| 1. |
- Cook, Jackie, et al.
(författare)
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Loop-mediated isothermal amplification (LAMP) for point-of-care detection of asymptomatic low-density malaria parasite carriers in Zanzibar
- 2015
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875 .- 1475-2875. ; 14, s. 43-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Asymptomatic, low parasite density malaria infections are difficult to detect with currently available point-of-care diagnostics. This study piloted a loop-mediated isothermal amplification (LAMP) kit for field-friendly, high-throughput detection of asymptomatic malaria infections during mass screening and treatment (MSAT) in Zanzibar, a malaria pre-elimination setting. Methods: Screening took place in three known hotspot areas prior to the short rains in November. Finger-prick blood was taken for screening by rapid diagnostic test (RDT) and LAMP and collected on filter paper for subsequent polymerase chain reaction (PCR) analyses. LAMP results were compared to RDT and to PCR using McNemar's test. Results: Approximately 1,000 people were screened. RDT detected ten infections (1.0% (95% CI 0.3-1.6)) whilst both LAMP and PCR detected 18 (1.8% (95% CI 0.9-2.6)) infections. However, PCR identified three infections that LAMP did not detect and vice versa. LAMP testing was easy to scale-up in field conditions requiring minimal training and equipment, with results ready one to three hours after screening. Conclusions: Despite lower than expected prevalence, LAMP detected a higher number of infections than the currently used diagnostic, RDT. LAMP is a field-friendly, sensitive diagnostic test that could be useful for MSAT malaria campaigns which require quick results to enable prompt treatment.
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| 2. |
- Cook, Jackie, et al.
(författare)
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Mass Screening and Treatment on the Basis of Results of a Plasmodium falciparum-Specific Rapid Diagnostic Test Did Not Reduce Malaria Incidence in Zanzibar
- 2015
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Ingår i: The Internet Journal of Infectious Diseases. - : Oxford University Press (OUP). - 1528-8366 .- 0022-1899 .- 1537-6613. ; 211:9, s. 1476-1483
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Seasonal increases in malaria continue in hot spots in Zanzibar. Mass screening and treatment (MSAT) may help reduce the reservoir of infection; however, it is unclear whether rapid diagnostic tests (RDTs) detect a sufficient proportion of low-density infections to influence subsequent transmission.METHODS: Two rounds of MSAT using Plasmodium falciparum-specific RDT were conducted in 5 hot spots (population, 12 000) in Zanzibar in 2012. In parallel, blood samples were collected on filter paper for polymerase chain reaction (PCR) analyses. Data on confirmed malarial parasite infections from health facilities in intervention and hot spot control areas were monitored as proxy for malaria transmission.RESULTS: Approximately 64% of the population (7859) were screened at least once. P. falciparum prevalence, as measured by RDT, was 0.2% (95% confidence interval [CI], .1%-.3%) in both rounds, compared with PCR measured prevalences (for all species) of 2.5% (95% CI, 2.1%-2.9%) and 3.8% (95% CI, 3.2%-4.4%) in rounds 1 and 2, respectively. Two fifths (40%) of infections detected by PCR included non-falciparum species. Treatment of RDT-positive individuals (4% of the PCR-detected parasite carriers) did not reduce subsequent malaria incidence, compared with control areas.CONCLUSIONS: Highly sensitive point-of-care diagnostic tools for detection of all human malaria species are needed to make MSAT an effective strategy in settings where malaria elimination programs are in the pre-elimination phase.
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| 3. |
- Morris, Ulrika, et al.
(författare)
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Field deployment of loop-mediated isothermal amplification for centralized mass-screening of asymptomatic malaria in Zanzibar : a pre-elimination setting
- 2015
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875 .- 1475-2875. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Molecular tools for detection of low-density asymptomatic Plasmodium infections are needed in malaria elimination efforts. This study reports results from the hitherto largest implementation of loop-mediated isothermal amplification (LAMP) for centralized mass screening of asymptomatic malaria in Zanzibar.METHODS: Healthy individuals present and willing to participate in randomly selected households in 60 villages throughout Zanzibar were screened for malaria by rapid diagnostic tests (RDT). In 50 % of the study households, participants were asked to provide 60 μL of finger-prick blood for additional LAMP screening. LAMP was conducted in two centralized laboratories in Zanzibar, by trained technicians with limited or no previous experience of molecular methods. The LAMP assay was performed with Loopamp(TM) MALARIA Pan/Pf Detection Kit (Eiken Chemical Company, Japan). Samples positive for Plasmodium genus (Pan)-LAMP were re-tested using Plasmodium falciparum-specific LAMP kits.RESULTS: Paired RDT and LAMP samples were available from 3983 individuals. The prevalence of asymptomatic malaria was 0.5 % (CI 95 % 0.1-0.8) and 1.6 % (CI 95 % 1.1-2.2) by RDT and Pan-LAMP, respectively. LAMP detected 3.4 (CI 95 % 2.2-5.2) times more Plasmodium positive samples than RDT. DNA contamination was experienced, but solved by repetitive decontamination of all equipment and reagents.CONCLUSIONS: LAMP is a simple and sensitive molecular tool, and has potential in active surveillance and mass-screening programmes for detection of low-density asymptomatic malaria in pre-elimination settings. However, in order to deploy LAMP more effectively in field settings, protocols may need to be adapted for processing larger numbers of samples. A higher throughput, affordable closed system would be ideal to avoid contamination.
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