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Benjamin-Chung J, Li H, Nguyen A, Barratt Heitmann G, Bennett A, Ntuku H, Prach LM, Tambo M, Wu L, Drakeley C, Gosling R, Mumbengegwi D, Kleinschmidt I, Smith JL, Hubbard A, van der Laan M, Hsiang MS. Extension of efficacy range for targeted malaria-elimination interventions due to spillover effects. Nat Med 2024:10.1038/s41591-024-03134-z. [PMID: 38965434 DOI: 10.1038/s41591-024-03134-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 06/13/2024] [Indexed: 07/06/2024]
Abstract
Malaria-elimination interventions aim to extinguish hotspots and prevent transmission to nearby areas. Here, we re-analyzed a cluster-randomized trial of reactive, focal interventions (chemoprevention using artemether-lumefantrine and/or indoor residual spraying with pirimiphos-methyl) delivered within 500 m of confirmed malaria index cases in Namibia to measure direct effects (among intervention recipients within 500 m) and spillover effects (among non-intervention recipients within 3 km) on incidence, prevalence and seroprevalence. There was no or weak evidence of direct effects, but the sample size of intervention recipients was small, limiting statistical power. There was the strongest evidence of spillover effects of combined chemoprevention and indoor residual spraying. Among non-recipients within 1 km of index cases, the combined intervention reduced malaria incidence by 43% (95% confidence interval, 20-59%). In analyses among non-recipients within 3 km of interventions, the combined intervention reduced infection prevalence by 79% (6-95%) and seroprevalence, which captures recent infections and has higher statistical power, by 34% (20-45%). Accounting for spillover effects increased the cost-effectiveness of the combined intervention by 42%. Targeting hotspots with combined chemoprevention and vector-control interventions can indirectly benefit non-recipients up to 3 km away.
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Affiliation(s)
- Jade Benjamin-Chung
- Department of Epidemiology and Population Health, Stanford University, Stanford, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
| | - Haodong Li
- Division of Biostatistics, University of California, Berkeley, Berkeley, CA, USA
| | - Anna Nguyen
- Department of Epidemiology and Population Health, Stanford University, Stanford, CA, USA
| | | | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, USA
- PATH, Seattle, WA, USA
| | - Henry Ntuku
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, USA
| | - Lisa M Prach
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, USA
| | - Munyaradzi Tambo
- Multidisciplinary Research Centre, University of Namibia, Windhoek, Namibia
| | - Lindsey Wu
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Roly Gosling
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, USA
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | | | - Immo Kleinschmidt
- MRC International Statistics and Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
- Wits Research Institute for Malaria, Wits/SAMRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Southern African Development Community Malaria Elimination Eight Secretariat, Windhoek, Namibia
| | - Jennifer L Smith
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, USA
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA, USA
| | - Alan Hubbard
- Division of Biostatistics, University of California, Berkeley, Berkeley, CA, USA
| | - Mark van der Laan
- Division of Biostatistics, University of California, Berkeley, Berkeley, CA, USA
| | - Michelle S Hsiang
- Chan Zuckerberg Biohub, San Francisco, CA, USA
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco, San Francisco, CA, USA
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA, USA
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Benjamin-Chung J, Li H, Nguyen A, Heitmann GB, Bennett A, Ntuku H, Prach LM, Tambo M, Wu L, Drakeley C, Gosling R, Mumbengegwi D, Kleinschmidt I, Smith JL, Hubbard A, van der Laan M, Hsiang MS. Targeted malaria elimination interventions reduce Plasmodium falciparum infections up to 3 kilometers away. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.09.19.23295806. [PMID: 37790419 PMCID: PMC10543053 DOI: 10.1101/2023.09.19.23295806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Malaria elimination interventions in low-transmission settings aim to extinguish hot spots and prevent transmission to nearby areas. In malaria elimination settings, the World Health Organization recommends reactive, focal interventions targeted to the area near malaria cases shortly after they are detected. A key question is whether these interventions reduce transmission to nearby uninfected or asymptomatic individuals who did not receive interventions. Here, we measured direct effects (among intervention recipients) and spillover effects (among non-recipients) of reactive, focal interventions delivered within 500m of confirmed malaria index cases in a cluster-randomized trial in Namibia. The trial delivered malaria chemoprevention (artemether lumefantrine) and vector control (indoor residual spraying with Actellic) separately and in combination using a factorial design. We compared incidence, infection prevalence, and seroprevalence between study arms among intervention recipients (direct effects) and non-recipients (spillover effects) up to 3 km away from index cases. We calculated incremental cost-effectiveness ratios accounting for spillover effects. The combined chemoprevention and vector control intervention produced direct effects and spillover effects. In the primary analysis among non-recipients within 1 km from index cases, the combined intervention reduced malaria incidence by 43% (95% CI 20%, 59%). In secondary analyses among non-recipients 500m-3 km from interventions, the combined intervention reduced infection by 79% (6%, 95%) and seroprevalence 34% (20%, 45%). Accounting for spillover effects increased the cost-effectiveness of the combined intervention by 37%. Our findings provide the first evidence that targeting hot spots with combined chemoprevention and vector control interventions can indirectly benefit non-recipients up to 3 km away.
