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2016-10-17 - Colloque/Présentation - communication orale - Anglais - 1 page(s)

Traore Orokia, Kiendrebeogo Martin, Okusa P.N., Compaoré M., Duez Pierre , Blankert Bertrand , "Development of a magnetic microfluidic device for the diagnosis of malaria: modeling and physico-chemical validation of the process" in 19th Forum of Pharmaceutical Sciences, Bruxelles, Belgique, 2016

  • Codes CREF : Chimie analytique (DI1314), Pharmacognosie (DI3410), Sciences pharmaceutiques (DI3400), Toxicologie pharmaceutique (DI3440)
  • Unités de recherche UMONS : Chimie thérapeutique et Pharmacognosie (M136)
  • Instituts UMONS : Institut des Sciences et Technologies de la Santé (Santé)

Abstract(s) :

(Anglais) Malaria is the first global parasitic endemic with 214 million cases and 438.000 deaths reported in 2015, according to the World Health Organization [1]. Different diagnostic methods exist, each with their strengths and weaknesses. Microscopy is the reference method [2] that allows the visualization of parasites with an optic microscope after giemsa staining. It is very sensitive and moreover allows to differentiate the parasitic species responsible for the disease. However, the method requires a qualified staff for slides preparation and interpretation. RDT (rapid diagnostic tests) are based on the detection of the parasite’s antigens in the circulating blood [3]. They have the advantage of being easy to use and do not require qualified staff. However they present somewhat lower sensitivity than microscopy, do not identify the Plasmodium species, do not yield quantitative data and can detect antigens persistent after treatment, yielding false positives (false positive antigenemia has been shown to occur in 29 % (histidine-rich protein 2, HRP2) and 42% (panmalarial antigen, PMA) of treated patients on day 7 and in 10% (HRP2) and 23% (PMA) on day 14 [4]. The highly sensitive and selective PCR methods are not manageable so far in endemic zones. The diagnostic method described here is based on the selective magnetic filtration of the malarial pigment, namely haemozoin. This polymer is a product of hemoglobin degradation during Plasmodium infection. The parasite living in the red blood cell digests hemoglobin for its source of amino acids (globin) [5]. The liberated heme, that is toxic to the parasite, is detoxified in the form of haemozoin. The haemozoin paramagnetic properties [6] are exploited by the developed equipment to quantify the malarial pigment and to determine the level of parasitemia. Current assays with aqueous suspensions of β-haematin (haemozoin synthetic analogue), and blood samples spiked with cultures of Plasmodium have led to the following estimates of detectability: 80 parasites/µL and 25 parasites/µL, respectively. These preliminary results are in accordance with the WHO requirements which recommend to reach a detection limit of 100 parasites/µL [7]. In comparison to the reference diagnostic method which has a practical limit of 50 parasites/µL [8], and the RDT, which is about 100 parasites/µL [8], the designed magnetic set-up, thanks to its detectability and easiness of use, could be an asset in the diagnostic and the monitoring of the disease. References 1. OMS, World Malaria Report 2015, 2015. p. 157. 2. Murray, C.K., et al., Update on Rapid Diagnostic Testing for Malaria. Clinical Microbiology Reviews, 2008. 21(1): p. 97-110. 3. Chakour, M., et al., Diagnostic biologique rapide en contexte épidémique : état des lieux, perspectives. Médecine et maladies infectieuses, 2003. 33: p. 396-412. 4. Tjitra, E et al, Persistent ICT malaria P.f/P.v panmalarial and HRP2 antigen reactivity after treatment of Plasmodium falciparum malaria is associated with gametocytemia and results in false-positive diagnoses of Plasmodium vivax in convalescence. J Clin Microbiol. 2001;39(3):1025-31. 5. Egan, T.J., Haemozoin formation. Molecular and Biochemical Parasitology, 2008. 157(2): p. 127-136. 6. Newman, D.M., et al., A Magneto-Optic Route toward the In Vivo Diagnosis of Malaria: Preliminary Results and Preclinical Trial Data. Biophysical Journal, 2008. 95(2): p. 994-1000. 7. OMS, Note d’information sur les critères de sélection recommandés pour l’acquisition de tests de diagnostic rapide du paludisme, 2014. p. 14. 8. Moody, A., Rapid Diagnostic Tests for Malaria Parasites. Clinical Microbiology Reviews, 2002. 15(1): p. 66-78.

