Optimal cut-off value for detecting colorectal cancer with fecal immunochemical tests according to age and sex

In the fecal immunological test, a suitable cut-off value may be selected to classify results as either positive or negative. Our aim is to estimate the optimal cut-off value for detecting colorectal cancer in different age and sex groups. This is a multicentric retrospective cohort study of participants in CRC screening programs with FIT between 2006 and 2012. A total of 545,505 participations were analyzed. Cancers diagnosed outside of the program were identified after a negative test result (IC_test) up until 2014. The Wilcoxon test was used to compare fecal hemoglobin levels. ROC curves were used to identify the optimal cut-off value for each age and sex group. Screening program results were estimated for different cut-off values. The results show that the Hb concentration was higher in colorectal cancer (average = 179.6μg/g) vs. false positives (average = 55.2μg/g), in IC_test (average = 3.1μg/g) vs. true negatives (average = 0μg/g), and in men (average = 166.2μg/g) vs. women (average = 140.2μg/g) with colorectal cancer. The optimal cut-off values for women were 18.3μg/g (50-59y) and 14.6μg/g (60-69y), and 16.8μg/g (50-59y) and 19.9μg/g (60-69y) for men. Using different cut-off values for each age and sex group lead to a decrease in the IC_test rate compared to the 20μg/g cut-off value (from 0.40‰ to 0.37‰) and an increase in the false positive rate (from 6.45% to 6.99%). Moreover, test sensitivity improved (90.7%), especially in men and women aged 50-59y (89.4%; 90%) and women aged 60-69y (90.2%). In conclusion, the optimal cut-off value varies for different sex and age groups and the use of an optimal cut-off value for each group improves sensitivity and leads to a small decrease in IC_tests, but also to a larger increase in false positives.

Hepatitis C virus antigen detection is an appropriate test for screening and early diagnosis of hepatitis C virus infection in at-risk populations and immunocompromised hosts

Early diagnosis remains key for effective prevention and treatment. Unfortunately, current screening with anti-hepatitis C virus antibody (anti-HCV Ab) test may have limited utility in the diagnosis of HCV infection and reinfection. This is of special concern to at-risk population, such as immunocompromised hosts and end-stage renal failure patients on hemodialysis. HCV antigen (Ag) could be useful in identifying the ongoing infection in such clinical scenarios. Hence, we aimed to study the utility of HCV Ag testing for the diagnosis of acute and chronic hepatitis C. Of 89 samples studied, 19 were from acute hepatitis C patients who were immunocompromised or were on hemodialysis, 43 were from active chronic hepatitis C patients and 27 were from patients treated for chronic hepatitis C. All samples were tested for HCV Ag using the Abbott ARCHITECT HCV Ag assay. HCV Ag was reactive in 19/19 samples from acute hepatitis C patients and 42/43 samples from active chronic hepatitis C patients. It was nonreactive in all samples from treated patients. The test showed a sensitivity and specificity of 98.4% and 100.0%, respectively. The positive and negative predictive values were 100.0% and 96.4%, respectively. The HCV antigen test has high clinical sensitivity and specificity and is useful for the diagnosis of acute and chronic hepatitis C infection in at-risk and immunocompromised patients. Its short turnaround time and relatively low cost are advantageous for use in patients on hemodialysis and other at-risk patients who require monitoring of HCV infection and reinfection.

Factors associated with differential T cell responses to antigens ESAT-6 and CFP-10 in pulmonary tuberculosis patients

The T-SPOT.TB assay detects cellular immune responses to 2 core Mycobacterium tuberculosis antigens, early secreted antigenic target of 6-kDa protein (ESAT-6) and culture filtrate protein-10 (CFP-10). T-SPOT.TB has been recently used for auxiliary diagnosis of active pulmonary tuberculosis (PTB). However, testing can produce inconsistent results due to differential PTB patient immune responses to these antigens, prompting us to identify factors underlying inconsistent results.Data were retrospectively analyzed from 1225 confirmed PTB patients who underwent T-SPOT.TB testing at 5 specialized tuberculosis hospitals in China between December 2012 and November 2015. Numbers of spot-forming cells (SFCs) reflecting T cell responses to ESAT-6 and CFP-10 antigens were recorded then analyzed via multivariable logistic regression to reveal factors underlying discordant T cell responses to these antigens.The agreement rate of 84.98% (82.85%-86.94%) between PTB patient ESAT-6 and CFP-10 responses demonstrated high concordance. Additionally, positivity rates were higher for ESAT-6 than for CFP-10 (84.8% vs 80.7%, P < .001), with ESAT-6 and CFP-10 microwell SFC numbers for each single positive group not differing significantly (P > .99), while spot numbers of the single positive group were lower than numbers for the double positive group (P < .001). Elderly patients (aged ≥66 years) and patients receiving retreatment were most likely to have discordance results.ESAT-6 promoted significantly more positive T-SPOT.TB results than did CFP-10 in PTB patients. Advanced age and retreatment status were correlated with discordant ESAT-6 and CFP-10 results. Assessment of factors underlying discordance may lead to improved PTB diagnosis using T-SPOT.TB.

Analytical performance of lateral flow immunoassay for SARS-CoV-2 exposure screening on venous and capillary blood samples

OBJECTIVES

We validate the use of a lateral flow immunoassay (LFI) intended for rapid screening and qualitative detection of anti-SARS-CoV-2 IgM and IgG in serum, plasma, and whole blood, and compare results with ELISA. We also seek to establish the value of LFI testing on blood obtained from a capillary blood sample.

METHODS

Samples collected by venous blood draw and finger stick were obtained from patients with SARS-CoV-2 detected by RT-qPCR and control patients. Samples were tested with Biolidics 2019-nCoV IgG/IgM Detection Kit lateral flow immunoassay, and antibody calls were compared with ELISA.

RESULTS

Biolidics LFI showed clinical sensitivity of 92% with venous blood at 7 days after PCR diagnosis of SARS-CoV-2. Test specificity was 92% for IgM and 100% for IgG. There was no significant difference in detecting IgM and IgG with Biolidics LFI and ELISA at D0 and D7 (p = 1.00), except for detection of IgM at D7 (p = 0.04). Capillary blood of SARS-CoV-2 patients showed 93% sensitivity for antibody detection.

CONCLUSIONS

Clinical performance of Biolidics 2019-nCoV IgG/IgM Detection Kit is comparable to ELISA and was consistent across sample types. This provides an opportunity for decentralized rapid testing and may allow point-of-care and longitudinal self-testing for the presence of anti-SARS-CoV-2 antibodies.

