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Newby G, Cotter C, Roh ME, Harvard K, Bennett A, Hwang J, Chitnis N, Fine S, Stresman G, Chen I, Gosling R, Hsiang MS. Testing and treatment for malaria elimination: a systematic review. Malar J 2023; 22:254. [PMID: 37661286 PMCID: PMC10476355 DOI: 10.1186/s12936-023-04670-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 08/07/2023] [Indexed: 09/05/2023] Open
Abstract
BACKGROUND Global interest in malaria elimination has prompted research on active test and treat (TaT) strategies. METHODS A systematic review and meta-analysis were conducted to assess the effectiveness of TaT strategies to reduce malaria transmission. RESULTS A total of 72 empirical research and 24 modelling studies were identified, mainly focused on proactive mass TaT (MTaT) and reactive case detection (RACD) in higher and lower transmission settings, respectively. Ten intervention studies compared MTaT to no MTaT and the evidence for impact on malaria incidence was weak. No intervention studies compared RACD to no RACD. Compared to passive case detection (PCD) alone, PCD + RACD using standard diagnostics increased infection detection 52.7% and 11.3% in low and very low transmission settings, respectively. Using molecular methods increased this detection of infections by 1.4- and 1.1-fold, respectively. CONCLUSION Results suggest MTaT is not effective for reducing transmission. By increasing case detection, surveillance data provided by RACD may indirectly reduce transmission by informing coordinated responses of intervention targeting.
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Affiliation(s)
- Gretchen Newby
- Malaria Elimination Initiative, Institute for Global Health Sciences, University of California San Francisco (UCSF), 550 16th Street, San Francisco, CA, 94143, USA
| | - Chris Cotter
- Malaria Elimination Initiative, Institute for Global Health Sciences, University of California San Francisco (UCSF), 550 16th Street, San Francisco, CA, 94143, USA
- Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden
| | - Michelle E Roh
- Malaria Elimination Initiative, Institute for Global Health Sciences, University of California San Francisco (UCSF), 550 16th Street, San Francisco, CA, 94143, USA
- Department of Epidemiology and Biostatistics, UCSF, San Francisco, CA, USA
| | - Kelly Harvard
- Malaria Elimination Initiative, Institute for Global Health Sciences, University of California San Francisco (UCSF), 550 16th Street, San Francisco, CA, 94143, USA
| | - Adam Bennett
- Malaria Elimination Initiative, Institute for Global Health Sciences, University of California San Francisco (UCSF), 550 16th Street, San Francisco, CA, 94143, USA
- Department of Epidemiology and Biostatistics, UCSF, San Francisco, CA, USA
- PATH, Seattle, WA, USA
| | - Jimee Hwang
- Malaria Branch, Centers for Disease Control and Prevention, U.S. President's Malaria Initiative, Atlanta, GA, USA
| | - Nakul Chitnis
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Sydney Fine
- Malaria Elimination Initiative, Institute for Global Health Sciences, University of California San Francisco (UCSF), 550 16th Street, San Francisco, CA, 94143, USA
| | - Gillian Stresman
- College of Public Health, University of South Florida, Tampa, FL, USA
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Ingrid Chen
- Malaria Elimination Initiative, Institute for Global Health Sciences, University of California San Francisco (UCSF), 550 16th Street, San Francisco, CA, 94143, USA
- Department of Epidemiology and Biostatistics, UCSF, San Francisco, CA, USA
| | - Roly Gosling
- Malaria Elimination Initiative, Institute for Global Health Sciences, University of California San Francisco (UCSF), 550 16th Street, San Francisco, CA, 94143, USA
- Department of Epidemiology and Biostatistics, UCSF, San Francisco, CA, USA
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Michelle S Hsiang
- Malaria Elimination Initiative, Institute for Global Health Sciences, University of California San Francisco (UCSF), 550 16th Street, San Francisco, CA, 94143, USA.
- Department of Epidemiology and Biostatistics, UCSF, San Francisco, CA, USA.
- Department of Pediatrics, UCSF, San Francisco, CA, USA.
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Ippolito MM, Gebhardt ME, Ferriss E, Schue JL, Kobayashi T, Chaponda M, Kabuya JB, Muleba M, Mburu M, Matoba J, Musonda M, Katowa B, Lubinda M, Hamapumbu H, Simubali L, Mudenda T, Wesolowski A, Shields TM, Hackman A, Shiff C, Coetzee M, Koekemoer LL, Munyati S, Gwanzura L, Mutambu S, Stevenson JC, Thuma PE, Norris DE, Bailey JA, Juliano JJ, Chongwe G, Mulenga M, Simulundu E, Mharakurwa S, Agre PC, Moss WJ. Scientific Findings of the Southern and Central Africa International Center of Excellence for Malaria Research: Ten Years of Malaria Control Impact Assessments in Hypo-, Meso-, and Holoendemic Transmission Zones in Zambia and Zimbabwe. Am J Trop Med Hyg 2022; 107:55-67. [PMID: 36228903 PMCID: PMC9662223 DOI: 10.4269/ajtmh.21-1287] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 04/08/2022] [Indexed: 11/07/2022] Open
Abstract
For a decade, the Southern and Central Africa International Center of Excellence for Malaria Research has operated with local partners across study sites in Zambia and Zimbabwe that range from hypo- to holoendemic and vary ecologically and entomologically. The burden of malaria and the impact of control measures were assessed in longitudinal cohorts, cross-sectional surveys, passive and reactive case detection, and other observational designs that incorporated multidisciplinary scientific approaches: classical epidemiology, geospatial science, serosurveillance, parasite and mosquito genetics, and vector bionomics. Findings to date have helped elaborate the patterns and possible causes of sustained low-to-moderate transmission in southern Zambia and eastern Zimbabwe and recalcitrant high transmission and fatality in northern Zambia. Cryptic and novel mosquito vectors, asymptomatic parasite reservoirs in older children, residual parasitemia and gametocytemia after treatment, indoor residual spraying timed dyssynchronously to vector abundance, and stockouts of essential malaria commodities, all in the context of intractable rural poverty, appear to explain the persistent malaria burden despite current interventions. Ongoing studies of high-resolution transmission chains, parasite population structures, long-term malaria periodicity, and molecular entomology are further helping to lay new avenues for malaria control in southern and central Africa and similar settings.
