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Evaluation Of The Efficacy Of The Carestart Malaria HRP2 And PLDH/HRP2…
Evaluation of the
efficacy of the Carestart Malaria HRP2 and pLDH/HRP2 Combo compared to
microscopy in the diagnosis of malaria. (Microbiology)
CHAPTER ONE
1.0 INTRODUCTION
Malaria is a life-threatening illness, that
has continued to pose public health challenges. It affects millions of people
all around the globe especially, in Africa, Asia and South America. Malaria is
currently endemic in over 100 countries with 3 billion people at risk of
infection and around 225 million cases in 2009, leading to approximately
781,000 deaths (WHO, 2010). Malaria has remained a major public health problem in Nigeria,
and is responsible
for 30% childhood and 11% maternal mortality (FMoH, 2005). It accounts for
300,000 deaths each year and about 60% of outpatient visits (President’s
Malaria Iniative, 2011). Together
Nigeria, and the Democratic Republic of Congo account for over 40% the
estimated total malaria burden and deaths globally (WHO, 2012). It
is caused by the asexual form of the parasitic protozoan know as Plasmodium. The species incriminated arePlasmodium
falciparum, Plasmodium vivax, Plasmodium malariae, and
Plasmodium ovale which is found
humans and Plasmodium knowlesi which found in non-humans. Among
these parasites, Plasmodium falciparum and Plasmodium vivax are
the most widespread and common causes of mixed-species malaria, which is
defined as co-infection with more than one species or genotype of Plasmodium
(Mayxay et al., 2004).
Most cases of malaria are uncomplicated,
commonly presenting with fever and sometimes with other non-specific symptoms
including headache, and aches and pains elsewhere in the body (Gilles, 1991; WHO,
2003). Mtoni and Senosi (2007) noted that early diagnosis and treatment are key
to addressing morbidity and mortality due to malaria. Proper management of malaria cases
within the first 24 hours of onset is considered to be the best way to reduce
its morbidity and mortality (Singh et
al., 2013). This would be adequately achieved if most of the patients have
access to laboratory facilities (Kamugisha et
al.,
2008). Most victims of malaria still die, because the disease is not diagnosedin
time by health workers (Uzochukwu et al.,
2009). Microscopy is the gold
standard for laboratory diagnosis of malaria in many developing countries, though
expertise may be lacking in both endemic and non-endemic settings (Moody,
2002), especially in Nigeria. However, in situations lacking reliable microscopic diagnosis,
rapid diagnostic tests
(RDTs) may offer a useful alternative to microscopy (Nour
et al., 2009).
In general, RDTs are fast, easy to
perform and relatively cheap (Lubell et
al., 2007). A lot of research and development has
been going on to develop alternative methods for laboratory diagnosis of
malaria. Rapid diagnostic tests have been developed, validated and field
tested. It was introduced in
the nineties, but has now undergone many improvements (Martha et al., 2010). Malaria rapid diagnostic
test plays a key role in malaria control and elimination programmes in order to avoid
unnecessary anti-malarial therapy, to prevent drug resistance and to enhance
case finding (Eibach et al., 2013). The RDTs are based on the principle of immunochromatography, which require
finger prick blood and detect malaria
specific antigen. There
are three different RDTs that are available commercially; one of them is
specific for detecting P. falcipraum antigens, while the other two detects one or more of
the three human malaria
species. The RDTs
provide quick results, are reliable, and require less skilled persons as compared to microscopic diagnosis. They do not require
electricity or any equipment. It promotes patient’s
confidence as well as health services.
More than 60 RDT
brands and over 200 different products have been developed. Of these, the WHO
and Foundation for Innovative New Diagnostics (FIND) evaluated 70 from 26
manufacturers (WHO, 2008; 2009). Of these products, 39 are three-band tests
that detect and differentiate P. falciparum from non falciparum species
(Martha et al., 2010). The CareStart™
Malaria HRP-2/ pLDH (Pf/pan) Combo Test and the SD Bioline Ag pf/pan, HRP-2 and
pan-pLDH are both a three-band RDT detecting HRP-2 and pan-pLDH. This present study is focused on evaluating
the efficacy of two of the many RDTs; SD Bioline and CareStart™ Malaria kits
using it microscopy test as the gold standard for the diagnosis of malaria.
