• Comparison of an rK39 dipstick rapid test with direct agglutination test and splenic aspiration for the diagnosis of kala-azar in Sudan.

      Veeken, H; Ritmeijer, K; Seaman, J; Davidson, R N; Médecins sans Frontières-Holland, Amsterdam, The Netherlands. hans_veeken@amsterdam.msf.org (Wiley-Blackwell, 2003-02)
      We compared an rK39 dipstick rapid test (Amrad ICT, Australia) with a direct agglutination test (DAT) and splenic aspirate for the diagnosis of kala-azar in 77 patients. The study was carried out under field conditions in an endemic area of north-east Sudan. The sensitivity of the rK39 test compared with splenic aspiration was 92% (46/50), the specificity 59% (16/27), and the positive predictive value 81% (46/57). Compared with the diagnostic protocol used by Médecins sans Frontières, the sensitivity of the rK39 test was 93% (50/54), the specificity 70% (16/23), and the positive predictive value 88% (50/57). Compared with splenic aspirates, the sensitivity of a DAT with a titre > or =1:400 was 100% (50/50), but its specificity only 55% (15/27) and the positive predictive value was 80% (50/62). Using a DAT titre > or =1:6400, the sensitivity was 84% (42/50), the specificity 85% (23/27) and the positive predictive value 91% (42/46). All four patients with DAT titre > or =1:6400 but negative splenic aspirate were also rK39 positive; we consider these are probably 'true' cases of kala-azar, i.e. false negative aspirates, rather than false DAT and rK39 seropositives. There were no false negative DATs (DAT titre < or =1:400 and aspirate positive), but there were four false negative rK39 tests (rK39 negative and aspirate positive). The rK39 dipstick is a good screening test for kala-azar; but further development is required before it can replace the DAT as a diagnostic test in endemic areas of the Sudan.
    • Diagnostic accuracy of two rK39 antigen-based dipsticks and the formol gel test for rapid diagnosis of visceral leishmaniasis in northeastern Uganda.

      Chappuis, F; Mueller, Y; Nguimfack, A; Rwakimari, J; Couffignal, S; Boelaert, M; Cavailler, P; Loutan, L; Piola, P; Travel and Migration Medicine Unit, Geneva University Hospital, Rue Micheli-du-Crest 24, 1211 Geneva 14, Switzerland. francois.chappuis@hcuge.ch (American Society for Microbiology, 2005-12)
      The development of an accurate, practical, and affordable diagnostic test is essential to improve the management of visceral leishmaniasis (VL) in remote health centers. We evaluated the Formol Gel test (FGT) and two rK39 antigen-based dipsticks, the DUAL-IT L/M, and the Kalazar Detect for VL diagnosis in Amudat Hospital in Uganda. The DUAL-IT L/M was also evaluated for the diagnosis of malaria. All patients clinically suspect of VL were prospectively included in the study between October 2003 and March 2004. The gold standard used to define a VL case was a positive spleen aspirate or a direct agglutination test titer of >1:12,800 with an appropriate clinical response to antileishmanial therapy. A total of 131 VL and 112 non-VL patients were included in the analysis. The DUAL IT L/M was found to be more sensitive than the Kalazar Detect: 97% (95% confidence interval [95%CI] = 92 to 99%) versus 82% (95%CI = 74 to 87%). The Kalazar Detect and the DUAL IT L/M were highly specific (99% [95%CI = 95 to 100%] and 97% [95%CI = 92 to 99%], respectively). The FGT lacked both sensitivity (66% [95%CI = 57 to 73%]) and specificity (90% [95%CI = 83 to 94%]). The sensitivity of the DUAL IT L/M for malaria was only 57% (95%CI = 37 to 76%). The two rK39 dipsticks can be used for diagnostic confirmation of VL in this region. The DUAL-IT L/M without its malaria diagnostic component (DiaMed-IT LEISH) will be adopted as first-line test for VL in Uganda.
    • Evaluation of a New Recombinant K39 Rapid Diagnostic Test for Sudanese Visceral Leishmaniasis.