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Affiliation(s)
- Jade Benjamin-Chung
- Department of Epidemiology and Population Health, Stanford University, Stanford, United States
- Chan Zuckerberg Biohub, San Francisco, United States
| | - Haodong Li
- Division of Biostatistics, University of California, Berkeley
| | - Anna Nguyen
- Department of Epidemiology and Population Health, Stanford University, Stanford, United States
| | | | - Adam Bennett
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco (UCSF) , San Francisco, United States
- PATH, Seattle, United States
| | - Henry Ntuku
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco (UCSF) , San Francisco, United States
| | - Lisa M. Prach
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco (UCSF) , San Francisco, United States
| | - Munyaradzi Tambo
- Multidisciplinary Research Centre, University of Namibia, Windhoek, Namibia
| | - Lindsey Wu
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Roly Gosling
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco (UCSF) , San Francisco, United States
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | | | - Immo Kleinschmidt
- MRC International Statistics and Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
- Wits Research Institute for Malaria, Wits/SAMRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Southern African Development Community Malaria Elimination Eight Secretariat, Windhoek, Namibia
| | - Jennifer L. Smith
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco (UCSF) , San Francisco, United States
| | - Alan Hubbard
- Division of Biostatistics, University of California, Berkeley
| | | | - Michelle S. Hsiang
- Chan Zuckerberg Biohub, San Francisco, United States
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco (UCSF) , San Francisco, United States
- Department of Epidemiology and Biostatistics, UCSF, San Francisco, United States
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Zou L, Ning K, Deng W, Zhang X, Sharifi MS, Luo J, Bai Y, Wang X, Zhou W. Study on the use and effectiveness of malaria preventive measures reported by employees of chinese construction companies in Western Africa in 2021. BMC Public Health 2023; 23:813. [PMID: 37138259 PMCID: PMC10158225 DOI: 10.1186/s12889-023-15737-1] [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: 05/15/2022] [Accepted: 04/23/2023] [Indexed: 05/05/2023] Open
Abstract
BACKGROUND As malaria continues to be a significant global public health concern, especially in Sub-Saharan Africa, Chinese workers in Africa are at increased risk of malaria. The effectiveness of malaria prevention measures implemented by Chinese companies and workers is a question that may correlate with the malaria infection rate in this population. This study explored the use and effectiveness of malaria prevention measures for Chinese employees in West Africa to provide a reference for companies and individuals on improving malaria prevention and control. METHODS Using a cross-sectional approach, we surveyed 256 participants in 2021, mainly from Nigeria, Mali, Côte d'Ivoire, Ghana, Guinea, Sierra Leone, and Senegal in West Africa. The survey duration is from July to the end of September 2021. We selected two companies from the 2020 ENR "World's Largest 250 International Contractors" list, which featured 6 Chinese companies, all of which are state-owned and have a 61.9% market share in Africa. The participants were Chinese workers with more than a year of work experience in construction companies in Africa. A 20-minute WeChat-based structured online questionnaire was used to obtain information on malaria infection status and malaria prevention measures. Descriptive statistical analysis, chi-square test, principal components analysis, and ordinal logistic regression analysis are used to analyze the data obtained. The difference in Statistical significance was set at P < 0.05. RESULTS Ninety six (37.5%) participants contracted malaria more than once within a year. The principal components analysis found a low correlation between public and individual preventive measures. No significant correlation was found between public preventive measures and malaria infection (p > 0.05), while standardized use of mosquito nets (P = 0.016) and pesticide spraying (P = 0.047) contributed significantly to fewer malaria infections at the individual level, but the removal of vegetation around houses (P = 0.028) at the individual level related to higher malaria infection. CONCLUSIONS In our sample of Chinese construction workers going to Africa, some individual preventive measures had a stronger association with malaria prevention than a variety of public environmental measures. Furthermore, individual and public preventive measures were not associated with each other. Both of these findings are surprising and require further investigation in larger and more diverse samples. This- study provides important clues about the challenges that risk reduction programs face for migrant workers from China and elsewhere.
