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Jiao J, Suarez GP, Fefferman NH. How public reaction to disease information across scales and the impacts of vector control methods influence disease prevalence and control efficacy. PLoS Comput Biol 2021; 17:e1008762. [PMID: 34181645 PMCID: PMC8270472 DOI: 10.1371/journal.pcbi.1008762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 07/09/2021] [Accepted: 05/28/2021] [Indexed: 11/10/2022] Open
Abstract
With the development of social media, the information about vector-borne disease incidence over broad spatial scales can cause demand for local vector control before local risk exists. Anticipatory intervention may still benefit local disease control efforts; however, infection risks are not the only focal concerns governing public demand for vector control. Concern for environmental contamination from pesticides and economic limitations on the frequency and magnitude of control measures also play key roles. Further, public concern may be focused more on ecological factors (i.e., controlling mosquito populations) or on epidemiological factors (i.e., controlling infection-carrying mosquitoes), which may lead to very different control outcomes. Here we introduced a generic Ross-MacDonald model, incorporating these factors under three spatial scales of disease information: local, regional, and global. We tailored and parameterized the model for Zika virus transmitted by Aedes aegypti mosquito. We found that sensitive reactivity caused by larger-scale incidence information could decrease average human infections per patch breeding capacity, however, the associated increase in total control effort plays a larger role, which leads to an overall decrease in control efficacy. The shift of focal concerns from epidemiological to ecological risk could relax the negative effect of the sensitive reactivity on control efficacy when mosquito breeding capacity populations are expected to be large. This work demonstrates that, depending on expected total mosquito breeding capacity population size, and weights of different focal concerns, large-scale disease information can reduce disease infections without lowering control efficacy. Our findings provide guidance for vector-control strategies by considering public reaction through social media.
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Affiliation(s)
- Jing Jiao
- National Institute for Mathematical and Biological Synthesis, The University of Tennessee, Knoxville, Tennessee, United States of America
- Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America
| | - Gonzalo P. Suarez
- Department of Agriculture and Biological Engineering, University of Florida, Gainesville, Florida, United States of America
| | - Nina H. Fefferman
- National Institute for Mathematical and Biological Synthesis, The University of Tennessee, Knoxville, Tennessee, United States of America
- Ecology & Evolutionary Biology, The University of Tennessee, Knoxville, Tennessee, United States of America
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Lemanski NJ, Schwab SR, Fonseca DM, Fefferman NH. Coordination among neighbors improves the efficacy of Zika control despite economic costs. PLoS Negl Trop Dis 2020; 14:e0007870. [PMID: 32569323 PMCID: PMC7332071 DOI: 10.1371/journal.pntd.0007870] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 07/02/2020] [Accepted: 03/30/2020] [Indexed: 01/09/2023] Open
Abstract
Emerging mosquito-borne viruses like Zika, dengue, and chikungunya pose a major threat to public health, especially in low-income regions of Central and South America, southeast Asia, and the Caribbean. Outbreaks of these diseases are likely to have long-term social and economic consequences due to Zika-induced congenital microcephaly and other complications. Larval control of the container-inhabiting mosquitoes that transmit these infections is an important tool for mitigating outbreaks. However, metapopulation theory suggests that spatiotemporally uneven larvicide treatment can impede control effectiveness, as recolonization compensates for mortality within patches. Coordinating the timing of treatment among patches could therefore substantially improve epidemic control, but we must also consider economic constraints, since coordination may have costs that divert resources from treatment. To inform practical disease management strategies, we ask how coordination among neighbors in the timing of mosquito control efforts influences the size of a mosquito-borne infectious disease outbreak under the realistic assumption that coordination has costs. Using an SIR (Susceptible-Infectious-Recovered)/metapopulation model of mosquito and disease dynamics, we examine whether sharing surveillance information and coordinating larvicide treatment among neighboring patches reduces human infections when incorporating coordination costs. We examine how different types of coordination costs and different surveillance methods jointly influence the effectiveness of larval control. We find that the effect of coordination depends on both costs and the type of surveillance used to inform treatment. With epidemiological surveillance, coordination improves disease outcomes, even when costly. With demographic surveillance, coordination either improves or hampers disease control, depending on the type of costs and surveillance sensitivity. Our results suggest coordination among neighbors can improve management of mosquito-borne epidemics under many, but not all, assumptions about costs. Therefore, estimating coordination costs is an important step for most effectively applying metapopulation theory to strategies for managing outbreaks of mosquito-borne viral infections.
