rapid diagnostic test

Rapid diagnostic test (RDT) has been used in several influenza surveillance tests as a point-of-care test. This test provides assistance to diagnose influ- enza for doctors and paramedics as influenza has an array of clinical symptoms which are difficult to differentiate from other respiratory tract infections. RDTs are one of laboratory methods that could overcome the problems, especially in Indonesia as it is a vast archipelago country with limited transporta- tion access between islands and laboratory facilities. However, RDTs also have some drawbacks, including the sensitivity and specificity. Therefore, this study aimed to assess the performance of this assay against the reference diagnostic standards of RT-PCR in influenza-like illness (ILI) surveillance activity.

Large-scale maps of Plasmodium falciparum infection prevalence [1–3] are increasingly used to inform dis- ease control planning, implementation and evaluation at national to global scales [4], and as a basis for disease bur- den estimation and the monitoring of progress towards international targets [4–7]. Mapping at the continental or global scale relies on opportunistic assemblies of data on infection prevalence arising from thousands of P. fal- ciparum parasite rate (PfPR) surveys conducted in dif- ferent countries. The between-site variance observed in these PfPR estimates arises from both an underlying sig- nal component: the variation of the true infection preva- lence and the residual noise component, attributable, not only to the inherent random error, but also to a range of confounding factors that reduce the comparability of PfPR measurements from different surveys, most notably, immunological differences in the age ranges of subjects surveyed [8] and differences in parasite detection meth- ods. Whilst random error and age-standardization have been addressed in previous mapping efforts, the effect of different diagnostic methods has not. Previous research has defined the functional relationship between micros- copy and polymerase chain reaction (PCR) detection [9], but little research has explored the functional differences between microscopy and rapid diagnostic test (RDT). Given that the majority of PfPR data are based on positiv- ity rates measured by either microscopy or RDT, and that the sensitivity and specificity of these approaches are not identical [10], it is crucial to understand the functional differences between these two approaches.

Another major contributing factor is that the labora- tory diagnosis of malaria has up to now relied nearly exclusively on light microscopy which is a valuable tech- nique when performed correctly but unreliable and was- teful when poorly executed. A better utilization of microscopy and the development of alternative diagnos- tic techniques could substantially improve malaria con- trol [3]. This study aimed at evaluating and comparing the novel Partec Rapid Malaria Test ® (PT) (Partec GmbH, Münster, Germany) and the recently established Binax Now ® Malaria Rapid Diagnostic Test (BN RDT) (Binax, Inc., Portland, ME, USA) in malaria diagnosis among children from an endemic area using Giemsa stain microscopy as the reference standard. In a first report we compared PT with GM in a separate collec- tive of patients using a real time PCR assay as reference standard [4]. In this study we focused on the assessment of test result quality and applicability under the field conditions of a rural hospital laboratory.

This study also showed various outcomes in relation to the impact of RDT result on prescription practices using the report of patient exit interviews as a proxy. The compliance rate of 90.2% for a newly implemented programme is significant. This is consistent with obser- vations from other countries that have shown high pen- etration of RDTs among workers at the PHC levels [23, 24]. About one-third would give antibiotics, one-third would refer and one-third would give ACT. This is similar to reports from Tanzania [25]. There has been a persis- tent challenge regarding the best actions in the presence of RDT negative febrile patients. It is unlikely that this may be easily resolved by training and other communi- cations. This is largely because a single recommendation that would capture the variables involved in the man- agement of RDT negative febrile cases is a challenge at the moment. However, in the short term, there must be a sustained effort at ensuring compliance with RDT results, through periodic capacity development, supervi- sory visits and use of health workers forum to reinforce best practices. Ultimately having an integrated rapid diagnostic test kit that would simultaneously test for malaria, bacterial infections and possible viral pathology may be the direction to explore [16, 26, 27].

In recent time, there is so much concern in the control of the disease among which are the use of Artemisinin based combination therapy(ACT), long lasting insecticide treated nets, Intermittent preventive treatments and case management of the disease (WHO, 2010). Case management defined by rapid diagnosis and prompt treatment is a control strategy of interest to minimize complications as well as reduce mortality. Rapid Diagnostic Test (RDT), which permits malaria diagnosis within 15-30 minutes, can be used at community level for case management (Tangpukdee et al, 2009; Chansuda et al, 2007; Moody , 2002). Though reliable, RDTs are limited in detecting sub-microscopic parasitaemia levels.