      Ritmeijer, K; Melaku, Y; Mueller, M; Kipngetich, S; O'keeffe, C; Davidson, R N; Médecins sans Frontières-Holland, Amsterdam, The Netherlands. koert.ritmeijer@amsterdam.msf.org (Published by: American Society of Tropical Medicine and Hygiene, 2006-01)
      A new rK39 rapid diagnostic dipstick test (DiaMed-IT-Leish) was compared with aspiration and a direct agglutination test (DAT) for diagnosis of visceral leishmaniasis (VL) in 201 parasitologically confirmed cases, 133 endemic controls, and in 356 clinical suspects in disease-endemic and -epidemic areas in Sudan. The sensitivity of the rK39 test in parasitologically confirmed VL cases was 90%, whereas the specificity in disease-endemic controls was 99%. The sensitivity of the DAT was 98%. In clinically suspected cases, the sensitivity of the rK39 test was 81% and the specificity was 97%. When compared with the diagnostic protocol based on the DAT and aspiration used by Médecins sans Frontières in epidemic situations, the positive predictive value was 98%, and the negative predictive value was 71%. This rK39 rapid diagnostic test is suitable for screening as well as diagnosis of VL. Further diagnostic work-up of dipstick-negative patients with clinically suspected VL is important. The ease and convenience of the dipstick test will allow decentralization and improved access to care in disease-endemic areas in Sudan.
    • Evaluation of FASTPlaqueTB to diagnose smear-negative tuberculosis in a peripheral clinic in Kenya

      Bonnet, M; Gagnidze, L; Varaine, F; Ramsay, A; Githui, W; Guerin, P J; Epicentre, Paris, France; Liverpool School of Tropical Medicine, Liverpool, UK; United Nations Children’s Fund/United Nations Development Programme/World Bank/World Health Organization Special Programme for Research and Training for Tropical Diseases (TDR), Geneva, Switzerland; Centre for Respiratory Diseases Research, Kenya Medical Research Institute, Nairobi, Kenya (2009-09-01)
      OBJECTIVE: To evaluate the performance and feasibility of FASTPlaqueTB in smear-negative tuberculosis (TB) suspects in a peripheral clinic after laboratory upgrading. DESIGN: Patients with cough > or=2 weeks, two sputum smear-negative results, no response to 1 week of amoxicillin and abnormal chest X-ray were defined as smear-negative suspects. One sputum sample was collected, decontaminated and divided into two: half was tested with FASTPlaqueTB in the clinic laboratory and the other half was cultured on Löwenstein-Jensen medium in the Kenyan Medical Research Institute. Test sensitivity and specificity were evaluated in all patients and in human immunodeficiency virus (HIV) infected patients. Feasibility was assessed by the contamination rate and the resources required to upgrade the laboratory. RESULTS: Of 208 patients included in the study, 56.2% were HIV-infected. Of 203 FASTPlaqueTB tests, 95 (46.8%) were contaminated, which interfered with result interpretation and led to the interruption of the study. Sensitivity and specificity were respectively 31.2% (95%CI 12.1-58.5) and 94.9% (95%CI 86.8-98.4) in all patients and 33.3% (95%CI 9.9-65.1) and 93.9% (95%CI 83.1-98.7) in HIV-infected patients. Upgrading the laboratory cost euro 20,000. CONCLUSION: FASTPlaqueTB did not perform satisfactorily in this setting. If contamination can be reduced, in addition to laboratory upgrading, its introduction in peripheral clinics would require further assessment in smear-negative and HIV co-infected patients and test adaptation for friendlier use.
    • Evaluation of three parasite lactate dehydrogenase-based rapid diagnostic tests for the diagnosis of falciparum and vivax malaria

