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Mkali HR, Lalji SM, Al-Mafazy AW, Joseph JJ, Mwaipape OS, Ali AS, Abbas FB, Ali MH, Hassan WS, Reaves EJ, Kitojo C, Serbantez N, Kabula BI, Nyinondi SS, McKay M, Cressman G, Ngondi JM, Reithinger R. How Real-Time Case-Based Malaria Surveillance Helps Zanzibar Get a Step Closer to Malaria Elimination: Description of Operational Platform and Resources. GLOBAL HEALTH, SCIENCE AND PRACTICE 2023; 11:e2200522. [PMID: 37903584 PMCID: PMC10615242 DOI: 10.9745/ghsp-d-22-00522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 09/26/2023] [Indexed: 11/01/2023]
Abstract
Testing and treating asymptomatic populations have the potential to reduce the population's parasite reservoir and reduce malaria transmission. Zanzibar's malaria case notification (MCN) platform collects detailed sociodemographic and epidemiological data from all confirmed malaria cases to inform programmatic decision-making. We describe the design and operationalization process of the platform and other malaria surveillance resources that are enabling Zanzibar's progress toward malaria elimination.The MCN platform consists of an interactive short message service (SMS) system for case notification, a software application for Android mobile devices, a visual question set and workflow manager, a back-end database server, and a web browser-based application for data analytics, configuration, and management. Malaria case data were collected from August 2012 to December 2021 and reported via SMS from all public and private health facilities to a central database and then to district malaria surveillance officers' mobile devices. Data included patient names, shehia (administrative area), and date of diagnosis, enabling officers to track patients, ideally within 24 hours of reporting. Patients' household members were tested for malaria using conventional rapid diagnostic tests (RDTs). Treatment using artemisinin-based combination therapy was provided for persons testing positive.Between 2012 and 2021, a total of 48,899 index malaria cases were confirmed at health facilities, 22,152 (45.3%) within 24 hours of reporting; 41,886 (85.7%) cases were fully investigated and followed up to the household level. A total of 111,811 additional household members were tested with RDTs, of whom 10,602 (9.5%) were malaria positive.The MCN platform reports malaria case data in near real time, enabling prompt follow-up of index cases and prompt testing and treatment of members in index case households. Along with routine testing and treatment and other preventive interventions, the MCN platform is foundational to the programmatic efforts in further reducing malaria and ultimately eliminating autochthonous malaria transmission in Zanzibar.
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Affiliation(s)
| | - Shabbir M Lalji
- RTI International, Dar es Salaam, United Republic of Tanzania
| | | | - Joseph J Joseph
- RTI International, Dar es Salaam, United Republic of Tanzania
| | - Osia S Mwaipape
- RTI International, Dar es Salaam, United Republic of Tanzania
| | - Abdullah S Ali
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, United Republic of Tanzania
| | - Faiza B Abbas
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, United Republic of Tanzania
| | - Mohamed H Ali
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, United Republic of Tanzania
| | - Wahida S Hassan
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, United Republic of Tanzania
| | - Erik J Reaves
- U.S. President's Malaria Initiative, U.S. Centers for Disease Control and Prevention, Dar es Salaam, United Republic of Tanzania
| | - Chonge Kitojo
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, United Republic of Tanzania
| | - Naomi Serbantez
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, United Republic of Tanzania
| | - Bilali I Kabula
- RTI International, Dar es Salaam, United Republic of Tanzania
| | | | - Mike McKay
- RTI International, Research Triangle Park, USA
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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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Holzschuh A, Lerch A, Gerlovina I, Fakih BS, Al-Mafazy AWH, Reaves EJ, Ali A, Abbas F, Ali MH, Ali MA, Hetzel MW, Yukich J, Koepfli C. Multiplexed ddPCR-amplicon sequencing reveals isolated Plasmodium falciparum populations amenable to local elimination in Zanzibar, Tanzania. Nat Commun 2023; 14:3699. [PMID: 37349311 PMCID: PMC10287761 DOI: 10.1038/s41467-023-39417-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 06/13/2023] [Indexed: 06/24/2023] Open
Abstract
Zanzibar has made significant progress toward malaria elimination, but recent stagnation requires novel approaches. We developed a highly multiplexed droplet digital PCR (ddPCR)-based amplicon sequencing method targeting 35 microhaplotypes and drug-resistance loci, and successfully sequenced 290 samples from five districts covering both main islands. Here, we elucidate fine-scale Plasmodium falciparum population structure and infer relatedness and connectivity of infections using an identity-by-descent (IBD) approach. Despite high genetic diversity, we observe pronounced fine-scale spatial and temporal parasite genetic structure. Clusters of near-clonal infections on Pemba indicate persistent local transmission with limited parasite importation, presenting an opportunity for local elimination efforts. Furthermore, we observe an admixed parasite population on Unguja and detect a substantial fraction (2.9%) of significantly related infection pairs between Zanzibar and the mainland, suggesting recent importation. Our study provides a high-resolution view of parasite genetic structure across the Zanzibar archipelago and provides actionable insights for prioritizing malaria elimination efforts.
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Affiliation(s)
- Aurel Holzschuh
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Indiana, IN, USA.
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland.
| | - Anita Lerch
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Indiana, IN, USA
| | - Inna Gerlovina
- EPPIcenter Research Program, Division of HIV, ID and Global Medicine, Department of Medicine, University of California, San Francisco, CA, USA
| | - Bakar S Fakih
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | | | - Erik J Reaves
- U.S. Centers for Disease Control and Prevention, President's Malaria Initiative, Dar es Salaam, United Republic of Tanzania
| | - Abdullah Ali
- Zanzibar Malaria Elimination Programme, Zanzibar, United Republic of Tanzania
| | - Faiza Abbas
- Zanzibar Malaria Elimination Programme, Zanzibar, United Republic of Tanzania
| | - Mohamed Haji Ali
- Zanzibar Malaria Elimination Programme, Zanzibar, United Republic of Tanzania
| | - Mohamed Ali Ali
- Zanzibar Malaria Elimination Programme, Zanzibar, United Republic of Tanzania
| | - Manuel W Hetzel
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Joshua Yukich
- School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA, USA
| | - Cristian Koepfli
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Indiana, IN, USA.
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van Dijk N, Carter J, Omondi W, Mens P, Schallig H. Clinical features, immunological interactions and household determinants of visceral leishmaniasis and malaria coinfections in West Pokot, Kenya: protocol for an observational study. BMJ Open 2023; 13:e068679. [PMID: 37068901 PMCID: PMC10111886 DOI: 10.1136/bmjopen-2022-068679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/19/2023] Open
Abstract
INTRODUCTION Visceral leishmaniasis (VL) and malaria are two deadly parasitic diseases that coexist in West Pokot County, Kenya. The local population is at considerable risk of coinfection with VL and malaria; however, few studies have described the clinical implications of this comorbidity. Questions remain regarding the immune responses responsible for possible predisposing or protective effects. Moreover, characterisation of environmental and household risk factors for co-acquiring VL and malaria is warranted to increase awareness and guide implementation of targeted control strategies. This protocol intends to address these knowledge gaps concerning VL-malaria coinfections. METHODS AND ANALYSIS This observational research project will have a multimethod approach, starting with a cross-sectional study at Kacheliba Sub-County Hospital in West Pokot, Kenya. Patients with laboratory confirmation of a VL and/or malaria infection will be clinically assessed and symptomatology of monoinfections and coinfections will be compared. Second, a questionnaire will be addressed to all included patients and to healthy controls in local communities. This case-control study will aim to describe household and environmental determinants associated with VL-malaria coinfection. Lastly, blood samples will be collected from a small cohort of VL and malaria monoinfected and coinfected patients during treatment of their infection(s), and from healthy controls and asymptomatic VL and malaria cases recruited in local communities. These specimens will be used for serum cytokine measurements and molecular quantitation of Plasmodium and Leishmania. In this way, the immune response and parasite dynamics during VL-malaria coinfection will be characterised longitudinally and compared with those observed in clinical and asymptomatic monoinfections. ETHICS AND DISSEMINATION Ethical approval was obtained from the Ethics and Scientific Research Committee of Amref Health Africa. The study findings will be presented at international conferences and published in open-access, peer-reviewed journals. TRIAL REGISTRATION NUMBER ISRCTN Registry (ISRCTN15023306).
