273 research outputs found
Hemozoin-detection by Laser-Flowcytometry in malaria patients in Lambaréné, Gabun: Sensitivity, specificity and prognostic value
No full textMalaria ist weltweit eine der bedeutendsten Infektionskrankheiten. Jährlich erkranken bis zu 500 Millionen Menschen an einer Malariainfektion, etwa zwei Millionen Menschen versterben an einer durch Plasmodium falciparum hervorgerufenen Malaria tropica. Besonders gefährdet durch Malaria sind Kleinkinder, die noch keine ausreichende Immunität besitzen.
Neben umfassender Prävention und adäquater Behandlung der Infektion mit Chemotherapeutika hat vor allem die rechtzeitige Diagnose große Bedeutung im Management der Malaria.
In den letzten Jahren wurde der Nachweis von hämozoinhaltigen Leukozyten als Marker für eine akute Malariainfektion wiederentdeckt. Hämozoin, ein Abbauprodukt des Malariaerregers, wird von Monozyten und neutrophilen Granulozyten phagozytiert und ist mikroskopisch an seiner doppelbrechenden optischen Eigenschaft erkennbar. Der Nachweis von pigmenthaltigen Leukozyten wurde nicht nur als diagnostisches Kriterium beschrieben, sondern auch als prognostischer Marker mit der Schwere der Erkrankung in Verbindung gebracht.
Laser-Durchflusszytometer vom Typ des Blutanalysegerätes Cell-Dyn 3000® sind in der Lage, hämozoinhaltige Leukozyten anhand der optischen Eigenschaften des Hämozoin-Kristalles als fehlklassifizierte Punktsignale zu identifizieren. In verschiedenen Studien wurden bereits sog. atypische violette Punktsignale zur Malariadiagnostik genutzt. Unklar war bisher die Bedeutung von atypischen grünen Punktsignale geblieben, welche hämozoinhaltige neutrophile Granulozyten repräsentieren.
In der vorliegenden Studie wurden die durchflusszytometrischen Daten von Kindern und schwangeren Frauen in Lambaréné, Gabun, untersucht, um Sensitivität, Spezifität und prognostischen Wert des Cell-Dyn 3000®-Gerätes in Bezug auf Malariainfektion zu prüfen.
Es stellte sich heraus, dass bei Kindern das Auftreten von atypischen violetten und grünen Punktsignalen hoch sensitiv und spezifisch für eine Malariainfektion (AVPs: 95,4% respektive 95,4%; AGPs: 82,9% respektive 96,3%) ist. Erstaunlicherweise sind Sensitivität und Spezifität bei Erwachsenen deutlich niedriger (AVPs: 81,3% respektive 83,6%; AGPs: 68,8% respektive 95,2%), hohe Raten an falsch positiven Fällen wurden beobachtet. Ursächlich für diese Ergebnisse sind neben der noch nicht vollständig ausgereiften Identifizierungsmethode von atypischen Punktsignalen auch die unterschiedliche Immunitätslage von Kindern und Erwachsenen, insbesondere schwangeren Frauen. In holoendemischen Gebieten wie Lambaréné scheint die Durchflusszytometrie als Screeningmethode durchaus sinnvoll zu sein. Die Ergebnisse in der Gruppe der schwangeren Frauen jedoch müssen durch zukünftige Studien genauer evaluiert werden.
Des weiteren wurden bei Kindern atypische Punktsignale auf ihr Potential zur Diagnose der Schwere der Malaria untersucht. Es zeigten sich signifikante Unterschiede in den Mengen der atypischen violetten und grünen Punktsignale zwischen unkomplizierter und komplizierter Malaria (21 AVPs vs. 33 AVPs [p=0,026] respektive sechs AGPs vs. 15 AGPs [p<0,001]). Allerdings scheiterten Versuche, einen Schwellenwert zu finden, welcher dem Kliniker eine Klassifikation in komplizierte und unkomplizierte Malaria allein anhand der Anzahl der Punktsignale ermöglichen sollte. Die Signale sind in beiden Gruppen zu gleichmäßig verteilt, als dass eine klare Unterscheidung möglich ist. Weitere Studien sind notwendig, um die Schwellenwerte der Cell-Dyn 3000® für atypische Signale zu verbessern und genauere Aussagen über die Verlaufsprognose von malariakranken Patienten zu ermöglichen.Malaria is one of the most important infectious diseases worldwide. Every year Plasmodium spp. causes 500 million acute illnesses and an estimated two million deaths predominantly due to Plasmodium falciparum malaria (malaria tropica). The main burden of morbidity and mortality is found in children, as immunity to Plasmodium spp. is not yet sufficiently developed.
Besides extensive prevention and adequate treatment with chemotherapeutics opportune diagnosis of malaria infection is of utmost importance in disease management.
In the last years detection of hemozoin containing leukocytes as a marker for acute plasmodium falciparum infection has been rediscovered. Hemozoin, a side product of parasite metabolism, is phagocytosed by monocytes and neutrophile granolocytes and can by detected microscopically by its birefringent nature. Detection of hemozoin containing leukocytes was not only described as a diagnostic tool but was also found to be a prognostic marker for disease severity.