Culture is currently the gold standard diagnostic test for melioidosis, with 100% specificity but an estimated sensitivity of only 60% (7). However, culture confirmation takes a minimum of 48 to 72 h (7) and requires specific media for optimal sensitivity in nonsterile samples (8) and laboratory containment and expertise often not available in areas of endemicity. B. pseudomallei is intrinsically resistant to many antibiotics, and therefore melioidosis does not respond to most agents used for empirical treatment of sepsis, pneumonia, and abscesses in developing countries (9). Therefore, life-saving treatment is often fatally delayed if a specific diagnosis cannot be confirmed. Simple, rapid diagnostic tests for melioidosis for use directly on clinical samples are needed, not only for improving patient outcomes but also to improve epidemiological surveillance of melioidosis and thereby strengthen public health interventions. Immunofluores- cence to detect B. pseudomallei directly in clinical samples (10) and latex agglutination for rapid identification of positive cultures (11, 12) are used in some areas where melioidosis is endemic. However, these tests require equipment, expertise, and re- agents that are not widely available. More recently, an immunochromatographic lateral flow rapid diagnostic test (RDT) to detect B. pseudomallei extracellular polysaccharide antigen directly in clinical samples has been developed (Active Melioidosis Detect [AMD]; InBios, USA) (13). The method is simple, rapid (results are available within 15 min), and relatively inexpensive (estimated cost, $2/test) and does not require addi- tional equipment; in addition, the kit may be stored at room temperature, making it ideal for use in resource-limited settings. To date, this kit has undergone only limited clinical evaluations (13, 14). We evaluated the diagnostic performance of AMD on a variety of clinical samples (including blood culture broths, pus, sterile fluid, sputum, and urine) over two rainy seasons from patients with suspected and culture-confirmed melioidosis presenting to Mahosot Hospital, Vientiane, Laos.

Background: Malaria is a protozoan disease transmitted by the bite of infected female anopheles mosquitoes is one of the most important parasitic diseases of human with transmission in 109 countries, affecting more than one billion people worldwide. This study was planned to compare the gold standard i.e. peripheral blood smear examination and the newer rapid diagnostic test (malaria plasmodium falciparum/ plasmodium vivax antigen card) to know the diagnostic accuracy of Rapid Diagnostic Test (RDT) kits.

A rapid diagnostic test (RDT) incorporating S. mansoni cercarial transformation fluid (SmCTF) (Vision Biotech; Cape Town, South Africa) has recently been developed fol- lowing promising preliminary results on this antigen’s abil- ity to detect anti-schistosome antibodies in an enzyme- linked immunosorbent assay (ELISA) format [19-21]. The antigen performed equivalently to schistosome soluble egg antigens in ELISA, an assay that is regularly employed in travellers’ medicine clinics for diagnosis [22,23] and has also been shown to perform well in schistosome-endemic areas [12,24]. This study was designed to determine the performance of the SmCTF-RDT for the diagnosis of S. mansoni and S. haematobium among preschool-aged children in a mixed infection focus of south Côte d’Ivoire in comparison with standard microscopy methods. This evaluation was integrated in a larger study pertaining to

This study involved two phases: the first was a prospective cross-sectional comparison of a three band RDT with mi- croscopy for the diagnosis of P. falciparum and the second was validation of the three-band RDT for recruitment of patients with falciparum malaria in the context of a ran- domized clinical trial [13]. The commercially available RDT used in both phases of this study (First Response Malaria Ag. (pLDH/HRP2) Combo Rapid Diagnostic Test, Premier Medical Corporation Limited, India) is the highest-ranked assay by a standardized WHO testing methodology [14]. Previous reports of its use in India [7] and Yemen [15] sup- port its high sensitivity and specificity.

Typhoid fever is a common cause of fever in Cambodian children but diagnosis and treatment are usually presumptive owing to the lack of quick and accurate tests at an initial consultation. This study aimed to evaluate the cost-effectiveness of using a rapid diagnostic test (RDT) for typhoid fever diagnosis, an immunoglobulin M lateral flow assay (IgMFA), in a remote health centre setting in Cambodia from a healthcare provider perspective. A cost-effectiveness analysis (CEA) with decision analytic modelling was conducted. We constructed a decision tree model comparing the IgMFA versus clinical diagnosis in a hypothetical cohort with 1000 children in each arm. The costs included direct medical costs only. The eligibility was children (≤14 years old) with fever. Time horizon was day seven from the initial consultation. The number of treatment success in typhoid fever cases was the primary health outcome. The number of correctly diagnosed typhoid fever cases (true-positives) was the intermediate health outcome. We obtained the incremental cost effectiveness ratio (ICER), expressed as the difference in costs divided by the difference in the number of treatment success between the two arms. Sensitivity analyses were conducted. The IgMFA detected 5.87 more true- positives than the clinical diagnosis (38.45 versus 32.59) per 1000 children and there were 3.61 more treatment successes (46.78 versus 43.17). The incremental cost of the IgMFA was estimated at $5700; therefore, the ICER to have one additional treatment success was estimated to be $1579. The key drivers for the ICER were the relative sensitivity of IgMFA versus clinical diagnosis, the cost of IgMFA, and the prevalence of typhoid fever or multi-drug resistant strains. The IgMFA was more costly but more effective than the clinical diagnosis in the base-case analysis. An IgMFA could be more cost-effective than the base-case if the sensitivity of IgMFA was higher or cost lower. Decision 16

