Use of HRP-2-based rapid diagnostic test for Plasmodium falciparum malaria: assessing accuracy and cost-effectiveness in the villages of Dielmo and Ndiop, Senegal.

Unité d'Epidémiologie des Maladies Infectieuses, Institut Pasteur de Dakar, BP 220-Dakar, Sénégal.
Malaria Journal (Impact Factor: 3.49). 01/2010; 9:153. DOI: 10.1186/1475-2875-9-153
Source: PubMed

ABSTRACT In 2006, the Senegalese National Malaria Control Programme (NMCP) has recommended artemisinin-based combination therapy (ACT) as the first-line treatment for uncomplicated malaria and, in 2007, mandated testing for all suspected cases of malaria with a Plasmodium falciparum HRP-2-based rapid diagnostic test for malaria (RDT(Paracheck). Given the higher cost of ACT compared to earlier anti-malarials, the objectives of the present study were i) to study the accuracy of Paracheck compared to the thick blood smear (TBS) in two areas with different levels of malaria endemicity and ii) analyse the cost-effectiveness of the strategy of the parasitological confirmation of clinically suspected malaria cases management recommended by the NMCP.
A cross-sectional study was undertaken in the villages of Dielmo and Ndiop (Senegal) nested in a cohort study of about 800 inhabitants. For all the individuals consulting between October 2008 and January 2009 with a clinical diagnosis of malaria, a questionnaire was filled and finger-prick blood samples were taken both for microscopic examination and RDT. The estimated costs and cost-effectiveness analysis were made considering five scenarios, the recommendations of the NMCP being the reference scenario. In addition, a sensitivity analysis was performed assuming that all the RDT-positive patients and 50% of RDT-negative patients were treated with ACT.
A total of 189 consultations for clinically suspected malaria occurred during the study period. The sensitivity, specificity, positive and negative predictive values were respectively 100%, 98.3%, 80.0% and 100%. The estimated cost of the reference scenario was close to 700 euros per 1000 episodes of illness, approximately twice as expensive as most of the other scenarios. Nevertheless, it appeared to us cost-effective while ensuring the diagnosis and the treatment of 100% of malaria attacks and an adequate management of 98.4% of episodes of illness. The present study also demonstrated that full compliance of health care providers with RDT results was required in order to avoid severe incremental costs.
A rational use of ACT requires laboratory testing of all patients presenting with presumed malaria. Use of RDTs inevitably has incremental costs, but the strategy associating RDT use for all clinically suspected malaria and prescribing ACT only to patients tested positive is cost-effective in areas where microscopy is unavailable.

