presentation on laboratory diagnosis of malarial parasite - microbiology

1. Laboratory Diagnosis
1. Microscopic tests –
(a) Peripheral Blood Smear – gold
standard confirmatory test
(i) Thick smear – useful in detecting
the parasites, Quantification of
parasitemia, demonstrating the malarial
pigments.
(ii) thin smear – useful in speciation
of malarial parasite based on detection of
ring forms, schizont, gametocytes, types of
pigment and RBC size.

3. (b) Fluorescence Microscopy –
Kawamoto technique
Steps - Blood smears are prepared – stained with acridine orange –
examined under a fluorescence microscope.
Nuclear DNA is stained green.
(c) Quantitative Buffy Coat examination –

4. Advantages – faster, more sensitive and
quantification is possible.
Disadvantages – expensive, less specific and
speciation is difficult.
2. Non – Microscopic Test –
(a) Antigen Detection by RDT –
Interpretation is based on immobilization of
malarial antigens at test lines 1 and/or 2
forming colored bands.
1. If band is formed at only test line 1: indicates
P.
falciparum infection
2. If band is formed at only test line 2: indicates
Plasmodium species other than P. falciparum
infection

5. 3. If bands are formed at both test lines 1 and
2: indicates P. falciparum or mixed infection.
Note: The band at control line must come to
validate the test; if it does not come, test is
considered invalid. Control line is coated with
antibody against polyclonal malarial antibody
present in buffer.
 Ab detection tests – banned
 Automated systems – Parasite F digital
cytometry, automated microscopy methods
 Non – specific tests – normocytic hemolytic
anemia, leukopenia, raised ESR, metabolic
acidosis, hypoglycemia.