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Affiliation(s)
- Natalie J. Lemanski
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee, United States of America
- * E-mail:
| | - Samantha R. Schwab
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Dina M. Fonseca
- Center for Vector Biology, Department of Entomology, Rutgers University, New Brunswick, New Jersey, United States of America
| | - Nina H. Fefferman
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee, United States of America
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Zhao Z, Hui C, Plant RE, Su M, Papadopoulos NT, Carpenter TE, Li Z, Carey JR. The failure of success: cyclic recurrences of a globally invasive pest. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01991. [PMID: 31400182 DOI: 10.1002/eap.1991] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 07/05/2019] [Accepted: 07/19/2019] [Indexed: 06/10/2023]
Abstract
In the six decades since 1960, the oriental fruit fly, Bactrocera dorsalis (Hendel), has been announced successfully eradicated in California by the U.S. Department of Agriculture a total of 564 times. This includes eradication declarations in one city a total of 25 different years, in 12 cities 8-19 different years, and in 101 cities 2-7 different years. We here show that the false negatives in declaring elimination success hinge on the easily achieved regulatory criteria, which have virtually guaranteed the failure of complete extirpation of this pest. Analyses of the time series of fly detection over California placed on a grid of 100-km2 cells revealed (1) partial success of the eradication program in controlling the invasion of the oriental fruit fly; (2) low prevalence of the initial detection in these cells is often followed by high prevalence of recurrences; (3) progressively shorter intervals between years of consecutive detections; and (4) high likelihood of early-infested cells also experiencing the most frequent outbreaks. Facing the risk of recurrent invasions, such short-term eradication programs have only succeeded annually according to the current regulatory criteria but have failed to achieve the larger goal of complete extirpation of the oriental fruit fly. Based on the components and running costs of the current programs, we further estimated the efficiency of eradication programs with different combinations of eradication radius, duration, and edge impermeability in reducing invasion recurrences and slowing the spread of the oriental fruit fly. We end with policy implications including the need for agricultural agencies worldwide to revisit eradication protocols in which monitoring and treatments are terminated when the regulatory criteria for declaring eradication are met. Our results also have direct implications to invasion biologists and agriculture policy makers regarding long-term risks of short-term expediency.
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Affiliation(s)
- Zihua Zhao
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Cang Hui
- Department of Mathematical Sciences, Centre for Invasion Biology, Stellenbosch University, Matieland, 7602, South Africa
- Mathematical and Physical Biosciences, African Institute for Mathematical Sciences, Muizenberg, 7945, South Africa
| | - Richard E Plant
- Department of Plant Sciences and Biological and Agricultural Engineering, University of California, Davis, California, 95616, USA
| | - Min Su
- School of Mathematics, Hefei University of Technology, Hefei, 230009, China
| | - Nikos T Papadopoulos
- Laboratory of Entomology and Agricultural Zoology, School of Agricultural Sciences, University of Thessaly, Thessaly, 38446, Greece
| | - Tim E Carpenter
- School of Veterinary Medicine, University of California, Davis, California, 95616, USA
| | - Zhihong Li
- Department of Entomology, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - James R Carey
- Department of Entomology, University of California, Davis, California, 95616, USA
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Stone CM, Schwab SR, Fonseca DM, Fefferman NH. Contrasting the value of targeted versus area-wide mosquito control scenarios to limit arbovirus transmission with human mobility patterns based on different tropical urban population centers. PLoS Negl Trop Dis 2019; 13:e0007479. [PMID: 31269020 PMCID: PMC6608929 DOI: 10.1371/journal.pntd.0007479] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 05/20/2019] [Indexed: 11/18/2022] Open
Abstract