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    ABSTRACT: Introduction Parasitological confirmation before administration of antimalarial treatment has been recommended by the World Health Organization in everyone presenting with symptoms suggestive of malaria at all levels of the health system. Methods The authors assessed the performance of a histidine-rich protein 2-based malaria rapid diagnostic test used by community health workers in the context of an integrated approach to diagnosis and treatment for malaria and pneumonia. A total of 525 children below 5 years of age were recruited into the study. Children with fever/history of fever within the last 24 h were tested with the rapid diagnostic test (RDT) and a blood smear was obtained for delayed reading. Results Overall, the FirstSign™ Malaria Pf (Unimed International Inc, South San Francisco, USA) has shown a high sensitivity profile of 97.9% (95% CI 96.3–98.8), but a low specificity of 53.4% (95% CI 49.1–57.7). The specificity was significantly lower during the high transmission season at 25.4% (95% CI 20.5–31.0) compared to 63.7% (95% CI 57.6–69.4%) at the low transmission season. The negative predictive value (NPV) was 95.4% (95% CI 93.2–96.9) and positive predictive value was 71.7% (95% CI 67.7–75.4). The NPV was significantly higher during the low transmission season at 98.2% (95% CI 95.7–99.3) than compared to 80.0% (95% CI 74.7–84.4) at the high transmission season. Conclusion With such a low specificity, caution should be exercised when using these RDTs for community case management of malaria.
    Infectious Diseases and Therapy. 12/2013; 2(1).
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    ABSTRACT: BACKGROUND: Rapid diagnostic tests (RDT) for malaria have been demonstrated to be effective and they should replace microscopy in certain areas. METHOD: The cost-effectiveness of five RDT and thick smear microscopy was estimated and compared. Data were collected on Brazilian Extra-Amazon Region. Data sources included the National Malaria Control Programme of the Ministry of Health, the National Healthcare System reimbursement table, laboratory suppliers and scientific literature. The perspective was that of the Brazilian public health system, the analytical horizon was from the start of fever until the diagnostic results provided to patient and the temporal reference was that of year 2010. Two costing methods were produced, based on exclusive-use microscopy or shared-use microscopy. The results were expressed in costs per adequately diagnosed cases in 2010 U.S. dollars. One-way sensitivity analysis was performed considering key model parameters. RESULTS: In the cost-effectiveness analysis with exclusive-use microscopy, the RDT CareStartTM was the most cost-effective diagnostic strategy. Microscopy was the most expensive and most effective, with an additional case adequately diagnosed by microscopy costing US$ 35,550.00 in relation to CareStartTM. In opposite, in the cost-effectiveness analysis with shared-use microscopy, the thick smear was extremely cost-effective. Introducing into the analytic model with shared-use microscopy a probability for individual access to the diagnosis, assuming a probability of 100% of access for a public health system user to any RDT and, hypothetically, of 85% of access to microscopy, this test saw its effectiveness reduced and was dominated by the RDT CareStartTM. CONCLUSION: The analysis of cost-effectiveness of malaria diagnosis technologies in the Brazilian Extra- Amazon Region depends on the exclusive or shared use of the microscopy. Following the assumptions of this study, shared-use microscopy would be the most cost-effective strategy of the six technologies evaluated. However, if used exclusively for diagnosing malaria, microscopy would be the worst use of resources. Microscopy would not be the most costeffective strategy, even when structure is shared with other programmes, when the probability of a patient having access to it was reduced. Under these circumstances, the RDT CareStartTM would be the most cost-effective strategy.
    Malaria Journal 11/2012; 11(1):390. · 3.49 Impact Factor
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    ABSTRACT: BACKGROUND: An accurate diagnosis is essential for the rapid and appropriate treatment of malaria. The accuracy of the histidine-rich protein 2 (PfHRP2)-based rapid diagnostic test (RDT) Palutop+4(R) was assessed here. One possible factor contributing to the failure to detect malaria by this test is the diversity of the parasite PfHRP2 antigens. METHODS: PfHRP2 detection with the Palutop+4(R) RDT was carried out. The pfhrp2 and pfhrp3 genes were amplified and sequenced from 136 isolates of Plasmodium falciparum that were collected in Dakar, Senegal from 2009 to 2011. The DNA sequences were determined and statistical analyses of the variation observed between these two genes were conducted. The potential impact of PfHRP2 and PfHRP3 sequence variation on malaria diagnosis was examined. RESULTS: Seven P. falciparum isolates (5.9% of the total isolates, regardless of the parasitaemia; 10.7% of the isolates with parasitaemia <=0.005% or <=250 parasites/mul) were undetected by the PfHRP2 Palutop+4(R) RDT. Low parasite density is not sufficient to explain the PfHRP2 detection failure. Three of these seven samples showed pfhrp2 deletion (2.4%). The pfhrp3 gene was deleted in 12.8%. Of the 122 PfHRP2 sequences, 120 unique sequences were identified. Of the 109 PfHRP3 sequences, 64 unique sequences were identified. Using the Baker's regression model, at least 7.4% of the P. falciparum isolates in Dakar were likely to be undetected by PfHRP2 at a parasite density of <=250 parasites/mul (slightly lower than the evaluated prevalence of 10.7%). This predictive prevalence increased significantly between 2009 and 2011 (P = 0.0046). CONCLUSION: In the present work, 10.7% of the isolates with a parasitaemia <=0.005% (<=250 parasites/mul) were undetected by the PfHRP2 Palutop+4(R) RDT (7.4% by the predictive Baker'model). In addition, all of the parasites with pfhrp2 deletion (2.4% of the total samples) and 2.1% of the parasites with parasitaemia >0.005% and presence of pfhrp2 were not detected by PfHRP2 RDT. PfHRP2 is highly polymorphic in Senegal. Efforts should be made to more accurately determine the prevalence of non-sensitive parasites to pfHRP2.
    Malaria Journal 01/2013; 12(1):34. · 3.49 Impact Factor

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