      Ashley, Elizabeth A; Touabi, Malek; Ahrer, Margareta; Hutagalung, Robert; Htun, Khayae; Luchavez, Jennifer; Dureza, Christine; Proux, Stephane; Leimanis, Mara; Lwin, Myo Min; et al. (2009-10-27)
      BACKGROUND: In areas where non-falciparum malaria is common rapid diagnostic tests (RDTs) capable of distinguishing malaria species reliably are needed. Such tests are often based on the detection of parasite lactate dehydrogenase (pLDH). METHODS: In Dawei, southern Myanmar, three pLDH based RDTs (CareStart Malaria pLDH (Pan), CareStart Malaria pLDH (Pan, Pf) and OptiMAL-IT)were evaluated in patients presenting with clinically suspected malaria. Each RDT was read independently by two readers. A subset of patients with microscopically confirmed malaria had their RDTs repeated on days 2, 7 and then weekly until negative. At the end of the study, samples of study batches were sent for heat stability testing. RESULTS: Between August and November 2007, 1004 patients aged between 1 and 93 years were enrolled in the study. Slide microscopy (the reference standard) diagnosed 213 Plasmodium vivax (Pv) monoinfections, 98 Plasmodium falciparum (Pf) mono-infections and no malaria in 650 cases. The sensitivities (sens) and specificities (spec), of the RDTs for the detection of malaria were- CareStart Malaria pLDH (Pan) test: sens 89.1% [CI95 84.2-92.6], spec 97.6% [CI95 96.5-98.4]. OptiMal-IT: Pf+/- other species detection: sens 95.2% [CI95 87.5-98.2], spec 94.7% [CI95 93.3-95.8]; non-Pf detection alone: sens 89.6% [CI95 83.6-93.6], spec 96.5% [CI95 94.8-97.7]. CareStart Malaria pLDH (Pan, Pf): Pf+/- other species: sens 93.5% [CI95 85.4-97.3], spec 97.4% [95.9-98.3]; non-Pf: sens 78.5% [CI95 71.1-84.4], spec 97.8% [CI95 96.3-98.7]. Inter-observer agreement was excellent for all tests (kappa > 0.9). The median time for the RDTs to become negative was two days for the CareStart Malaria tests and seven days for OptiMAL-IT. Tests were heat stable up to 90 days except for OptiMAL-IT (Pf specific pLDH stable to day 20 at 35 degrees C). CONCLUSION: None of the pLDH-based RDTs evaluated was able to detect non-falciparum malaria with high sensitivity, particularly at low parasitaemias. OptiMAL-IT performed best overall and would perform best in an area of high malaria prevalence among screened fever cases. However, heat stability was unacceptable and the number of steps to perform this test is a significant drawback in the field. A reliable, heat-stable, highly sensitive RDT, capable of diagnosing all Plasmodium species has yet to be identified.
    • Field evaluation of rK39 test and direct agglutination test for diagnosis of visceral leishmaniasis in a population with high prevalence of human immunodeficiency virus in Ethiopia

      ter Horst, Rachel; Tefera, Tewodros; Assefa, Gessesse; Ebrahim, Abdurazik Z; Davidson, Robert N; Ritmeijer, Koert; Médecins Sans Frontières, Humera, Ethiopia; Kahsay Abera Hospital, Humera, Ethiopia; Ethiopian Health and Nutrition Research Institute, Addis Ababa, Ethiopia; Department of Infection and Tropical Medicine, Northwick Park Hospital, Harrow, United Kingdom; Médecins Sans Frontières, Amsterdam, The Netherlands (2009-06-01)
      Accuracy of an rK39 rapid diagnostic test (DiaMed-IT-Leish ) for visceral leishmaniasis (VL) was compared with splenic aspiration and the direct agglutination test (DAT) in a population with a high prevalence of infection with human immunodeficiency virus (HIV) in Ethiopia. There were 699 patients clinically suspected of having VL (153 parasitologically confirmed, 482 DAT confirmed, and 130 DAT negative), and 97 DAT-negative controls. A total of 84% were tested for HIV and 34% were HIV positive. Sensitivity of the rK39 test in parasitologically confirmed VL patients was 84% (77% in HIV positive and 87% in HIV negative; P = 0.25). Sensitivity of the DAT was higher (94%; P = 0.01), 89% in HIV-positive patients and 95% in HIV-negative patients; P = 0.27). Specificity of the rK39 test was 99% in DAT-negative controls and 92% in DAT-negative patients clinically suspected of having VL. A diagnostic algorithm combining DAT and the rK39 test had a sensitivity of 98% in HIV-positive VL patients and 99% in HIV-negative VL patients. Despite the lower sensitivity in a population with a high prevalence of HIV, the DiaMed-IT-Leish rK39 test enables decentralization of diagnosis. Patients clinically suspected of having VL who show negative results on the rK39 antigen test should undergo follow-up DAT testing, especially if they are HIV positive.
    • Field evaluation of the CATT/Trypanosoma brucei gambiense on blood-impregnated filter papers for diagnosis of human African trypanosomiasis in southern Sudan.