Analytical performance of lateral flow immunoassay for SARS-CoV-2 exposure screening on venous and capillary blood samples

Objectives

We validate the use of a lateral flow immunoassay (LFI) intended for rapid screening and qualitative detection of anti-SARS-CoV-2 IgM and IgG in serum, plasma, and whole blood, and compare results with ELISA. We also seek to establish the value of LFI testing on blood obtained from a capillary blood sample.

Methods

Samples collected by venous blood draw and finger stick were obtained from patients with SARS-CoV-2 detected by RT-qPCR and control patients. Samples were tested with Biolidics 2019-nCoV IgG/IgM Detection Kit lateral flow immunoassay, and antibody calls were compared with ELISA.

Results

Biolidics LFI showed clinical sensitivity of 92% with venous blood at 7 days after PCR diagnosis of SARS-CoV-2. Test specificity was 92% for IgM and 100% for IgG. There was no significant difference in detecting IgM and IgG with Biolidics LFI and ELISA at D0 and D7 (p = 1.00), except for detection of IgM at D7 (p = 0.04). Capillary blood of SARS-CoV-2 patients showed 93% sensitivity for antibody detection.

Conclusions

Clinical performance of Biolidics 2019-nCoV IgG/IgM Detection Kit is comparable to ELISA and was consistent across sample types. This provides an opportunity for decentralized rapid testing and may allow point-of-care and longitudinal self-testing for the presence of anti-SARS-CoV-2 antibodies.

Comparison of double antigen sandwich and indirect enzyme-linked immunosorbent assay for the diagnosis of hepatitis C virus antibodies

BACKGROUND

The aim of this study is to compare double-antigen sandwich enzyme-linked immunosorbent assay (ELISA) and indirect ELISA in the diagnosis of hepatitis C virus（HCV）infection.

METHODS AND MATERIALS

A total of 176 samples from the Tumor Hospital Affiliated to Xin Jiang Medical University were utilized to comparison. All serum samples were tested using double-antigen sandwich ELISA and indirect ELISA. Cohen's kappa statistics were used to assess the agreement between the two assays, and multivariate analysis was used to evaluate risk factors for the discordance between the double-antigen ELISA and indirect ELISA.

RESULTS

The positivities of indirect ELISA (Beijing Wantai), double-antigen sandwich ELISA (Beijing Wantai), and indirect ELISA (Beijing Jinhao) were 74.43%, 68.75%, and 73.30%, respectively. The agreement between the indirect ELISA (Beijing Wantai) and double-antigen sandwich ELISA (Beijing Wantai) was high (κ = 0.829;P < .001), and the agreement between the double-antigen sandwich ELISA (Beijing Wantai) and indirect ELISA (Beijing Jinhao) was high (κ = 0.847;P < .001). Variables associated with discordant results between the double-antigen sandwich and indirect ELISA in multivariate analysis were as follows: female (OR:1.462; P < .05), age (<35 years old; OR:3.667; P < .05), and cancer (suffer from malignant tumor; OR:3.621; P < .05).

CONCLUSION

In detection of HCV, high agreement was found between the double-antigen sandwich ELISA and indirect ELISA. Female, younger age, and suffer from malignant tumor were significant risk factors for the discordance. Based on double-antigen sandwich ELISA has distinct methodological advantages over indirect ELISA. It is recommended for the diagnosis of HCV infection.

Use of Humanized Fluorescent Reporter Cell Line RBL NFAT-DsRed for the Detection of Allergen-Specific IgE in Patient Sera Using Allergen Microarrays

The presence of allergen-specific IgE (sIgE) in human sera can be determined by measuring the binding of sIgE to solid phase-bound preparations containing the allergens to be tested. These can be complex extracts, purified or recombinant allergens, or peptides. Older methods, such as the IgE CAP test, only allow sIgE measurements to multiple allergens in individual measurements. Newer technologies such as the ImmunoCAP® ISAC test allows semiquantitative testing of sIgE to over a hundred allergens on a protein array. Allergen arrays have higher numerical power, allowing testing to many allergens at the same time, using only a small amount of serum. We have previously demonstrated how allergen arrays can be used in combination with purified peripheral blood basophils, introducing a clinically relevant readout. Here, we describe a protocol and materials that allow the testing of sIgE with multiple allergens in array format, using a humanized fluorescent IgE reporter system (RBL NFAT-DsRed).

Performance Evaluation of Mindray SAL 8000: a New Integrated Clinical Chemistry and Immunoassay Analyzer System

BACKGROUND

The Mindray SAL 8000 is an integrated serum analyzer for photometric, electrochemical, and im-munological assays. The technical, analytical, and workflow performance of the system were evaluated in this study.

METHODS

The technical evaluation was performed using protocols adopted from the guidelines of the China Food and Drug Administration (CFDA). The precision, linearity, interference, and method comparison were carried out according to the Clinical and Laboratory Standards Institute (CLSI) protocols. The verification of carryover and turnaround time were conducted using specimens containing different analytes.

RESULTS

The technical performance was acceptable for all evaluated aspects. The repeatability and within-labora-tory coefficients of variation (CVs) ranged between 0.22% and 4.23% for routine chemistry and between 1.05% and 6.89% for immunochemistry, respectively. All evaluated analytes exhibited linearity over the ranges claimed by the manufacturer. Significant interferences were observed during low concentration TBIL and P measure-ments due to the presence of lipemia. Method comparisons showed good agreement with the comparison systems and with the correlation coefficients ≥ 0.988 except for anti-HBs (r = 0.812). No significant intra-module and inter-module carryovers were detected. For all the 1,220 samples, 25%, 54%, 63%, 79%, 91%, and 100% samples com-pleted analysis in 16.3 minutes, 30 minutes, 60 minutes, 120 minutes, 180 minutes, and 320 minutes, respectively.

CONCLUSIONS

The Mindray SAL 8000 integrated system achieved optimal technical performance and met most of the criteria regarding analytical performance. The workflow study of the system met the turnaround time (TAT) requirements of laboratories. Therefore, it is a good candidate to be used in medium and large-sized laboratories.