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Affiliation(s)
- Norbert van Dijk
- Department of Medical Microbiology and Infection Prevention, Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam, Amsterdam, The Netherlands
- Infectious Diseases Programme, Amsterdam Institute for Infection and Immunity, Amsterdam, The Netherlands
| | - Jane Carter
- Clinical and Diagnostics Programme, Amref Health Africa, Nairobi, Kenya
| | - Wyckliff Omondi
- Division of Vector Borne and Neglected Tropical Diseases, Kenya Ministry of Health, Nairobi, Kenya
| | - Petra Mens
- Department of Medical Microbiology and Infection Prevention, Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam, Amsterdam, The Netherlands
- Infectious Diseases Programme, Amsterdam Institute for Infection and Immunity, Amsterdam, The Netherlands
| | - Henk Schallig
- Department of Medical Microbiology and Infection Prevention, Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam, Amsterdam, The Netherlands
- Infectious Diseases Programme, Amsterdam Institute for Infection and Immunity, Amsterdam, The Netherlands
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Ntuku H, Smith-Gueye C, Scott V, Njau J, Whittemore B, Zelman B, Tambo M, Prach LM, Wu L, Schrubbe L, Kang Dufour MS, Mwilima A, Uusiku P, Sturrock H, Bennett A, Smith J, Kleinschmidt I, Mumbengegwi D, Gosling R, Hsiang M. Cost and cost effectiveness of reactive case detection (RACD), reactive focal mass drug administration (rfMDA) and reactive focal vector control (RAVC) to reduce malaria in the low endemic setting of Namibia: an analysis alongside a 2×2 factorial design cluster randomised controlled trial. BMJ Open 2022; 12:e049050. [PMID: 35738650 PMCID: PMC9226870 DOI: 10.1136/bmjopen-2021-049050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
OBJECTIVES To estimate the cost and cost effectiveness of reactive case detection (RACD), reactive focal mass drug administration (rfMDA) and reactive focal vector control (RAVC) to reduce malaria in a low endemic setting. SETTING The study was part of a 2×2 factorial design cluster randomised controlled trial within the catchment area of 11 primary health facilities in Zambezi, Namibia. PARTICIPANTS Cost and outcome data were collected from the trial, which included 8948 community members that received interventions due to their residence within 500 m of malaria index cases. OUTCOME MEASURES The primary outcome was incremental cost effectiveness ratio (ICER) per in incident case averted. ICER per prevalent case and per disability-adjusted life years (DALY) averted were secondary outcomes, as were per unit interventions costs and personnel time. Outcomes were compared as: (1) rfMDA versus RACD, (2) RAVC versus no RAVC and (3) rfMDA+RAVC versus RACD only. RESULTS rfMDA cost 1.1× more than RACD, and RAVC cost 1.7× more than no RAVC. Relative to RACD only, the cost of rfMDA+RAVC was double ($3082 vs $1553 per event). The ICERs for rfMDA versus RACD, RAVC versus no RAVC and rfMDA+RAVC versus RACD only were $114, $1472 and $842, per incident case averted, respectively. Using prevalent infections and DALYs as outcomes, trends were similar. The median personnel time to implement rfMDA was 20% lower than for RACD (30 vs 38 min per person). The median personnel time for RAVC was 34 min per structure sprayed. CONCLUSION Implemented alone or in combination, rfMDA and RAVC were cost effective in reducing malaria incidence and prevalence despite higher implementation costs in the intervention compared with control arms. Compared with RACD, rfMDA was time saving. Cost and time requirements for the combined intervention could be decreased by implementing rfMDA and RAVC simultaneously by a single team. TRIAL REGISTRATION NUMBER NCT02610400; Post-results.
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Affiliation(s)
- Henry Ntuku
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Cara Smith-Gueye
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Valerie Scott
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Joseph Njau
- JoDon Consulting Group LLC, Atlanta, Georgia, USA
| | - Brooke Whittemore
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Brittany Zelman
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Munyaradzi Tambo
- Multidisciplinary Research Centre, University of Namibia, Windhoek, Namibia
| | - Lisa M Prach
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Lindsey Wu
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Leah Schrubbe
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Mi-Suk Kang Dufour
- Division of Prevention Science, University of California San Francisco, San Francisco, California, USA
| | - Agnes Mwilima
- Ministry of Health and Social Services, Zambezi Region, Katima Mulilo, Namibia
| | - Petrina Uusiku
- Ministry of Health and Social Services, Windhoek, Namibia
| | - Hugh Sturrock
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Jennifer Smith
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Immo Kleinschmidt
- Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Davis Mumbengegwi
- Multidisciplinary Research Centre, University of Namibia, Windhoek, Namibia
| | - Roly Gosling
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Michelle Hsiang
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Clustering of subpatent infections in households with asymptomatic rapid diagnostic test-positive cases in Bioko Island, Equatorial Guinea independent of travel to regions of higher malaria endemicity: a cross-sectional study. Malar J 2021; 20:313. [PMID: 34247643 PMCID: PMC8274032 DOI: 10.1186/s12936-021-03844-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 07/03/2021] [Indexed: 11/27/2022] Open
Abstract
Background Prevalence of falciparum malaria on Bioko Island remains high despite sustained, intensive control. Progress may be hindered by high proportions of subpatent infections that are not detected by rapid diagnostic tests (RDT) but contribute to onward transmission, and by imported infections. Better understanding of the relationship between subpatent infections and RDT-detected infections, and whether this relationship is different from imported versus locally acquired infections, is imperative to better understand the sources of infection and mechanisms of transmission to tailor more effective interventions. Methods Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was performed on a sub-set of samples from the 2015 Malaria Indicator Survey to identify subpatent infections. Households with RDT(+) individuals were matched 1:4 with households with no RDT(+) individuals. The association between living in a household with an RDT(+) individual and having a subpatent infection was evaluated using multivariate hierarchical logistic regression models with inverse probability weights for selection. To evaluate possible modification of the association by potential importation of the RDT(+) case, the analysis was repeated among strata of matched sets based on the reported eight-week travel history of the RDT(+) individual(s). Results There were 142 subpatent infections detected in 1,400 individuals (10.0%). The prevalence of subpatent infections was higher in households with versus without an RDT(+) individual (15.0 vs 9.1%). The adjusted prevalence odds of subpatent infection were 2.59-fold greater (95% CI: 1.31, 5.09) for those in a household with an RDT(+) individual compared to individuals in a household without RDT(+) individuals. When stratifying by travel history of the RDT(+) individual, the association between subpatent infections and RDT(+) infections was stronger in the strata in which the RDT(+) individual(s) had not recently travelled (adjusted prevalence odds ratio (aPOR) 2.95; 95% CI:1.17, 7.41), and attenuated in the strata in which recent travel was reported (aPOR 1.76; 95% CI: 0.54, 5.67). Conclusions There is clustering of subpatent infections around RDT(+) individual(s) when both imported and local infection are suspected. Future control strategies that aim to treat whole households in which an RDT(+) individual is found may target a substantial portion of infections that would otherwise not be detected. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03844-6.
