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Search Results: 1 - 10 of 33949 matches for " Jef Van den Ende "
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The Role of Rapid Diagnostic Tests in Managing Malaria
Zeno Bisoffi ,Federico Gobbi,Andrea Angheben,Jef Van den Ende
PLOS Medicine , 2009, DOI: 10.1371/journal.pmed.1000063
Buffer substitution in malaria rapid diagnostic tests causes false-positive results
Philippe Gillet, Marcella Mori, Jef Van den Ende, Jan Jacobs
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-215
Abstract: Twenty-seven RDT brands were run with EDTA-blood samples of five malaria-free subjects, who were negative for rheumatoid factor and antinuclear antibodies. Saline, distilled water and tap water were used as substitute liquids. RDTs were also run with distilled water, without adding blood. Results were compared to those obtained with the RDT kit's buffer and Plasmodium positive samples.Only eight cassettes (in four RDT brands) showed no control line and were considered invalid. Visible test lines occurred for at least one malaria-free sample and one of the substitutes in 20/27 (74%) RDT brands (saline: n = 16; distilled water: n = 17; and tap water: n = 20), and in 15 RDTs which were run with distilled water only. They occurred for all Plasmodium antigens and RDT formats (two-, three- and four-band RDTs). Clearance of the background of the strip was excellent except for saline. The aspects (colour, intensity and crispness) of the control and the false-positive test lines were similar to those obtained with the RDT kits' buffer and Plasmodium positive samples.Replacement of the RDT kit's dedicated buffer by saline, distilled water and tap water can cause false-positive test results.Malaria rapid diagnostic tests (RDTs) detect Plasmodium parasites in blood by an antibody-antigen reaction on a nitrocellulose strip. Reactions are visible as cherry-red lines. Two-band RDTs are mostly designed to detect Plasmodium falciparum; they display a control line and a test line, which targets either histidine-rich protein-2 (HRP-2) or P. falciparum-specific parasite lactate dehydrogenase (Pf-pLDH). Three- and four-band RDTs display a control line and two or three test lines, one targeting P. falciparum specific antigen, another line targeting antigens common to the four species, such as pan-Plasmodium-specific lactate parasite dehydrogenase (pan-pLDH) or aldolase, and, in case of the four band RDTs, a third line which targets Plasmodium vivax-specific pLDH (Pv-pLDH).RDTs are curren
Zeno Bisoffi,Federico Gobbi,Dora Buonfrate,Jef Van den Ende
Mediterranean Journal of Hematology and Infectious Diseases , 2012, DOI: 10.4084/mjhid.2012.
Abstract: The revised W.H.O. guidelines for malaria management in endemic countries recommend that treatment should be reserved to laboratory confirmed cases, both for adults and children. Currently the most widely used tools are rapid diagnostic tests (RDTs), that are accurate and reliable in diagnosing malaria infection. However, an infection is not necessarily a clinical malaria, and RDTs may give positive results in febrile patients who have another cause of fever. Excessive reliance on RDTs may cause overlooking potentially severe non malarial febrile illnesses (NMFI) in these cases. In countries or areas where transmission intensity remains very high, fever management in children (especially in the rainy season) should probably remain presumptive, as a test-based management may not be safe, nor cost effective. In contrast, in countries with low transmission, including those targeted for malaria elimination, RDTs are a key resource to limit unnecessary antimalarial prescription and to identify pockets of infected individuals. Research should focus on very sensitive tools for infection on one side, and on improved tools for clinical management on the other, including biomarkers of clinical malaria and/or of alternative causes of fever.