An international external quality assessment for laboratory diagnosis of heparin-induced thrombocytopenia

Essentials A pilot study for External Quality Assessment for testing of HIT is described. The qualitative accordance for the PF4/heparin IgG test was 97.6%. The qualitative accordance for functional HIT tests was considerably lower. External Quality Assessment for functional HIT tests is required. SUMMARY: Objective Heparin-induced thrombocytopenia (HIT) is a potentially life-threatening complication of heparin exposure. Diagnosis is most reliable using a combination of an enzyme immunoassay (EIA) that detects antibodies against platelet factor 4 (PF4)/heparin complexes ("antigen" assay) and a "functional" assay that detects platelet-activating properties of the pathogenic HIT antibodies. No External Quality Assessment (EQA) is available for a combination of the tests. Here we report on the results of the first international EQA. Methods The pilot EQA was organized by the Department of Transfusion Medicine, Universitätsmedizin Greifswald, Germany. Six serum samples of patients, which were referred to Greifswald for HIT diagnosis, and one negative control sample were distributed to seven participants in Germany, Canada, and Singapore. Participants were asked to report the optical density (OD) values of their local EIA test for IgG-specific antibodies against the PF4/heparin complexes and the results for a functional assay (HIPA or SRA). Consensus was defined as a minimum 70% agreement, i.e., agreement among at least five of the seven participating laboratories. Results and conclusion Six out of seven participants reported results for EIA, with a high quantitative accordance (97.6%). For the functional assay, consensus was reached for all samples except the negative control, for which some participants reported nonspecific reactivity. All HIT-negative samples were correctly diagnosed by all participants; for HIT-positive samples, consensus of 70% was reached. Although the limited availability of sample material is an obstacle to overcome, an EQA combining both EIA and functional testing is feasible.

Standardization of Allergen Extracts

Allergens are molecules with the capacity to elicit IgE responses in humans. When stimulated with allergens, most allergic patients respond with production of IgE specific for several proteins/allergens in the source material. The standardization of allergen extracts is essential in order to control variability and to achieve consistency and reproducibility in a clinical setting.Because the IgE binding capacity of an allergen extract is related to the content of one or a few major allergens, it is important that the standardization procedure ensures consistency, not only in the overall IgE binding potency, but also in the content and ratio of individual major allergens. Owing to the complexity of allergen extracts, a key element in standardization of allergen extracts is the use of standards.This chapter describes the principles for standardization of allergen extracts to be used by research laboratories. Other chapters in this volume describe in vitro methods in detail.

Allergy Testing: Common Questions and Answers

An estimated 10% to 30% of the global population has an allergic disease. Clinical presentations of allergic diseases, respiratory infections, and autoimmune conditions have similar features. Allergy and immunologic testing can help clarify the diagnosis and guide treatment. Immediate immunoglobulin E (IgE) and delayed T cell-mediated reactions are the main types of allergic responses. The allergens suspected in an immediate IgE-mediated response are identified through serum IgE-specific antibody or skin testing. For patients with an inhalant allergy, skin or IgE-specific antibody testing is preferred. In patients with food allergies, eliminating the suspected allergenic food from the diet is the initial treatment. If this is ineffective, IgE-specific antibody or skin testing can exclude allergens. An oral food challenge should be performed to confirm the diagnosis. Patients with an anaphylactic reaction to an insect sting should undergo IgE-specific antibody or skin testing. Skin testing for penicillin has a high negative predictive value and can help when penicillin administration is indicated and there are limited alternatives. Testing for other drug allergies has less well-determined sensitivity and specificity, but can guide the diagnosis. Patch testing can help identify the allergen responsible for contact dermatitis.

Cut-off values of immunological tests to identify patients at high risk of severe lupus nephritis

Cut-off values for anti-dsDNA, anti-nucleosome and anti-C1q antibodies tests and for complementmediated hemolytic activity (CH50) were explored to identify patients with high risk of developing severe lupus nephritis (LN). Forty-one patients with confirmed systemic lupus erythematosus (SLE) were identified; their levels for the three antibodies and complement had been measured on a same serum sample. These patients were classified based on the presence of renal involvem ent; sixteen had active proliferative LN. With the cut-off values accepted in the laboratory for SLE diagnosis (anti-dsDNA > 100 UI/ml, anti-nucleosome > 50 U/ml or CH50 < 190 UCH50%) no significant differences were found between patients with and without LN. Anti-C1q > 40 U/ml showed a statistically significant association with LN and had 80% of specificity. Cut-off values for LN identified by Receiver Operating Characteristic curves (ROC) were higher for anti-dsDNA (> 455 IU/ml) and antinucleosome (>107 U/ml), lower for CH50 (< 150 UCH50%) and, for anti-C1q (> 41 U/ml) coincided with the cut-off values accepted for SLE. Anti-C1q > 134 U/ml had a 92% of specificity, 56% of sensibility and was associated with a fifteen-fold increased risk of LN. The simultaneous presence of anti-nucleosome > 107 U/ml and anti-C1q > 134 U/ml was associated with a 27-fold higher probability for LN. According to these results, the cut-off values used to detect SLE activity could be inadequate to identify patients at high risk of severe LN.

Patient factors associated with unidentified reactivity in solid-phase and polyethylene glycol antibody detection methods

BACKGROUND

Several publications have reported an increase in nonspecific reactions when automated technologies such as solid phase are used for the detection of red blood cell alloantibodies. However, there is little known about patient-specific factors associated with these reactions and the clinical importance of these nonspecific reactions.

STUDY DESIGN AND METHODS

We performed a 6-year retrospective review of our blood bank records and all newly reported unidentified (UID) reactivity using a test tube polyethylene glycol (t-PEG) and solid-phase method for the detection and identification of alloantibodies was recorded. Patient factors, such as underlying diagnosis, age, sex, ABO, Rh type, ethnicity, and subsequent antibody formation were recorded in each case.

RESULTS

We determined that there was a significant increase in new UID reactions recorded in solid phase (20 per 10,000 tests) when compared to the t-PEG (1.8 per 10,000 tests) method for the detection of antibodies (p ≤ 0.0001). Solid-phase UID reactions were significantly associated with female sex (p = 0.04) and certain diagnoses, such as chronic or autoimmune disease, cancer, pregnancy, surgery, and trauma. Approximately 16% of patients developed a new auto- or alloantibody subsequent to their detected UID using solid phase.

CONCLUSIONS

When solid phase is used for antibody identification, there is greater sensitivity toward nonspecific reactivity when compared to the t-PEG method. Patient sex and underlying diagnosis may explain the increased incidence of new UID reactivity in the solid-phase technology. Finally, UID reactivity should not be overlooked due to a notable percentage of subsequent clinically significant antibodies after UID detection.