Laser-Flowcytometry as used by the cell-counter Cell-Dyn 3000® displays hemozoin containing leukocytes as misclassified signals in the machine’s scatter blots due to the optical properties of the hemozoin crystal. Various studies already used atypically distributed purple dots (representing hemozoin containing monocytes) for diagnosis of malaria infection. Yet the relevance of atypical distributed green dots which seem to represent hemozoin containing neutrophile granolocytes remained unclear.
The present study evaluates flowcytometric data of children and pregnant women in Lambaréné, Gabun, to assess sensitivity, specificity and prognostic value of the Cell-Dyn 3000® in patients with malaria infection.
In children, detection of atypically distributed purple (AVPs) and green dots (AGPs) was found to be highly sensitive and specific for malaria infection (AVPs: 95.4% and 95.4%, respectively; AGPs: 82.9% and 96.3%, respectively), whereas in adults results were lower (AVPs: 81.3% and 83.6%, respectively; AGPs: 68.8% and 95.2%, respectively) and high rates of false positive cases were observed.
These findings could be explained as follows: (i) the identification process of atypically distributed signals is still experimental and not yet developed to its full potential and (ii) the immune status is different in children and adults, in particular in pregnant women. In holoendemic regions like Lambaréné flowcytometry seems to be helpful as a screening method. Nevertheless, the results concerning pregnant women should be reassessed in further studies.
In children atypically distributed signals were investigated to determine their diagnostic potential regarding the severity of disease. In uncomplicated and complicated malaria the amount of atypical distributed purple and green dots differed significantly (21 AVPs vs. 33 AVPs [p=0,026] and six AGPs vs. 15 AGPs [p<0,001]). Although, attempts to create a threshold allowing a classification of complicated and uncomplicated malaria according to signal counts failed. Signals within both groups were almost evenly distributed making a clear differentiation impossible. Further studies are therefore necessary to improve threshold values for atypically distributed signals of the Cell-Dyn 3000®, thus providing a more accurate prognosis in the course of malaria infection
Assessing the Consequences of Stigma for Tuberculosis Patients in Urban Zambia
No full textAssessing the consequences of stigma for tuberculosis patients in urban zambia Cremers, A.L.; de Laat, M.M.; Kapata, N.; Gerrets, R.P.M.; Klipstein-Grobusch, K.; Grobusch, M.P. Published in: PLoS ONE DOI: 10.1371/journal.pone.0119861 Link to publication Citation for published version (APA): Cremers, A. L., de Laat, M. M., Kapata, N., Gerrets, R., Klipstein-Grobusch, K., & Grobusch, M. P. (2015). Assessing the consequences of stigma for tuberculosis patients in urban zambia. PLoS ONE, 10(3), [e0119861]. https://doi.org/10.1371/journal.pone.0119861 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract Background Stigma is one of the many factors hindering tuberculosis (TB) control by negatively affecting hospital delay and treatment compliance. In Zambia, the morbidity and mortality due to TB remains high, despite extended public health attempts to control the epidemic and to diminish stigma. Study Aim To enhance understanding of TB-related stigmatizing perceptions and to describe TB patients' experiences of stigma in order to point out recommendations to improve TB policy. Methods We conducted a mixed method study at Kanyama clinic and surrounding areas, in Lusaka, Zambia; structured interviews with 300 TB patients, multiple in-depth interviews with 30 TB patients and 10 biomedical health workers, 3 focus group discussions with TB patients and treatment supporters, complemented by participant observation and policy analysis of the TB control program. Predictors of stigma were identified by use of multivariate regression analyses; qualitative analysis of the in-depth interviews, focus group discussions and participant observation was used for triangulation of the study findings. Results We focused on the 138/300 patients that described TB-related perceptions and attitudes, of whom 113 (82%) reported stigma. Data Availability Statement: All relevant data from the TBAC study are contained within the paper. Additional data will be made available by our first author. The original data contain information which may lead to the identification of study subjects and in order to protect their privacy, a request to gain access to the original data is needed. Funding: No specific funding was received for this study other than the personal grants for ALC specified below. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. both among children and adults and included low self-esteem, insults, ridicule, discrimination, social exclusion, and isolation leading to a decreased quality of life and social status, non-disclosure, and/or difficulties with treatment compliance and adherence. Women had significantly more stigma-related problems than men. Conclusions The findings illustrate that many TB patients faced stigma-related issues, often hindering effective TB control and suggesting that current efforts to reduce stigma are not yet optimal. The content and implementation of sensitization programs should be improved and more emphasis needs to be placed on women and children. Introduction Alongside biological, economic, and cultural barriers to effective tuberculosis (TB) control, stigma constitutes one of the major social factors causing hospital delay and hindering compliance among TB patients The importance of addressing stigma related to TB is illustrated by the fact that this disease is one of the major causes of death worldwide. Zambia ranks 29 th among the world's top TB countries identified by the World Health Organisation (WHO) having 427/100.000 incident TB cases in the year 2012. HIV co-infection rate is 61% and MDR-TB prevails in 0.3% of new Consequences of Stigma for Tuberculosis Patients in Urban Zambia PLOS ONE
Therapy of uncomplicated falciparum malaria in Europe: MALTHER - a prospective observational multicentre study
No full textWhat does 'Tropical Medicine' stand for today?
No full textIn deze rede gaat de auteur in op het ontstaan en de evolutie van de tropische geneeskunde. Tevens geeft hij een persoonlijke kijk op de huidige stand van zaken binnen het vakgebied en de positie van het AMC Tropencentrum daarin
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