BOF: 11
A 32-year-old male has
returned from a holiday in Gambia six weeks ago.
He presents with fever, chills and rigors and on clinical examination is found
to have an enlarged spleen.
Initial thin film examination for malarial parasites is negative.
You are aware that local experience and expertise in diagnosing malaria is not
adequate
As the clinical suspicion of malaria is very high in this patient, what would
your next course of action be?
a) Repeat
the thin film examination in 48 hours
b) Do a
thick film examination
c) Do a
dipstick assay of Plasmodium Lactate dehydrogenase (pLDH)
d) Give
empirical treatment for malaria
e) Repeat
thick and thin films in 72 hours
Answer:
c)
In patients with malaria,
examination of a thin film is useful for making the diagnosis of the
particular type of malaria and assessing the degree of parasitaemia.
However, this depends on local expertise.
If an initial film is negative it is best to repeat the test in 12 hours and
then again in 24 hours if still negative.
Thin films are more sensitive than thick films but this depends on the
expertise of the person performing the examination.
Dipstick assay is available for detection of all four types of malaria.
The assay can differentiate between P.falciparum and P.vivax
The test is an antigen detection system for Plasmodium Lactate Dehydrogenase
(pLDH)
p LDH is an abundant intracellular enzyme produced by malarial parasites.
The dipstick is coated with monoclonal antibodies against this intracellular
metabolic enzyme pLDH.
The test is effective, sensitive and may be performed rapidly.
It has almost the same sensitivity as examination of a thick film by an
expert.
It should be used as a supplement to thin film examination where expertise is
lacking.
Revision Tip
Revise malaria
KEYS to SUCCESS in Medicine page 559-561
