A COMPARISON BETWEEN MICROSCOPY AND RAPID DIAGNOSTIC TEST AMONG CHILDREN 10-15 YEARS AT ONITSHA GENERAL HOSPITAL, ANAMBRA STATE

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A COMPARISON BETWEEN MICROSCOPY AND RAPID DIAGNOSTIC TEST AMONG CHILDREN 10-15 YEARS AT ONITSHA GENERAL HOSPITAL, ANAMBRA STATE

 

ABSTRACT

This study centres on a comparison between microscopy and rapid diagnostic test among children 10-15 years at Onitsha General Hospital, Anambra State. The study was conducted between the month of July and August. Geimsa thick film and Rapid Diagnostic Test were used to detect malaria parasite in the blood. A total of 150 participants comprising of 68(45.3) males and 82 (54.78) females selected from patients referred for malaria tests at General Hospital Onitsha  Participants were aged 10–15 years. The prevalence of malaria in the study area was 26.7% for microscopy and 22.0% for rapid diagnostic test. Males were more infected with a prevalence rate of 14.7% (microscopy) and 11.3% (RDT) than with females a prevalence rate of 12.0% (Microscopy) and 10.7% (RDT). The difference in prevalence was not significant (p=0.610). Malaria prevalence in relation to age in the study shows that children within the age of 10 has the highest prevalence which decrease with the increase in years with the least prevalence been those with 15 years of age. Result shows that the use of microscopy is more reliable than the use of RDT. However, it is recommended that only the antigen based  method kits  be imported and, or used  in Nigeria.

TABLE OF CONTENTS

Title Page                                                                                                    i

Declaration                                                                                                 ii

Approval Page                                                                                           iii

Dedication                                                                                                  iv

Acknowledgments                                                                                      v

Abstract                                                                                                      vi

Table of Contents                                                                                       vii

List of Figures                                                                                            ix

List of Tables                                                                                              x

CHAPTER ONE

1.0 INTRODUCTION                                                                              1

1.1 Aims of the Study                                                                   5

1.2 Specific Objectives                                                              5

 

CHAPTER TWO                                                                      7

LITERATURE REVIEW                                                          7

2.1 Malaria in Children                                                              7

2.2 Epidemiology of Malaria                                                      7

2.3 Life cycle of Malarial parasite                                                      10

2.4 Pathogenesis of Malaria                                                               12

2.5 People at risk of severe form of malaria                                        17

2.6 Malaria Diagnostic Techniques and Trends                           18

2.7 Presumptive diagnosis and misdiagnosis of malaria and

their implication                                                                        19

2.8 Malaria Rapid Diagnostic Tests: sensitivity and specificity            21

2.9 Factors influencing sensitivity, specificity, and predictive value

of a RDT for P. falciparum                                                        23

2.10 Proportion of the different Plasmodium species in children  24

2.11 Factors affecting the utilisation of laboratory services in clinical

and community settings                                                     26

2.12 The capacity of laboratory staff and the laboratory for

malaria diagnosis using microscopy in a clinical setting               28

 

CHAPTER THREE

MATERIALS AND METHODS

3.1 Study Area                                                                          30

3.2 Design of Study                                                                   31

3.3 Sample Population                                                                      31

3.4 Sample Size                                                                                 31

3.5 Permission Obtainment                                                                31

3.6 Method for Investigating the Prevalence of Malaria and

associated factors in Awka                                                        32

3.7 Data Analysis                                                                      35

 

CHAPTER FOUR

RESULT                                                                                  36

 

CHAPTER FIVE

DISCUSSION, CONCLUSION AND RECOMMENDATIONS

5.1 Discussion                                                                          40

5.2 Conclusion                                                                          42

5.3 Recommendation                                                                 42

References                                                                                        43

Appendix                                                                                  52

 

 

CHAPTER ONE

INTRODUCTION

Malaria  is  a  disease  of the  tropics and  sub-tropics and  is  transmitted by a  vector, female Anopheles mosquito. It is caused by Plasmodium (P.) falciparum, P. malariae, P. ovale and P. vivax. In Nigeria, the prevalent species is Plasmodium falciparum accounting for >90% of all diagnosed cases (95-98%), P. ovale (<2%), P malariae (2-5%) while P. vivax is not endemic in Nigeria. The dominant vector species are Anopheles (An) gambiae s.l. and the An. Funestus(Molta, 2003; 2004; FMH, 2008).

