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. 2015 May 1;211(9):1476-83.
doi: 10.1093/infdis/jiu655. Epub 2014 Nov 26.

Mass screening and treatment on the basis of results of a Plasmodium falciparum-specific rapid diagnostic test did not reduce malaria incidence in Zanzibar

Jackie Cook  1 , Weiping Xu  1 , Mwinyi Msellem  2 , Marlotte Vonk  1 , Beatrice Bergström  1 , Roly Gosling  3 , Abdul-Wahid Al-Mafazy  2 , Peter McElroy  4 , Fabrizio Molteni  5 , Ali K Abass  2 , Issa Garimo  6 , Mahdi Ramsan  6 , Abdullah Ali  2 , Andreas Mårtensson  7 , Anders Björkman  1
Affiliations

Mass screening and treatment on the basis of results of a Plasmodium falciparum-specific rapid diagnostic test did not reduce malaria incidence in Zanzibar

Jackie Cook et al. J Infect Dis. .

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.

Keywords: Plasmodium falciparum; Plasmodium malariae; Plasmodium ovale; Plasmodium vivax; Zanzibar; diagnostic tests; malaria elimination; mass screening and treatment; molecular methods; subpatent.

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Conflict of interest statement

Potential conflicts of interest. All authors: No reported conflicts.

All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Figures

Figure 1.
Figure 1.
Map of control (striped) and intervention (grey) study shehias and health facilities (black dot), Unguja Island, Zanzibar.
Figure 2.
Figure 2.
Prevalence of Plasmodium species, by polymerase chain reaction (PCR) findings, across age groups in round 1 (A) and round 2 (B).
Figure 3.
Figure 3.
Number of confirmed malarial parasite infections reported from public health facilities (bars) and average weekly incidence in the control and intervention areas (lines). Screening occurred in weeks 20 and 24.
See this image and copyright information in PMC

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