SENIORLAB: a prospective observational study investigating laboratory parameters and their reference intervals in the elderly

BACKGROUND

In clinical practice, laboratory results are often important for making diagnostic, therapeutic, and prognostic decisions. Interpreting individual results relies on accurate reference intervals and decision limits. Despite the considerable amount of resources in clinical medicine spent on elderly patients, accurate reference intervals for the elderly are rarely available. The SENIORLAB study set out to determine reference intervals in the elderly by investigating a large variety of laboratory parameters in clinical chemistry, hematology, and immunology.

METHODS/DESIGN

The SENIORLAB study is an observational, prospective cohort study. Subjectively healthy residents of Switzerland aged 60 years and older were included for baseline examination (n = 1467), where anthropometric measurements were taken, medical history was reviewed, and a fasting blood sample was drawn under optimal preanalytical conditions. More than 110 laboratory parameters were measured, and a biobank was set up. The study participants are followed up every 3 to 5 years for quality of life, morbidity, and mortality. The primary aim is to evaluate different laboratory parameters at age-related reference intervals. The secondary aims of this study include the following: identify associations between different parameters, identify diagnostic characteristics to diagnose different circumstances, identify the prevalence of occult disease in subjectively healthy individuals, and identify the prognostic factors for the investigated outcomes, including mortality.

DISCUSSION

To obtain better grounds to justify clinical decisions, specific reference intervals for laboratory parameters of the elderly are needed. Reference intervals are obtained from healthy individuals. A major obstacle when obtaining reference intervals in the elderly is the definition of health in seniors because individuals without any medical condition and any medication are rare in older adulthood. Reference intervals obtained from such individuals cannot be considered representative for seniors in a status of age-specific normal health. In addition to the established methods for determining reference intervals, this longitudinal study utilizes a unique approach, in that survival and long-term well-being are taken as indicators of health in seniors. This approach is expected to provide robust and representative reference intervals that are obtained from an adequate reference population and not a collective of highly selected individuals.

TRIAL REGISTRATION

The present study was registered under International Standard Randomized Controlled Trial Number registry: ISRCTN53778569.

A pilot study to assess relationship between total IgE and 95% predictive decision points of food specific IgE concentration

BACKGROUND

False positive test results in children who are tested for food allergies may lead to inappropriate dietary restrictions.

OBJECTIVE

The aim of this study was to report our experience with a 3 year-old boy, who presented with "multiple food allergies" and, however, passed the food challenges, and to review our experience regarding management of children with high specific food IgEs with high total IgE.

METHODS

Medical records of 16 children with food challenges were reviewed. Median age of subjects was 39 months, with a history of adverse clinical reaction to a food, a specific IgE greater than the decision point, and an elevated total serum IgE level of 500 IU, underwent challenges to the offending food.

RESULTS

13 out of 16 subjects were successfully re-exposed to the suspected foods and continued to tolerate these foods well.

CONCLUSION

Our finding suggests a much lower clinical risk with previously defined specific IgE decision points in children with very high levels of total IgE (> 6000 IU/ml).

[FROM THEORY TO PRACTICE. THE ROLE OF QUALITY CONTROL OF ANALYTICAL STAGE OF STUDIES IN INCREASING CLINICAL INFORMATIVENESS OF LABORATORY TESTS]

Nowadays, improving accuracy and clinical informativeness of results of studies is one of main directions of development of laboratory. The article presents originally developed algorithm of evaluation of quality of immunochemical studies in part related to analytical stage. The case of application in practice of the results of such evaluation is presented.

Establishment and maintenance of a PBMC repository for functional cellular studies in support of clinical vaccine trials

A large repository of cryopreserved peripheral blood mononuclear cells (PBMCs) samples was created to provide laboratories testing the specimens from human immunodeficiency virus-1 (HIV-1) vaccine clinical trials the material for assay development, optimization, and validation. One hundred thirty-one PBMC samples were collected using leukapheresis procedure between 2007 and 2013 by the Comprehensive T cell Vaccine Immune Monitoring Consortium core repository. The donors included 83 human immunodeficiency virus-1 (HIV-1) seronegative and 32 HIV-1 seropositive subjects. The samples were extensively characterized for the ability of T cell subsets to respond to recall viral antigens including cytomegalovirus, Epstein-Barr virus, influenza virus, and HIV-1 using Interferon-gamma (IFN-γ) enzyme linked immunospot (ELISpot) and IFN-γ/interleukin 2 (IL-2) intracellular cytokine staining (ICS) assays. A subset of samples was evaluated over time to determine the integrity of the cryopreserved samples in relation to recovery, viability, and functionality. The principal results of our study demonstrate that viable and functional cells were consistently recovered from the cryopreserved samples. Therefore, we determined that this repository of large size cryopreserved cellular samples constitutes a unique resource for laboratories that are involved in optimization and validation of assays to evaluate T, B, and NK cellular functions in the context of clinical trials.

[Systemic autoimmune rheumatic diseases in 2013: problems of laboratory diagnosis]

Progress in the laboratory diagnosis of systemic autoimmune rheumatic diseases (SRAD) is caused by the ever increasing clinical introduction of new highly productive methods for immune analysis using computer-aided systems and multiplex proteomic technologies. The urgent problem in the laboratory diagnosis of SRAD is the standardization of current methods for the detection of autoantibodies (autoAb), including the preparation of international reference materials for the calibration and external quality assessment of immunological assay. New autoAb technologies have a higher analytical validity than the previously used classical techniques immunodiffusion, agglutination, and immunofluorescence; however, their diagnostic sensitivity and specificity for SRAD have been poorly studied. Particular emphasis is laid on the standardization of the methods for examining antinuclear antibodies (ANAb), the major serologic marker of SRAD. According to the EULAR/ACR guidelines, indirect immunofluorescence reaction (IIFR) using human HEp-2 cells as substrate is the gold standard and a primary screening ANAb method. New methods for solid-phase analysis (enzyme immunoassay, multiplex test systems, etc.) cannot substitute the primary screening of ANAb using IIFR-HEp-2 as they identify antibodies to the limited number of antigens, increasing the number of false- negative results. The computer-aided systems for interpreting cell fluorescence tests contribute to the standardization and enhancement of the efficiency of detection of ANAb and other autoAb by IIFR. The use of complex diagnostic indices based on the multiparametric analysis of laboratory biomarkers in the serum makes it possible to most fully and objectively assess complex molecular mechanisms for the pathogenesis of SRAD, thus radically improving the early diagnosis, the estimation of the activity and severity of disease, the prediction of the outcomes of a pathological process and the response to treatment.