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Russell TL, Grignard L, Apairamo A, Kama N, Bobogare A, Drakeley C, Burkot TR. Getting to zero: micro-foci of malaria in the Solomon Islands requires stratified control. Malar J 2021; 20:248. [PMID: 34090430 PMCID: PMC8180101 DOI: 10.1186/s12936-021-03779-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/22/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The Solomon Islands has made significant progress in the control of malaria through vector control, access and use of improved diagnostics and therapeutic drugs. As transmission is reduced there is a need to understand variations in transmission risk at the provincial and village levels to stratify control methods. METHODS A cross-sectional survey of malaria in humans was conducted in the Solomon Islands during April 2018. Nineteen villages across 4 provinces were included. The presence of Plasmodium species parasites in blood samples was detected using PCR. RESULTS Blood samples were analysed from 1,914 participants. The prevalence of DNA of Plasmodium falciparum was 1.2 % (n = 23) and for Plasmodium vivax was 1.5 % (n = 28). 22 % (n = 5/23) of P. falciparum DNA positive participants were febrile and 17 % of P. vivax DNA positive participants (n = 5/28). The prevalence of both P. falciparum and P. vivax was extremely spatially heterogeneous. For P. falciparum, in particular, only 2 small foci of transmission were identified among 19 villages. Plasmodium falciparum infections were uniformly distributed across age groups. Insecticide-treated bed net use the night prior to the survey was reported by 63 % of participants and significantly differed by province. CONCLUSIONS Malaria transmission across the Solomon Islands has become increasingly fragmented, affecting fewer villages and provinces. The majority of infections were afebrile suggesting the need for strong active case detection with radical cure with primaquine for P. vivax. Village-level stratification of targeted interventions based on passive and active case detection data could support the progress towards a more cost-effective and successful elimination programme.
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Affiliation(s)
- Tanya L Russell
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Australia.
| | - Lynn Grignard
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Alan Apairamo
- National Vector Borne Disease Control Programme, Ministry of Health and Medical Services, Honiara, Solomon Islands
| | - Nathan Kama
- National Vector Borne Disease Control Programme, Ministry of Health and Medical Services, Honiara, Solomon Islands
| | - Albino Bobogare
- National Vector Borne Disease Control Programme, Ministry of Health and Medical Services, Honiara, Solomon Islands
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Thomas R Burkot
- Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Australia
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Rogier E, Hamre KES, Joseph V, Plucinski MM, Presume J, Romilus I, Mondelus G, Elisme T, van den Hoogen L, Lemoine JF, Drakeley C, Ashton RA, Chang MA, Existe A, Boncy J, Stresman G, Druetz T, Eisele TP. Conventional and High-Sensitivity Malaria Rapid Diagnostic Test Performance in 2 Transmission Settings: Haiti 2017. J Infect Dis 2020; 221:786-795. [PMID: 31630194 DOI: 10.1093/infdis/jiz525] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 10/16/2019] [Indexed: 01/24/2023] Open
Abstract
Accurate malaria diagnosis is foundational for control and elimination, and Haiti relies on histidine-rich protein 2 (HRP2)-based rapid diagnostic tests (RDTs) identifying Plasmodium falciparum in clinical and community settings. In 2017, 1 household and 2 easy-access group surveys tested all participants (N = 32 506) by conventional and high-sensitivity RDTs. A subset of blood samples (n = 1154) was laboratory tested for HRP2 by bead-based immunoassay and for P. falciparum 18S rDNA by photo-induced electron transfer polymerase chain reaction. Both RDT types detected low concentrations of HRP2 with sensitivity estimates between 2.6 ng/mL and 14.6 ng/mL. Compared to the predicate HRP2 laboratory assay, RDT sensitivity ranged from 86.3% to 96.0% between tests and settings, and specificity from 90.0% to 99.6%. In the household survey, the high-sensitivity RDT provided a significantly higher number of positive tests, but this represented a very small proportion (<0.2%) of all participants. These data show that a high-sensitivity RDT may have limited utility in a malaria elimination setting like Haiti.
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Affiliation(s)
- Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Karen E S Hamre
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Vena Joseph
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - Mateusz M Plucinski
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Jacquelin Presume
- Laboratorie National de Santé Publique, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Ithamare Romilus
- Laboratorie National de Santé Publique, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Gina Mondelus
- Laboratorie National de Santé Publique, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Tamara Elisme
- Laboratorie National de Santé Publique, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Lotus van den Hoogen
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jean Frantz Lemoine
- Programme National de Contrôle de la Malaria, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Ruth A Ashton
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
| | - Michelle A Chang
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Alexandre Existe
- Laboratorie National de Santé Publique, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Jacques Boncy
- Laboratorie National de Santé Publique, Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Gillian Stresman
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Thomas Druetz
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA.,Department of Social and Preventive Medicine, University of Montreal School of Public Health, Montreal, Quebec, Canada
| | - Thomas P Eisele
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, USA
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9
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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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10
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Stresman G, Whittaker C, Slater HC, Bousema T, Cook J. Quantifying Plasmodium falciparum infections clustering within households to inform household-based intervention strategies for malaria control programs: An observational study and meta-analysis from 41 malaria-endemic countries. PLoS Med 2020; 17:e1003370. [PMID: 33119589 PMCID: PMC7595326 DOI: 10.1371/journal.pmed.1003370] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 09/11/2020] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Reactive malaria strategies are predicated on the assumption that individuals infected with malaria are clustered within households or neighbourhoods. Despite the widespread programmatic implementation of reactive strategies, little empirical evidence exists as to whether such strategies are appropriate and, if so, how they should be most effectively implemented. METHODS AND FINDINGS We collated 2 different datasets to assess clustering of malaria infections within households: (i) demographic health survey (DHS) data, integrating household information and patent malaria infection, recent fever, and recent treatment status in children; and (ii) data from cross-sectional and reactive detection studies containing information on the household and malaria infection status (patent and subpatent) of all-aged individuals. Both datasets were used to assess the odds of infections clustering within index households, where index households were defined based on whether they contained infections detectable through one of 3 programmatic strategies: (a) Reactive Case Detection (RACD) classifed by confirmed clinical cases, (b) Mass Screen and Treat (MSAT) classifed by febrile, symptomatic infections, and (c) Mass Test and Treat (MTAT) classifed by infections detectable using routine diagnostics. Data included 59,050 infections in 208,140 children under 7 years old (median age = 2 years, minimum = 2, maximum = 7) by microscopy/rapid diagnostic test (RDT) from 57 DHSs conducted between November 2006 and December 2018 from 23 African countries. Data representing 11,349 infections across all ages (median age = 22 years, minimum = 0.5, maximum = 100) detected by molecular tools in 132,590 individuals in 43 studies published between April 2006 and May 2019 in 20 African, American, Asian, and Middle Eastern countries were obtained from the published literature. Extensive clustering was observed-overall, there was a 20.40 greater (95% credible interval [CrI] 0.35-20.45; P < 0.001) odds of patent infections (according to the DHS data) and 5.13 greater odds (95% CI 3.85-6.84; P < 0.001) of molecularly detected infections (from the published literature) detected within households in which a programmatically detectable infection resides. The strongest degree of clustering identified by polymerase chain reaction (PCR)/ loop mediated isothermal amplification (LAMP) was observed using the MTAT strategy (odds ratio [OR] = 6.79, 95% CI 4.42-10.43) but was not significantly different when compared to MSAT (OR = 5.2, 95% CI 3.22-8.37; P-difference = 0.883) and RACD (OR = 4.08, 95% CI 2.55-6.53; P-difference = 0.29). Across both datasets, clustering became more prominent when transmission was low. However, limitations to our analysis include not accounting for any malaria control interventions in place, malaria seasonality, or the likely heterogeneity of transmission within study sites. Clustering may thus have been underestimated. CONCLUSIONS In areas where malaria transmission is peri-domestic, there are programmatic options for identifying households where residual infections are likely to be found. Combining these detection strategies with presumptively treating residents of index households over a sustained time period could contribute to malaria elimination efforts.