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Affiliation(s)
- Matthew M. Ippolito
- Johns Hopkins University School of Medicine, Baltimore, Maryland
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Mary E. Gebhardt
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Ellen Ferriss
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Jessica L. Schue
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Tamaki Kobayashi
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | | | | | | | | | | | | | | | | | | | | | - Amy Wesolowski
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | - Andre Hackman
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Clive Shiff
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Maureen Coetzee
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Lizette L. Koekemoer
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Institute for Communicable Diseases, Johannesburg, South Africa
| | - Shungu Munyati
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | - Lovemore Gwanzura
- Biomedical Research and Training Institute, Harare, Zimbabwe
- University of Zimbabwe Faculty of Medicine and Health Sciences, Harare, Zimbabwe
| | | | - Jennifer C. Stevenson
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
- Macha Research Trust, Choma, Zambia
| | | | - Douglas E. Norris
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | - Jonathan J. Juliano
- University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | | | - Modest Mulenga
- Directorate of Research and Postgraduate Studies, Lusaka Apex Medical University, Lusaka, Zambia
| | | | - Sungano Mharakurwa
- Biomedical Research and Training Institute, Harare, Zimbabwe
- Africa University, Mutare, Zimbabwe
| | - Peter C. Agre
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - William J. Moss
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
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3
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Okebe J, Dabira E, Jaiteh F, Mohammed N, Bradley J, Drammeh NF, Bah A, Masunaga Y, Achan J, Muela Ribera J, Yeung S, Balen J, Peeters Grietens K, D'Alessandro U. Reactive, self-administered malaria treatment against asymptomatic malaria infection: results of a cluster randomized controlled trial in The Gambia. Malar J 2021; 20:253. [PMID: 34098984 PMCID: PMC8186162 DOI: 10.1186/s12936-021-03761-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 05/11/2021] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Selectively targeting and treating malaria-infected individuals may further decrease parasite carriage in low-burden settings. Using a trans-disciplinary approach, a reactive treatment strategy to reduce Plasmodium falciparum prevalence in participating communities was co-developed and tested. METHODS This is a 2-arm, open-label, cluster-randomized trial involving villages in Central Gambia during the 2017 and 2018 malaria transmission season. Villages were randomized in a 1:1 ratio using a minimizing algorithm. In the intervention arm, trained village health workers delivered a full course of pre-packed dihydroartemisinin-piperaquine to all residents of compounds where clinical cases were reported while in the control arm, compound residents were screened for infection at the time of the index case reporting. All index cases were treated following national guidelines. The primary endpoint was malaria prevalence, determined by molecular methods, at the end of the intervention period. RESULTS The trial was carried out in 50 villages: 34 in 2017 and 16 additional villages in 2018. At the end of the 2018 transmission season, malaria prevalence was 0.8% (16/1924, range 0-4%) and 1.1% (20/1814, range 0-17%) in the intervention and control arms, respectively. The odds of malaria infection were 29% lower in the intervention than in the control arm after adjustment for age (OR 0.71, 95% CI 0.27-1.84, p = 0.48). Adherence to treatment was high, with 98% (964/979) of those treated completing the 3-day treatment. Over the course of the study, only 37 villages, 20 in the intervention and 17 in the control arm, reported at least one clinical case. The distribution of clinical cases by month in both transmission seasons was similar and the odds of new clinical malaria cases during the trial period did not vary between arms (OR 1.04, 95% CI 0.57-1.91, p = 0.893). All adverse events were classified as mild to moderate and resolved completely. CONCLUSION The systematic and timely administration of an anti-malarial treatment to residents of compounds with confirmed malaria cases did not significantly decrease malaria prevalence and incidence in communities where malaria prevalence was already low. Treatment coverage and adherence was very high. Results were strongly influenced by the lower-than-expected malaria prevalence, and by no clinical cases in villages with asymptomatic malaria-infected individuals. TRIAL REGISTRATION This study is registered with ClinicalTrials.gov, NCT02878200. Registered 25 August 2016. https://clinicaltrials.gov/ct2/show/NCT02878200 .
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Affiliation(s)
- Joseph Okebe
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Edgard Dabira
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Fatou Jaiteh
- Medical Anthropology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- Amsterdam Institute of Social Science Research, Amsterdam, The Netherlands
| | - Nuredin Mohammed
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Ndey-Fatou Drammeh
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Amadou Bah
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Yoriko Masunaga
- Medical Anthropology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- Amsterdam Institute of Social Science Research, Amsterdam, The Netherlands
| | - Jane Achan
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
- Malaria Consortium, Cambridge Heath, London, UK
| | | | - Shunmay Yeung
- Clinical Research Department, London School of Hygiene and Tropical Medicine, London, UK
| | - Julie Balen
- School of Health and Related Research, The University of Sheffield, Sheffield, UK
| | | | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia.
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4
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Searle KM, Katowa B, Musonda M, Pringle JC, Hamapumbu H, Matoba J, Lubinda M, Shields T, Kobayashi T, Stevenson JC, Norris DE, Thuma PE, Wesolowski A, Moss WJ, For The Southern And Central Africa International Center Of Excellence For Malaria Research. Sustained Malaria Transmission despite Reactive Screen-and-Treat in a Low-Transmission Area of Southern Zambia. Am J Trop Med Hyg 2020; 104:671-679. [PMID: 33236715 PMCID: PMC7866307 DOI: 10.4269/ajtmh.20-0947] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 09/28/2020] [Indexed: 12/30/2022] Open
Abstract
Malaria elimination strategies are designed to more effectively identify and treat infected individuals to interrupt transmission. One strategy, reactive screen-and-treat, starts with passive detection of symptomatic cases at health facilities. Individuals residing within the index case and neighboring households are screened with a malaria rapid diagnostic test (RDT) and treated if positive. However, it is unclear to what extent this strategy is effective in reducing transmission. Reactive screen-and-treat was implemented in Choma district, Southern Province, Zambia, in 2013, in which residents of the index case and neighboring households within 140 m were screened with an RDT. From March 2016 to July 2018, the screening radius was extended to 250-m, and additional follow-up visits at 30 and 90 days were added to evaluate the strategy. Plasmodium falciparum parasite prevalence was measured using an RDT and by quantitative PCR (qPCR). A 24-single nucleotide polymorphism molecular bar-code assay was used to genotype parasites. Eighty-four index case households with 676 residents were enrolled between March 2016 and March 2018. Within each season, parasite prevalence declined significantly in index households at the 30-day visit and remained low at the 90-day visit. However, parasite prevalence was not reduced to zero. Infections identified by qPCR persisted between study visits and were not identified by RDT. Parasites identified within the same household were most genetically related; however, overall parasite relatedness was low and similar across time and space. Thus, despite implementation of a reactive screen-and-treat program, parasitemia was not eliminated, and persisted in targeted households for at least 3 months.