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Affiliation(s)
- Li Zou
- School of literature and journalism, Central South University, Changsha, Hunan Province, China
| | - Ke Ning
- School of literature and journalism, Central South University, Changsha, Hunan Province, China
| | - Wenyu Deng
- Insurance Professional College, Changsha, Hunan Province, China
| | - Xufei Zhang
- School of literature and journalism, Central South University, Changsha, Hunan Province, China
| | - Mohammad Shahir Sharifi
- School of literature and journalism, Central South University, Changsha, Hunan Province, China
| | - Junfei Luo
- School of literature and journalism, Central South University, Changsha, Hunan Province, China
| | - Yin Bai
- School of literature and journalism, Central South University, Changsha, Hunan Province, China
| | - Xiner Wang
- School of literature and journalism, Central South University, Changsha, Hunan Province, China
| | - Wenjuan Zhou
- School of literature and journalism, Central South University, Changsha, Hunan Province, China.
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Echodu DC, Yeka A, Eganyu T, Odude W, Bukenya F, Amoah B, Wanzira H, Colborn K, Elliott RC, Powell SE, Kilama M, Mulebeke R, Nankabirwa J, Giorgi E, Roskosky M, Omoding O, Gonahasa S, Opigo J. Impact of population based indoor residual spraying with and without mass drug administration with dihydroartemisinin-piperaquine on malaria prevalence in a high transmission setting: a quasi-experimental controlled before-and-after trial in northeastern Uganda. BMC Infect Dis 2023; 23:72. [PMID: 36747133 PMCID: PMC9901833 DOI: 10.1186/s12879-023-07991-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 01/06/2023] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Declines in malaria burden in Uganda have slowed. Modelling predicts that indoor residual spraying (IRS) and mass drug administration (MDA), when co-timed, have synergistic impact. This study investigated additional protective impact of population-based MDA on malaria prevalence, if any, when added to IRS, as compared with IRS alone and with standard of care (SOC). METHODS The 32-month quasi-experimental controlled before-and-after trial enrolled an open cohort of residents (46,765 individuals, 1st enumeration and 52,133, 4th enumeration) of Katakwi District in northeastern Uganda. Consented participants were assigned to three arms based on residential subcounty at study start: MDA+IRS, IRS, SOC. IRS with pirimiphos methyl and MDA with dihydroartemisinin- piperaquine were delivered in 4 co-timed campaign-style rounds 8 months apart. The primary endpoint was population prevalence of malaria, estimated by 6 cross-sectional surveys, starting at baseline and preceding each subsequent round. RESULTS Comparing malaria prevalence in MDA+IRS and IRS only arms over all 6 surveys (intention-to-treat analysis), roughly every 6 months post-interventions, a geostatistical model found a significant additional 15.5% (95% confidence interval (CI): [13.7%, 17.5%], Z = 9.6, p = 5e-20) decrease in the adjusted odds ratio (aOR) due to MDA for all ages, a 13.3% reduction in under 5's (95% CI: [10.5%, 16.8%], Z = 4.02, p = 5e-5), and a 10.1% reduction in children 5-15 (95% CI: [8.5%, 11.8%], Z = 4.7, p = 2e-5). All ages residents of the MDA + IRS arm enjoyed an overall 80.1% reduction (95% CI: [80.0%, 83.0%], p = 0.0001) in odds of qPCR confirmed malaria compared with SOC residents. Secondary difference-in-difference analyses comparing surveys at different timepoints to baseline showed aOR (MDA + IRS vs IRS) of qPCR positivity between 0.28 and 0.66 (p < 0.001). Of three serious adverse events, one (nonfatal) was considered related to study medications. Limitations include the initial non-random assignment of study arms, the single large cluster per arm, and the lack of an MDA-only arm, considered to violate equipoise. CONCLUSIONS Despite being assessed at long time points 5-7 months post-round, MDA plus IRS provided significant additional protection from malaria infection over IRS alone. Randomized trials of MDA in large areas undergoing IRS recommended as well as cohort studies of impact on incidence. TRIAL REGISTRATION This trial was retrospectively registered 11/07/2018 with the Pan African Clinical Trials Registry (PACTR201807166695568).