 

Malaria is a public health problem in Nigeria and accounts for 110 million clinically diagnosed cases per year. The disease is responsible for about 60% outpatient care-visits and 30% hospitalizations.   At least 300,000 children die of malaria per year in Nigeria and up to 30% childhood deaths, 25% of deaths in children under one year and 11% maternal deaths are due to malaria (Federal Ministry of Health, 2005; United Nations Children Fund, 2010).  It is estimated that 50% of the population will have at least one episode of malaria annually, with 2-4 episodes in under-5 year old children (Federal Ministry of Health, 2008). An estimated N132 billion is lost due to malaria annually in form of treatment costs, prevention, loss of man hours (Federal Ministry of Health, 2005; United Nations Children Fund, 2010). In 2008; 9,591 deaths were reported out of 3,481,220 reported cases of malaria in Nigeria, giving a Case Fatality Rate of about 0.3% compared to 0.2% in 2001 (Federal Ministry of Health, 2010).  On a global scale,  in 2008 there was an estimated 243 million cases of malaria worldwide with the majority of cases (85%) in the African Region, followed by the South-East Asia (10%) and Eastern Mediterranean Regions- 4% (World Malaria Report, 2009).

 

Over-prescription  of  antimalarial  medicines  is  a  very  common  phenomenon  because  the diagnosis  of  malaria  is  often  presumptive,  despite  recommendation  of  routine  laboratory diagnosis of malaria by the World Health Organisation (WHO) (Reyburn, Mbakilwa, Mwangi, Mwerinde, Olomi, Drakeley, Whitty, 2007). The use of laboratory methods has  become  necessary because  health workers cannot  identify malaria  cases  reliably using clinical signs and symptoms alone (Perkins, Zucker, Otieno, 2007; Weber, Mulholland, Jaffar, Troedsson, Grove, Greenwood, 2007).  Conventional light microscopy of a blood smear is the reference gold standard for the detection of malaria parasites and the established method for the laboratory confirmation of malaria. It is sensitive and can detect densit ies as low as 5–10 parasites/µL of blood when used by skilled and careful technicians, (World Health Organization, 2000)  but realistically at 100 parasites/µL under field conditions (World Health Organisation, 2008). Microscopy provides information on parasite species (P. falciparumP. vivaxP. ovale, and/or P. malariae) and their circulating stages (e.g. trophozoites, schizonts, gametocytes). It aids quantification of the parasite densities and assessment of parasitological response to chemotherapy in severe malaria cases. It can provide a permanent record (the smears) of the diagnostic findings and be subjected to quality control. However, malaria diagnosis based on microscopy is labour-intensive and time-consuming, requiring at least  60 minutes from specimen collection and  availability of result.  Long delays occur in providing microscopy results to the clinician and as such, decisions on treatment are often taken without the benefit of the results (World Health Organisation, 2000). Microscopy depends absolutely on good techniques, reagents, microscopes  and,  most  importantly,  well  trained  and  well  supervised  technicians.  These conditions are  hardly  met  at  the  more  peripheral levels  of the  health care  system making microscopic diagnosis an unreliable tool.

Rapid diagnostic tests (RDT) are recommended by WHO to enhance diagnosis and management of cases, prevention of complications of delayed treatment, prolonging survival and monitoring of treatment especially in children. Moreover, studies have shown that it is acceptable both to the practising physicians and the patients (Reyburn, Mbakilwa, Mwangi, Mwerinde, Olomi, Drakeley, Whitty, 2007). It is timely for case management of malaria and avoids the drawbacks of defective microscope and erratic power supply (Reyburn et al, 2007). It aids selective treatment of only patients with positive dipstick  results and  thus slows down the  development  of drug resistance by preventing drug pressure (Rimon, Kheng, Hoyer, Thach, Ly, Permin, and Piechie, 2003). Health workers with minimal skills can be trained in RDT techniques within periods varying from three hours to one day.(World Health Organisation, 2000), (Banchongaksorn, Prajakwong, Rooney, and Vickers)    RDT is robust, non- cold chain dependent and the degree of variability of test reliability and performance among individual users is relatively small.(World Health Organisation, 2000) The specificity and sensitivity of 97% and ≥95% respectively have been shown, for self-diagnosis among travellers from endemic areas returning to United Kingdom and in remote areas of Philippines (Whitty, Armstrong and Behrens, 2000; Bell, Go, Miguel, Walker, Cacal, Saul and 2001).

