Rdt

RAPID DIAGNOSTIC TESTS FOR
MALARIA
Pospective study

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


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)
RDTs Test

Microscopy

Total

+ve

-ve

Positive

28

11

39

Negative

1

3

4

29

14

43

Total

11 cases of falciparum malaria missed by microscopy
were diagnosed by RDTs. But RDTs missed 1 case
diagnosed by microscopy.

OBSERVATION
When microscopy is considered as “gold standard ”, the
values for RDTs are:
Sensitivity
P.falciparum

Specificity
of RDTs
P.falciparum

96.55%

21.43%

PPV of
RDTs
P.falciparum

NPV of
RDTs
P.falciparum

71.79%

75%

of RDTs


OBSERVATION
RDTs in comparison to Microscopy
(Plasmodium vivax malaria)
RDTs TEST

MICROSCOPY

TOTAL

+VE

-VE

Positive

2

0

2

Negative

3

38

41

Total

5

38

43

No any case of vivax malaria missed by microscopy and
all were diagnosed by RDTs. But RDTs missed 3 cases
diagnosed by microscopy.

OBSERVATION

When microscopy is considered as “gold standard ”, the
values for RDTs are :

Sensitivity of
RDTs

Specificity of
RDTs

40%

100%
P.Vivax
malaria

PPV of RDTs

100%

NPVof RDTs
92.68%

OBSERVATION
Efficacy of RDTs Test (n=43)
RDTs Not
Diagnosed

RDTs Diagnosed

41

2

Microscopy
diagnosed

Microscopy Not
Diagnosed

34

9
CHI -SQUARE

χ2= 5.12
P < 0.05


OBSERVATION
RDTs

50
40

Microscopy

41
34

30
20

2

10

9

0

Diagnosed

Not Diagnosed

RESULT
 Over all Result from the Obervations found in the

present study :
 For P.falciparum Malaria :
False
+ve
11 cases

RDTs Diag.

39 cases
Microscopy
29 cases

False
–ve
1 case

For P.falciparum
Malaria

RESULT
 For P.vivax Malaria :

False
+ve
0 case

RDTs Diag.

2 cases
Microscopy

5 cases
False
–ve
3 case

For P.vivax

Malaria

RESULT
 For Total No. of cases, ie; n =43
Mixed
2 cases
P.Falciparum

P.Vivax

38 cases

3 cases
Total cases

43 cases
Of study
group

CONCLUSION
Efficacy of RDTs test

43

• Total Malarial cases
selected for present study

41

• Diagnosed by RDTs Test

34

• Diagnosed by Microscopy

CONCLUSION
Distribution of Plasmodium Species in Malaria cases
(diagnosed cases , n = 43)

38(88.37%)

•P. falciparum

3(6.98%)

•P. vivax

2(4.65%)

•Mixed


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.

THANKS……

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

RESULT
 Antigen detection test for P.falciparum & P.vivax by

Immunochromatographic dipstick assay is useful for
Rapid diagnosis of malaria, as in the present study.


Rdt

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