(Anglais) Malaria is the first global parasitic endemic with 214 million cases and 438.000 deaths reported in 2015, according to the World Health Organization [1]. Different diagnostic methods exist, each with their strengths and weaknesses. Microscopy is the reference method [2] that allows the visualization of parasites with an optic microscope after giemsa staining. It is very sensitive and moreover allows to differentiate the parasitic species responsible for the disease. However, the method requires a qualified staff for slides preparation and interpretation. RDT (rapid diagnostic tests) are based on the detection of the parasite’s antigens in the circulating blood [3]. They have the advantage of being easy to use and do not require qualified staff. However they present somewhat lower sensitivity than microscopy, do not identify the Plasmodium species, do not yield quantitative data and can detect antigens persistent after treatment, yielding false positives (false positive antigenemia has been shown to occur in 29 % (histidine-rich protein 2, HRP2) and 42% (panmalarial antigen, PMA) of treated patients on day 7 and in 10% (HRP2) and 23% (PMA) on day 14 [4]. The highly sensitive and selective PCR methods are not manageable so far in endemic zones. The diagnostic method described here is based on the selective magnetic filtration of the malarial pigment, namely haemozoin. This polymer is a product of hemoglobin degradation during Plasmodium infection. The parasite living in the red blood cell digests hemoglobin for its source of amino acids (globin) [5]. The liberated heme, that is toxic to the parasite, is detoxified in the form of haemozoin. The haemozoin paramagnetic properties [6] are exploited by the developed equipment to quantify the malarial pigment and to determine the level of parasitemia. Current assays with aqueous suspensions of β-haematin (haemozoin synthetic analogue), and blood samples spiked with cultures of Plasmodium have led to the following estimates of detectability: 80 parasites/µL and 25 parasites/µL, respectively. These preliminary results are in accordance with the WHO requirements which recommend to reach a detection limit of 100 parasites/µL [7]. In comparison to the reference diagnostic method which has a practical limit of 50 parasites/µL [8], and the RDT, which is about 100 parasites/µL [8], the designed magnetic set-up, thanks to its detectability and easiness of use, could be an asset in the diagnostic and the monitoring of the disease. References 1. OMS, World Malaria Report 2015, 2015. p. 157. 2. Murray, C.K., et al., Update on Rapid Diagnostic Testing for Malaria. Clinical Microbiology Reviews, 2008. 21(1): p. 97-110. 3. Chakour, M., et al., Diagnostic biologique rapide en contexte épidémique : état des lieux, perspectives. Médecine et maladies infectieuses, 2003. 33: p. 396-412. 4. Tjitra, E et al, Persistent ICT malaria P.f/P.v panmalarial and HRP2 antigen reactivity after treatment of Plasmodium falciparum malaria is associated with gametocytemia and results in false-positive diagnoses of Plasmodium vivax in convalescence. J Clin Microbiol. 2001;39(3):1025-31. 5. Egan, T.J., Haemozoin formation. Molecular and Biochemical Parasitology, 2008. 157(2): p. 127-136. 6. Newman, D.M., et al., A Magneto-Optic Route toward the In Vivo Diagnosis of Malaria: Preliminary Results and Preclinical Trial Data. Biophysical Journal, 2008. 95(2): p. 994-1000. 7. OMS, Note d’information sur les critères de sélection recommandés pour l’acquisition de tests de diagnostic rapide du paludisme, 2014. p. 14. 8. Moody, A., Rapid Diagnostic Tests for Malaria Parasites. Clinical Microbiology Reviews, 2002. 15(1): p. 66-78.

(Anglais) Malaria is the first global parasitic endemic with 214 million cases and 438.000 deaths reported in 2015, according to the World Health Organization [1]. Different diagnostic methods exist, each with their strengths and weaknesses. Microscopy is the reference method [2] that allows the visualization of parasites with an optic microscope after giemsa staining. It is very sensitive and moreover allows to differentiate the parasitic species responsible for the disease. However, the method requires a qualified staff for slides preparation and interpretation. RDT (rapid diagnostic tests) are based on the detection of the parasite’s antigens in the circulating blood [3]. They have the advantage of being easy to use and do not require qualified staff. However they present somewhat lower sensitivity than microscopy, do not identify the Plasmodium species, do not yield quantitative data and can detect antigens persistent after treatment, yielding false positives (false positive antigenemia has been shown to occur in 29 % (histidine-rich protein 2, HRP2) and 42% (panmalarial antigen, PMA) of treated patients on day 7 and in 10% (HRP2) and 23% (PMA) on day 14 [4]. The highly sensitive and selective PCR methods are not manageable so far in endemic zones. The diagnostic method described here is based on the selective magnetic filtration of the malarial pigment, namely haemozoin. This polymer is a product of hemoglobin degradation during Plasmodium infection. The parasite living in the red blood cell digests hemoglobin for its source of amino acids (globin) [5]. The liberated heme, that is toxic to the parasite, is detoxified in the form of haemozoin. The haemozoin paramagnetic properties [6] are exploited by the developed equipment to quantify the malarial pigment and to determine the level of parasitemia. Current assays with aqueous suspensions of β-haematin (haemozoin synthetic analogue), and blood samples spiked with cultures of Plasmodium have led to the following estimates of detectability: 80 parasites/µL and 25 parasites/µL, respectively. These preliminary results are in accordance with the WHO requirements which recommend to reach a detection limit of 100 parasites/µL [7]. In comparison to the reference diagnostic method which has a practical limit of 50 parasites/µL [8], and the RDT, which is about 100 parasites/µL [8], the designed magnetic set-up, thanks to its detectability and easiness of use, could be an asset in the diagnostic and the monitoring of the disease. References 1. OMS, World Malaria Report 2015, 2015. p. 157. 2. Murray, C.K., et al., Update on Rapid Diagnostic Testing for Malaria. Clinical Microbiology Reviews, 2008. 21(1): p. 97-110. 3. Chakour, M., et al., Diagnostic biologique rapide en contexte épidémique : état des lieux, perspectives. Médecine et maladies infectieuses, 2003. 33: p. 396-412. 4. Tjitra, E et al, Persistent ICT malaria P.f/P.v panmalarial and HRP2 antigen reactivity after treatment of Plasmodium falciparum malaria is associated with gametocytemia and results in false-positive diagnoses of Plasmodium vivax in convalescence. J Clin Microbiol. 2001;39(3):1025-31. 5. Egan, T.J., Haemozoin formation. Molecular and Biochemical Parasitology, 2008. 157(2): p. 127-136. 6. Newman, D.M., et al., A Magneto-Optic Route toward the In Vivo Diagnosis of Malaria: Preliminary Results and Preclinical Trial Data. Biophysical Journal, 2008. 95(2): p. 994-1000. 7. OMS, Note d’information sur les critères de sélection recommandés pour l’acquisition de tests de diagnostic rapide du paludisme, 2014. p. 14. 8. Moody, A., Rapid Diagnostic Tests for Malaria Parasites. Clinical Microbiology Reviews, 2002. 15(1): p. 66-78.