Centers for Disease Control and Prevention. Evaluation of 11 commercially available rapid influenza diagnostic tests--United States, 2011-2012

Accurate diagnosis of influenza is critical for clinical management, infection control, and public health actions to minimize the burden of disease. Commercially available rapid influenza diagnostic tests (RIDTs) that detect the influenza virus nucleoprotein (NP) antigen are widely used in clinical practice for diagnosing influenza because they are simple to use and provide results within 15 minutes; however, there has not been a recent comprehensive analytical evaluation of available RIDTs using a standard method with a panel of representative seasonal influenza viruses. This report describes an evaluation of 11 Food and Drug Administration (FDA)-cleared RIDTs using 23 recently circulating influenza viruses under identical conditions in a laboratory setting to assess analytical performance. Most RIDTs detected viral antigens in samples with the highest influenza virus concentrations, but detection varied by virus type and subtype at lower concentrations. Clinicians should be aware of the variability of RIDTs when interpreting negative results and should collect test samples using methods that can maximize the concentration of virus antigen in the sample, such as collecting adequate specimens using appropriate methods in the first 24-72 hours after illness onset. The study design described in this report can be used to evaluate the performance of RIDTs available in the United States now and in the future.

Evaluation of the implementation of a rapid streptococcal antigen test in a routine primary health care setting: from recommendations to practice

BACKGROUND AND AIM

Pharyngitis is a common reason for consultation in General Practice. Despite the development of diagnostic criteria it remains difficult to clinically diagnose the bacterial type. Therefore, current guidelines recommend the additional use of objective tests. In Austria, the Burgenländische Gebietskrankenkasse introduced a test as service for patients and regular payment position for GPs. It was the aim of this study to analyze this implementation process in General Practice and a possible change in antibiotic prescriptions.

METHODS

The retrospective evaluation lasted from April 2006 to September 2009; in April 2007, rapid-streptococcal-antigen-tests (RSATs) were introduced. GPs were grouped into three clusters according to their use of RSATs. In addition, all antibiotic prescriptions within the evaluation period were analyzed and correlated to the three clusters before and after the implementation.

RESULTS

The overall number of RSATs performed was 6,401. Half of the GPs utilized it regularly. After its introduction, the relative antibiotic prescription frequency was significantly reduced (17.1 vs. 16.4 %, p = 0.0001). The results for the subgroup analyses yielded a significant reduction for the regular user group only (16.0 vs. 15.0 %, p = 0.0001).

CONCLUSION

GPs using the RSAT regularly seem to apply the test appropriately. The decrease of the relative antibiotic prescriptions of all GPs seems to be due to the regular user group of GPs. This could be interpreted as a consequence of the RSAT use. The results show a positive trend for an improvement in diagnostic quality and for an appropriate use of antibiotic prescriptions.

TSH receptor autoantibody immunoassay in patients with Graves' disease: improvement of diagnostic accuracy over different generations of methods. Systematic review and meta-analysis

BACKGROUND

TSH receptor antibodies (TRAb) are the diagnostic hallmark of Graves' disease (GD) and immunoassays for their detection have been available for more than 30 years over three generations of laboratory methods. Despite a growing body of data produced by clinical and laboratory research which demonstrates its elevated sensitivity and specificity, TRAb testing is poorly used for diagnosing GD. The aim of our systematic review and meta-analysis is to verify the diagnostic performance of TRAb detected with 2nd and 3rd generation immunoassay methods.

METHODS

We searched for English articles using MEDLINE with the search terms "TSH receptor antibody assay", "TSH Receptor antibody tests" and "Graves' disease". We analyzed studies reporting on TSH receptor antibody tests performed by quantitative immunoassays, on untreated patients with GD as the index disease (sensitivity) and on a control group of either healthy subjects or patients affected by other thyroid diseases (specificity). A total of 681 titles were initially identified with the search strategy described. 560 publications were excluded based on abstract and title. Full-text review was undertaken as the next step on 111 publications providing data on TRAb testing; 58 articles were subsequently excluded because they did not include untreated GD patients, or used either bioassays or 1st generation immunoassays. 32 were also excluded because they included data only on sensitivity or only on specificity of the assay, or were duplicates. Finally, 21 articles were selected for meta-analysis. Extraction of data from selected articles was performed by two authors independently, using predefined criteria: the number of patients with GD and the number of healthy or diseased controls; specification of the analytical method used to detect TRAb; sensitivity and specificity of the assay.

RESULTS

The meta-analysis showed that the overall pooled sensitivity and specificity of the 2nd and 3rd generation TRAb assays are 97.1% and 97.4%, and 98.3% and 99.2%, respectively, with little difference between the types of immunoassay methods employed (human or porcine receptor, manual or automated procedure). The likelihood of a TRAb-positive individual to have GD is 1367- to 3420-fold greater (depending upon the type of assay) compared to a TRAb-negative person.

CONCLUSIONS

Data from the meta-analysis showed that TRAb measured with 2nd and 3rd generation immunoassay methods have very high sensitivity and specificity in the diagnosis of GD. The difference between 2nd and 3rd generation methods is small and is equally useful. In contrast with recommendations made by clinical endocrinologists who are not familiar with the state of the art in diagnostic technologies of autoimmunology laboratories, we propose a wide application of these tests in clinical practice to screen all hyperthyroid patients.

Centers for Disease Control and Prevention (CDC). Notes from the field: false-positive measles test - Maine, February 2012

On February 7, 2012, the Maine Center for Disease Control and Prevention was notified of suspected measles infection in an unvaccinated woman aged 57 years. The patient went to her medical provider on January 30 after 3 days of headache and fever and 2 days of papular rash. The rash began on her neck and spread to her abdomen, legs, and back. Two days later she developed coryza and cough. The rash resolved by February 6. A serum specimen collected on January 31 demonstrated a high titer of measles immunoglobulin M (IgM) and was positive for measles immunoglobulin G (IgG) on testing at a reference laboratory.

[The actual issues of comparing the results of quantitative immune-enzyme tests]

The analysis was applied to the situation on national market of immune-enzyme diagnosticums with further quantitative reporting of results. The issues of coincidence and interpretation of results and causes of discrepancy are considered The notions of biologic ambiguity and metrological traceability are explained.

Development of a standardized low-dose double-blind placebo-controlled challenge vehicle for the EuroPrevall project

BACKGROUND

  Double-blind placebo-controlled food challenge (DBPCFC) is the gold standard for diagnosing food allergy. Standardized materials and protocols are essential for comparing DBPCFC results for multicentre studies such as EuroPrevall. This required the development and piloting of a standardized vehicle and low-dose protocol for confirming food allergy and determination of minimum eliciting doses (MEDs).

