Malaria Flashcards
What are the factors that contribute to the burden of Malaria?
- Drug resistance (malaria)
- Insecticide resistance (vector)
- Wars and civil disturbance
- Environmental changes
- Travel
- Population increase
- Pandemic
What is it transmitted by
Anopheles mosquitoes
(others: transfusion, congenital, lab-acquired)
What is the phylum?
Apicomplexa
What parasites cause?
Intracellular parasites (Plasmodium, Toxoplasma, Cryptosporidum)
Describe Plasmodium life cycle
Sporozoite in mosquito -> Merozoite in liver -> Asexual forms in RBC/Sexual forms - Gametocytes in RBC -> Mosquito
What causes the disease?
Development of Plasmodium spp. within host red blood cells
What diagnosis to take from patient?
Clinical, travel history, presence of parasites in peripheral blood
What Plasmodium spp.?
P.falciparum, P.vivax, P.malariae, P.ovale, P.knowlesi
What is the aim of blood examination for malaria parasites?
- If patient is infected
- Level of infection
- Which is the infected species
What are the laboratory diagnostic methods?
- Rapid diagnostic test
- Microscopic examination of blood films
- Nucleic acid amplification test
Describe the use of microscopy to diagnose
- Thin and thick blood smear + staining
- Gold standard
+ve: simple, cheap, sensitive, specific, quantitative
-ve: time consuming, laborious, requires trained personnel
What is the biosafety of laboratory diagnosis?
Pathogens (Hepatitis B, HIV) potentially found in blood
What does thick smear and thin smear detect?
Thick - presence of parasite
Thin - Malaria species
What is the Giemsa staining procedure?
- Make smear
- Fix in methanol (only for thin smear) for 30s
- Add Giemsa stain 5% stock in buffered water pH 7.2 for 20 minutes
- Flush with tap water
- Dry and observe under oil immersion (x100)
Describe the use of thick blood films and how do parasites appear
- Acts as concentration method
- Trophozoites: streaks of blue cytoplasm with detached nuclear dots
- Broken or irregular rings as commas, swallows, exclamation marks
- Schizonts and gametocytes retain normal appearance