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Affiliation(s)
- Gillian Stresman
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
- * E-mail:
| | - Charlie Whittaker
- Department of Infectious Disease Epidemiology, London Centre for Neglected Tropical Disease Research and MRC Centre for Outbreak Analysis and Modelling, Imperial College London, London, United Kingdom
| | - Hannah C. Slater
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
- PATH, Seattle, Washington, United States of America
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jackie Cook
- MRC Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, United Kingdom
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11
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Stuck L, Fakih BS, Al-Mafazy AWH, Hofmann NE, Holzschuh A, Grossenbacher B, Bennett A, Cotter C, Reaves E, Ali A, der Horst TV, Felger I, Hetzel MW, Yukich J. Malaria infection prevalence and sensitivity of reactive case detection in Zanzibar. Int J Infect Dis 2020; 97:337-346. [PMID: 32534138 PMCID: PMC8450816 DOI: 10.1016/j.ijid.2020.06.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/04/2020] [Accepted: 06/05/2020] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Reactive case detection (RCD) is a commonly used strategy for malaria surveillance and response in elimination settings. Many approaches to RCD assume detectable infections are clustered within and around homes of passively detected cases (index households), which has been evaluated in a number of settings with disparate results. METHODS Household questionnaires and diagnostic testing were conducted following RCD investigations in Zanzibar, Tanzania, including the index household and up to 9 additional neighboring households. RESULTS Of 12,487 participants tested by malaria rapid diagnostic test (RDT), 3·2% of those residing in index households and 0·4% of those residing in non-index households tested positive (OR = 8·4; 95%CI: 5·7, 12·5). Of 6,281 participants tested by quantitative polymerase chain reaction (qPCR), 8·4% of those residing in index households and 1·3% of those residing in non-index households tested positive (OR = 7·1; 95%CI: 6·1, 10·9). Within households of index cases defined as imported, odds of qPCR-positivity amongst members reporting recent travel were 1·4 times higher than among those without travel history (95%CI: 0·2, 4·4). Amongst non-index households, odds of qPCR-detectable infection were no different between households located within 50 m of the index household as compared with those located farther away (OR = 0·8, 95%CI: 0·5, 1·4). Sensitivity of RDT to detect qPCR-detectable infections was 34% (95%CI: 26·4, 42·3). CONCLUSIONS Malaria prevalence in index households in Zanzibar is much higher than in non-index households, in which prevalence is very low. Travelers represent a high-risk population. Low sensitivity of RDTs due to a high prevalence of low-density infections results in an RCD system missing a large proportion of the parasite reservoir.
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Affiliation(s)
- Logan Stuck
- Tulane School of Public Health and Tropical Medicine, New Orleans, LA, USA.
| | - Bakar S Fakih
- Ifakara Health Institute, Dar es Salaam, United Republic of Tanzania
| | - Abdul-Wahid H Al-Mafazy
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, United Republic of Tanzania
| | - Natalie E Hofmann
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - Aurel Holzschuh
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - Benjamin Grossenbacher
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, CA, USA
| | - Chris Cotter
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, CA, USA
| | - Erik Reaves
- U.S. President's Malaria Initiative, Malaria Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Abdullah Ali
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, United Republic of Tanzania
| | - Tina van der Horst
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - Manuel W Hetzel
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
| | - Joshua Yukich
- Tulane School of Public Health and Tropical Medicine, New Orleans, LA, USA
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12
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How to Estimate Optimal Malaria Readiness Indicators at Health-District Level: Findings from the Burkina Faso Service Availability and Readiness Assessment (SARA) Data. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17113923. [PMID: 32492901 PMCID: PMC7312483 DOI: 10.3390/ijerph17113923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/26/2020] [Accepted: 05/28/2020] [Indexed: 12/25/2022]
Abstract
One of the major contributors of malaria-related deaths in Sub-Saharan African countries is the limited accessibility to quality care. In these countries, malaria control activities are implemented at the health-district level (operational entity of the national health system), while malaria readiness indicators are regionally representative. This study provides an approach for estimating health district-level malaria readiness indicators from survey data designed to provide regionally representative estimates. A binomial-hierarchical Bayesian spatial prediction method was applied to Burkina Faso Service Availability and Readiness Assessment (SARA) survey data to provide estimates of essential equipment availability and readiness for malaria care. Predicted values of each indicator were adjusted by the type of health facility, location, and population density. Then, a health district composite readiness profile was built via hierarchical ascendant classification. All surveyed health-facilities were mandated by the Ministry of Health to manage malaria cases. The spatial distribution of essential equipment and malaria readiness was heterogeneous. Around 62.9% of health districts had a high level of readiness to provide malaria care and prevention during pregnancy. Low-performance scores for managing malaria cases were found in big cities. Health districts with low coverage for both first-line antimalarial drugs and rapid diagnostic tests were Baskuy, Bogodogo, Boulmiougou, Nongr-Massoum, Sig-Nonghin, Dafra, and Do. We provide health district estimates and reveal gaps in basic equipment and malaria management resources in some districts that need to be filled. By providing local-scale estimates, this approach could be replicated for other types of indicators to inform decision makers and health program managers and to identify priority areas.