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Affiliation(s)
- Kelly M Searle
- Division of Epidemiology and Community Health, University of Minnesota School of Public Health, Minneapolis, Minnesota
| | | | | | - Julia C Pringle
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | | | | | - Timothy Shields
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Tamaki Kobayashi
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Jennifer C Stevenson
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,Macha Research Trust, Macha, Zambia
| | - Douglas E Norris
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Philip E Thuma
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,Macha Research Trust, Macha, Zambia
| | - Amy Wesolowski
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - William J Moss
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
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5
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Bhondoekhan FRP, Searle KM, Hamapumbu H, Lubinda M, Matoba J, Musonda M, Katowa B, Shields TM, Kobayashi T, Norris DE, Curriero FC, Stevenson JC, Thuma PE, Moss WJ. Improving the efficiency of reactive case detection for malaria elimination in southern Zambia: a cross-sectional study. Malar J 2020; 19:175. [PMID: 32381005 PMCID: PMC7206707 DOI: 10.1186/s12936-020-03245-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/23/2020] [Indexed: 01/20/2023] Open
Abstract
Background Reactive case detection (RCD) seeks to enhance malaria surveillance and control by identifying and treating parasitaemic individuals residing near index cases. In Zambia, this strategy starts with passive detection of symptomatic incident malaria cases at local health facilities or by community health workers, with subsequent home visits to screen-and-treat residents in the index case and neighbouring (secondary) households within a 140-m radius using rapid diagnostic tests (RDTs). However, a small circular radius may not be the most efficient strategy to identify parasitaemic individuals in low-endemic areas with hotspots of malaria transmission. To evaluate if RCD efficiency could be improved by increasing the probability of identifying parasitaemic residents, environmental risk factors and a larger screening radius (250 m) were assessed in a region of low malaria endemicity. Methods Between January 12, 2015 and July 26, 2017, 4170 individuals residing in 158 index and 531 secondary households were enrolled and completed a baseline questionnaire in the catchment area of Macha Hospital in Choma District, Southern Province, Zambia. Plasmodium falciparum prevalence was measured using PfHRP2 RDTs and quantitative PCR (qPCR). A Quickbird™ high-resolution satellite image of the catchment area was used to create environmental risk factors in ArcGIS, and generalized estimating equations were used to evaluate associations between risk factors and secondary households with parasitaemic individuals. Results The parasite prevalence in secondary (non-index case) households was 0.7% by RDT and 1.8% by qPCR. Overall, 8.5% (n = 45) of secondary households had at least one resident with parasitaemia by qPCR or RDT. The risk of a secondary household having a parasitaemic resident was significantly increased in proximity to higher order streams and marginally with increasing distance from index households. The adjusted OR for proximity to third- and fifth-order streams were 2.97 (95% CI 1.04–8.42) and 2.30 (95% CI 1.04–5.09), respectively, and that for distance to index households for each 50 m was 1.24 (95% CI 0.98–1.58). Conclusion Applying proximity to streams as a screening tool, 16% (n = 3) more malaria-positive secondary households were identified compared to using a 140-m circular screening radius. This analysis highlights the potential use of environmental risk factors as a screening strategy to increase RCD efficiency.
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Affiliation(s)
- Fiona R P Bhondoekhan
- MACS/WIHS Combined Cohort Study, Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
| | - Kelly M Searle
- MACS/WIHS Combined Cohort Study, Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, USA
| | | | | | | | | | - Ben Katowa
- Macha Research Trust, Choma District, Zambia
| | - Timothy M Shields
- MACS/WIHS Combined Cohort Study, Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Tamaki Kobayashi
- MACS/WIHS Combined Cohort Study, Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Douglas E Norris
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Frank C Curriero
- MACS/WIHS Combined Cohort Study, Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Jennifer C Stevenson
- Macha Research Trust, Choma District, Zambia.,Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Philip E Thuma
- Macha Research Trust, Choma District, Zambia.,Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - William J Moss
- MACS/WIHS Combined Cohort Study, Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
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6
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Pringle JC, Tessema S, Wesolowski A, Chen A, Murphy M, Carpi G, Shields TM, Hamapumbu H, Searle KM, Kobayashi T, Katowa B, Musonda M, Stevenson JC, Thuma PE, Greenhouse B, Moss WJ, Norris DE. Genetic Evidence of Focal Plasmodium falciparum Transmission in a Pre-elimination Setting in Southern Province, Zambia. J Infect Dis 2020; 219:1254-1263. [PMID: 30445612 DOI: 10.1093/infdis/jiy640] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 11/09/2018] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Southern Province, Zambia has experienced a dramatic decline in Plasmodium falciparum malaria transmission in the past decade and is targeted for elimination. Zambia's National Malaria Elimination Program recommends reactive case detection (RCD) within 140 m of index households to enhance surveillance and eliminate remaining transmission foci. METHODS To evaluate whether RCD captures local transmission, we genotyped 26 microsatellites from 106 samples collected from index (n = 27) and secondary (n = 79) cases detected through RCD in the Macha Hospital catchment area between January 2015 and April 2016. RESULTS Participants from the same RCD event harbored more genetically related parasites than those from different RCD events, suggesting that RCD captures, at least in part, infections related through local transmission. Related parasites clustered in space and time, up to at least 250 m from index households. Spatial analysis identified a putative focal transmission hotspot. CONCLUSIONS The current RCD strategy detects focal transmission events, although programmatic guidelines to screen within 140 m of index households may fail to capture all secondary cases. This study highlights the utility of parasite genetic data in assessing programmatic interventions, and similar approaches may be useful to malaria elimination programs seeking to tailor intervention strategies to the underlying transmission epidemiology.
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Affiliation(s)
- Julia C Pringle
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | - Amy Wesolowski
- Department of Epidemiology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Anna Chen
- Department of Medicine, University of California, San Francisco
| | - Maxwell Murphy
- Department of Medicine, University of California, San Francisco.,Division of Biostatistics, University of California, Berkeley
| | - Giovanna Carpi
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,Department of Biological Sciences, Purdue University, West Lafayette, Indiana
| | - Timothy M Shields
- Department of Epidemiology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | - Kelly M Searle
- Department of Epidemiology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Tamaki Kobayashi
- Department of Epidemiology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | | | | | - Jennifer C Stevenson
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,Macha Research Trust, Choma, Zambia
| | | | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco.,Chan Zuckerberg Biohub, San Francisco, California
| | - William J Moss
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.,Department of Epidemiology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Douglas E Norris
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
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7
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Deutsch-Feldman M, Hamapumbu H, Lubinda J, Musonda M, Katowa B, Searle KM, Kobayashi T, Shields TM, Stevenson JC, Thuma PE, Moss WJ, For The Southern Africa International Centers Of Excellence For Malaria Research. Efficiency of a Malaria Reactive Test-and-Treat Program in Southern Zambia: A Prospective, Observational Study. Am J Trop Med Hyg 2018; 98:1382-1388. [PMID: 29557330 DOI: 10.4269/ajtmh.17-0865] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
To improve malaria surveillance and achieve elimination, the Zambian National Malaria Elimination Program implemented a reactive test-and-treat program in Southern Province in 2013 in which individuals with rapid diagnostic test (RDT)-confirmed malaria are followed-up at their home within 1 week of diagnosis. Individuals present at the index case household and those residing within 140 m of the index case are tested with an RDT and treated with artemether-lumefantrine if positive. This study evaluated the efficiency of this reactive test-and-treat strategy by characterizing infected individuals missed by the RDT and the current screening radius. The radius was expanded to 250 m, and a quantitative polymerase chain reaction (qPCR) test was performed on dried blood spot specimens. From January 2015 through March 2016, 145 index cases were identified at health centers and health posts. A total of 3,333 individuals residing in 525 households were screened. Excluding index cases, the parasite prevalence was 1.1% by RDT (33 positives of 3,016 participants) and 2.4% by qPCR (73 positives of 3,016 participants). Of the qPCR-positive cases, 62% of 73 individuals tested negative by RDT. Approximately half of the infected individuals resided within the index case household (58% of RDT-positive individuals and 48% of qPCR-positive individuals). The low sensitivity of the RDT and the high proportion of secondary cases within the index case household decreased the efficiency of this reactive test-and-treat strategy. Reactive focal drug administration in index case households would be a more efficient approach to treating infected individuals associated with a symptomatic case.
