Loop-mediated isothermal amplification (LAMP) for point-of-care detection of asymptomatic low-density malaria parasite carriers in Zanzibar

Jackie Cook, Berit Aydin-Schmidt, Iveth J González, David Bell, Elin Edlund, Majda H Nassor, Mwinyi Msellem, Abdullah Ali, Ali K Abass, Andreas Mårtensson, Anders Björkman, Jackie Cook, Berit Aydin-Schmidt, Iveth J González, David Bell, Elin Edlund, Majda H Nassor, Mwinyi Msellem, Abdullah Ali, Ali K Abass, Andreas Mårtensson, Anders Björkman

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.

Figures

Figure 1
Figure 1
Venn diagram showing the distribution of positive RDT, Pan-LAMP and PCR results.

References

    1. Okell LC, Ghani AC, Lyons E, Drakeley CJ. Submicroscopic infection in Plasmodium falciparum-endemic populations: a systematic review and meta-analysis. J Infect Dis. 2009;200:1509–17. doi: 10.1086/644781.
    1. Bousema JT, Gouagna LC, Drakeley CJ, Meutstege AM, Okech BA, Akim IN, et al. Plasmodium falciparum gametocyte carriage in asymptomatic children in western Kenya. Malar J. 2004;3:18. doi: 10.1186/1475-2875-3-18.
    1. Karl S, Gurarie D, Zimmerman PA, King CH, St Pierre TG, Davis TM. A sub-microscopic gametocyte reservoir can sustain malaria transmission. PLoS One. 2011;6:e20805. doi: 10.1371/journal.pone.0020805.
    1. Programme ZME. Malaria Epidemic Early Detection System. 2013.
    1. Shakely D, Elfving K, Aydin-Schmidt B, Msellem MI, Morris U, Omar R, et al. The usefulness of rapid diagnostic tests in the new context of low malaria transmission in Zanzibar. PLoS One. 2013;8:e72912. doi: 10.1371/journal.pone.0072912.
    1. Cook J, Xu W, Msellem M, Vonk M, Bergstrom B, Gosling R, Al-Mafazy A, McElroy P, Molteni F, Abass AK, Garimo I, Ramsan M, Ali A, Mårtensson A, Björkman A: Mass screening and treatment on the basis of results of a Plasmodium falciparum-specific rapid diagnostic test did not reduce malaria incidence in Zanzibar. J Infect Dis 2014, pii: jiu655. [Epub ahead of print]
    1. Fancony C, Sebastiao YV, Pires JE, Gamboa D, Nery SV. Performance of microscopy and RDTs in the context of a malaria prevalence survey in Angola: a comparison using PCR as the gold standard. Malar J. 2013;12:284. doi: 10.1186/1475-2875-12-284.
    1. Alemayehu S, Feghali KC, Cowden J, Komisar J, Ockenhouse CF, Kamau E. Comparative evaluation of published real-time PCR assays for the detection of malaria following MIQE guidelines. Malar J. 2013;12:277. doi: 10.1186/1475-2875-12-277.
    1. Kamau E, Alemayehu S, Feghali KC, Tolbert LS, Ogutu B, Ockenhouse CF. Development of a TaqMan allelic discrimination assay for detection of single nucleotides polymorphisms associated with anti-malarial drug resistance. Malar J. 2012;11:23. doi: 10.1186/1475-2875-11-23.
    1. Cotter C, Sturrock HJ, Hsiang MS, Liu J, Phillips AA, Hwang J, et al. The changing epidemiology of malaria elimination: new strategies for new challenges. Lancet. 2013;382:900–11. doi: 10.1016/S0140-6736(13)60310-4.
    1. Kamau E, Alemayehu S, Feghali KC, Juma DW, Blackstone GM, Marion WR, et al. Sample-ready multiplex qPCR assay for detection of malaria. Malar J. 2014;13:158. doi: 10.1186/1475-2875-13-158.
    1. Aydin-Schmidt B, Xu W, Gonzalez IJ, Polley SD, Bell D, Shakely D, et al. Loop-mediated isothermal amplification (LAMP) accurately detects malaria DNA from filter paper blood samples of low density parasitaemias. PLoS One. 2014;9:e103905. doi: 10.1371/journal.pone.0103905.
    1. Hopkins H, Gonzalez IJ, Polley SD, Angutoko P, Ategeka J, Asiimwe C, et al. Highly sensitive detection of malaria parasitemia in a malaria-endemic setting: performance of a new loop-mediated isothermal amplification kit in a remote clinic in Uganda. J Infect Dis. 2013;208:645–52. doi: 10.1093/infdis/jit184.
    1. Hartung CLA, Anokwa Y, Tseng C, Brunette W, Borrielo G. 4th ACM/IEEE International Conference on Information and Communication Technologies and Development. 2010. Open data kit: tools to build information services for developing regions; p. 18.
    1. FIND: Manual of Standard Operating Procedures for malaria LAMP. []
    1. Wooden J, Kyes S, Sibley CH. PCR and strain identification in Plasmodium falciparum. Parasitol Today. 1993;9:303–5. doi: 10.1016/0169-4758(93)90131-X.
    1. Kamau E, Alemayehu S, Feghali KC, Saunders D, Ockenhouse CF. Multiplex qPCR for detection and absolute quantification of malaria. PLoS One. 2013;8:e71539. doi: 10.1371/journal.pone.0071539.
    1. Zanzibar Malaria Control Program . Zanzibar malaria program performance review; Strengthening health systems and community based malaria control and elimination. Zanzibar: Ministry of Health; 2011.

Source: PubMed

Sponsorer og samarbejdspartnere

Medicinske tilstande

Narkotikainterventioner

3
Abonner