Rdt

RAPID DIAGNOSTIC TESTS FOR
MALARIA
Dr. PRABHASH KUMAR
Deptt. Of Pediatrics,
J.L.N.H R.C.,Bhilai Steel Plant.
www.dnbpediatrics.com

AIMS AND OBJECTIVES
 To Evaluate the usefulness of the rapid diagnostic
test(RDTs) for diagnosis of Malaria.
 To compare RDTs with microscopic examination for the
diagnosis of Malaria.

INTRODUCTION
 Malaria is the most common serious parasitic disease
of human beings, killing one person every 12
seconds.The majority of these deaths being seen in the
pediatric age group and pregnant women
 Microscopy - the “Gold standard” for diagnosis of
malaria, but requires up to 60 minutes for reporting of
result.
 Poor result particularly at low levels of parasitemia and
requires expertise for interpretation.

INTRODUCTION cont….
The Immunochromatographic test(RDTs) for malaria -
introduced in the early 1990s
RDTs tests capture the parasite antigens from the
peripheral blood using either monoclonal or polyclonal
antibodies against the parasite antigen targets.
 Currently, RDTs tests can target :
 the histidine-rich protein 2 of P. falciparum(PfHRP2)
 the parasite specific lactate dehydrogenase(pLDH).

INTRODUCTION cont….
 If both microscopy and rapid diagnostic tests are
used concurrently, they contribute to each other. In
remote areas where trained staffs are not available to
do microscopy and in severe malaria e.g. cerebral
malaria, where we need urgent diagnosis, RDTs are
very useful.
 So, the present study aims to evaluate the usefulness
of RDTs as compare to microscopy for detection of
malarial parasite.

MATERIAL AND METHOD
 STUDY AREA :
Department of Pediatrics, JLN Hospital & Research
Centre, Bhilai, CG.
 STUDY POPULATION:
All patients in the age group upto 14 years admitted to
the paediatric wards and PICU on suspicion of malaria.
 SAMPLE SIZE :
Study group consisted of 43 cases diagnosed as
malaria based on either on microscopy and / or +ve
RDTs test.

MATERIALS AND METHODS
STUDY PERIOD :
From Aug.’2008 to Feb.’2010.
STUDY DESIGN:
Prospective and Comparative study.
STATISTICAL ANALYSIS:
 Chi square test (χ2 )

MATERIALS AND METHODS
 SELECTION OF CASES
 INCLUSION CRITERIA:
Patients with any of the following clinical features
were included in the study group :
Acute febrile illness with or without chills or rigor.
Acute febrile illness with -
 altered sensorium.
 jaundice or pallor.
 oliguria.
 seizures.
splenomegaly or hepatomegaly
Atypical presentations with suspected malaria.

RAPID DIAGNOSIS OF MALARIA BY RDTs
TEST KIT

Immunochromatographic dipstick Assay for Malaria

BAND INTERPRETATION OF RDTs
TEST
The PfHRP2 test strips have 2 lines, I for the control
and the other for the PfHRP2 antigen
 The pLDH test strips have 3 lines, 1 for control, and
the other 2 for P. falciparum (PfHRP2 or pLDH
specific for P. falciparum) and non-falciparum
antigens (pan specific pLDH), respectively.
 Change of color on the control line is necessary to
validate the test and its non-appearance, with or
without color changes on the test lines, invalidates
the test.
 With color change only on the control line and
without color change on the other lines, the test is
interpreted as negative www.dnbpediatrics.com

INTERPRETATION OF THE
RDTs TEST
o FALSE POSITIVE :
gametocytemia, with no persistent viable asexual-
stage parasitemia.
persistence of antigens due to sequestration.
delayed clearance of circulating antigen (free or in
antigen-antibody complexes).
 cross reaction with non-falciparum malaria or
rheumatoid factor.

INTERPRETATION OF THE RDTs TEST
 FALSE NEGATIVITY:
genetic heterogeneity of PfHRP2 expression.
deletion of HRP-2 gene.
presence of blocking antibodies for PfHRP2 antigen
or immune-complex formation.
prozone phenomenon at high antigenemia.