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Affiliation(s)
- Molly Deutsch-Feldman
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina
| | | | | | | | - Ben Katowa
- Macha Research Trust, Choma District, Zambia
| | - Kelly M Searle
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Tamaki Kobayashi
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Timothy M Shields
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Jennifer C Stevenson
- Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland.,Macha Research Trust, Choma District, Zambia
| | - Philip E Thuma
- Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland.,Macha Research Trust, Choma District, Zambia
| | - William J Moss
- Department of Molecular Microbiology and Immunology, Johns Hopkins Malaria Research Institute, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland.,Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
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8
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Reactive case detection of Plasmodium falciparum in western Kenya highlands: effective in identifying additional cases, yet limited effect on transmission. Malar J 2018. [PMID: 29534709 PMCID: PMC5851086 DOI: 10.1186/s12936-018-2260-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Background Identifying asymptomatic reservoirs of malaria parasites using index cases as entry points into the community is potentially a cost-effective way towards achieving malaria elimination. Methods Within 1 year, 1430 confirmed malaria cases were identified in Marani hospital, western Kenya. Fifty cases were followed up, and 108 index case household members and 612 neighbours within a 100 m radius were screened. As controls, samples were collected from 510 individuals matched with index cases and located at a distance of ≥ 500 m from them. Infections were diagnosed by microscopy and PCR while simultaneously collecting malaria vectors indoor using pyrethrum spray catches. Results In the index case and neighbour households, the prevalence of infection was approximately twice as high as in control households (by PCR: index cases households: 28.9%, neighbours: 25.3%, matched controls: 12.9%). In index case households, the indoor vector density (Anopheles gambiae and Anopheles funestus) was higher (0.46 female/house/night) than in neighbouring (0.31 f/h/n) and control houses (0.29 f/h/n). Conclusions Screening index case households and neighbours approximately doubles the chance to detect asymptomatic infections compared to randomly selected households. However, even if all cases were followed up, only a small proportion (˂ 10%) of the asymptomatic reservoir in the population would have been identified. Control programmes need to weigh the increased chance to find cases around index cases vs. the logistical challenges to target this subgroup within the population.
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9
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Cotter C, Sudathip P, Herdiana H, Cao Y, Liu Y, Luo A, Ranasinghe N, Bennett A, Cao J, Gosling RD. Piloting a programme tool to evaluate malaria case investigation and reactive case detection activities: results from 3 settings in the Asia Pacific. Malar J 2017; 16:347. [PMID: 28830519 PMCID: PMC5568298 DOI: 10.1186/s12936-017-1991-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 08/10/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Case investigation and reactive case detection (RACD) activities are widely-used in low transmission settings to determine the suspected origin of infection and identify and treat malaria infections nearby to the index patient household. Case investigation and RACD activities are time and resource intensive, include methodologies that vary across eliminating settings, and have no standardized metrics or tools available to monitor and evaluate them. METHODS In response to this gap, a simple programme tool was developed for monitoring and evaluating (M&E) RACD activities and piloted by national malaria programmes. During the development phase, four modules of the RACD M&E tool were created to assess and evaluate key case investigation and RACD activities and costs. A pilot phase was then carried out by programme implementers between 2013 and 2015, during which malaria surveillance teams in three different settings (China, Indonesia, Thailand) piloted the tool over a period of 3 months each. This study describes summary results of the pilots and feasibility and impact of the tool on programmes. RESULTS All three study areas implemented the RACD M&E tool modules, and pilot users reported the tool and evaluation process were helpful to identify gaps in RACD programme activities. In the 45 health facilities evaluated, 71.8% (97/135; min 35.3-max 100.0%) of the proper notification and reporting forms and 20.0% (27/135; min 0.0-max 100.0%) of standard operating procedures (SOPs) were available to support malaria elimination activities. The tool highlighted gaps in reporting key data indicators on the completeness for malaria case reporting (98.8%; min 93.3-max 100.0%), case investigations (65.6%; min 61.8-max 78.4%) and RACD activities (70.0%; min 64.7-max 100.0%). Evaluation of the SOPs showed that knowledge and practices of malaria personnel varied within and between study areas. Average monthly costs for conducting case investigation and RACD activities showed variation between study areas (min USD $844.80-max USD $2038.00) for the malaria personnel, commodities, services and other costs required to carry out the activities. CONCLUSION The RACD M&E tool was implemented in the three pilot areas, identifying key gaps that led to impacts on programme decision making. Study findings support the need for routine M&E of malaria case reporting, case investigation and RACD activities. Scale-up of the RACD M&E tool in malaria-eliminating settings will contribute to improved programme performance to the high level that is required to reach elimination.
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Affiliation(s)
- Chris Cotter
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco (UCSF), 550 16th Street, 3rd floor, San Francisco, CA, 94158, USA. .,Department of Women's and Children's Health, International Maternal and Child Health (IMCH), Uppsala University, Uppsala, Sweden.
| | - Prayuth Sudathip
- Department of Disease Control, Bureau of Vector Borne Diseases, Ministry of Public Health, Nonthaburi, Thailand
| | - Herdiana Herdiana
- Paritrana Asia Foundation, Jakarta, Indonesia.,United Nations Children's Fund (UNICEF), Aceh Field Office, Banda Aceh, Indonesia
| | - Yuanyuan Cao
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi, Jiangsu, People's Republic of China
| | - Yaobao Liu
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi, Jiangsu, People's Republic of China
| | - Alex Luo
- Global Health Sciences, University of California, San Francisco (UCSF), San Francisco, USA
| | | | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco (UCSF), 550 16th Street, 3rd floor, San Francisco, CA, 94158, USA.,Department of Epidemiology & Biostatistics, School of Medicine, University of California, San Francisco (UCSF), San Francisco, USA
| | - Jun Cao
- Key Laboratory of National Health and Family Planning Commission on Parasitic Disease Control and Prevention, Jiangsu Provincial Key Laboratory on Parasite and Vector Control Technology, Jiangsu Institute of Parasitic Diseases, Wuxi, Jiangsu, People's Republic of China
| | - Roly D Gosling
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco (UCSF), 550 16th Street, 3rd floor, San Francisco, CA, 94158, USA.,Department of Epidemiology & Biostatistics, School of Medicine, University of California, San Francisco (UCSF), San Francisco, USA
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10
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Yukich J, Bennett A, Yukich R, Stuck L, Hamainza B, Silumbe K, Smith T, Chitnis N, Steketee RW, Finn T, Eisele TP, Miller JM. Estimation of malaria parasite reservoir coverage using reactive case detection and active community fever screening from census data with rapid diagnostic tests in southern Zambia: a re-sampling approach. Malar J 2017; 16:317. [PMID: 28784122 PMCID: PMC5547485 DOI: 10.1186/s12936-017-1962-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 07/29/2017] [Indexed: 12/21/2022] Open
Abstract
Background and methods In areas where malaria transmission has been suppressed by vector control interventions many malaria control and elimination programmes are actively seeking new interventions to further reduce malaria prevalence, incidence and transmission. Malaria infection prevalence and incidence has been shown to cluster geographically, especially at lower transmission levels, and as such a reactive strategy is frequently used, by which index cases presenting to a passive surveillance system are used to target small areas for testing and treatment, reactive case detection (RCD), or focal drug administration (fDA). This study utilizes geo-located data from a census with parasitological testing with rapid diagnostic tests (RDTs) and treatment-seeking data collection conducted in southern Zambia to estimate the coverage of RCD or fDA in terms of the population and parasite reservoir as well as the operational requirements of such strategies, using a re-sampling algorithm developed exclusively for this purpose. This re-sampling algorithm allows for the specification of several parameters, such that different operational variants of these reactive strategies can be examined, including varying the search radius, screening for fever, or presumptive treatment (fDA). Results Results indicate that RCD, fDA and active fever screening followed by RCD, even with search radii over several hundered meters will only yield limited coverage of the RDT positive parasite reservoir during a short period. Long-term use of these strategies may increase this proportion. Reactive strategies detect a higher proportion of the reservoir of infections than random searches, but this effect appears to be greater in areas of low, but not moderate malaria prevalence in southern Zambia. Discussion Increases in the sensitivity of RDTs could also affect these results. The number of individuals and households that need to be searched increase rapidly, but approximately linearly with search radius. Conclusions Reactive strategies in southern Zambia yield improved identification of the parasite reservoir when targeted to areas with prevalence less than 10%. The operational requirements of delivering reactive strategies routinely are likely to prevent their uptake until prevalence falls far below this level.