SD Bioline (Ag pf/pan, Cassette, RDT, kit) is a one step differential diagnosis by detecting HRP-II
antigen from Plasmodiumfalciparum and pLDH antigen from other
species (P. vivax, P. malariae, P. ovale)
in human whole blood. The CareStart
(Combo, dev., RDT) is a test designed for the differential
diagnosis between Plasmodiumfalciparum and other Plasmodium species such as Plasmodium vivax, Plasmodium ovale and Plasmodium
malariae. Though, the gold standard for malaria testing
remains microscopy, but the limitations associated with this technique could
affect the speed of delivery of quality services to the patients (Ameh et al., 2012).
1.1 Statement
of the Problem
Microscopy has been in use for over 100
years and is inexpensive, rapid and relatively sensitive when used
appropriately (Laveran, 1891). Microscopy is regarded as the ‘gold standard’
for malaria diagnosis (WHO, 1999). However, the lack of skilled scientists in
medical facilities in affected areas often leads to poor interpretation of
data. In addition, microscopy is time consuming, labour intensive, and cannot
detect sequestered P. falciparum
parasites (Leke et al., 1999). It is
less reliable at low-density parasitaemia that is, 50 parasites (ml blood)
(Kilian et al., 2000; Bell et al., 2005). Even though microscopy is cheap, reliable and
available on an instant base, it has limitations. For instance, in
resource-limited centres, there are problems of equipment, training manpower, and
workload, whereas in non-endemic countries, laboratory staff may lack
sufficient exposure to malaria positive samples resulting in low expertise (Moody, 2002; Hanscheid, 2003).
In Nigeria, RDTs are still new to the people, and they are unsure
of the efficacy, accuracy and authenticity. It has been 7 years since the
launching of malaria RDTs in Nigeria but the populace know little or nothing
about Malaria RDTs due to poor promoting from the part of manufacturers. In
addition, the implementation of RDTs also faces many difficulties such as
logistics; transport and continuous supply, limited shelf life and the need of proper storage
rooms. RDTs are quickly affected by humidity and extreme temperatures (Wongsrichanalai et al., 2007). They are not able to quantify parasitaemia
and may give false positive
results
owing to the persistence of antigens that can remain in the circulation of a
patient after treatment (Wongsrichanalai
et al., 2007).
1.2 Significance of the Study
The
essence of continuous research and development is to find a way to improve the
lives of people around the globe. Thus,
finding an alternatively cheap, fast, convenient and effective way to diagnosis
malaria is a key to control malaria.
This study is therefore significant in many ways:
1. The
finding of this study will be useful and helpful to the Federal and State Government
with regard to malaria eradication in making
decisions on implementation of RDTs for routine diagnosis in the Nigeria,
especially in rural areas.
2. The
findings of this study will provide an alternative, effective and reliable
diagnosis of malaria patients in both those that are asymptomatic and
symptomatic.
3. RDTs
are fast, easy to perform and relatively cheap and can easily be used by both
the trained and untrained.
1.3 Research
Questions
1.
What is the efficacy of SD Bioline
and Carestart when compared to microscopy?
2.
Can RDTs such as SD
Bioline and Carestart be alternative for the gold standard (microscopy) in the diagnosis
of malaria.
1.4 Research Hypothesis
HA: RDTs are more
efficient in the detecting of malaria cases than microscopy
HO: Microscopy
is more efficient in defecting malaria than RDTs
1.
Aims
and Objectives of the Study
The aims and objectives
of this study were to:
1.
Evaluate the efficacy
of the Carestart Malaria HRP2 and pLDH/HRP2 Combo compared to microscopy in the
diagnosis of malaria.
2.
Determine the
sensitivity, specificity, positive and negative predictive values of the
malaria RDTs to microscopy.
3.
Determine the
relationship between malaria parasite density and results of malaria RDTs.
4.
Correlate results of
negative malaria detection rate by microscopy to results of malaria RDTs.
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