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Affiliation(s)
| | - Adoke Yeka
- grid.11194.3c0000 0004 0620 0548Makerere University College of Health Sciences, School of Public Health, P.O. Box 7072, Kampala, Uganda
| | - Thomas Eganyu
- Pilgrim Africa, Plot 8 Engwau Road, PO Box 577, Soroti, Uganda
| | - Wycliff Odude
- Pilgrim Africa, Plot 8 Engwau Road, PO Box 577, Soroti, Uganda
| | - Fred Bukenya
- Pilgrim Africa, Plot 8 Engwau Road, PO Box 577, Soroti, Uganda
| | - Benjamin Amoah
- grid.7445.20000 0001 2113 8111School of Public Health, Imperial College London, Sir Alexander Fleming Building, South Kensington Campus, London, SW7 2AZ UK
| | | | - Kathryn Colborn
- grid.430503.10000 0001 0703 675XUniversity of Colorado Anschutz Medical Campus, 12631 East 17th Avenue, Aurora, CO 80045 USA
| | - Richard C. Elliott
- Pilgrim Africa, 8001 14th Avenue NE, Suite A, Seattle, WA 98115 USA ,grid.184764.80000 0001 0670 228XMicron School of Materials Science and Engineering, Boise State University, Engineering Building, Suite 338, Boise, ID 83725 USA
| | | | - Maxwell Kilama
- Pilgrim Africa, Plot 8 Engwau Road, PO Box 577, Soroti, Uganda
| | - Ronald Mulebeke
- grid.11194.3c0000 0004 0620 0548Makerere University College of Health Sciences, School of Public Health, P.O. Box 7072, Kampala, Uganda
| | - Joaniter Nankabirwa
- grid.463352.50000 0004 8340 3103Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Emanuele Giorgi
- grid.9835.70000 0000 8190 6402Lancaster University Medical School, Centre for Health Informatics, Computing and Statistics, Lancaster, UK
| | - Mellisa Roskosky
- Pilgrim Africa, 8001 14th Avenue NE, Suite A, Seattle, WA 98115 USA ,grid.21107.350000 0001 2171 9311Johns Hopkins Bloomberg School of Public Health, Baltimore, MD USA
| | - Osborn Omoding
- Pilgrim Africa, Plot 8 Engwau Road, PO Box 577, Soroti, Uganda
| | - Samuel Gonahasa
- grid.463352.50000 0004 8340 3103Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Jimmy Opigo
- grid.415705.2National Malaria Control Division, Ministry of Health Uganda, Kampala, Uganda
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Opiyo M, Sherrard-Smith E, Malheia A, Nhacolo A, Sacoor C, Nhacolo A, Máquina M, Jamu L, Cuamba N, Bassat Q, Saúte F, Paaijmans K. Household modifications after the indoor residual spraying (IRS) campaign in Mozambique reduce the actual spray coverage and efficacy. PLOS GLOBAL PUBLIC HEALTH 2022; 2:e0000227. [PMID: 36962153 PMCID: PMC10021718 DOI: 10.1371/journal.pgph.0000227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 03/02/2022] [Indexed: 11/18/2022]
Abstract
Indoor residual spraying of insecticides (IRS) is a key malaria vector control strategy. Whilst human attitude towards IRS is monitored before or shortly after implementation, human activities leading to the modification of insecticide-treated walls post-IRS are not. This could inadvertently reduce the protective effects of IRS. We monitored the extent of modifications to the sprayed indoor wall surfaces by household owners for six months post-IRS campaigns in two districts targeted for malaria elimination in southern Mozambique. In parallel, we assessed building of any additional rooms onto compounds, and mosquito net use. We quantified the contribution of wall modifications, added rooms, prolonged spray campaigns, and product residual efficacies on actual IRS coverage and relative mosquito bite reduction, using a mechanistic approach. Household owners continually modified insecticide-treated walls and added rooms onto compounds. Household surveys in southern Mozambique showed frequent modification of indoor walls (0-17.2% of households modified rooms monthly) and/or added rooms (0-16.2% of households added rooms monthly). Actual IRS coverage reduced from an assumed 97% to just 39% in Matutuine, but only from 96% to 91% in Boane, translating to 43% and 5.8% estimated increases in relative daily mosquito bites per person. Integrating post-IRS knowledge, attitude, and practice (KAP) surveys into programmatic evaluations to capture these modification and construction trends can help improve IRS program efficiency and product assessment.