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13
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Taylor SM, Sumner KM, Freedman B, Mangeni JN, Obala AA, Prudhomme O'Meara W. Direct Estimation of Sensitivity of Plasmodium falciparum Rapid Diagnostic Test for Active Case Detection in a High-Transmission Community Setting. Am J Trop Med Hyg 2020; 101:1416-1423. [PMID: 31674301 DOI: 10.4269/ajtmh.19-0558] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Community-based active case detection of malaria parasites with conventional rapid diagnostic tests (cRDTs) is a strategy used most commonly in low-transmission settings. We estimated the sensitivity of this approach in a high-transmission setting in Western Kenya. We tested 3,547 members of 912 households identified in 2013-2014 by index children with (case) and without (control) cRDT-positive malaria. All were tested for Plasmodium falciparum with both a cRDT targeting histidine-rich protein 2 and with an ultrasensitive real-time polymerase chain reaction (PCR). We computed cRDT sensitivity against PCR as the referent, compared prevalence between participant types, and estimated cRDT detectability as a function of PCR-estimated parasite density. Parasite prevalence was 22.9% by cRDTs and 61.5% by PCR. Compared with children aged < 5 years or adults aged > 15 years, geometric mean parasite densities (95% CI) were highest in school-age children aged 5-15 years (8.4 p/uL; 6.6-10.6). The overall sensitivity of cRDT was 36%; among asymptomatic household members, cRDT sensitivity was 25.5% and lowest in adults aged > 15 years (15.8%). When modeled as a function of parasite density, relative to school-age children, the probability of cRDT positivity was reduced in both children aged < 5 years (odds ratio [OR] 0.48; 95% CI: 0.34-0.69) and in adults aged > 15 years (OR: 0.35; 95% CI: 0.27-0.47). An HRP2-detecting cRDT had poor sensitivity for active P. falciparum case detection in asymptomatic community members, and sensitivity was lowest in highly prevalent low-density infections and in adults. Future studies can model the incremental effects of high-sensitivity rapid diagnostic tests and the impacts on transmission.
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Affiliation(s)
- Steve M Taylor
- Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina.,Department of Epidemiology, University of North Carolina Gillings School of Global Public Health, Chapel Hill, North Carolina.,Duke Global Health Institute, Durham, North Carolina
| | - Kelsey M Sumner
- Department of Epidemiology, University of North Carolina Gillings School of Global Public Health, Chapel Hill, North Carolina.,Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina
| | - Betsy Freedman
- Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina
| | | | - Andrew A Obala
- College of Health Sciences, Moi University, Eldoret, Kenya
| | - Wendy Prudhomme O'Meara
- College of Health Sciences, Moi University, Eldoret, Kenya.,Duke Global Health Institute, Durham, North Carolina.,Division of Infectious Diseases, Duke University Medical Center, Durham, North Carolina
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14
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Grossenbacher B, Holzschuh A, Hofmann NE, Omar KA, Stuck L, Fakih BS, Ali A, Yukich J, Hetzel MW, Felger I. Molecular methods for tracking residual Plasmodium falciparum transmission in a close-to-elimination setting in Zanzibar. Malar J 2020; 19:50. [PMID: 31996210 PMCID: PMC6988349 DOI: 10.1186/s12936-020-3127-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 01/16/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Molecular detection of low-density Plasmodium falciparum infections is essential for surveillance studies conducted to inform malaria control strategies in close-to-elimination settings. Molecular monitoring of residual malaria infections usually requires a large study size, therefore sampling and diagnostic processes need to be economical and optimized for high-throughput. A method comparison was undertaken to identify the most efficient diagnostic procedure for processing large collections of community samples with optimal test sensitivity, simplicity, and minimal costs. METHODS In a reactive case detection study conducted on Zanzibar, parasitaemia of 4590 individuals of all ages was investigated by a highly sensitive quantitative (q) PCR that targets multiple var gene copies per parasite genome. To reduce cost, a first round of positivity screening was performed on pools of dried blood spots from five individuals. Ten cycles of a pre-PCR were performed directly on the filter paper punches, followed by qPCR. In a second round, samples of positive pools were individually analysed by pre-PCR and qPCR. RESULTS Prevalence in household members and neighbors of index cases was 1.7% (78/4590) with a geometric mean parasite density of 58 parasites/µl blood. Using qPCR as gold standard, diagnostic sensitivity of rapid diagnostic tests (RDTs) was 37% (29/78). Infections positive by qPCR but negative by RDT had mean densities of 15 parasites/µl blood. CONCLUSION The approach of pre-screening reactive case detection samples in pools of five was ideal for a low prevalence setting such as in Zanzibar. Performing direct PCR on filter paper punches saves substantial time and justifies the higher cost for a polymerase suitable for amplifying DNA directly from whole blood. Molecular monitoring in community samples provided a more accurate picture of infection prevalence, as it identified a potential reservoir of infection that was largely missed by RDT. The developed qPCR-based methodology for screening large sample sets represents primarily a research tool that should inform the design of malaria elimination strategies. It may also prove beneficial for diagnostic tasks in surveillance-response activities.
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Affiliation(s)
- Benjamin Grossenbacher
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Aurel Holzschuh
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Natalie E Hofmann
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Kali Abdullah Omar
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, United Republic of Tanzania
| | - Logan Stuck
- School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA
| | | | - Abdullah Ali
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, United Republic of Tanzania
| | - Joshua Yukich
- School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA
| | - Manuel W Hetzel
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
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15
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Morgan AP, Brazeau NF, Ngasala B, Mhamilawa LE, Denton M, Msellem M, Morris U, Filer DL, Aydemir O, Bailey JA, Parr JB, Mårtensson A, Bjorkman A, Juliano JJ. Falciparum malaria from coastal Tanzania and Zanzibar remains highly connected despite effective control efforts on the archipelago. Malar J 2020; 19:47. [PMID: 31992305 PMCID: PMC6988337 DOI: 10.1186/s12936-020-3137-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 01/22/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Tanzania's Zanzibar archipelago has made significant gains in malaria control over the last decade and is a target for malaria elimination. Despite consistent implementation of effective tools since 2002, elimination has not been achieved. Importation of parasites from outside of the archipelago is thought to be an important cause of malaria's persistence, but this paradigm has not been studied using modern genetic tools. METHODS Whole-genome sequencing (WGS) was used to investigate the impact of importation, employing population genetic analyses of Plasmodium falciparum isolates from both the archipelago and mainland Tanzania. Ancestry, levels of genetic diversity and differentiation, patterns of relatedness, and patterns of selection between these two populations were assessed by leveraging recent advances in deconvolution of genomes from polyclonal malaria infections. RESULTS Significant decreases in the effective population sizes were inferred in both populations that coincide with a period of decreasing malaria transmission in Tanzania. Identity by descent analysis showed that parasites in the two populations shared long segments of their genomes, on the order of 5 cM, suggesting shared ancestry within the last 10 generations. Even with limited sampling, two of isolates between the mainland and Zanzibar were identified that are related at the expected level of half-siblings, consistent with recent importation. CONCLUSIONS These findings suggest that importation plays an important role for malaria incidence on Zanzibar and demonstrate the value of genomic approaches for identifying corridors of parasite movement to the island.
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Affiliation(s)
- Andrew P Morgan
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Nicholas F Brazeau
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Billy Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Lwidiko E Mhamilawa
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
- Department of Women's and Children's Health, International Maternal and Child Health (IMCH), Uppsala University, Uppsala, Sweden
| | - Madeline Denton
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Mwinyi Msellem
- Training and Research, Mnazi Mmoja Hospital, Zanzibar, Tanzania
| | - Ulrika Morris
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Dayne L Filer
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Ozkan Aydemir
- Department of Laboratory Medicine and Pathology, Brown University, Providence, RI, 02912, USA
| | - Jeffrey A Bailey
- Department of Laboratory Medicine and Pathology, Brown University, Providence, RI, 02912, USA
| | - Jonathan B Parr
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Andreas Mårtensson
- Department of Women's and Children's Health, International Maternal and Child Health (IMCH), Uppsala University, Uppsala, Sweden
| | - Anders Bjorkman
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, 17177, Stockholm, Sweden
| | - Jonathan J Juliano
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, 27599, USA.