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Affiliation(s)
- Joshua Yukich
- Center for Applied Malaria Research and Evaluation (CAMRE), Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, 70112, United States.
| | - Adam Bennett
- Global Health Group, University of California San Francisco, San Francisco, CA, United States
| | - Rudy Yukich
- Sensorstar Inc., Ellicott City, MD, United States
| | - Logan Stuck
- Center for Applied Malaria Research and Evaluation (CAMRE), Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, 70112, United States
| | - Busiku Hamainza
- National Malaria Control Centre, Ministry of Health, Lusaka, Zambia
| | - Kafula Silumbe
- Malaria Control and Elimination Partnership in Africa (MACEPA), PATH, Lusaka, Zambia
| | - Tom Smith
- Swiss Tropical and Public Health Institute, and University of Basel, Basel, CH, Switzerland
| | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, and University of Basel, Basel, CH, Switzerland
| | - Richard W Steketee
- Malaria Control and Elimination Partnership in Africa (MACEPA), PATH, Lusaka, Zambia
| | - Timothy Finn
- Center for Applied Malaria Research and Evaluation (CAMRE), Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, 70112, United States
| | - Thomas P Eisele
- Center for Applied Malaria Research and Evaluation (CAMRE), Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, 70112, United States
| | - John M Miller
- Malaria Control and Elimination Partnership in Africa (MACEPA), PATH, Lusaka, Zambia
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11
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Fontoura PS, Finco BF, Lima NF, de Carvalho JF, Vinetz JM, Castro MC, Ferreira MU. Reactive Case Detection for Plasmodium vivax Malaria Elimination in Rural Amazonia. PLoS Negl Trop Dis 2016; 10:e0005221. [PMID: 27941968 PMCID: PMC5179126 DOI: 10.1371/journal.pntd.0005221] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/22/2016] [Accepted: 12/01/2016] [Indexed: 12/31/2022] Open
Abstract
Background Malaria burden in Brazil has reached its lowest levels in 35 years and Plasmodium vivax now accounts for 84% of cases countrywide. Targeting residual malaria transmission entrenched in the Amazon is the next major challenge for ongoing elimination efforts. Better strategies are urgently needed to address the vast reservoir of asymptomatic P. vivax carriers in this and other areas approaching malaria elimination. Methods We evaluated a reactive case detection (RCD) strategy tailored for P. vivax transmission in farming settlements in the Amazon Basin of Brazil. Over six months, 41 cases detected by passive surveillance triggered four rounds of RCD (0, 30, 60, and 180 days after index case enrollment), using microscopy- and quantitative real-time polymerase chain reaction (qPCR)-based diagnosis, comprising subjects sharing the household (HH) with the index case (n = 163), those living in the 5 nearest HHs within 3 km (n = 878), and individuals from 5 randomly chosen control HHs located > 5 km away from index cases (n = 841). Correlates of infection were identified with mixed-effects logistic regression models. Molecular genotyping was used to infer local parasite transmission networks. Principal findings/Conclusions Subjects in index and neighbor HHs were significantly more likely to be parasitemic than control HH members, after adjusting for potential confounders, and together harbored > 90% of the P. vivax biomass in study subjects. Clustering patterns were temporally stable. Four rounds of microscopy-based RCD would identify only 49.5% of the infections diagnosed by qPCR, but 76.8% of the total parasite biomass circulating in the proximity of index HHs. However, control HHs accounted for 27.6% of qPCR-positive samples, 92.6% of them from asymptomatic carriers beyond the reach of RCD. Molecular genotyping revealed high P. vivax diversity, consistent with complex transmission networks and multiple sources of infection within clusters, potentially complicating malaria elimination efforts. Addressing the vast reservoir of asymptomatic Plasmodium vivax carriers clustered in hard-to-reach rural communities is a major challenge faced by countries approaching malaria elimination across Latin America and Asia. Routine surveillance targets subjects presenting with fever or reporting recent fever, but overlooks asymptomatic infections that might be otherwise detected by periodic mass blood surveys of the entire population at risk. Here we show that subjects living in close proximity to malaria cases detected by routine passive surveillance are much more likely to carry both symptomatic and asymptomatic infections than randomly selected inhabitants in the same farming settlements in the Amazon Basin of Brazil. Four rounds of microscopy-based screening for malaria parasites targeted at these high-risk subjects would identify 49.5% of the parasite carriers (who together harbored 76.8% of the total P. vivax biomass circulating in the proximity of index cases) detected by a more sensitive molecular method. Whether subpatent and asymptomatic carriers outside the identified clusters of symptomatic infections, beyond the reach of our screening, represent a significant parasite reservoir remains undetermined. The extensive genetic diversity found in local P. vivax populations suggests that multiple sources of infection fuel ongoing residual transmission within malaria clusters, further complicating current elimination efforts.