      Chappuis, F; Pittet, A; Bovier, P A; Adams, K; Godineau, V; Hwang, S Y; Magnus, E; Büscher, P; Médecins Sans Frontières (MSF) - Switzerland, Geneva, Switzerland. francois.chappuis@hcuge.ch (Wiley-Blackwell, 2002-11)
      Most Human African Trypanosomiasis (HAT) control programmes in areas endemic for Trypanosoma brucei gambiense rely on a strategy of active mass screening with the Card Agglutination Test for Trypanosomiasis (CATT)/T. b. gambiense. We evaluated the performance, stability and reproducibility of the CATT/T. b. gambiense on blood-impregnated filter papers (CATT-FP) in Kajo-Keji County, South-Sudan, where some areas are inaccessible to mobile teams. The CATT-FP was performed with a group of 100 people with a positive CATT on whole blood including 17 confirmed HAT patients and the results were compared with the CATT on plasma (CATT-P). The CATT-FP was repeated on impregnated filter papers stored at ambient and refrigerated temperature for 1, 3, 7 and 14 days. Another 82 patients with HAT, including 78 with a positive parasitology, were tested with the CATT-FP and duplicate filter paper samples were sent to a reference laboratory to assess reproducibility. The CATT-FP was positive in 90 of 99 patients with HAT (sensitivity: 91%). It was less sensitive than the CATT-P (mean dilution difference: -2.5). There was no significant loss of sensitivity after storage for up to 14 days both at ambient and cool temperature. Reproducibility of the CATT-FP was found to be excellent (kappa: 0.84). The CATT-FP can therefore be recommended as a screening test for HAT in areas where the use of CATT-P is not possible. Further studies on larger population samples in different endemic foci are still needed before the CATT-FP can be recommended for universal use.
    • Kala-azar control, Uganda [letter]

      Kolaczinski, J H; Worku, D; Chappuis, F; Reithinger, R; Kabatereine, N; Onapa, A; Brooker, S; Malaria Consortium Africa, Kampala, Uganda; London School of Hygiene & Tropical Medicine, London, UK; Médecins Sans Frontières, Kampala, Uganda; Médecins Sans Frontières, Geneva, Switzerland; Geneva University Hospital, Geneva, Switzerland; Ministry of Health, Kampala, Uganda (2007-03)
    • Meningitis Dipstick Rapid Test: Evaluating Diagnostic Performance During an Urban Neisseria Meningitidis Serogroup A Outbreak, Burkina Faso, 2007