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599, USA.
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16
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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: 19] [Impact Index Per Article: 4.8] [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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17
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Khandekar E, Kramer R, Ali AS, Al-Mafazy AW, Egger JR, LeGrand S, Mkali HR, McKay M, Ngondi JM. Evaluating Response Time in Zanzibar's Malaria Elimination Case-Based Surveillance-Response System. Am J Trop Med Hyg 2019; 100:256-263. [PMID: 30526729 DOI: 10.4269/ajtmh.17-0546] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
As countries transition toward malaria elimination, malaria programs rely on surveillance-response systems, which are often supported by web- and mobile phone-based reporting tools. Such surveillance-response systems are interventions for elimination, making it important to determine if they are operating optimally. A metric to measure this by is timeliness. This study used a mixed-methods approach to investigate the response time of Zanzibar's malaria elimination surveillance-response system, Malaria Case Notification (MCN). MCN conducts both passive and reactive case detection, supported by a mobile phone-based reporting tool called Coconut Surveillance. Using data obtained from RTI International and the Zanzibar Malaria Elimination Program (ZAMEP), analysis of summary statistics was conducted to investigate the association of response time with geography, and time series techniques were used to investigate trends in response time and its association with the number of reported cases. Results indicated that response time varied by the district in Zanzibar (0.6-6.05 days) and that it was not associated with calendar time or the number of reported cases. Survey responses and focus groups with a cadre of health workers, district malaria surveillance officers, shed light on operational challenges faced during case investigation, such as incomplete health records and transportation issues, which stem from deficiencies in aspects of ZAMEP's program management. These findings illustrate that timely response for malaria elimination depends on effective program management, despite the automation of web-based or mobile phone-based tools. For surveillance-response systems to work optimally, malaria programs should ensure that optimal management practices are in place.
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Affiliation(s)
- Eeshan Khandekar
- Duke Global Health Institute, Duke University, Durham, North Carolina
| | - Randall Kramer
- Duke Global Health Institute, Duke University, Durham, North Carolina
| | - Abdullah S Ali
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | | | - Joseph R Egger
- Duke Global Health Institute, Duke University, Durham, North Carolina
| | - Sara LeGrand
- Duke Global Health Institute, Duke University, Durham, North Carolina
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18
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Nelson CS, Sumner KM, Freedman E, Saelens JW, Obala AA, Mangeni JN, Taylor SM, O'Meara WP. High-resolution micro-epidemiology of parasite spatial and temporal dynamics in a high malaria transmission setting in Kenya. Nat Commun 2019; 10:5615. [PMID: 31819062 PMCID: PMC6901486 DOI: 10.1038/s41467-019-13578-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 11/14/2019] [Indexed: 01/03/2023] Open
Abstract
Novel interventions that leverage the heterogeneity of parasite transmission are needed to achieve malaria elimination. To better understand spatial and temporal dynamics of transmission, we applied amplicon next-generation sequencing of two polymorphic gene regions (csp and ama1) to a cohort identified via reactive case detection in a high-transmission setting in western Kenya. From April 2013 to July 2014, we enrolled 442 symptomatic children with malaria, 442 matched controls, and all household members of both groups. Here, we evaluate genetic similarity between infected individuals using three indices: sharing of parasite haplotypes on binary and proportional scales and the L1 norm. Symptomatic children more commonly share haplotypes with their own household members. Furthermore, we observe robust temporal structuring of parasite genetic similarity and identify the unique molecular signature of an outbreak. These findings of both micro- and macro-scale organization of parasite populations might be harnessed to inform next-generation malaria control measures. Here, Nelson et al. use amplicon next-generation sequencing of two P. falciparum polymorphic gene regions to investigate the genetic similarity of parasite populations across time and space in a pediatric cohort in Kenya. They identify both micro- and macro-scale structuring of malaria parasites in this high-transmission setting, which could inform future intervention strategies.
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Affiliation(s)
- Cody S Nelson
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA.
| | - Kelsey M Sumner
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA.,Division of Infectious Diseases, Duke University School of Medicine, Durham, North Carolina, USA
| | - Elizabeth Freedman
- Division of Infectious Diseases, Duke University School of Medicine, Durham, North Carolina, USA
| | - Joseph W Saelens
- Division of Infectious Diseases, Duke University School of Medicine, Durham, North Carolina, USA
| | - Andrew A Obala
- School of Medicine, Moi University College of Health Sciences, Eldoret, Kenya
| | - Judith N Mangeni
- School of Nursing, Moi University College of Health Sciences, Eldoret, Kenya
| | - Steve M Taylor
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA.,Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA.,Division of Infectious Diseases, Duke University School of Medicine, Durham, North Carolina, USA
| | - Wendy P O'Meara
- Duke Global Health Institute, Duke University, Durham, North Carolina, USA.,Division of Infectious Diseases, Duke University School of Medicine, Durham, North Carolina, USA
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19
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Howes RE, Franchard T, Rakotomanga TA, Ramiranirina B, Zikursh M, Cramer EY, Tisch DJ, Kang SY, Ramboarina S, Ratsimbasoa A, Zimmerman PA. Risk Factors for Malaria Infection in Central Madagascar: Insights from a Cross-Sectional Population Survey. Am J Trop Med Hyg 2019; 99:995-1002. [PMID: 30182923 DOI: 10.4269/ajtmh.18-0417] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Community prevalence of infection is a widely used, standardized metric for evaluating malaria endemicity. Conventional methods for measuring prevalence include light microscopy and rapid diagnostic tests (RDTs), but their detection thresholds are inadequate for diagnosing low-density infections. The significance of submicroscopic malaria infections is poorly understood in Madagascar, a country of heterogeneous malaria epidemiology. A cross-sectional community survey in the western foothills of Madagascar during the March 2014 transmission season found malaria infection to be predominantly submicroscopic and asymptomatic. Prevalence of Plasmodium infection diagnosed by microscopy, RDT, and molecular diagnosis was 2.4%, 4.1%, and 13.8%, respectively. This diagnostic discordance was greatest for Plasmodium vivax infection, which was 98.5% submicroscopic. Village location, insecticide-treated bednet ownership, and fever were significantly associated with infection outcomes, as was presence of another infected individual in the household. Duffy-negative individuals were diagnosed with P. vivax, but with reduced odds relative to Duffy-positive hosts. The observation of high proportions of submicroscopic infections calls for a wider assessment of the parasite reservoir in other regions of the island, particularly given the country's current focus on malaria elimination and the poorly documented distribution of the non-P. falciparum parasite species.