METHODS

  A low-dose DBPCFC protocol was developed, with eight titrated protein doses from 3 μg to 1 g. This was delivered using a simple, microbiologically stable food base incorporating allergenic food ingredients manufactured at three sites and centrally distributed to clinical centres. Allergen blinding was assessed by a professional sensory testing panel using a triangle test. Homogeneity and allergen content were confirmed by ELISA and clinical efficacy was assessed in a pilot study, using celeriac and hazelnut as exemplars.

RESULTS

  Celeriac and hazelnut ingredients were sufficiently blinded in the dessert. The dessert meals were successfully piloted with hazelnut in allergy clinics in Spain, the Netherlands and Italy and with celeriac and hazelnut in Zurich. The challenges elicited a range of subjective and objective reactions ranging in severity from mild itching of the oral mucosa to bronchospasm.

CONCLUSIONS

  A standardized challenge vehicle proven to sufficiently blind processed, powdered hazelnut and celeriac ingredients and that can be reproducibly manufactured has been developed. This pilot study shows that the vehicle is promising for the confirmation of food allergy and determination of MEDs in adults and children with body weight >28.8 kg (approximately 7-11 years old).

[The standardization of technique of detection of blood cells cytokine production ex vivo]

The standardized technique to detect the blood cells cytokine production ex vivo was developed. The complex of mitogens of phytohemagglutinin P, phytohemagglutinin M, lipopolysaccharide, concanavalin A is applied to provide the mitogen activation. This approach permits to activate the different types of immunocompetent cells and to induce the secretion of cytokine representative series. It is demonstrated that the application of this technique permits to receive the reproducible results of the secretion of cytokine following the standard procedure. The standard values of spontaneous and mitogene-induced production of cytokines by blood cells of healthy human are determined.

Primary immunodeficiency diseases in Latin America: proceedings of the Second Latin American Society for Immunodeficiencies (LASID) Advisory Board

Early diagnosis and appropriate therapy are essential for the best prognosis and quality of life in patients with primary immunodeficiency diseases (PIDDs). Experts from several Latin American countries have been meeting on a regular basis as part of an ongoing effort to improve the diagnosis and treatment of PIDD in this region. Three programmes are in development that will expand education and training and improve access to testing facilities throughout Latin America. These programmes are: an educational outreach programme (The L-Project); an immunology fellowship programme; and the establishment of a laboratory network to expand access to testing facilities. This report provides the status of these programmes based on the most recent discussions and describes the next steps toward full implementation of these programmes.

Nasal provocation test: how to maximize its clinical use?

In order to diagnose allergic rhinitis (AR), skin prick tests and serum specific IgE level are the most common used methods. But there are some conditions which the results of both methods do not correlate with the clinical presentation of AR. Nasal provocation test is the method of detecting local IgE at the shock organ. There are some variations of NPT in terms of dosage, allergen administration, evaluation and scoring system. This article summarized the usefulness of NPT, its indication and contraindication, dosage and instillation techniques for allergens and evaluation of outcome in the hope that if we can standardize the procedure and make it easier to perform, NPT will be applied more in clinical practice. In addition normal values among Asian ethnics are presented for appropriate interpretation of the test.

Rational use of immunodiagnostic tools for tuberculosis infection: guidelines and cost effectiveness studies

Tuberculosis (TB) remains a public health challenge and its control requires the use efficient diagnostic tools. Mycobacterium tuberculosis (MTB) elicits a strong immune response upon infection, a phenomenon measured by the old tuberculin skin test (TST). However, this test has many limitations and a high rate of positivity in BCG-vaccinated subjects. Recent studies have identified several MTB-antigens for diagnostic use, including the ESAT-6 and CFP-10 proteins. Based on these antigens, one of the most significant developments in the diagnostic armamentarium for TB has been the assays based on IFN- determination (IGRAs). The assays stem from the principle that T-cells of infected individuals produce IFN-gamma when they re-encounter the MTB antigens in vitro and this can be measured by a conventional ELISA test. The evaluation of IGRAs in different clinical settings showed many advantages over TST. The worldwide diffusion of IGRAs has increased the knowledge on their clinical use and a number of guidelines have been devised for their application. The two-step approach (first using TST followed by IGRA for confirmation) is the most favored strategy for IGRA-use in the general population, while the use of IGRAs alone is suggested in particular clinical settings and/or patient groups. Even if these tests are still costly there are a number of cost effective advantages in the "targeted" use of IGRAs over the TST. The work we present summarises all these aspects.

Evaluation of an in vitro sulphidoleukotriene release test for diagnosis of insect bite hypersensitivity in horses

REASONS FOR PERFORMING STUDY

Insect bite hypersensitivity (IBH) is an IgE-mediated allergic dermatitis caused by bites of Culicoides and Simulium species, and improved means of diagnosis are required.

OBJECTIVES

The cellular antigen simulation test (CAST) with C. nubeculosus and S. vittatum extracts was assessed in a population of IBH-affected and healthy horses. Variations in test results over a one year period and possible cross-reactivity between different insect extracts was studied.

METHODS

A total of 314 mature horses were studied using the CAST. Influence of severity of clinical signs, gender and age were evaluated, and 32 horses were tested repeatedly over one year. The kappa reliability test was used to assess agreement of the test results with different insect extracts.

RESULTS

Horses with IBH had significantly higher sLT release than controls with C. nubeculosus and S. vittatum. The highest diagnostic sensitivity and specificity levels were attained when using adult C. nubeculosus extracts with the CAST (78% and 97%, respectively), suggesting that most horses with IBH are sensitised against Culicoides allergens. A proportion of IBH-affected horses was found to be sensitised to allergens of Simulium spp. in addition to those of C. nubeculosus. The CAST with C. nubeculosus had positive and negative predictive values > or = 80% for a true prevalence of IBH of 12-52%. In the follow-up study, the proportion of IBH-affected horses with a positive test result ranged from 90% in November to 68% in March. Severity of clinical signs or age did not influence test results significantly. However, IBH-affected males achieved significantly more positive test results than IBH-affected females.

CONCLUSIONS

The CAST with adult C. nubeculosus has high specificity and good sensitivity for diagnosis of IBH. Horses with IBH are mainly sensitised to Culicoides allergens, and some horses are additionally also sensitised to allergens in Simulium spp.

POTENTIAL RELEVANCE

The CAST is likely to be a useful test for diagnosis of IBH, even allowing the identification of IBH-affected but asymptomatic horses. This test may also help in further characterisation of allergens involved in this condition.

