scholarly journals Diagnostic Performance of Hrp2 Based Diagnostic Test Kits and Frequency of Pfhrp2 Gene Deletion in Plasmodium falciparum Isolates of Osogbo, Southwestern Nigeria

2021 ◽  
pp. 20-25
Author(s):  
A. S. Nassar ◽  
A. S. Bakarey ◽  
A. A. Abdulazeez ◽  
O. O. Fayemi
Keyword(s):  
Plasmodium Falciparum ◽  
Diagnostic Test ◽  
Gene Deletion ◽  
False Negative ◽  
University Teaching ◽  
Pcr Analysis ◽  
Southwestern Nigeria ◽  
Blood Samples ◽  
Negative Results ◽  
Test Kit

Introduction: The introduction of P. falciparum encoded HRP-2 based malaria Rapid Diagnostic Test (RDT) kits is widely accepted in Nigeria and worldwide as a simplified form of diagnosis and a cheaper alternative to the microscopy technique (gold standard). However, deletion of Pfhrp2 gene contributes to false negative results and large number of such deletions has been reported in advanced countries thereby highlighting the importance of surveillance to detect such deletions in our local environment. Methodology: Microscopy as well as RDT techniques (using Rapid malaria test kit: SD BIOLINE Malaria Ag P.f/Pv, South Korea) were carried out on the blood samples of three hundred and twenty-three (323) febrile subjects attending Ladoke Akintola University Teaching Hospital, Osogbo, Osun State Nigeria. PCR analysis was also conducted on 50 blood samples that were positive for microscopy but negative for RDT. Results: The results from the study revealed that microscopy had a sensitivity of 99% and specificity of 99.2%. The RDT however had a sensitivity of 100% and a specificity of 60.1%. Fifty (50) samples that were positive for microscopy but negative for RDT were subjected to further PCR examination to detect the possible deletion of the Pfhrp-2 gene and the result revealed that the gene was present in 39 (78%) of the blood samples while remaining 11 (22%) samples lacked the gene which could possibly be the reason for the negative results obtained using the RDT kits. Conclusion: This study provides evidence of low level of presence of Pfhrp-2 gene deletion of Plasmodium falciparum parasites in our healthcare facility setting in Osogbo, Nigeria.

Detection of Genetic markers associated with Plasmodium falciparum drug resistance among malaria patients in Kaduna State, Nigeria

2021 ◽  
Vol 42 (2) ◽  
pp. 206-213
Author(s):  
G.Y. Benjamin ◽  
H.I. Inabo ◽  
M.H.I. Doko ◽  
B.O. Olayinka
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Phylogenetic Tree ◽  
Genetic Markers ◽  
Cross Sectional Study ◽  
Sub Saharan Africa ◽  
Health Concern ◽  
Cross Sectional ◽  
Blood Samples ◽  
Test Kit

Malaria is a disease of public health concern in Nigeria and sub-Saharan Africa. It is caused by intracellular parasites of the genus Plasmodium. The aim of this study was to detect genetic markers associated with Plasmodium falciparum drug resistance among malaria patients in Kaduna State, Nigeria. The study was a cross-sectional study that lasted from May 2018 to October 2018. Three hundred blood samples were collected from consenting individuals attending selected hospitals, in the three senatorial districts of Kaduna State, Nigeria. Structured questionnaire were used to obtain relevant data from study participants. The blood samples were screened for malaria parasites using microscopy and rapid diagnostic test kit. Polymerase Chain Reaction was used for detection of the drug resistance genes. Pfcrt, pfmdr1, pfdhfr, pfdhps and pfatpase6 genes were detected at expected amplicon sizes from the malaria positive samples. The pfatpase6 PCR amplicons were sequenced and a phylogenetic tree was created to determine their relatedness. Result showed that Pfcrt (80%) had the highest prevalence, followed by pfdhfr (60%), pfmdr1 (36%) and pfdhps (8%). Pfatpase6 was also detected in 73.3% of the samples, and a phylogenetic tree showed relatedness between the pfatpase6  sequences in this study and those deposited in the GenBank. In conclusion, the study detected that Plasmodium falciparum genes were associated with drug resistance to commonly used antimalarials.

scholarly journals Average Weighted Accuracy: Pragmatic Analysis for a Rapid Diagnostics in Categorizing Acute Lung Infections (RADICAL) Study