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Affiliation(s)
- Pablo S. Fontoura
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Bruna F. Finco
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Nathália F. Lima
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Jaques F. de Carvalho
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Joseph M. Vinetz
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA, United States of America
- Alexander von Humboldt Institute of Tropical Medicine and Faculty of Sciences, Department of Cellular and Molecular Sciences, Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Márcia C. Castro
- Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, MA, United States of America
| | - Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
- * E-mail:
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12
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Parker DM, Landier J, von Seidlein L, Dondorp A, White L, Hanboonkunupakarn B, Maude RJ, Nosten FH. Limitations of malaria reactive case detection in an area of low and unstable transmission on the Myanmar-Thailand border. Malar J 2016; 15:571. [PMID: 27887652 PMCID: PMC5124267 DOI: 10.1186/s12936-016-1631-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 11/21/2016] [Indexed: 11/10/2022] Open
Abstract
Background Reactive case detection is an approach that has been proposed as a tool for malaria elimination in low-transmission settings. It is an intuitively justified approach based on the concept of space–time clustering of malaria cases. When an index malaria clinical case is detected, it triggers reactive screening and treatment in the index house and neighbouring houses. However, the efficacy of this approach at varying screening radii and malaria prevalence remains ill defined. Methods Data were obtained from a detailed demographic and geographic surveillance study in four villages on the Myanmar–Thailand border. Clinical cases were recorded at village malaria clinics and were linked back to patients’ residencies. These data were used to simulate the efficacy of reactive case detection for clinical cases using rapid diagnostic tests (RDT). Simulations took clinical cases in a given month and tabulated the number of cases that would have been detected in the following month at varying screening radii around the index houses. Simulations were run independently for both falciparum and vivax malaria. Each simulation of a reactive case detection effort was run in comparison with a strategy using random selection of houses for screening. Results In approximately half of the screenings for falciparum and 10% for vivax it would have been impossible to detect any malaria cases regardless of the screening strategy because the screening would have occurred during times when there were no cases. When geographically linked cases were present in the simulation, reactive case detection would have only been successful at detecting most malaria cases using larger screening radii (150-m radius and above). At this screening radius and above, reactive case detection does not perform better than random screening of an equal number of houses in the village. Screening within very small radii detects only a very small proportion of cases, but despite this low performance is better than random screening with the same sample size. Conclusions The results of these simulations indicate that reactive case detection for clinical cases using RDTs has limited ability in halting transmission in regions of low and unstable transmission. This is linked to high spatial heterogeneity of cases, acquisition of malaria infections outside the village, as well missing asymptomatic infections. When cases are few and sporadic, reactive case detection would result in major time and budgetary losses. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1631-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Daniel M Parker
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand.
| | - Jordi Landier
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand
| | - Lorenz von Seidlein
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Arjen Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Lisa White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | | | - Richard J Maude
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand.,Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK.,Harvard T.H. Chan School of Public Health, Harvard University, Boston, USA
| | - François H Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Tak, Thailand.,Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
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13
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Searle KM, Hamapumbu H, Lubinda J, Shields TM, Pinchoff J, Kobayashi T, Stevenson JC, Bridges DJ, Larsen DA, Thuma PE, Moss WJ. Evaluation of the operational challenges in implementing reactive screen-and-treat and implications of reactive case detection strategies for malaria elimination in a region of low transmission in southern Zambia. Malar J 2016; 15:412. [PMID: 27527347 PMCID: PMC4986207 DOI: 10.1186/s12936-016-1460-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 07/29/2016] [Indexed: 11/16/2022] Open
Abstract
Background As malaria transmission declines in many regions of sub-Saharan Africa, interventions to identify the asymptomatic reservoir are being deployed with the goals of improving surveillance and interrupting transmission. Reactive case detection strategies, in which individuals with clinical malaria are followed up at their home and household residents and neighbours are screened and treated for malaria, are increasingly used as part of malaria elimination programmes. Methods A reactive screen-and-treat programme was implemented by the National Malaria Control Centre in Southern Province, Zambia, in which individuals residing within 140 m of an index case were screened with a malaria rapid diagnostic test (RDT) and treated if positive. The operational challenges during the early stages of implementing this reactive screen-and-treat programme in the catchment area of Macha Hospital in Southern Province, Zambia were assessed using rural health centre records, ground truth evaluation of community health worker performance, and data from serial cross-sectional surveys. The proportion of individuals infected with Plasmodium falciparum who were identified and treated was estimated by simulating reactive screen-and-treat and focal drug administration cascades. Results Within the 1st year of implementation, community health workers followed up 32 % of eligible index cases. When index cases were followed up, 66 % of residents were at home in the index households and 58 % in neighbouring households. Forty-one neighbouring households of 26 index households were screened, but only 13 (32 %) were within the 140-m screening radius. The parasite prevalence by RDT was 22 % in index households and 5 % in neighbouring households. In a simulation model with complete follow-up, 22 % of the total infected population would be detected with reactive screen-and-treat but 57 % with reactive focal drug administration. Conclusions With limited resources, coverage and diagnostic tools, reactive screen-and-treat will likely not be sufficient to achieve malaria elimination in this setting. However, high coverage with reactive focal drug administration could be efficient at decreasing the reservoir of infection and should be considered as an alternative strategy. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1460-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kelly M Searle
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA. .,Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
| | | | | | - Timothy M Shields
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Jessie Pinchoff
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Tamaki Kobayashi
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Jennifer C Stevenson
- Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Macha Research Trust, Choma District, Zambia
| | | | - David A Larsen
- Akros, Cresta Golfview Grounds, Great East Road, Lusaka, Zambia.,Department of Public Health, Food Studies and Nutrition, Syracuse University, Syracuse, NY, USA
| | - Philip E Thuma
- Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Macha Research Trust, Choma District, Zambia
| | - William J Moss
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.,Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
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14
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Hustedt J, Canavati SE, Rang C, Ashton RA, Khim N, Berne L, Kim S, Sovannaroth S, Ly P, Ménard D, Cox J, Meek S, Roca-Feltrer A. Reactive case-detection of malaria in Pailin Province, Western Cambodia: lessons from a year-long evaluation in a pre-elimination setting. Malar J 2016; 15:132. [PMID: 26931488 PMCID: PMC4774174 DOI: 10.1186/s12936-016-1191-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Accepted: 02/23/2016] [Indexed: 12/22/2022] Open
Abstract
Background As momentum towards malaria elimination grows, strategies are being developed for scale-up in elimination settings. One prominent strategy, reactive case detection (RACD), involves screening and treating individuals living in close proximity to passively detected, or “index” cases. This study aims to use RACD to quantify Plasmodium parasitaemia in households of index cases, and identify risk factors for infection; these data could inform reactive screening approaches and identify target risk groups. Methods This study was conducted in the Western Cambodian province of Pailin between May 2013 and March 2014 among 440 households. Index participants/index cases (n = 270) and surrounding households (n = 110) were screened for Plasmodium infection with rapid diagnostic tests (RDT), microscopy and real-time polymerase chain reaction (PCR). Participants were interviewed to identify risk factors. A comparison group of 60 randomly-selected households was also screened, to compare infection levels of RACD and non-RACD households. In order to identify potential risk factors that would inform screening approaches and identify risk groups, multivariate logistic regression models were applied. Results Nine infections were identified in households of index cases (RACD approach) through RDT screening of 1898 individuals (seven Plasmodium vivax, two Plasmodium falciparum); seven were afebrile. Seventeen infections were identified through PCR screening of 1596 individuals (15 P. vivax, and 22 % P. falciparum/P. vivax mixed infections). In the control group, 25 P. falciparum infections were identified through PCR screening of 237 individuals, and no P. vivax was found. Plasmodium falciparum infection was associated with fever (p = 0.013), being a member of a control household (p ≤ 0.001), having a history of malaria infection (p = 0.041), and sleeping without a mosquito net (p = 0.011). Significant predictors of P. vivax infection, as diagnosed by PCR, were fever (p = 0.058, borderline significant) and history of malaria infection (p ≤ 0.001). Conclusion This study found that RACD identified very few secondary infections when targeting index and neighbouring households for screening. The results suggest RACD is not appropriate, where exposure to malaria occurs away from the community, and there is a high level of treatment-seeking from the private sector. Piloting RACD in a range of transmission settings would help to identify the ideal environment for feasible and effective reactive screening methods.