Malaria rapid diagnostic tests: Plasmodium falciparum infections with high parasite densities may generate false positive Plasmodium vivax pLDH lines
Jessica Maltha, Philippe Gillet, Lieselotte Cnops, Jef van den Ende, Marjan van Esbroeck, Jan Jacobs
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-198
Abstract: Nine P. vivax-specific RDTs were tested with 85 P. falciparum samples of high (≥2%) parasite density. Mixed P. falciparum/P. vivax infections were ruled out by real-time PCR. The RDTs included two-band (detecting Pv-pLDH), three-band (detecting P. falciparum-antigen and Pv-pLDH) and four-band RDTs (detecting P. falciparum, Pv-pLDH and pan-pLDH).False positive Pv-pLDH lines were observed in 6/9 RDTs (including two- three- and four-band RDTs). They occurred in the individual RDT brands at frequencies ranging from 8.2% to 29.1%. For 19/85 samples, at least two RDT brands generated a false positive Pv-pLDH line. Sixteen of 85 (18.8%) false positive lines were of medium or strong line intensity. There was no significant relation between false positive results and parasite density or geographic origin of the samples.False positive Pv-pLDH lines in P. falciparum samples with high parasite density occurred in 6/9 P. vivax-specific RDTs. This is of concern as P. falciparum and P. vivax are co-circulating in many regions. The diagnosis of life-threatening P. falciparum malaria may be missed (two-band Pv-pLDH RDT), or the patient may be treated incorrectly with primaquine (three- or four-band RDTs).Malaria rapid diagnostic tests (RDTs) are immunochromatographic tests targeting antigens of one or more Plasmodium species. Signals are visible as cherry-red to purple coloured lines, comprising a control line (which indicates that the test has been performed well) and one or two test lines. The initially developed two band tests generate a test line that targets P. falciparum by detecting either histidine-rich protein 2 (HRP-2) or P. falciparum-specific parasite lactate dehydrogenase (Pf-pLDH). The later developed three band tests include a second target that is common to the four Plasmodium species, such as aldolase or pan-specific parasite lactate dehydrogenase (pan-pLDH). However, the conventional three-band RDTs, detecting a P. falciparum-specific antigen and a pan-Plasmodium a
Incidence and Risk Factors of Serious Adverse Events during Antituberculous Treatment in Rwanda: A Prospective Cohort Study
Natalie Lorent,Osee Sebatunzi,Gloria Mukeshimana,Jef Van den Ende,Joannes Clerinx
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0019566
Abstract: Tuberculosis (TB) and TB-human immunodeficiency virus infection (HIV) coinfection is a major public health concern in resource-limited settings. Although TB treatment is challenging in HIV-infected patients because of treatment interactions, immunopathological reactions, and concurrent infections, few prospective studies have addressed this in sub-Saharan Africa.
A Systematic Review and Meta-Analysis of the Performance of Two Point of Care Typhoid Fever Tests, Tubex TF and Typhidot, in Endemic Countries
Kamala Thriemer, Benedikt Ley, Joris Menten, Jan Jacobs, Jef van den Ende
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0081263
Abstract: Background In the absence of well-equipped laboratory infrastructure in many developing countries the accurate diagnosis of typhoid fever is challenging. Rapid diagnostic tests (RDT) with good performance indicators would be helpful to improve clinical management of suspected cases. We performed a systematic literature review and meta- analysis to determine the performance of TUBEX TF and Typhidot for the diagnosis of typhoid fever using PRISMA guidelines. Methods Titles and abstracts were reviewed for relevance. Articles were screened for language, reference method and completeness. Studies were categorized according to control groups used. Meta-analysis was performed only for categories where enough data was available to combine sensitivity and specificity estimates. Sub-analysis was performed for the Typhidot test to determine the influence of indeterminate results on test performance. Results A total of seven studies per test were included. The sensitivity of TUBEX TF ranged between 56% and 95%, Specificity between 72% and 95%. Meta-analysis showed an average sensitivity of 69% (95%CI: 45–85) and an average specificity of 88% (CI95%:83–91). A formal meta-analysis for Typhidot was not possible due to limited data available. Across the extracted studies, sensitivity and specificity estimates ranged from 56% to 84% and 31% to 97% respectively. Conclusion The observed performance does not support the use of either rapid diagnostic test exclusively as the basis for diagnosis and treatment. There is a need to develop an RDT for typhoid fever that has a performance level comparable to malaria RDTs.