2019 ◽  
Vol 70 (12) ◽  
pp. 2736-2742 ◽  
Author(s):  
Ying Liu ◽  
Ephraim L Tsalik ◽  
Yunyun Jiang ◽  
Emily R Ko ◽  
Christopher W Woods ◽  
...  
Keyword(s):  
Diagnostic Test ◽  
Diagnostic Yield ◽  
False Negative ◽  
Rapid Diagnostics ◽  
Likelihood Ratios ◽  
Clinical Value ◽  
Predictive Values ◽  
Negative Results ◽  
Treatment Standard ◽  
Lung Infections

Abstract Patient management relies on diagnostic information to identify appropriate treatment. Standard evaluations of diagnostic tests consist of estimating sensitivity, specificity, positive/negative predictive values, likelihood ratios, and accuracy. Although useful, these metrics do not convey the tests’ clinical value, which is critical to informing decision-making. Full appreciation of the clinical impact of a diagnostic test requires analyses that integrate sensitivity and specificity, account for the disease prevalence within the population of test application, and account for the relative importance of specificity vs sensitivity by considering the clinical implications of false-positive and false-negative results. We developed average weighted accuracy (AWA), representing a pragmatic metric of diagnostic yield or global utility of a diagnostic test. AWA can be used to compare test alternatives, even across different studies. We apply the AWA methodology to evaluate a new diagnostic test developed in the Rapid Diagnostics in Categorizing Acute Lung Infections (RADICAL) study.

scholarly journals Validation of Two Commercial Lateral Flow Devices for the Detection of Peanut Proteins in Cookies: Interlaboratory Study

2006 ◽  
Vol 89 (2) ◽  
pp. 462-468 ◽  
Author(s):  
Arjon J van Hengel ◽  
Claudia Capelletti ◽  
Marcel Brohee ◽  
Elke Anklam ◽  
M-C S Baumgartner ◽  
...  
Keyword(s):  
False Negative ◽  
Lateral Flow ◽  
Food Matrix ◽  
Negative Results ◽  
False Negative Results ◽  
Test Kit ◽  
Interlaboratory Validation ◽  
Peanut Proteins ◽  
Flow Devices ◽  
Positive Results

Abstract Results are reported for an interlaboratory validation study of 2 commercially available lateral flow devices (dipstick tests) designed to detect peanut residues in food matrixes. The test samples used in this study were cookies containing peanuts at 7 different concentrations in the range of 030 mg peanuts/kg food matrix. The test samples with sufficient and proven homogeneity were prepared in our laboratory. The analyses of the samples (5 times per level by each laboratory) were performed by 18 laboratories worldwide, which submitted a total of 1260 analytical results. One laboratory was found to be an outlier for one of the test kits. In general, both test kits performed well. However, some false-negative results were reported for all matrixes containing <21 mg peanuts/kg cookie. It must be stressed that the test kits were challenged beyond their cut-off limits (5 mg/kg, depending on the food matrix). One test kit showed fewer false-negative results, but it led to some false-positive results for the blank materials. The sensitivity of the dipstick tests approaches that achieved with enzyme-linked immunosorbent assays.

scholarly journals Evaluation of anti-SARS-CoV-2 antibody testing in asymptomatic or mild COVID-19 patients in outbreak on a cruise ship

2021 ◽  
Author(s):  
Norihito Kaku ◽  
Fumitaka Nishimura ◽  
Yui Shigeishi ◽  
Rina Tachiki ◽  
Hironori Sakai ◽  
...  
Keyword(s):  
Genetic Test ◽  
False Negative ◽  
Enzyme Linked Immunosorbent Assay ◽  
Cruise Ship ◽  
Igg Antibodies ◽  
Antibody Testing ◽  
Predictive Values ◽  
Blood Samples ◽  
Negative Results ◽  
Genetic Test Results

AbstractBackgroundA few studies on antibody testing have focused on asymptomatic or mild coronavirus disease 2019 (COVID-19) patients with low initial anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody responses. Anti-SARS-CoV-2 antibody-testing performance was evaluated using blood samples from asymptomatic or mild COVID-19 patients.MethodsBlood samples were collected from 143 COVID-19 patients during an outbreak on a cruise ship 3 weeks after diagnosis. Simultaneously, a second SARS-CoV-2 genetic test was performed. Samples stored before the COVID-19 pandemic were also used to evaluate the lateral flow immunochromatographic assay (LFA) and electrochemiluminescence immunoassay (ECLIA). Titers of anti-SARS-CoV-2 IgM and IgG antibodies against the nucleocapsid and spike proteins were measured using the enzyme-linked immunosorbent assay to compare false-negative- with positive-result samples.ResultsSensitivity, specificity, positive-predictive, and negative-predictive values of LFA-detected IgM antibodies were 0.231, 1.000, 1.000, and 0.613, respectively; those of LFA-detected IgG antibodies were 0.483, 0.989, 0.972, and 0.601, respectively; and those of ECLIA-detected total antibodies were 0.783, 1.000, 1.000, and 0.848, respectively. IgM-, IgG-, and total-antibody positivity rates in the patients with negative results from the second genetic testing were 22.9%, 47.6%, and 72.4%, respectively. All antibody titers, especially those of the IgG antibody against nucleocapsid protein, were significantly lower in blood samples with false-negative results than in those with positive results.ConclusionsThese findings suggest that anti-SARS-CoV-2 antibody testing has lower performance in asymptomatic or mild COVID-19 patients than required in the guidelines, and situations in which it is useful are limited.Key pointsAnti-SARS-CoV-2 antibody testing in asymptomatic or mild COVID-19 patients is lower than the required clinical sensitivity, although it may be useful in patients at 3–4 weeks after symptom onset but with negative SARS-CoV-2 genetic test results.