      Rose, Angela M C; Mueller, Judith E; Gerstl, Sibylle; Njanpop-Lafourcade, Berthe-Marie; Page, Anne-Laure; Nicolas, Pierre; Traoré, Ramata Ouédraogo; Caugant, Dominique A; Guerin, Philippe J; Epicentre, France; Chronic Disease Research Centre, University of the West Indies, West Indies; Agence de Medecine Preventive, France; Institut de Medecine Tropicale du Service de Sante des Armees (IMTSSA); World Health Organization Collaborating Centre for Reference and Research on Meningococci, France; Laboratoire de Biologie, Centre Hospitalier Universitaire Pediatrique Charles de Gaulle, Burkina Faso; World Health Organization, Collaborating Centre for Reference and Research on Meningococci, Norwegian Institute of Public Health, Norway; Institute of General Practice and Community Medicine, University of Oslo, Norway (2010-06-11)
      Meningococcal meningitis outbreaks occur every year during the dry season in the "meningitis belt" of sub-Saharan Africa. Identification of the causative strain is crucial before launching mass vaccination campaigns, to assure use of the correct vaccine. Rapid agglutination (latex) tests are most commonly available in district-level laboratories at the beginning of the epidemic season; limitations include a short shelf-life and the need for refrigeration and good technical skills. Recently, a new dipstick rapid diagnostic test (RDT) was developed to identify and differentiate disease caused by meningococcal serogroups A, W135, C and Y. We evaluated the diagnostic performance of this dipstick RDT during an urban outbreak of meningitis caused by N. meningitidis serogroup A in Ouagadougou, Burkina Faso; first against an in-country reference standard of culture and/or multiplex PCR; and second against culture and/or a highly sensitive nested PCR technique performed in Oslo, Norway. We included 267 patients with suspected acute bacterial meningitis. Using the in-country reference standard, 50 samples (19%) were positive. Dipstick RDT sensitivity (N = 265) was 70% (95%CI 55-82) and specificity 97% (95%CI 93-99). Using culture and/or nested PCR, 126/259 (49%) samples were positive; dipstick RDT sensitivity (N = 257) was 32% (95%CI 24-41), and specificity was 99% (95%CI 95-100). We found dipstick RDT sensitivity lower than values reported from (i) assessments under ideal laboratory conditions (>90%), and (ii) a prior field evaluation in Niger [89% (95%CI 80-95)]. Specificity, however, was similar to (i), and higher than (ii) [62% (95%CI 48-75)]. At this stage in development, therefore, other tests (e.g., latex) might be preferred for use in peripheral health centres. We highlight the value of field evaluations for new diagnostic tests, and note relatively low sensitivity of a reference standard using multiplex vs. nested PCR. Although the former is the current standard for bacterial meningitis surveillance in the meningitis belt, nested PCR performed in a certified laboratory should be used as an absolute reference when evaluating new diagnostic tests.
    • Paracheck-Pf accuracy and recently treated Plasmodium falciparum infections: is there a risk of over-diagnosis?

      Swarthout, T D; Counihan, H; Senga, R K K; van den Broek, I; Médecins Sans Frontières, London, UK. toddswarth@yahoo.com (Elsevier, 2007)
      BACKGROUND: An assessment of the accuracy of Paracheck Pf, a malaria rapid diagnostic test (RDT) detecting histidine rich protein 2 was undertaken amongst children aged 6-59 months in eastern Democratic Republic of Congo. METHODS: This RDT assessment occurred in conjunction with an ACT efficacy trial. Febrile children were simultaneously screened with both RDT and high quality microscopy and those meeting inclusion criteria were followed for 35 days. RESULTS: 358 febrile children were screened with 180 children recruited for five weeks follow-up. On screening, the RDT accurately diagnosed all 235 true malaria cases, indicating 100% RDT sensitivity. Of the 123 negative slides, the RDT gave 59 false-positive results, indicating 52.0% (64/123) RDT specificity. During follow-up after treatment with an artemisinin-based combination therapy, 98.2% (110/112), 94.6% (106/112), 92.0% (103/112) and 73.5% (50/68) of effectively treated children were still false-positive by RDT at days 14, 21, 28 and 35, respectively. CONCLUSION: Results show that though the use of Paracheck-Pf is as sensitive as microscopy in detecting true malaria cases, a low specificity did present a high frequency of false-positive RDT results. What's more, a duration of RDT false-positivity was found that significantly surpassed the 'fortnight' after effective treatment reported by its manufacturer. Though further research is needed in assessing RDT accuracy, study results showing the presence of frequent false positivity should be taken into consideration to avoid clinicians inappropriately focusing on malaria, not identifying the true cause of illness, and providing unnecessary treatment.
    • Rapid malaria diagnostic tests vs. clinical management of malaria in rural Burkina Faso: safety and effect on clinical decisions. A randomized trial