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Affiliation(s)
- Rosalind E Howes
- Malaria Atlas Project, Nuffield Department of Medicine, Oxford Big Data Institute, University of Oxford, Oxford, United Kingdom.,The Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Thierry Franchard
- National Malaria Control Programme of Madagascar, Ministry of Health, Antananarivo, Madagascar
| | | | - Brune Ramiranirina
- National Malaria Control Programme of Madagascar, Ministry of Health, Antananarivo, Madagascar
| | - Melinda Zikursh
- The Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Estee Y Cramer
- The Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Daniel J Tisch
- The Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Su Y Kang
- Malaria Atlas Project, Nuffield Department of Medicine, Oxford Big Data Institute, University of Oxford, Oxford, United Kingdom
| | - Stéphanie Ramboarina
- National Malaria Control Programme of Madagascar, Ministry of Health, Antananarivo, Madagascar.,The Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Arsène Ratsimbasoa
- Faculty of Sciences, University of Antananarivo, Antananarivo, Madagascar.,Faculty of Medicine, University of Antananarivo, Antananarivo, Madagascar.,National Malaria Control Programme of Madagascar, Ministry of Health, Antananarivo, Madagascar
| | - Peter A Zimmerman
- The Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
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20
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Stresman G, Bousema T, Cook J. Malaria Hotspots: Is There Epidemiological Evidence for Fine-Scale Spatial Targeting of Interventions? Trends Parasitol 2019; 35:822-834. [PMID: 31474558 DOI: 10.1016/j.pt.2019.07.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/29/2019] [Accepted: 07/29/2019] [Indexed: 12/20/2022]
Abstract
As data at progressively granular spatial scales become available, the temptation is to target interventions to areas with higher malaria transmission - so-called hotspots - with the aim of reducing transmission in the wider community. This paper reviews literature to determine if hotspots are an intrinsic feature of malaria epidemiology and whether current evidence supports hotspot-targeted interventions. Hotspots are a consistent feature of malaria transmission at all endemicities. The smallest spatial unit capable of supporting transmission is the household, where peri-domestic transmission occurs. Whilst the value of focusing interventions to high-burden areas is evident, there is currently limited evidence that local-scale hotspots fuel transmission. As boundaries are often uncertain, there is no conclusive evidence that hotspot-targeted interventions accelerate malaria elimination.
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Affiliation(s)
- Gillian Stresman
- Infection Biology Department, London School of Hygiene and Tropical Medicine, London, UK.
| | - Teun Bousema
- Radboud University Medical Centre, Department of Microbiology, HB Nijmegen, The Netherlands.
| | - Jackie Cook
- Medical Research Council (MRC) Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
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21
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Björkman A, Shakely D, Ali AS, Morris U, Mkali H, Abbas AK, Al-Mafazy AW, Haji KA, Mcha J, Omar R, Cook J, Elfving K, Petzold M, Sachs MC, Aydin-Schmidt B, Drakeley C, Msellem M, Mårtensson A. From high to low malaria transmission in Zanzibar-challenges and opportunities to achieve elimination. BMC Med 2019; 17:14. [PMID: 30665398 PMCID: PMC6341737 DOI: 10.1186/s12916-018-1243-z] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 12/17/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Substantial global progress in the control of malaria in recent years has led to increased commitment to its potential elimination. Whether this is possible in high transmission areas of sub-Saharan Africa remains unclear. Zanzibar represents a unique case study of such attempt, where modern tools and strategies for malaria treatment and vector control have been deployed since 2003. METHODS We have studied temporal trends of comprehensive malariometric indices in two districts with over 100,000 inhabitants each. The analyses included triangulation of data from annual community-based cross-sectional surveys, health management information systems, vital registry and entomological sentinel surveys. RESULTS The interventions, with sustained high-community uptake, were temporally associated with a major malaria decline, most pronounced between 2004 and 2007 and followed by a sustained state of low transmission. In 2015, the Plasmodium falciparum community prevalence of 0.43% (95% CI 0.23-0.73) by microscopy or rapid diagnostic test represented 96% reduction compared with that in 2003. The P. falciparum and P. malariae prevalence by PCR was 1.8% (95% CI 1.3-2.3), and the annual P. falciparum incidence was estimated to 8 infections including 2.8 clinical episodes per 1000 inhabitants. The total parasite load decreased over 1000-fold (99.9%) between 2003 and 2015. The incidence of symptomatic malaria at health facilities decreased by 94% with a trend towards relatively higher incidence in age groups > 5 years, a more pronounced seasonality and with reported travel history to/from Tanzania mainland as a higher risk factor. All-cause mortality among children < 5 years decreased by 72% between 2002 and 2007 mainly following the introduction of artemisinin-based combination therapies whereas the main reduction in malaria incidence followed upon the vector control interventions from 2006. Human biting rates decreased by 98% with a major shift towards outdoor biting by Anopheles arabiensis. CONCLUSIONS Zanzibar provides new evidence of the feasibility of reaching uniquely significant and sustainable malaria reduction (pre-elimination) in a previously high endemic region in sub-Saharan Africa. The data highlight constraints of optimistic prognostic modelling studies. New challenges, mainly with outdoor transmission, a large asymptomatic parasite reservoir and imported infections, require novel tools and reoriented strategies to prevent a rebound effect and achieve elimination.
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Affiliation(s)
- A Björkman
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden.
| | - D Shakely
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden.,Health Metrics at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - A S Ali
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - U Morris
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden
| | - H Mkali
- MEASURE Evaluation, Dar es Salaam, Tanzania
| | - A K Abbas
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - A-W Al-Mafazy
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - K A Haji
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - J Mcha
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - R Omar
- Zanzibar Malaria Elimination Programme, Zanzibar, Tanzania
| | - J Cook
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden.,London School of Hygiene and Tropical Medicine, London, UK
| | - K Elfving
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden.,Department of Infectious Diseases, University of Gothenburg, Gothenburg, Sweden
| | - M Petzold
- Centre for Applied Biostatistics, University of Gothenburg, Gothenburg, Sweden
| | - M C Sachs
- Biostatistics Unit, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - B Aydin-Schmidt
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Solnavägen 9, SE-171 77, Stockholm, Sweden
| | - C Drakeley
- London School of Hygiene and Tropical Medicine, London, UK
| | - M Msellem
- Training and Research, Mnazi Mmoja Hospital, Zanzibar, Tanzania
| | - A Mårtensson
- Department of Women's and Children's Health, International Maternal and Child Health, Uppsala University, Uppsala, Sweden
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22
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Stresman GH, Mwesigwa J, Achan J, Giorgi E, Worwui A, Jawara M, Di Tanna GL, Bousema T, Van Geertruyden JP, Drakeley C, D'Alessandro U. Do hotspots fuel malaria transmission: a village-scale spatio-temporal analysis of a 2-year cohort study in The Gambia. BMC Med 2018; 16:160. [PMID: 30213275 PMCID: PMC6137946 DOI: 10.1186/s12916-018-1141-4] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 07/31/2018] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Despite the biological plausibility of hotspots fueling malaria transmission, the evidence to support this concept has been mixed. If transmission spreads from high burden to low burden households in a consistent manner, then this could have important implications for control and elimination program development. METHODS Data from a longitudinal cohort in The Gambia was analyzed. All consenting individuals residing in 12 villages across the country were sampled monthly from June (dry season) to December 2013 (wet season), in April 2014 (mid dry season), and monthly from June to December 2014. A study nurse stationed within each village recorded passively detected malaria episodes between visits. Plasmodium falciparum infections were determined by polymerase chain reaction and analyzed using a geostatistical model. RESULTS Household-level observed monthly incidence ranged from 0 to 0.50 infection per person (interquartile range = 0.02-0.10) across the sampling months, and high burden households exist across all study villages. There was limited evidence of a spatio-temporal pattern at the monthly timescale irrespective of transmission intensity. Within-household transmission was the most plausible hypothesis examined to explain the observed heterogeneity in infections. CONCLUSIONS Within-village malaria transmission patterns are concentrated in a small proportion of high burden households, but patterns are stochastic regardless of endemicity. Our findings support the notion of transmission occurring at the household and village scales but not the use of a targeted approach to interrupt spreading of infections from high to low burden areas within villages in this setting.
