Malaria diagnosis Flashcards
(17 cards)
Name the 6 types of diagnosis method.
1) Clinical diagnosis
2) Microscopy
3) Quantitive buffy coat (QBC)
4) Antigen detection
5) RT-PCR
6) Antibody detection
1) Clinical diagnosis
fever followed by:
a) cold stage
b) hot stage
c) sweating stage
2) Microscopy
~ perform blood smear (detect sp. + count no.)
~ two types: thick + thin
3) Quantitive buffy coat (QBC)
a) add acridine orange (fluorescent dye)
b) parasite seen between RBC layer + granulocytes in buffy coat
4) Antigen detection
~ rapid detection tests
e.g. Paracheck pf + BinaxNOW
5) RT-PCR
plasmid controls for all 4 species + run against sample to determine sp. of Plamodium
6) Antibody detection
e.g. ELISA + IFAT
Sweating stage
increased sweating causes decrease in temp
Thick film
sensitivity = proportion of true +ves
Thin film
specificity = proportion of true -ves
Paracheck pf
~ detects HRP2 = protein synthesised by P. falciparum
~ as sensitive as microscopy at detecting true malaria cases
BinaxNOW
detects HRP2 (P.f) + aldose (panmalarial antigen)
ELISA
a.k.a. enzyme-linked immunosorbent assay
~ antigens used to qualify parasite-related antibodies
~ doesn’t indicate state of infection - could be from previous infection
IFAT
a.k.a. indirect fluorescence antibody test
~ fluorescent antibodies used to test for specific antibody
~ expensive + used before ELISA available (now outdated)
Laboratory diagnosis
~ RT-PCR
~ ELISA/IFAT
~ Microscopy/QBC
~ requires laboratory, infrastructure + trained staff
Field diagnosis
~ Paracheck pf
~ BinaxNOW (results in 15mins) - uses fingerstick blood collection
~ easy to interpret + no trained staff needed
What is the limitation of Paracheck pf?
frequent false positive results –> could could resistance to treatment