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Affiliation(s)
- John Hustedt
- Malaria Consortium Cambodia, Phnom Penh Office, House #91, St. 95, Boeung Trabek, Chamcar Morn, Phnom Penh, Cambodia.
| | - Sara E Canavati
- Malaria Consortium Cambodia, Phnom Penh Office, House #91, St. 95, Boeung Trabek, Chamcar Morn, Phnom Penh, Cambodia. .,Faculty of Tropical Medicine, Mahidol University, 420/6 Ratchawithi Road, Ratchathewi, Bangkok, 10400, Thailand.
| | - Chandary Rang
- Malaria Consortium Cambodia, 113 (6th floor of Parkway Square), Mao Tse Toung Blvd. Chamcar Morn, Phnom Penh, Cambodia.
| | - Ruth A Ashton
- Malaria Consortium Cambodia, Phnom Penh Office, House #91, St. 95, Boeung Trabek, Chamcar Morn, Phnom Penh, Cambodia.
| | - Nimol Khim
- Institut Pasteur in Cambodia, 5, Blvd Monivong, Phnom Penh, Cambodia.
| | - Laura Berne
- Institut Pasteur in Cambodia, 5, Blvd Monivong, Phnom Penh, Cambodia.
| | - Saorin Kim
- Institut Pasteur in Cambodia, 5, Blvd Monivong, Phnom Penh, Cambodia.
| | - Siv Sovannaroth
- The National Center for Parasitology, Entomology and Malaria Control, Ministry of Health, Corner street 92, Trapaing Svay village, Sankat Phnom Penh Thmey, Khan Sensok, Phnom Penh, Cambodia.
| | - Po Ly
- The National Center for Parasitology, Entomology and Malaria Control, Ministry of Health, Corner street 92, Trapaing Svay village, Sankat Phnom Penh Thmey, Khan Sensok, Phnom Penh, Cambodia.
| | - Didier Ménard
- Institut Pasteur in Cambodia, 5, Blvd Monivong, Phnom Penh, Cambodia.
| | - Jonathan Cox
- Malaria Consortium Cambodia, Phnom Penh Office, House #91, St. 95, Boeung Trabek, Chamcar Morn, Phnom Penh, Cambodia. .,Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
| | - Sylvia Meek
- Malaria Consortium, Development House, 56-64 Leonard Street, London, EC2A 4LT, UK.
| | - Arantxa Roca-Feltrer
- Faculty of Tropical Medicine, Malaria Consortium Asia, Mahidol University, Room 805, 420/6 Rajavidhi Road, Bangkok, 10400, Thailand.
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15
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van Eijk AM, Ramanathapuram L, Sutton PL, Kanagaraj D, Sri Lakshmi Priya G, Ravishankaran S, Asokan A, Tandel N, Patel A, Desai N, Singh R, Sullivan SA, Carlton JM, Srivastava HC, Eapen A. What is the value of reactive case detection in malaria control? A case-study in India and a systematic review. Malar J 2016; 15:67. [PMID: 26852118 PMCID: PMC4744450 DOI: 10.1186/s12936-016-1120-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 01/22/2016] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Reactive case detection (RCD) for malaria is a strategy to identify additional malaria infections in areas of low malaria transmission and can complement passive surveillance. This study describes experiences with RCD in two Indian sites, and aimed to synthesize experiences with RCD across endemic countries. METHODS RCD programmes were piloted in two urban areas of India with a low prevalence of mainly Plasmodium vivax malaria in 2014. Cases were identified in a clinic by microscopy and contacts were screened within 2 weeks; PCR, in addition to microscopy, was used to detect Plasmodium parasites. A systematic review was conducted to identify RCD experiences in the literature. RESULTS In Chennai, 868 contacts were enrolled for 18 index cases of clinical malaria; in Nadiad, 131 contacts were enrolled for 20 index cases. No new malaria infections were detected in Nadiad among contacts, and four new infections were detected in Chennai (three P. vivax and one Plasmodium falciparum), of which two were among household members of index cases. An additional five studies describing results from an RCD strategy were identified in the literature: four in Africa and one in Thailand. Including the results from India, the average number of contacts screened per index case in a total of seven studies ranged from four to 50, and 126 in a case study in Thailand with one index case. Malaria was detected in 0-45 % of the contacted persons. The average number of index cases needed to be traced to find one new case of malaria ranged from one to five, and could not be assessed in one study in India (no contacts positive for 20 cases). Sharing the household with an index case was associated with a five-fold increased risk of malaria compared to contacts from households without an index case (pooled risk ratio 5.29, 95 % CI 3.31-8.47, I(2) 0 %, four studies). CONCLUSIONS RCD in areas of low malaria transmission is a labour-intensive strategy, and its benefit is not clear. Studies are needed to assess how RCD can be optimized or into alternatives where interventions are targeted to family members or hotspots.
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Affiliation(s)
- Anna Maria van Eijk
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA.
| | - Lalitha Ramanathapuram
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA.
| | - Patrick L Sutton
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA. .,Acsel Health, 500 5th Ave, Suite 2760, New York, NY, 10110, USA.
| | - Deena Kanagaraj
- National Institute of Malaria Research Field Unit, Indian Council of Medical Research, National Institute of Epidemiology Campus, Ayapakkam, Chennai, Tamil Nadu, India.
| | - G Sri Lakshmi Priya
- National Institute of Malaria Research Field Unit, Indian Council of Medical Research, National Institute of Epidemiology Campus, Ayapakkam, Chennai, Tamil Nadu, India.
| | - Sangamithra Ravishankaran
- National Institute of Malaria Research Field Unit, Indian Council of Medical Research, National Institute of Epidemiology Campus, Ayapakkam, Chennai, Tamil Nadu, India.
| | - Aswin Asokan
- National Institute of Malaria Research Field Unit, Indian Council of Medical Research, National Institute of Epidemiology Campus, Ayapakkam, Chennai, Tamil Nadu, India.
| | - Nikunj Tandel
- National Institute of Malaria Research Field Unit, Civil Hospital, Nadiad, Gujarat, India.
| | - Ankita Patel
- National Institute of Malaria Research Field Unit, Civil Hospital, Nadiad, Gujarat, India.
| | - Nisha Desai
- National Institute of Malaria Research Field Unit, Civil Hospital, Nadiad, Gujarat, India.
| | - Ranvir Singh
- National Institute of Malaria Research Field Unit, Civil Hospital, Nadiad, Gujarat, India.
| | - Steven A Sullivan
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA.
| | - Jane M Carlton
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, 10003, USA.
| | - H C Srivastava
- National Institute of Malaria Research Field Unit, Civil Hospital, Nadiad, Gujarat, India.
| | - Alex Eapen
- National Institute of Malaria Research Field Unit, Indian Council of Medical Research, National Institute of Epidemiology Campus, Ayapakkam, Chennai, Tamil Nadu, India.