Repetition of the rapid antigen test in initially negative supposed streptococcal pharyngitis is not necessary in adults

AIMS

To determine whether the repetition of the rapid antigen detection test (RADT) in patients, with a high suspicion of presenting pharyngitis by group A beta-haemolytic streptococci (GABHS), with a previously negative test improves the validity of the test.

METHODS

Two hundred and twenty-two patients aged 14 years or more with acute pharyngitis and two or more Centor criteria--tonsillar exudates, fever, tenderness in the lymph glands and/or absence of cough--were consecutively recruited. In all patients, a pharyngotonsillar sample was obtained with two swabs, one for the RADT (OSOM Strep A Genzyme test, Genzyme Diagnostics, Cambridge, MA, USA) and the other was sent to the Department of Microbiology for culture. In patients with a negative RADT, the determination was repeated. The sensitivity, specificity and predictive values were determined.

RESULTS

Cultures were positive for GABHS in 55 patients (24.8%). Three false-negatives and 14 false-positives were observed by comparing the rapid test with throat culture, achieving a sensitivity of 94.5% and a specificity of 91.6%. Positive and negative predictive values were 78.8% and 98.1% respectively. Taking the second determination in the negative cases into account, the results were 96.4%, 91.6%, 79.1% and 98.7% respectively.

CONCLUSIONS

The negative predictive value achieved with the RADT determination was very high. Repetition of the test only slightly improved this percentage, making repetition of this test unnecessary.

Accuracy of immunodiagnostic tests for active tuberculosis using single and combined results: a multicenter TBNET-Study

Background

The clinical application of IFN-γ release assays (IGRAs) has recently improved the diagnosis of latent tuberculosis infection. In a multicenter study of the Tuberculosis Network European Trialsgroup (TBNET) we aimed to ascertain in routine clinical practice the accuracy of a novel assay using selected peptides encoded in the mycobacterial genomic region of difference (RD) 1 for the diagnosis of active tuberculosis in comparison with tuberculin skin test (TST), QuantiFERON-TB GOLD In-Tube (Cellestis Ltd., Carnegie, Australia) and T-SPOT.TB (Oxfordimmunotec, Abingdon, UK).

Principal Findings

425 individuals from 6 different European centres were prospectively enrolled. We found that sensitivity of the novel test, TST, QuantiFERON-TB GOLD In-Tube and T-SPOT.TB was respectively 73.1%, 85.3%, 78.1%, and 85.2%; specificity was respectively 70.6%, 48.0%, 61.9% and 44.3%; positive likelihood ratios were respectively 2.48, 1.64, 2.05, and 1.53; negative likelihood ratios were respectively 0.38, 0.31, 0.35, 0.33. Sensitivity of TST combined with the novel test, QuantiFERON-TB GOLD In-Tube and T-SPOT.TB increased up to 92.4%, 97.7% and 97.1%, respectively. The likelihood ratios of combined negative results of TST with, respectively, the novel test, QuantiFERON-TB GOLD In-Tube and T-SPOT.TB were 0.19, 0.07 and 0.10.

Conclusions

The assay based on RD1 selected peptides has similar accuracy for active tuberculosis compared with TST and commercial IGRAs. Then, independently of the spectrum of antigens used in the assays to elicit mycobacterial specific immune responses, the novel test, IGRAs, and the TST do not allow an accurate identification of active tuberculosis in clinical practice. However, the combined use of the novel assay or commercial IGRAs with TST may allow exclusion of tuberculosis.

Population screening for coeliac disease in primary care by district nurses using a rapid antibody test: diagnostic accuracy and feasibility study

OBJECTIVE

To evaluate the feasibility and diagnostic accuracy of screening for coeliac disease by rapid detection of IgA antibodies to tissue transglutaminase performed in primary care.

DESIGN

District nurses screened 6 year old children using rapid antibody testing of finger prick blood. They also collected capillary blood samples for laboratory determination of IgA and IgG antibodies to endomysium and IgA antibodies to tissue transglutaminase. Children with positive rapid test results were directly sent for biopsy of the small intestine. Setting Primary care in Jász-Nagykun-Szolnok county, Hungary.

PARTICIPANTS

2690 children (77% of 6 year olds living in the county) and 120 nurses.

MAIN OUTCOME MEASURES

Positivity for antibodies to endomysium or transglutaminase in the laboratory and coeliac disease confirmed at biopsy.

RESULTS

37 children (1.4%, 95% confidence interval 0.9% to 1.8%) had biopsy confirmed coeliac disease. Only five of these children had been diagnosed clinically before screening. Rapid testing had a 78.1% sensitivity (70.0% to 89.3%) and 100% specificity (88.4% to 100%) for a final diagnosis of coeliac disease by biopsy. Sensitivity was 65.1% (50.2% to 77.6%) and specificity was 100% (99.8% to 100%) compared with combined results of IgA and IgG laboratory tests. Trained laboratory workers detected 30 of the 31 newly diagnosed IgA competent patients with the rapid test kit used blindly. Median time to biopsy after a positive rapid test result was significantly shorter (20 days, range 4-148) than after a positive laboratory result (142 days, 70-256; P<0.001). Children with coeliac disease detected at screening were smaller and had worse health status than their peers but they improved on a gluten-free diet.

CONCLUSIONS

A simple rapid antibody test enabled primary care nurses to detect patients with coeliac disease in the community who were not picked up in clinical care. Extra training is needed to improve sensitivity.

Development of an immunosensor for the diagnosis of bovine anaplasmosis

An optical immunosensor based in major surface protein 5 (MSP5) of Anaplasma marginale was developed towards detection of anti-Anaplasma sp. antibodies in acute infection as well as in vaccinated cattle. This study was performed using recombinant MSP5 covalently immobilised in controlled pore glass (CPG) beads to detect anti-MSP5 antibodies in serum samples. The quantification is based on the measurement of the Cy5 fluorescence of the detection antibody, anti bovine IgG, after reaction with serum. Sera were collected in enzootic and tick-free regions of Argentina. The immunosensor showed a detection range of 1.2 g/ml to 48 g/ml of antibody in sera, with a sensitivity of 93% and a specificity of 70%. The optical immunosensor developed is suitable for quantification of antibodies in sera of naturally or experimentally infected animals.

Meta-analysis: new tests for the diagnosis of latent tuberculosis infection: areas of uncertainty and recommendations for research

BACKGROUND

Until recently, the tuberculin skin test was the only test for detecting latent tuberculosis (TB) infection, but 2 ex vivo interferon-gamma release assays (IGRAs) are now commercially licensed.