      Bisoffi, Zeno; Sirima, Bienvenu Sodiomon; Angheben, Andrea; Lodesani, Claudia; Gobbi, Federico; Tinto, Halidou; Van den Ende, Jef; Centre for Tropical Diseases, Sacro Cuore Hospital, Negrar (Verona), Italy; Centre National de Recherche et de Formation sur le Paludisme, Ministry of Health, Ouagadougou, Burkina Faso; Medecins sans Frontieres, Democratic Republic of Congo; Centre Muraz, Bobo Dioulasso, Burkina Faso; Projet AnKaHeresso, Bobo Dioulasso, Burkina Faso; Department of Clinical Sciences, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium (2009-02-15)
      OBJECTIVES: To assess if the clinical outcome of patients treated after performing a Rapid Diagnostic Test for malaria (RDT) is at least equivalent to that of controls (treated presumptively without test) and to determine the impact of the introduction of a malaria RDT on clinical decisions. METHODS: Randomized, multi-centre, open clinical trial in two arms in 2006 at the end of the dry and of the rainy season in 10 peripheral health centres in Burkina Faso: one arm with use of RDT before treatment decision, one arm managed clinically. Primary endpoint: persistence of fever at day 4. Secondary endpoints: frequency of malaria treatment and of antibiotic treatment. RESULTS: A total of 852 febrile patients were recruited in the dry season and 1317 febrile patients in the rainy season, and randomized either to be submitted to RDT (P_RTD) or to be managed presumptively (P_CLIN). In both seasons, no significant difference was found between the two randomized groups in the frequency of antimalarial treatment, nor of antibiotic prescription. In the dry season, 80.8% and 79.8% of patients with a negative RDT were nevertheless diagnosed and treated for malaria, and so were 85.0% and 82.6% negative patients in the rainy season. In the rainy season only, both diagnosis and treatment of other conditions were significantly less frequent in RDT positive vs. negative patients (48.3% vs. 61.4% and 46.2% vs. 59.9%, P = 0.00 and 0.00, respectively). CONCLUSION: Our study was inconclusive on RDT safety (clinical outcome in the two randomized groups), because of an exceedingly and unexpectedly low compliance with the negative test result. Further research is needed on best strategies to promote adherence and on the safety of a test based strategy compared with the current, presumptive treatment strategy.
    • Validity, reliability and ease of use in the field of five rapid tests for the diagnosis of Plasmodium falciparum malaria in Uganda.

      Guthmann, J P; Ruiz, A; Priotto, G; Kiguli, J; Bonte, L; Legros, D; Epicentre, 4 rue Saint Sabin, 75011 Paris, France. jguthmann@epicentre.msf.org (Elsevier, 2008-02-14)
      A study was conducted to measure the overall performance of several rapid diagnostic tests for Plasmodium falciparum infection, in order to select the most appropriate test to be used in the field. A total of 742 patients attending the out-patient department of Mbarara Hospital with a clinical suspicion of malaria were included in the study. For each patient, a thick/thin film and 5 rapid tests based on the detection of histidine-rich protein II (HRP-II) (Paracheck Pf dipstick and device, ParaHIT f, Malaria Rapid and BIO P.F.) were performed. Outcomes were validity, inter-reader reliability and 'ease of use in the field', measured by both the general characteristics of the test and by the opinion of the readers. About half (57%) of the patients were positive for P. falciparum. The Paracheck Pf (dipstick and device) was considered as the most appropriate for the use in the field, being sensitive (97%), moderately specific (88%), reliable (kappa coefficient = 0.97), easy to use and cheap (about US$ 0.5/test). The ParaHIT f represented a good alternative.