OBSERVATION
The observations made during the course of study are
presented here :

OBSERVATION
Distribution of Plasmodium species in Malaria
cases (In species diagnosed cases) (n=43)
P.falciparum
P.vivax
Mixed
• 38cases
• 88.37%
• 3 cases
• 6.98%
• 2 cases
• 4.65%

,
Distribution of Plasmodium species in Malaria cases

OBSERVATION
RDTs in comparison to Microscopy
(Plasmodium falciparum malaria)
11 cases of falciparum malaria missed by microscopy
were diagnosed by RDTs. But RDTs missed 1 case
diagnosed by microscopy.
RDTs Test Microscopy Total
+ve -ve
Positive 28 11 39
Negative 1 3 4
Total 29 14 43

OBSERVATION
When microscopy is considered as “gold standard ”, the
values for RDTs are:
Sensitivity
of RDTs
P.falciparum
96.55%
Specificity
of RDTs
P.falciparum
21.43%
NPV of
RDTs
P.falciparum
75%
PPV of
RDTs
P.falciparum
71.79%

OBSERVATION
RDTs in comparison to Microscopy
(Plasmodium vivax malaria)
No any case of vivax malaria missed by microscopy and
all were diagnosed by RDTs. But RDTs missed 3 cases
diagnosed by microscopy.
RDTs TEST MICROSCOPY TOTAL
+VE -VE
Positive 2 0 2
Negative 3 38 41
Total 5 38 43

OBSERVATION
When microscopy is considered as “gold standard ”, the
values for RDTs are :
Sensitivity of
RDTs
40%
Specificity of
RDTs
100%
PPV of RDTs
100%
NPVof RDTs
92.68%
P.Vivax
malaria

OBSERVATION
Efficacy of RDTs Test (n=43)
RDTs Diagnosed
41
RDTs Not
Diagnosed
2
Microscopy
diagnosed
34
Microscopy Not
Diagnosed
9
CHI -SQUARE
χ2= 5.12
P < 0.05 www.dnbpediatrics.com

OBSERVATION
0
10
20
30
40
50 41
2
34
9
Diagnosed Not Diagnosed
RDTs Microscopy

RESULT
 Over all Result from the Obervations found in the
present study :
 For P.falciparum Malaria :
False
+ve
11 cases
False
–ve
1 case
RDTs Diag.
39 cases
Microscopy
29 cases
For P.falciparum
Malaria

RESULT
 For P.vivax Malaria :
False
+ve
0 case
False
–ve
3 case
RDTs Diag.
2 cases
Microscopy
5 cases
For P.vivax
Malaria

RESULT
 For Total No. of cases, ie; n =43
Total cases
43 cases
Of study
group
P.Falciparum
38 cases
Mixed
2 cases
P.Vivax
3 cases

CONCLUSION
Efficacy of RDTs test
• Total Malarial cases
selected for present study43
• Diagnosed by RDTs Test41
• Diagnosed by Microscopy34

CONCLUSION
Distribution of Plasmodium Species in Malaria cases
(diagnosed cases , n = 43)
•P. falciparum38(88.37%)
•P. vivax3(6.98%)
•Mixed2(4.65%)

CONCLUSION
 RDTs is an effective, simple, sensitive, specific and rapid
(within 20 minutes) test for diagnosing malaria especially in
falciparum malaria where immediate diagnosis and
management is required.
 Thus, availability of a simple, rapid and accurate test could
greatly aid in the early diagnosis of malaria including in
remote areas.
 RDTs is significantly better than microscopy in diagnosis of
malaria.
 The best approach for diagnosis of malaria would be the
combination of RDTs and microscopy.

RAPID DIAGNOSIS OF MALARIA
ABSTRACT……
Malaria is a resurging problem all over the country and
rapid diagnosis is mandatory to decrease the morbidity
and mortality.
Sensitivity & Specificity of RDTs evaluated and compared
with test with peripheral blood smear examination which
is the “gold standard ”.
RDTs diagnosed 41 cases out of 43 cases ultimately
diagnosed to have malaria and Microscopy diagnosed 34
cases. Out of these 43 cases diagnosed , 38 cases was
of P.falciparum, 2 cases was of P.vivax and 2 cases was
of mixed of both( which were ultimately taken as cases of
P.falciparum as RDTs.

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