Autochthonous Cases of Mycetoma in Europe: Report of Two Cases and Review of Literature
Dora Buonfrate, Federico Gobbi, Andrea Angheben, Stefania Marocco, Claudio Farina, Jef Van Den Ende, Zeno Bisoffi
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100590
Abstract: Background Mycetoma is a chronic granulomatous infection involving cutaneous and subcutaneous tissues. It is endemic in tropical and subtropical areas, but sporadic cases have been reported also in countries of temperate climate. The purpose of this paper is to review the cases of mycetoma in European subjects (and presumably acquired in Europe), to give an insight in the main factors associated with this condition, and to describe two previously unpublished cases observed at our Centre. Methods and Findings PubMed was systematically searched for case reports and case series of mycetoma in Europeans reported between 1980 and 2014, using specific search strategies. Two further cases diagnosed by the authors are described. Forty-two cases were collected. Eleven cases were caused by Scedosporium apiospermium, mainly in immunosuppressed patients from Bulgaria, Germany, the Netherlands, Portugal, Slovenia, Spain and the United Kingdom. Excluding all patients with immunosuppression, 29 cases remain. Most of them were reported from Bulgaria and in Albanian patients (all diagnosed outside Albania). In the Bulgarian case series many different micro-organisms, both bacteria and fungi, were isolated, while all the 5 cases from Albania were caused by Actinomadura spp. Other countries reporting cases were Greece, Italy and Turkey. In general, Actinomadura spp is the most frequent causative agent isolated, followed by Nocardia spp and Madurella mycetomatis. The foot was the most reported site involved. Most patients were medically treated, but unfortunately a long-term follow up (at least one year) was available only in a few cases. Conclusions Our review and our own cases suggest that Europeans without travel history can be affected by Madura foot. The lack of a surveillance system is likely to cause an underreporting of cases. Moreover, the unfamiliarity of Western doctors with this peculiar infection may cause a mismanagement, including unnecessary amputations.
Strict adherence to malaria rapid test results might lead to a neglect of other dangerous diseases: a cost benefit analysis from Burkina Faso
Zeno Bisoffi, Sodiomon B Sirima, Filip Meheus, Claudia Lodesani, Federico Gobbi, Andrea Angheben, Halidou Tinto, Bouma Neya, Klara Van den Ende, Annalisa Romeo, Jef Van den Ende
Malaria Journal , 2011, DOI: 10.1186/1475-2875-10-226
Abstract: A cost benefit analysis was carried out using a decision tree, based on data previously obtained, including a randomized controlled trial (RCT) recruiting 852 febrile patients during the dry season and 1,317 in the rainy season. Cost and benefit were calculated using both the real adherence found by the RCT and assuming an ideal adherence of 90% with the negative result. The main parameters were submitted to sensitivity analysis.At real adherence, the test-based strategy was dominated. Assuming ideal adherence, at the value of 525 € for a death averted, the total cost of managing 1,000 febrile children was 1,747 vs. 1,862 € in the dry season and 1,372 vs. 2,138 in the rainy season for the presumptive vs. the test-based strategy. For adults it was 2,728 vs. 1,983 and 2,604 vs. 2,225, respectively. At the subsidized policy adopted locally, assuming ideal adherence, the RDT would be the winning strategy for adults in both seasons and for children in the dry season.At sensitivity analysis, the factors most influencing the choice of the better strategy were the value assigned to a death averted and the proportion of potentially severe NMFI treated with antibiotics in patients with false positive RDT results. The test-based strategy appears advantageous for adults if a satisfactory adherence could be achieved. For children the presumptive strategy remains the best choice for a wide range of scenarios.For RDTs to be preferred, a positive result should not influence the decision to treat a potentially severe NMFI with antibiotics. In the rainy season the presumptive strategy always remains the better choice for children.Several economic studies have been carried out on malaria management with rapid diagnostic tests (RDTs) as a guide to initiate treatment, compared with the previously common presumptive approach and/or with microscopy [1-9]. RDTs have generally been found to be accurate, reliable and cost effective. New WHO guidelines on malaria management [10] state that a