Typhoid fever is a common cause of fever in Cambodian children but diagnosis and treat- ment are usually presumptive owing to the lack of quick and accurate tests at an initial con- sultation. This study aimed to evaluate the cost-effectiveness of using a rapid diagnostic test (RDT) for typhoid fever diagnosis, an immunoglobulin M lateral flow assay (IgMFA), in a remote health centre setting in Cambodia from a healthcare provider perspective. A cost- effectiveness analysis (CEA) with decision analytic modelling was conducted. We con- structed a decision tree model comparing the IgMFA versus clinical diagnosis in a hypotheti- cal cohort with 1000 children in each arm. The costs included direct medical costs only. The eligibility was children (�14 years old) with fever. Time horizon was day seven from the ini- tial consultation. The number of treatment success in typhoid fever cases was the primary health outcome. The number of correctly diagnosed typhoid fever cases (true-positives) was the intermediate health outcome. We obtained the incremental cost effectiveness ratio (ICER), expressed as the difference in costs divided by the difference in the number of treat- ment success between the two arms. Sensitivity analyses were conducted. The IgMFA detected 5.87 more true-positives than the clinical diagnosis (38.45 versus 32.59) per 1000 children and there were 3.61 more treatment successes (46.78 versus 43.17). The incre- mental cost of the IgMFA was estimated at $5700; therefore, the ICER to have one addi- tional treatment success was estimated to be $1579. The key drivers for the ICER were the relative sensitivity of IgMFA versus clinical diagnosis, the cost of IgMFA, and the prevalence of typhoid fever or multi-drug resistant strains. The IgMFA was more costly but more effec- tive than the clinical diagnosis in the base-case analysis. An IgMFA could be more cost- effective than the base-case if the sensitivity of IgMFA was higher or cost lower. Decision makers may use a willingness-to-pay threshold that considers the additional cost of hospita- lisation for treatment failures.

Approaches in malaria diagnosis include clinical diag- nosis, microscopic diagnosis, molecular diagnosis and serology [3], with clinical and presumptive diagnosis being the conventional diagnostic method [4]. However, clini- cal diagnosis using fever as an indicator has been shown to be a sensitive indicator of clinical malaria in children <5 years, but not in older children and adults [5]. Other diagnostic approaches require trained staff, expensive and fragile equipment, and electricity supply among others. These requirements and inherent potential for human and technical errors have been shown to result in misdiagnosis and over-diagnosis of malaria [3, 4, 6–9]. This over-diag- nosis of malaria exposes patients to needless anti-malarial therapy, waste of resources in resource-scarce setting, and may likely contribute to the development of drug resist- ance [10, 11]. The problem of misdiagnosis and over treat- ment of malaria led to the development of a more reliable, field-suitable and cost-effective diagnostic tool–rapid diag- nostic test (RDT) [12, 13]. Rapid diagnostic test, based on the detection of Plasmodium antigens in a little drop of the patients’ blood, saves cost and time while giving an almost instant result. It generally has high level of sensitivity and specificity, although its accuracy varies between brands, location and epidemiological setting [14, 15]. The accuracy and reliability of RDT made it a staple in malaria control programmes and a first choice malaria diagnostic tool [16, 17]. RDTs testing for falciparum malaria were shown in a Cochrane review to be very specific (range of about 92–100%) meaning that only 0–8% of patients who test positive would not actually have the disease [18]. Further- more, they were shown to be very sensitive (range of about 91–99%) meaning that only 1–9% of people with falcipa- rum malaria would actually get a negative test result [18].

WHO recommends prompt malaria diagnosis either by microscopy or mala- ria rapid diagnostic test (RDT) in all patients where malaria is suspected before administering treatment with antimalarials. Diagnostic testing improves the overall management of patients with febrile illnesses, and it may also help to re- duce the emergence and spread of drug resistance by reserving treatment with antimalarials for those who actually have the disease. In as much as microscopy plays an important role in diagnosis of malaria, a major disadvantage is that it

This is to certify that the dissertation titled, “EVALUATION OF DIAGNOSTIC TESTS IN MALARIA (EVALUATING THE DIAGNOSTIC VALUE OF QUANTITATIVE BUFFY COAT AND RAPID DIAGNOSTIC TEST USING PLASMODIUM LACTATE DEHYDROGENASE AGAINST THE PERIPHERAL SMEAR MICROSCOPY)” submitted by Dr.U.Sasireka, to the Faculty of Pediatrics, The Tamilnadu Dr.M.G.R Medical University, Chennai, in partial fulfilment of the requirements for the award of M.D. Degree (Pediatrics) is a bonafide research work carried out by her under our direct supervision and guidance, during the academic year 2009-2012.