 

Malaria RDT detects serum antigens of Plasmodium species using fixed antibodies on strips of paper.    There  are  three  types  of  newly  developed  RDTs  on  the  WHO  pre-qualified  list. According to WHO, Plasmodium Lactate Dehydrogenase (pLDH) based-tests can detect all the Plasmodium species that infect humans.(World Health Organisation, 2000)  They can distinguish P. falciparum from the non- falciparum species, but cannot distinguish between P. vivaxP. ovale and P. malariae (i.e. specific for P. falciparum).  Some tests detect Aldolase antigens of Plasmodium malariae, ovale and vivax or specifically that  of  P. falciparum while others detect  Plasmodium falciparum Histidine-Rich Protein II (HRP 2) antigen (Rock, Marsh, Saul, Wellems, Taylor, Maloy and Howard, 2007; Meier, Dobeli, and Certa, 2002; Makler, Piper and Milhous, 2008).  Other antigen(s) that are present  in all four species are also targeted in kits that combine detection of the HRP-II antigen of P. falciparum together with that of an, as yet unspecified, “pan-malarial” antigen of the other species (World Health Organisation, 2000). The choice of RDT depends on the malaria endemicity and species prevalence (Jimoh, 2006).

 

In 2009, WHO recommended that persons of all ages with suspected malaria cases should undergo rapid diagnostic tests, but only 18 of 35 countries reported adhering to this (World Malaria Report, 2009).  In 18 malaria  high-burden  African  Region countries  for  which  data  were  available,  22%  of the reported suspected malaria cases were confirmed with RDT in 2008 (World Malaria Report, 2009). The validity of some RDTs has been investigated over the years and has been shown to be of high specificity and sensitivity in comparison to light microscopy (Bell et al,2001; Bell et al,2005).  The WHO recommends a sensitivity of ≥95% at ≥100 parasites/µl for P. falciparum. (World Health Organisation, 2000; Bell et al, 2005).  Despite this recommendation and the reported validity of RDT, recent field and clinical-based studies indicated a low specificity and sensitivity compared with routine microscopy. The reasons alluded to were low parasitaemia, defective and inappropriate handling of RDT kits (World Malaria Report, 2009). The National Malaria programme has commenced the “roll out” of rapid diagnostic tests in some health facilities across the country, with the aim of scaling up its use in the field, where there is lack of skilled laboratory scientists and less than optimal conditions for routine microscopy. The  recent  trend of increasing mortality due to malaria in the general population and in high risk groups of pregnant women and children under the age of 5 years necessitates a more rapid scale up of malaria RDT (Federal Ministry of Health, 2010).

 

There is a high incidence of malaria in Nigeria with variability in endemicity. The southern part of Nigeria and the lower part of the northern region are associated with endemic and perennial episodes (7-12months). Transmission is endemic and seasonal (4-6months) in the upper north and  epidemic  or  strongly  seasonal  in  the  extreme  north-eastern part  of the  country (Federal Ministry of Health, 2008).   The proportion of malaria confirmed by laboratory diagnosis in Nigeria is unknown. Diagnosis of malaria is often clinical-based and unreliable (Reyburn et al, 2007). This could lead to over diagnosis, inappropriate treatment  and  potential  development  of  drug  resistance.  The  use  of  routine  laboratory microscopy to aid clinical diagnosis is minimal. However, the use of malaria rapid diagnostic tests is a new approach and its implementation is restricted to a few facilities in the country. Artemisinin-based combination therapy, the currently recommended treatment for malaria though efficacious, is costly. There is an urgent need to prioritise its use for cases that are purely due to P. falciparum because of possibility of potential development of drug resistance.

 

1.1 Aims of the Study  

This study therefore aims to conduct a comparative study between microscopy and rapid diagnostic test among children between 10-15 years in Onitsha Anambra state.

 

1.2 Specific Objectives

Specifically, this study aims to;

  1. Ascertain the prevalence of malaria among children within the age 10-15 years in Onitsha South Local Government Area.
  2. Find out the predictive value of malaria rapid diagnostic test in relation to routine light microscopy.

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