Is increasing complexity of algorithms the price for higher accuracy? virtual comparison of three algorithms for tertiary level management of chronic cough in people living with HIV in a low-income country
Constance Mukabatsinda, Jasmine Nguyen, Bettina Bisig, Lutgarde Lynen, Yerma D Coppens, Anita Asiimwe, Jef Van den Ende
BMC Medical Informatics and Decision Making , 2012, DOI: 10.1186/1472-6947-12-2
Abstract: Data were collected at the University Hospital of Kigali (CHUK) in a total of 201 HIV-positive hospitalised patients with chronic cough. We simulated management of each patient following the three algorithms. The first was locally tailored by clinicians from CHUK, the second and third were drawn from publications by Médecins sans Frontières (MSF) and the World Health Organisation (WHO). Semantic analysis techniques known as Clinical Algorithm Nosology were used to compare them in terms of complexity and similarity. For each of them, we assessed the sensitivity, delay to diagnosis and hypothetical harm of false positives and false negatives.The principal diagnoses were tuberculosis (21%) and pneumocystosis (19%). Sensitivity, representing the proportion of correct diagnoses made by each algorithm, was 95.7%, 88% and 70% for CHUK, MSF and WHO, respectively. Mean time to appropriate management was 1.86 days for CHUK and 3.46 for the MSF algorithm. The CHUK algorithm was the most complex, followed by MSF and WHO. Total harm was by far the highest for the WHO algorithm, followed by MSF and CHUK.This study confirms our hypothesis that sensitivity and patient safety (i.e. less expected harm) are proportional to the complexity of algorithms, though increased complexity may make them difficult to use in practice.The algorithmic approach to guidelines has been introduced and promoted on a large scale since the 1970s. This flowchart representation of step-by-step clinical logic guides the management of a patient with symptoms, clinical signs, or results of technical examinations. The transition from one step to the next is mostly dichotomous, which means that only one out of two choices can be made at each step. Moreover, the logic is serial: only one pathway can be followed by a single patient.The original purpose of algorithmic guideline implementation was twofold. First, with continuing concern over the rising costs of health care, health policy makers have been impressed b
Should Malaria Treatment Be Guided by a Point of Care Rapid Test? A Threshold Approach to Malaria Management in Rural Burkina Faso
Zeno Bisoffi, Halidou Tinto, Bienvenu Sodiomon Sirima, Federico Gobbi, Andrea Angheben, Dora Buonfrate, Jef Van den Ende
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0058019
Abstract: Background In Burkina Faso, rapid diagnostic tests for malaria have been made recently available. Previously, malaria was managed clinically. This study aims at assessing which is the best management option of a febrile patient in a hyperendemic setting. Three alternatives are: treating presumptively, testing, or refraining from both test and treatment. The test threshold is the tradeoff between refraining and testing, the test-treatment threshold is the tradeoff between testing and treating. Only if the disease probability lies between the two should the test be used. Methods and Findings Data for this analysis was obtained from previous studies on malaria rapid tests, involving 5220 patients. The thresholds were calculated, based on disease risk, treatment risk and cost, test accuracy and cost. The thresholds were then matched against the disease probability. For a febrile child under 5 in the dry season, the pre-test probability of clinical malaria (3.2%), was just above the test/treatment threshold. In the rainy season, that probability was 63%, largely above the test/treatment threshold. For febrile children >5 years and adults in the dry season, the probability was 1.7%, below the test threshold, while in the rainy season it was higher (25.1%), and situated between the two thresholds (3% and 60.9%), only if costs were not considered. If they were, neither testing nor treating with artemisinin combination treatments (ACT) would be recommended. Conclusions A febrile child under 5 should be treated presumptively. In the dry season, the probability of clinical malaria in adults is so low, that neither testing nor treating with any regimen should be recommended. In the rainy season, if costs are considered, a febrile adult should not be tested, nor treated with ACT, but a possible alternative would be a presumptive treatment with amodiaquine plus sulfadoxine-pyrimethamine. If costs were not considered, testing would be recommended.
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