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Affiliation(s)
- Gillian H Stresman
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.
| | - Julia Mwesigwa
- Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia.,University of Antwerp, Antwerp, Belgium
| | - Jane Achan
- Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia.,University of Antwerp, Antwerp, Belgium
| | - Emanuele Giorgi
- CHICAS, Lancaster Medical School, Lancaster University, Lancaster, UK
| | - Archibald Worwui
- Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia.,University of Antwerp, Antwerp, Belgium
| | - Musa Jawara
- Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia.,University of Antwerp, Antwerp, Belgium
| | | | - Teun Bousema
- Department of Medical Microbology, Radboud Medical University, Nijmegen, The Netherlands
| | | | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Umberto D'Alessandro
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.,Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine, Fajara, The Gambia.,University of Antwerp, Antwerp, Belgium
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23
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Malaria burden and treatment targets in Kachin Special Region II, Myanmar from 2008 to 2016: A retrospective analysis. PLoS One 2018; 13:e0195032. [PMID: 29614088 PMCID: PMC5882093 DOI: 10.1371/journal.pone.0195032] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 03/15/2018] [Indexed: 01/02/2023] Open
Abstract
Although drug-based treatment is the primary intervention for malaria control and elimination, optimal use of targeted treatments remains unclear. From 2008 to 2016, three targeted programs on treatment were undertaken in Kachin Special Region II (KR2), Myanmar. Program I (2008–2011) treated all confirmed, clinical and suspected cases; program II (2012–2013) treated confirmed and clinical cases; and program III (2014–2016) targeted confirmed cases only. This study aims to evaluate the impacts of the three programs on malaria burden individually based on the annual parasite incidence (API), slide positivity rate (SPR) and their relative values. The API is calculated from original collected data and the incidence rate ratio (IRR) for each year is calculated by using the first-year API as a reference in each program phase across the KR2. Same method is applied to calculate SPR and risk ratio (RR) at the sentinel hospital too. During program I (2008–2011), malaria burden was reduced by 61% (95%CI: 58%-74%) and the actual API decreased from 9.8 (95%CI: 9.6–10.1) per 100 person-years in 2008 to 3.8 (3.6–4.1) per 100 person-years in 2011. Amid program II (2012–2013), the malaria burden increased by 33% (95%CI: 22%-46%) and the actual API increased from 2.1(95%CI: 2.0–2.3) per 100 person-years in 2012 to 2.8 (95%CI: 2.7–2.9) per 100 person-years in 2013. During program III (2014–2016) the malaria burden increased furtherly by 60% (95%CI: 51% - 69%) and the actual API increased from 3.2(95%CI: 3.0–3.3) per 100 person-years in 2014 to 5.1 (95%CI: 4.9–5.2) per 100 person-years in 2016. Results of the slide positivity of the sentinel hospital also confirm these results. Resurgence of malaria was mainly due to Plasmodium vivax during program II and III. This study indicates that strategy adopted in program I (2008–2011) should be more appropriate for the KR2. Quality-assured treatment of all confirmed, clinical and suspected malaria cases may be helpful for the reduction of malaria burden.
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24
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Medzihradsky OF, Kleinschmidt I, Mumbengegwi D, Roberts KW, McCreesh P, Dufour MSK, Uusiku P, Katokele S, Bennett A, Smith J, Sturrock H, Prach LM, Ntuku H, Tambo M, Didier B, Greenhouse B, Gani Z, Aerts A, Gosling R, Hsiang MS. Study protocol for a cluster randomised controlled factorial design trial to assess the effectiveness and feasibility of reactive focal mass drug administration and vector control to reduce malaria transmission in the low endemic setting of Namibia. BMJ Open 2018; 8:e019294. [PMID: 29374672 PMCID: PMC5829876 DOI: 10.1136/bmjopen-2017-019294] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
INTRODUCTION To interrupt malaria transmission, strategies must target the parasite reservoir in both humans and mosquitos. Testing of community members linked to an index case, termed reactive case detection (RACD), is commonly implemented in low transmission areas, though its impact may be limited by the sensitivity of current diagnostics. Indoor residual spraying (IRS) before malaria season is a cornerstone of vector control efforts. Despite their implementation in Namibia, a country approaching elimination, these methods have been met with recent plateaus in transmission reduction. This study evaluates the effectiveness and feasibility of two new targeted strategies, reactive focal mass drug administration (rfMDA) and reactive focal vector control (RAVC) in Namibia. METHODS AND ANALYSIS This is an open-label cluster randomised controlled trial with 2×2 factorial design. The interventions include: rfMDA (presumptive treatment with artemether-lumefantrine (AL)) versus RACD (rapid diagnostic testing and treatment using AL) and RAVC (IRS with Acellic 300CS) versus no RAVC. Factorial design also enables comparison of the combined rfMDA+RAVC intervention to RACD. Participants living in 56 enumeration areas will be randomised to one of four arms: rfMDA, rfMDA+RAVC, RACD or RACD+RAVC. These interventions, triggered by index cases detected at health facilities, will be targeted to individuals residing within 500 m of an index. The primary outcome is cumulative incidence of locally acquired malaria detected at health facilities over 1 year. Secondary outcomes include seroprevalence, infection prevalence, intervention coverage, safety, acceptability, adherence, cost and cost-effectiveness. ETHICS AND DISSEMINATION Findings will be reported on clinicaltrials.gov, in peer-reviewed publications and through stakeholder meetings with MoHSS and community leaders in Namibia. TRIAL REGISTRATION NUMBER NCT02610400; Pre-results.
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Affiliation(s)
- Oliver F Medzihradsky
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
- Department of Pediatrics, Benioff Children's Hospital, University of California San Francisco, San Francisco, California, USA
| | - Immo Kleinschmidt
- Department of Infectious Disease Epidemiology, The London School of Hygiene and Tropical Medicine, London, UK
- Faculty of Health Sciences, School of Pathology, University of Witwatersrand, Johannesburg, South Africa
| | - Davis Mumbengegwi
- Multidisciplinary Research Centre, University of Namibia, Windhoek, Namibia
| | - Kathryn W Roberts
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Patrick McCreesh
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Mi-Suk Kang Dufour
- Division of Prevention Science, University of California San Francisco, San Francisco, California, USA
| | - Petrina Uusiku
- National Vector-borne Diseases Control Programme, Ministry of Health and Social Services, Windhoek, Namibia
| | - Stark Katokele
- National Vector-borne Diseases Control Programme, Ministry of Health and Social Services, Windhoek, Namibia
| | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Jennifer Smith
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Hugh Sturrock
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Lisa M Prach
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Henry Ntuku
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Munyaradzi Tambo
- Faculty of Health Sciences, School of Pathology, University of Witwatersrand, Johannesburg, South Africa
| | - Bradley Didier
- Clinton Health Access Initiative, Boston, Massachusetts, USA
| | - Bryan Greenhouse
- Division of Experimental Medicine, Department of Medicine, University of California San Francisco, San Francisco, California, USA
| | | | - Ann Aerts
- Novartis Foundation, Basel, Switzerland
| | - Roly Gosling
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
| | - Michelle S Hsiang
- Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, California, USA
- Department of Pediatrics, Benioff Children's Hospital, University of California San Francisco, San Francisco, California, USA
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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