparum
ACT
Atovaquone-proguanil
Treatment for P. vivax
kill schizonts: chloroquine
kill hypnozoites: primaquine
Why are Artemisinin not good options for prophylaxis
short-lasting
Prophylaxis for P. falciparum
Atovaquone proguanil
Prophylaxis for P. vivax and P. ovale
Chloroquine
High risk places to use prophylaxis
Sub-saharan Africa and Oceania