scholarly journals Combined Deletions ofpfhrp2andpfhrp3Genes Result in Plasmodium falciparum Malaria False-Negative Rapid Diagnostic Test

2011 ◽  
Vol 49 (7) ◽  
pp. 2694-2696 ◽  
Author(s):  
Sandrine Houzé ◽  
Véronique Hubert ◽  
Gaëlle Le Pessec ◽  
Jacques Le Bras ◽  
Jérôme Clain
Keyword(s):  
Plasmodium Falciparum ◽  
Falciparum Malaria ◽  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
False Negative ◽  
Plasmodium Falciparum Malaria

S235 – Diagnostic Test Validation: CHAMP in Endolymphatic Hydrops

2008 ◽  
Vol 139 (2_suppl) ◽  
pp. P154-P154
Author(s):  
Eveling Y Rojas ◽  
Leonardo Ordoñez ◽  
Victor Hernandez ◽  
Jose E Guzman ◽  
Juan Izquierdo ◽  
...  
Keyword(s):  
Diagnostic Test ◽  
Endolymphatic Hydrops ◽  
False Negative ◽  
High Specificity ◽  
Diagnostic Value ◽  
Clinical Value ◽  
Negative Results ◽  
False Negative Results ◽  
The Relationship

Objectives The Cochlear Hydrops Analysis Masking Procedure (CHAMP) has been reported with a high sensibility and specificity for the diagnosis of endolymphatic hydrops (ELH). Nevertheless, a complete validation of CHAMP with precise methods has not been done. Our objectives: To determine whether CHAMP has a diagnostic value in patients with definite, probable/possible diagnosis of Meniere's disease or endolymphatic hydrops, based on the criteria of the AAO-HNS. Methods Prospective validation study for a diagnostic test: phase II. Latency of wave V was assessed using CHAMP. We classified subjects in 5 groups: 1-Definite ELH, 2-Probable ELH, 3-Possible ELH, 4-subjects with other otovestibular symptoms, 5-normal hearing subjects. We included cases (groups 1–4) with an episode of vertigo with duration equal or longer than 20 minutes, with or without other otovestibular symptoms. Results We included 67 cases (132 ears). 38 cases (76 ears) completed the follow up and their results are presented. In group 1, the sensibility of CHAMP was 43% and its specificity was 100%. In groups 2–3, the sensitivity was 20% and the specificity 100%, with 0% false positive and 80% false negative results. Other indicators of validity for this diagnostic test are presented. Conclusions CHAMP has a high specificity and low sensibility for the diagnosis of ELH when the delay in wave V latency is used. Future studies may assess the relationship between wave amplitudes to improve the clinical value of CHAMP.

scholarly journals Diagnostic performance of HRP2-only malaria rapid diagnostic test in Ghanaian pregnant women with asymptomatic peripheral blood infection: the case of First Response® test kit

2020 ◽  
Vol 1 (2) ◽  
pp. 86-92
Author(s):  
Joseph Osarfo ◽  
Harry Tagbor ◽  
Michael Alifragis ◽  
Pascal Magnuess
Keyword(s):  
Pregnant Women ◽  
Diagnostic Test ◽  
Rapid Diagnostic Test ◽  
Peripheral Blood ◽  
Diagnostic Performance ◽  
False Negative ◽  
Malaria Rapid Diagnostic Test ◽  
First Response ◽  
Test Kit ◽  
In Pregnancy