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Affiliation(s)
- Malla R. Rao
- *Address correspondence to Malla R. Rao, Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, BG 5601Fl Room 8A38, 5601 Fishers Lane, Rockville, MD 20852. E-mail:
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Stresman GH, Baidjoe AY, Stevenson J, Grignard L, Odongo W, Owaga C, Osoti V, Makori E, Shagari S, Marube E, Cox J, Drakeley C, Bousema T. Focal Screening to Identify the Subpatent Parasite Reservoir in an Area of Low and Heterogeneous Transmission in the Kenya Highlands. J Infect Dis 2015; 212:1768-77. [PMID: 26019285 DOI: 10.1093/infdis/jiv302] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 05/14/2015] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Mass screening and treatment currently fails to identify a considerable fraction of low parasite density infections, while mass treatment exposes many uninfected individuals to antimalarial drugs. Here we test a hybrid approach to screen a sentinel population to identify clusters of subpatent infections in the Kenya highlands with low, heterogeneous malaria transmission. METHODS Two thousand eighty-two inhabitants were screened for parasitemia by nested polymerase chain reaction (nPCR). Children aged ≤ 15 years and febrile adults were also tested for malaria by rapid diagnostic test (RDT) and served as sentinel members to identify subpatent infections within the household. All parasitemic individuals were assessed for multiplicity of infections by nPCR and gametocyte carriage by nucleic acid sequence-based amplification. RESULTS Households with RDT-positive individuals in the sentinel population were more likely to have nPCR-positive individuals (odds ratio: 1.71, 95% confidence interval, 1.60-1.84). The sentinel population identified 64.5% (locality range: 31.6%-81.2%) of nPCR-positive households and 77.3% (locality range: 24.2%-91.0%) of nPCR-positive individuals. The sensitivity of the sentinel screening approach was positively associated with transmission intensity (P = .037). CONCLUSIONS In this low endemic area, a focal screening approach with RDTs prior to the high transmission season was able to identify the majority of the subpatent parasite reservoirs.
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Affiliation(s)
- Gillian H Stresman
- Department of Immunology and Infection; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | | | - Jennifer Stevenson
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom The Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Lynn Grignard
- Department of Immunology and Infection; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Wycliffe Odongo
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Chrispin Owaga
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Victor Osoti
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Euniah Makori
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Shehu Shagari
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Elisabeth Marube
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu
| | - Jonathan Cox
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Chris Drakeley
- Department of Immunology and Infection; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Teun Bousema
- Department of Immunology and Infection; Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, United Kingdom Radboud University Nijmegen Medical Centre, The Netherlands
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Ashton RA, Kefyalew T, Rand A, Sime H, Assefa A, Mekasha A, Edosa W, Tesfaye G, Cano J, Teka H, Reithinger R, Pullan RL, Drakeley CJ, Brooker SJ. Geostatistical modeling of malaria endemicity using serological indicators of exposure collected through school surveys. Am J Trop Med Hyg 2015; 93:168-177. [PMID: 25962770 PMCID: PMC4497890 DOI: 10.4269/ajtmh.14-0620] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Accepted: 02/25/2015] [Indexed: 11/23/2022] Open
Abstract
Ethiopia has a diverse ecology and geography resulting in spatial and temporal variation in malaria transmission. Evidence-based strategies are thus needed to monitor transmission intensity and target interventions. A purposive selection of dried blood spots collected during cross-sectional school-based surveys in Oromia Regional State, Ethiopia, were tested for presence of antibodies against Plasmodium falciparum and P. vivax antigens. Spatially explicit binomial models of seroprevalence were created for each species using a Bayesian framework, and used to predict seroprevalence at 5 km resolution across Oromia. School seroprevalence showed a wider prevalence range than microscopy for both P. falciparum (0–50% versus 0–12.7%) and P. vivax (0–53.7% versus 0–4.5%), respectively. The P. falciparum model incorporated environmental predictors and spatial random effects, while P. vivax seroprevalence first-order trends were not adequately explained by environmental variables, and a spatial smoothing model was developed. This is the first demonstration of serological indicators being used to detect large-scale heterogeneity in malaria transmission using samples from cross-sectional school-based surveys. The findings support the incorporation of serological indicators into periodic large-scale surveillance such as Malaria Indicator Surveys, and with particular utility for low transmission and elimination settings.
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Affiliation(s)
- Ruth A. Ashton
- *Address correspondence to Ruth A. Ashton, Malaria Consortium, Development House, 56-64 Leonard Street, London. E-mail:
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Mosha JF, Sturrock HJW, Greenwood B, Sutherland CJ, Gadalla NB, Atwal S, Hemelaar S, Brown JM, Drakeley C, Kibiki G, Bousema T, Chandramohan D, Gosling RD. Hot spot or not: a comparison of spatial statistical methods to predict prospective malaria infections. Malar J 2014; 13:53. [PMID: 24517452 PMCID: PMC3932034 DOI: 10.1186/1475-2875-13-53] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/06/2014] [Indexed: 12/02/2022] Open
Abstract
Background Within affected communities, Plasmodium falciparum infections may be skewed in distribution such that single or small clusters of households consistently harbour a disproportionate number of infected individuals throughout the year. Identifying these hotspots of malaria transmission would permit targeting of interventions and a more rapid reduction in malaria burden across the whole community. This study set out to compare different statistical methods of hotspot detection (SaTScan, kernel smoothing, weighted local prevalence) using different indicators (PCR positivity, AMA-1 and MSP-1 antibodies) for prediction of infection the following year. Methods Two full surveys of four villages in Mwanza, Tanzania were completed over consecutive years, 2010-2011. In both surveys, infection was assessed using nested polymerase chain reaction (nPCR). In addition in 2010, serologic markers (AMA-1 and MSP-119 antibodies) of exposure were assessed. Baseline clustering of infection and serological markers were assessed using three geospatial methods: spatial scan statistics, kernel analysis and weighted local prevalence analysis. Methods were compared in their ability to predict infection in the second year of the study using random effects logistic regression models, and comparisons of the area under the receiver operating curve (AUC) for each model. Sensitivity analysis was conducted to explore the effect of varying radius size for the kernel and weighted local prevalence methods and maximum population size for the spatial scan statistic. Results Guided by AUC values, the kernel method and spatial scan statistics appeared to be more predictive of infection in the following year. Hotspots of PCR-detected infection and seropositivity to AMA-1 were predictive of subsequent infection. For the kernel method, a 1 km window was optimal. Similarly, allowing hotspots to contain up to 50% of the population was a better predictor of infection in the second year using spatial scan statistics than smaller maximum population sizes. Conclusions Clusters of AMA-1 seroprevalence or parasite prevalence that are predictive of infection a year later can be identified using geospatial models. Kernel smoothing using a 1 km window and spatial scan statistics both provided accurate prediction of future infection.
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Affiliation(s)
- Jacklin F Mosha
- National Institute for Medical Research (NIMR), Mwanza Medical Research Centre, Mwanza, Tanzania.
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