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Affiliation(s)
- Mercy Opiyo
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, United Kingdom
| | - Arlindo Malheia
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Arsenio Nhacolo
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Charfudin Sacoor
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Ariel Nhacolo
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Mara Máquina
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Luis Jamu
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Nelson Cuamba
- National Malaria Control Programme of Mozambique (NMCP), Ministry of Health, Maputo, Mozambique
- PMI VectorLink Project, Abt Associates Inc., Maputo, Mozambique
| | - Quique Bassat
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- ICREA, Barcelona, Spain
- Pediatrics Department, Hospital Sant Joan de Déu, Universitat de Barcelona, Esplugues, Barcelona, Spain
- Consorcio de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
| | - Krijn Paaijmans
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
- The Biodesign Center for Immunotherapy, Vaccines, and Virotherapy, Arizona State University, Tempe, Arizona, United States of America
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, Arizona, United States of America
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Druetz T, Stresman G, Ashton RA, Joseph V, van den Hoogen L, Worges M, Hamre KES, Fayette C, Monestime F, Impoinvil D, Rogier E, Chang MA, Lemoine JF, Drakeley C, Eisele TP. The Immediate Effects of a Combined Mass Drug Administration and Indoor Residual Spraying Campaign to Accelerate Progress towards Malaria Elimination in Grande-Anse, Haiti. J Infect Dis 2021; 225:1611-1620. [PMID: 33993294 PMCID: PMC9071345 DOI: 10.1093/infdis/jiab259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/12/2021] [Indexed: 11/18/2022] Open
Abstract
Background Haiti is planning targeted interventions to accelerate progress toward malaria elimination. In the most affected department (Grande-Anse), a combined mass drug administration (MDA) and indoor residual spraying (IRS) campaign was launched in October 2018. This study assessed the intervention’s effectiveness in reducing Plasmodium falciparum prevalence. Methods An ecological quasi-experimental study was designed, using a pretest and posttest with a nonrandomized control group. Surveys were conducted in November 2017 in a panel of easy access groups (25 schools and 16 clinics) and were repeated 2–6 weeks after the campaign, in November 2018. Single-dose sulfadoxine-pyrimethamine and primaquine was used for MDA, and pirimiphos-methyl as insecticide for IRS. Results A total of 10 006 participants were recruited. Fifty-two percent of the population in the intervention area reported having received MDA. Prevalence diminished between 2017 and 2018 in both areas, but the reduction was significantly larger in the intervention area (ratio of adjusted risk ratios, 0.32 [95% confidence interval, .104–.998]). Conclusions Despite a moderate coverage, the campaign was effective in reducing P. falciparum prevalence immediately after 1 round. Targeted MDA plus IRS is useful in preelimination settings to rapidly decrease the parasite reservoir, an encouraging step to accelerate progress toward malaria elimination.