PURPOSE

To estimate sensitivity, specificity, and reproducibility of IGRAs (commercial or research versions of QuantiFERON [QFT] and Elispot) for diagnosing latent TB infection in healthy and immune-suppressed persons.

DATA SOURCES

The authors searched MEDLINE and reviewed citations of all original articles and reviews for studies published in English.

STUDY SELECTION

Studies had evaluated IGRAs using Mycobacterium tuberculosis-specific antigens (RD1 antigens) and overnight (16- to 24-h) incubation times. Reference standards had to be clearly defined without knowledge of test results. DATA EXTRACTION AND QUALITY ASSESSMENT: Specific criteria for quality assessment were developed for sensitivity, specificity, and reproducibility.

DATA SYNTHESIS

When newly diagnosed active TB was used as a surrogate for latent TB infection, sensitivity of all tests was suboptimal, although it was higher with Elispot. No test distinguishes active TB from latent TB. Sensitivity of the tuberculin skin test and IGRAs was similar in persons who were categorized into clinical gradients of exposure. Pooled specificity was 97.7% (95% CI, 96% to 99%) and 92.5% (CI, 86% to 99%) for QFT and for Elispot, respectively. Both assays were more specific than the tuberculin skin test in samples vaccinated with bacille Calmette-Guérin. Elispot was more sensitive than the tuberculin skin test in 3 studies of immune-compromised samples. Discordant tuberculin skin test and IGRA reactions were frequent and largely unexplained, although some may be related to varied definitions of positive test results. Reversion of IGRA results from positive to negative was common in 2 studies in which it was assessed.

LIMITATIONS

Most studies used cross-sectional designs with the inherent limitation of no gold standard for latent TB infection, and most involved small samples with a widely varying likelihood of true-positive and false-positive test results. There is insufficient evidence on IGRA performance in children, immune-compromised persons, and the elderly.

CONCLUSIONS

New IGRAs show considerable promise and have excellent specificity. Additional studies are needed to better define their performance in high-risk populations and in serial testing. Longitudinal studies are needed to define the predictive value of IGRAs.

Thermal stability of the WHO international standard of interferon alpha 2b (IFN-alpha 2b): application of new reporter gene assay for IFN-alpha 2b potency determinations

A World Health Organization requirement for biological standards is that they should exhibit long-term stability at their recommended storage temperature. Thermal stability is usually predicted in accelerated thermal degradation studies, where ampoules of the lyophilized standard are stored at elevated temperatures for relatively short times before testing. To confirm the predicted thermal stability of the 2nd international standard of human interferon alpha 2b (IFN-alpha2b; 95/566), we tested the potency of the ampouled contents of this standard after 9 years storage at the customary storage temperature of -20 degrees C in comparison with ampoules of the IS which had been stored continuously at temperatures ranging from -150 degrees C to 56 degrees C. Since IFN-alpha2b potency estimates derived from the results of antiviral assays (AVA) showed high within-assay variability, we investigated a novel reporter gene assay (RGA) based on induction of secreted alkaline phosphatase (SEAP) for comparability and precision of such estimations. We show that this RGA generated comparable estimates with overall lower variation. Additionally, the SEAP conversion of p-nitrophenyl phosphate to yellow product could be followed kinetically. Absorbance readings were shown to increase with time in proportion with increasing concentration of IFN-alpha2b. When the time-dependent increments of absorbance were plotted graphically, the slopes of lines corresponded to concentration. This approach enabled single dilutions of IFN samples, identical in molecular structure to an IFN-alpha2b standard, to be used for potency estimates by interpolation of slope value against those of the standard at fixed concentrations. It appears attractive for high through-put potency testing of various R&D IFN-alpha2b samples.

Ensuring quality and access for malaria diagnosis: how can it be achieved?

The replacement of conventional antimalarial drugs with high-cost, artemisinin-based alternatives has created a gap in the successful management of malaria. This gap reflects an increased need for accurate disease diagnosis that cannot be met by traditional microscopy techniques. The recent introduction of rapid diagnostic tests (RDTs) has the potential to meet this need, but successful RDT implementation has been curtailed by poor product performance, inadequate methods to determine the quality of products and a lack of emphasis and capacity to deal with these issues. Economics and a desire for improved case management will result in the rapid growth of RDT use in the coming years. However, for their potential to be realized, it is crucial that high-quality RDT products that perform reliably and accurately under field conditions are made available. In achieving this goal, the shift from symptom-based diagnosis to parasite-based management of malaria can bring significant improvements to tropical fever management, rather than represent a further burden on poor, malaria-endemic populations and their overstretched health services.

Ensuring quality and access for malaria diagnosis: how can it be achieved?

The replacement of conventional antimalarial drugs with high-cost, artemisinin-based alternatives has created a gap in the successful management of malaria. This gap reflects an increased need for accurate disease diagnosis that cannot be met by traditional microscopy techniques. The recent introduction of rapid diagnostic tests (RDTs) has the potential to meet this need, but successful RDT implementation has been curtailed by poor product performance, inadequate methods to determine the quality of products and a lack of emphasis and capacity to deal with these issues. Economics and a desire for improved case management will result in the rapid growth of RDT use in the coming years. However, for their potential to be realized, it is crucial that high-quality RDT products that perform reliably and accurately under field conditions are made available. In achieving this goal, the shift from symptom-based diagnosis to parasite-based management of malaria can bring significant improvements to tropical fever management, rather than represent a further burden on poor, malaria-endemic populations and their overstretched health services.

Ensuring quality and access for malaria diagnosis: how can it be achieved?

The replacement of conventional antimalarial drugs with high-cost, artemisinin-based alternatives has created a gap in the successful management of malaria. This gap reflects an increased need for accurate disease diagnosis that cannot be met by traditional microscopy techniques. The recent introduction of rapid diagnostic tests (RDTs) has the potential to meet this need, but successful RDT implementation has been curtailed by poor product performance, inadequate methods to determine the quality of products and a lack of emphasis and capacity to deal with these issues. Economics and a desire for improved case management will result in the rapid growth of RDT use in the coming years. However, for their potential to be realized, it is crucial that high-quality RDT products that perform reliably and accurately under field conditions are made available. In achieving this goal, the shift from symptom-based diagnosis to parasite-based management of malaria can bring significant improvements to tropical fever management, rather than represent a further burden on poor, malaria-endemic populations and their overstretched health services.