Background: The use of malaria rapid diagnostic test(RDT) enables targeted treatment that mitigates against the development of parasite drug resistance. With detection thresholds at ≥200 parasites/μL, their diagnostic performance in pregnant women may be challenging as asymptomatic infections with low parasite densities are common. Few data exist on the performance of histidine-rich protein-2 (HRP2) RDTs in Ghanaian pregnant women considering commonly occurring low parasite densities. Objective: The study sought to contribute more knowledge on test performance on First Response® test kit to guide the continuous evaluation of HRP2 RDTs in pregnancy. Methods: As part of an antimalarial drug trial in pregnancy, First Response® RDT results were compared to microscopy of peripheral blood slides in 1664 women. The diagnostic performance indicators were computed as proportions with 95% confidence intervals. The risk of having a positive RDT result was computed for age, gravidity and parasite density using binomial regression methods. Results: Parasitaemia prevalence by microscopy was 5.71%(n =95/1664) while that by RDT was 21.57%(n = 359/1664). Sensitivity was 82.11% (n=78/95), specificity was 82.09% (n=1288/1569), positive predictive value was 21.73% (n=78/359), and the likelihood ratio for a positive test was 4.58. False-negative RDT results were recorded for low parasite densities as well as densities ≥ 200/ μL while false-positive results were recorded in 281of 1664 tests. Primigravidae and younger aged women were more likely to have positive RDT results compared to multigravidae and women aged ≥ 30 yr. Conclusion: The moderate sensitivity, specificity and other diagnostic parameters reported suggest the First Response® malaria RDT is useful for detecting peripheral parasitaemia in pregnant women but the use of HRP2-only RDTs is limited by the existence of parasites with HRP2 gene deletion. The use of RDTs based on combined antigens continues to be recommended. Further research is needed on RDT performance in pregnant women with declining malaria transmission.

scholarly journals Diagnostic Value of Endoscopic Ultrasound after Neoadjuvant Chemotherapy for Gastric Cancer Restaging: A Meta-Analysis of Diagnostic Test

Diagnostics ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 100
Author(s):  
Victor Mihai Sacerdotianu ◽  
Bogdan Silviu Ungureanu ◽  
Sevastita Iordache ◽  
Adina Turcu-Stiolica ◽  
Antonio Facciorusso ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Diagnostic Test ◽  
Endoscopic Ultrasound ◽  
Meta Analysis ◽  
False Negative ◽  
Diagnostic Value ◽  
Significant Heterogeneity ◽  
True Negative ◽  
Negative Results ◽  
False Negative Results

This study aimed to evaluate the diagnostic value of endoscopic ultrasound (EUS) after neoadjuvant therapy (NT) for gastric cancer restaging by meta-analysis. We conducted a systematic search of studies published on PubMed and Web of Science up to 30th August 2021. Assessing the risk of bias in the included studies was done with the QUADAS-2 tool. We used R and Review Manager 5.4.1 for calculations and statistical analysis. To evaluate the diagnostic value of EUS after NT for gastric cancer restaging, we performed a meta-analysis on six studies, with a total of 283 patients, including true-positive, true-negative, false-positive, and false-negative results for T1-T4, N0. EUS as a diagnostic test for GC patients after chemotherapy has a relatively low DOR for the T2 (3.96) and T4 stages (4.79) and a relatively high partial AUC for the T2 (0.85) and T4 (0.71) stages. Our results reveal that the pooled sensitivity for T stages after chemotherapy is rather low (29–56%), except for the T3 stage (71%). A potential limitation of our study was the small number of included studies, but no significant heterogeneity was found between them. Our meta-analysis concludes that EUS is not recommended or is still under debate for GC restaging after NT.

scholarly journals Secondary analysis of malaria rapid diagnostic tests from rounds 5–8 of WHO product testing with a focus on false-negative results

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Biao Xu ◽  
Bo Tu ◽  
Fang Chu ◽  
Mohamed Jalloh ◽  
Jin-Song Mu ◽  
...  
Keyword(s):  
Gene Deletion ◽  
False Negative ◽  
Secondary Analysis ◽  
World Health ◽  
Product Testing ◽  
Negative Results ◽  
Malaria Rdts ◽  
False Negative Results ◽  
Malaria Rapid Diagnostic Tests ◽  
Health Organization

AbstractDespite the widespread use of malaria rapid diagnostic test (RDT) in clinical practice, there are a lot of challenges. We conducted a secondary analysis of 129 malaria RDT data from rounds 5–8 of the World Health Organization (WHO) product testing summary and discuss the causes of false-negative (FN) results with a focus on low parasite density, improper RDT storage, operation and interpretation, and plasmodium falciparum with a pfhrp2/3 gene deletion. The results demonstrated that the malaria RDTs currently commercially available might cause FN results in practice.

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