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Affiliation(s)
- Thomas Druetz
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans LA, USA.,Department of Social and Preventive Medicine, School of Public Health, University of Montreal, Montreal QC, Canada.,Centre de Recherche en Santé Publique, Montreal QC, Canada
| | - Gillian Stresman
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Ruth A Ashton
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans LA, USA
| | - Vena Joseph
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans LA, USA
| | - Lotus van den Hoogen
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans LA, USA
| | - Matt Worges
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans LA, USA
| | - Karen E S Hamre
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta GA, USA.,CDC Foundation, Atlanta GA, USA
| | | | | | - Daniel Impoinvil
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta GA, USA
| | - Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta GA, USA
| | - Michelle A Chang
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta GA, USA
| | - Jean Frantz Lemoine
- Programme National de Contrôle de la Malaria, Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Thomas P Eisele
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans LA, USA
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7
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ten Bosch QA, Wagman JM, Castro-Llanos F, Achee NL, Grieco JP, Perkins TA. Community-level impacts of spatial repellents for control of diseases vectored by Aedes aegypti mosquitoes. PLoS Comput Biol 2020; 16:e1008190. [PMID: 32976489 PMCID: PMC7541056 DOI: 10.1371/journal.pcbi.1008190] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 10/07/2020] [Accepted: 07/24/2020] [Indexed: 11/22/2022] Open
Abstract
Spatial repellents (SRs) reduce human-mosquito contact by preventing mosquito entrance into human-occupied spaces and interfering with host-seeking and blood-feeding. A new model to synthesize experimental data on the effects of transfluthrin on Aedes aegypti explores how SR effects interact to impact the epidemiology of diseases vectored by these mosquitoes. Our results indicate that the greatest impact on force of infection is expected to derive from the chemical’s lethal effect but delayed biting and the negative effect this may have on the mosquito population could elicit substantial impact in the absence of lethality. The relative contributions of these effects depend on coverage, chemical dose, and housing density. We also demonstrate that, through an increase in the number of potentially infectious mosquito bites, increased partial blood-feeding and reduced exiting may elicit adverse impacts, which could offset gains achieved by other effects. Our analysis demonstrates how small-scale experimental data can be leveraged to derive expectations of epidemiological impact of SRs deployed at larger scales. Mosquito control strategies that reduce bites to humans through multiple, non-lethal modes of action may be important in controlling mosquito-borne diseases where insecticidal strategies are ineffective. Assessing how effective such tools are in reducing infections is not clear-cut due to the multiple ways these products affect mosquitoes’ behavior and life cycle. We introduce a paired experimental and mathematical framework to analyze and combine data from experiments on the several effects of a transfluthrin formulation and assess its public health impact. We show that, while product-induced lethality accounts for the majority of the product’s impact, delayed blood feeding can, through its negative impact on mosquito population sizes, elicit its own substantial impact. Adverse effects of increased partial blood-feeding and reduced exiting could offset gains achieved by other effects such delayed blood feeding and lethality. Our model offers a way of synthesizing the results of feasible experiments at small scales to assess public health impact at large scales.
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Affiliation(s)
- Quirine A. ten Bosch
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail: (QAtB); (TAP)
| | - Joseph M. Wagman
- Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | | | - Nicole L. Achee
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - John P. Grieco
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - T. Alex Perkins
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail: (QAtB); (TAP)
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Combining next-generation indoor residual spraying and drug-based malaria control strategies: observational evidence of a combined effect in Mali. Malar J 2020; 19:293. [PMID: 32799873 PMCID: PMC7429948 DOI: 10.1186/s12936-020-03361-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 08/05/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ségou Region in central Mali is an area of high malaria burden with seasonal transmission. The region reports high access to and use of long-lasting insecticidal nets (LLINs), though the principal vector, Anopheles gambiae, is resistant to pyrethroids. From 2011 until 2016, several high-burden districts of Ségou also received indoor residual spraying (IRS), though in 2014 concerns about pyrethroid resistance prompted a shift in IRS products to a micro-encapsulated formulation of the organophosphate insecticide pirimiphos-methyl. Also in 2014, the region expanded a pilot programme to provide seasonal malaria chemoprevention (SMC) to children aged 3-59 months in two districts. The timing of these decisions presented an opportunity to estimate the impact of both interventions, deployed individually and in combination, using quality-assured passive surveillance data. METHODS A non-randomized, quasi-experimental time series approach was used to analyse monthly trends in malaria case incidence at the district level. Districts were stratified by intervention status: an SMC district, an IRS district, an IRS + SMC district, and control districts that received neither IRS nor SMC in 2014. The numbers of positive rapid diagnostic test (RDT +) results reported at community health facilities were aggregated and epidemiological curves showing the incidence of RDT-confirmed malaria cases per 10,000 person-months were plotted for the total all-ages and for the under 5 year old (u5) population. The cumulative incidence of RDT + malaria cases observed from September 2014 to February 2015 was calculated in each intervention district and compared to the cumulative incidence reported from the same period in the control districts. RESULTS Cumulative peak-transmission all-ages incidence was lower in each of the intervention districts compared to the control districts: 16% lower in the SMC district; 28% lower in the IRS district; and 39% lower in the IRS + SMC district. The same trends were observed in the u5 population: incidence was 15% lower with SMC, 48% lower with IRS, and 53% lower with IRS + SMC. The SMC-only intervention had a more moderate effect on incidence reduction initially, which increased over time. The IRS-only intervention had a rapid, comparatively large impact initially that waned over time. The impact of the combined interventions was both rapid and longer lasting. CONCLUSION Evaluating the impact of IRS with an organophosphate and SMC on reducing incidence rates of passive RDT-confirmed malaria cases in Ségou Region in 2014 suggests that combining the interventions had a greater effect than either intervention used individually in this high-burden region of central Mali with pyrethroid-resistant vectors and high rates of household access to LLINs.