and the second being the high prevalence of morbidity and mortality of clinical malaria infections among chil- dren in endemic regions [1, 3]. The World Health Organi- zation fully aware of this malaria diagnostic challenge common in endemic regions collaborated with manu- factures, scientists and clinicians in the development and introduction into clinical practice a rapid, easy to read and accurate diagnostic test in 2010 [4, 5]. Hence, rapid diagnostic test (RDT) was introduced into clinical man- agement of malaria and since then, more than one mil- lion RDTs are used yearly in various health facilities in malaria endemic areas [6, 7]. Although RDT can be used alone in areas where there is no microscopy, it is ideally not meant to replace microscopy which is the gold stand- ard for diagnosis, but rather to complement it [8, 9].

Staphylococcus aureus was identified using a rapid diag- nostic test on a platform Cepheid Xpert real time PCR assay (Cepheid, Sunnyvale, CA, USA). In the Marseille study center, an Xpert SA Nasal Complete Kit was used. In the Lyon study center, an Xpert MRSA/SA SSTI was used. The extraction, amplification and detection steps take place in different chambers of a self-contained, sin- gle-use cartridge containing all reagents required for the bacterial target detection. Samples were adsorbed onto a swab, which was inserted in the extraction buffer vial of the Xpert assay, transferred into the cartridge, and trea- ted according to the manufacturer ’ s instructions. Both the Xpert SA Nasal Complete and the Xpert MRSA/SA SSTI target the staphylococcal protein A (spa) gene, the gene for methicillin resistance (mecA) and the staphylo- coccal cassette chromosome (SCCmec) inserted into the S. aureus chromosomal attB insertion site, and an inter- nal-control sample processing control (SPC) three genetic markers (Bacillus globigii).

This is one of the first studies prospectively evaluating a rapid test for HBsAg in HIV-infected patients entirely at the point of care in an African peripheral health institution. We chose Determine HBsAg for its low waste production, undemanding storage requirements and most importantly for its preexisting supply chains, as Determine HIV rapid tests are already part of the routine HIV testing algorithm in Tanzania [22] and many other countries. Also, the assay’s procedures and interpretation are identical with the model used for the diagnosis of HIV; this has the benefit of cutting down efforts and expenses in training staff for appropriate handling of the test in case of a large-scale deployment. Studies performed in Ghana [23] and Madagascar [24] further indicated that it can be focused on such practical factors, as differences in diagnostic accuracies between different products for the detection of HBsAg are marginal. Additionally, a recent meta-analysis [25] on Determine HBsAg test character- istics in HIV-negative subjects showed excellent sensitivity and specificity of 98.2% and 99.9%, respectively.

Despite suboptimal operational characteristics, the FST remains the most widely used G6PD diagnostic in Asia and possibly worldwide [28, 35]. Any test to replace the FST will need to perform at least comparable and ideally show better operational characteristics. While the FST showed a perfect match in Laos if a 30% cut-off activ- ity was applied and intermediate results were catego- rized as G6PD normal. Applying a clinically appropriate approach and considering intermediate results G6PD deficient, the FST showed a sensitivity of above 95% in both countries, comparable to earlier reports from Asia [21, 27, 31, 36, 37]. The processing and interpretation of FSTs can be challenging under field conditions and this may be reflected in the lower performance of the test in Cambodia, where the laboratory technicians were less experienced than in Laos.

Malaria diagnosis has long been based on the micros- copy examination of Giemsa-stained blood film, despite the requirement for highly qualified microscopists and reliable equipment, which are often lacking in remote areas where malaria is most prevalent [4]. For over a decade, the development of malaria rapid diagnostic tests (RDTs) has enabled reliable biological diagnostic testing in all situations where previously only clinical diagnosis was available [5]. The main advantages of the malaria RDTs are that they are easy to use, do not require electricity or complex equipment and the results are

bility of the target antigens under freezing conditions has been questioned [11]. However, no obvious differences in test performance were presently found for samples stored for several (> 5) years compared to those stored for a shorter periods (results not shown). In addition, a pro- spective evaluation of fresh and stored samples revealed similar results in case of the HRP-2 antigen detection [12]. Another limitation is the fact that a calibrated pipette was used for the transfer of the blood; with an expected better accuracy as compared to the kit's application loop. In addition, the diagnosis and evaluation were carried out in a reference setting, which makes extrapolation of the present results to field settings difficult [4,11]. Likewise, the ease of use was checked by an expert team and not by untrained end users in remote areas, and it is known that expert technicians tend to score tests kits more favorably [13].