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Tangena JAA, Hendriks CMJ, Devine M, Tammaro M, Trett AE, Williams I, DePina AJ, Sisay A, Herizo R, Kafy HT, Chizema E, Were A, Rozier J, Coleman M, Moyes CL. Indoor residual spraying for malaria control in sub-Saharan Africa 1997 to 2017: an adjusted retrospective analysis. Malar J 2020; 19:150. [PMID: 32276585 PMCID: PMC7149868 DOI: 10.1186/s12936-020-03216-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 03/30/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Indoor residual spraying (IRS) is a key tool for controlling and eliminating malaria by targeting vectors. To support the development of effective intervention strategies it is important to understand the impact of vector control tools on malaria incidence and on the spread of insecticide resistance. In 2006, the World Health Organization (WHO) stated that countries should report on coverage and impact of IRS, yet IRS coverage data are still sparse and unspecific. Here, the subnational coverage of IRS across sub-Saharan Africa for the four main insecticide classes from 1997 to 2017 were estimated. METHODS Data on IRS deployment were collated from a variety of sources, including the President's Malaria Initiative spray reports and National Malaria Control Programme reports, for all 46 malaria-endemic countries in sub-Saharan Africa from 1997 to 2017. The data were mapped to the applicable administrative divisions and the proportion of households sprayed for each of the four main insecticide classes; carbamates, organochlorines, organophosphates and pyrethroids was calculated. RESULTS The number of countries implementing IRS increased considerably over time, although the focal nature of deployment means the number of people protected remains low. From 1997 to 2010, DDT and pyrethroids were commonly used, then partly replaced by carbamates from 2011 and by organophosphates from 2013. IRS deployment since the publication of resistance management guidelines has typically avoided overlap between pyrethroid IRS and ITN use. However, annual rotations of insecticide classes with differing modes of action are not routinely used. CONCLUSION This study highlights the gaps between policy and practice, emphasizing the continuing potential of IRS to drive resistance. The data presented here can improve studies on the impact of IRS on malaria incidence and help to guide future malaria control efforts.
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Affiliation(s)
- Julie-Anne A Tangena
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK.
| | - Chantal M J Hendriks
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF, UK
| | - Maria Devine
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF, UK
| | - Meghan Tammaro
- President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Anna E Trett
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Ignatius Williams
- Monitoring, & Evaluation Department, AngloGold Ashanti Malaria Limited, AO0540595 Obuasi Mine Road, P. O. Box 10, Obuasi, Ghana
| | - Adilson José DePina
- Malaria Pre-Elimination Program, CCS-SIDA/MSSS, Avenida Cidade Lisboa, "Prédio Bô Casa" 1º Andar, CP, 855, Praia, Cabo Verde
- Ecole Doctorale Des Sciences de La Vie, de la Santé et de l´Environnement (ED‑SEV), Université Cheikh Anta Diop (UCAD) de Dakar, BP 1386, Dakar, Sénégal
| | | | - Ramandimbiarijaona Herizo
- Programme national de lutte contre le paludisme, Androhibe en face ENAM, BP 101, Antananarivo, Madagascar
| | - Hmooda Toto Kafy
- Integrated Vector Management Department, Federal Ministry of Health, Khartoum, Sudan
| | - Elizabeth Chizema
- National Malaria Elimination Centre, Chainama Hills Hospital Grounds, Lusaka, Zambia
| | - Allan Were
- President's Malaria Initiative Africa Indoor Residual Spraying Project, Abt Associates, 6130 Executive Blvd, Rockville, MD, 20852, USA
| | - Jennifer Rozier
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF, UK
| | - Michael Coleman
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Catherine L Moyes
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF, UK.
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