Vector control is still our primary intervention for both prevention and mitigation of epidemics of many vector-borne diseases. Efficiently targeting control measures is important since control can involve substantial economic costs. Targeting is not always straightforward, as transmission of vector-borne diseases is affected by various types of host movement. Here we assess how taking daily commuting patterns into consideration can help improve vector control efforts. We examine three tropical urban centers (San Juan, Recife, and Jakarta) that have recently been exposed to Zika and/or dengue infections and consider whether the distribution of human populations and resulting commuting flows affects the optimal scale at which control interventions should be implemented. We developed a stochastic, spatial model and investigated four control scenarios. The scenarios differed in the spatial extent of their implementation and were: 1) a response at the level of an individual neighborhood; 2) a response targeted at a neighborhood in which infected humans were detected and the one with which it was most strongly connected by human movement; 3) a limited area-wide response where all neighborhoods within a certain radius of the focal area were included; and 4) a collective response where all participating neighborhoods implemented control. The relative effectiveness of the scenarios varied only slightly between different settings, with the number of infections averted over time increasing with the scale of implementation. This difference depended on the efficacy of control at the neighborhood level. At low levels of efficacy, the scenarios mirrored each other in infections averted. At high levels of efficacy, impact increased with the scale of the intervention. As a result, the choice between scenarios will not only be a function of the amount of effort decision-makers are willing to invest, but largely epend on the overall effectiveness of vector control approaches. Control and prevention of Aedes-transmitted viruses, such as dengue, chikungunya, or Zika relies heavily on vector control approaches. Given the effort and cost involved in implementation of vector control, targeting of control measures is highly desirable. However, it is unclear to what extent the effectiveness of highly focal and reactive control measures depends on the commuting and movement patterns of humans. To investigate this question, we developed a model and four control scenarios that ranged from highly focal to area-wide larval control. The distribution of humans and their commuting patterns were modelled after three major tropical urban centers, San Juan, Recife, and Jakarta. We show that as implementation is applied across a wider area, a greater number of infections is averted. Critically, this only occurs if the efficacy of control at the neighborhood level is sufficiently high. A consistent outcome across the three settings was that the focal strategy was most likely to provide the best outcome at lower levels of effort, and when the efficacy of control was low. These outcomes suggest that optimal control strategies will likely have to be tailored to individual settings by decision makers and would benefit from localized cost-effectiveness modelling studies.
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Affiliation(s)
- Chris M. Stone
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, Champaign, IL, United Sates of America
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, United Sates of America
- * E-mail:
| | - Samantha R. Schwab
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ, United Sates of America
| | - Dina M. Fonseca
- Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, NJ, United Sates of America
- Center for Vector Biology, Rutgers University, New Brunswick, NJ, United Sates of America
| | - Nina H. Fefferman
- Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN, United Sates of America
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Schwab SR, Stone CM, Fonseca DM, Fefferman NH. (Meta)population dynamics determine effective spatial distributions of mosquito-borne disease control. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01856. [PMID: 30681219 DOI: 10.1002/eap.1856] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 11/19/2018] [Accepted: 12/21/2018] [Indexed: 06/09/2023]
Abstract
Recent epidemics of mosquito-borne dengue and Zika viruses demonstrate the urgent need for effective measures to control these diseases. The best method currently available to prevent or reduce the size of outbreaks is to reduce the abundance of their mosquito vectors, but there is little consensus on which mechanisms of control are most effective, or when and where they should be implemented. Although the optimal methods are likely context dependent, broadly applicable strategies for mosquito control, such as how to distribute limited resources across a landscape in times of high epidemic risk, can mitigate (re)emerging outbreaks. We used mathematical simulations to examine how the spatial distribution of larval mosquito control affects the size of disease outbreaks, and how mosquito metapopulation dynamics and demography might impact the efficacy of different spatial distributions of control. We found that the birth rate and mechanism of density-dependent regulation of mosquito populations affected the average outbreak size across all control distributions. These factors also determined whether control distributions favoring the interior or the edges of the landscape most effectively reduced human infections. Thus, understanding local mosquito population regulation and dispersion can lead to more effective control strategies.
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Affiliation(s)
- Samantha R Schwab
- Graduate Program in Ecology and Evolution, Environmental & Natural Resource Sciences Building, Room 150, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, New Jersey 08901-8551, USA
| | - Chris M Stone
- Illinois Natural History Survey, University of Illinois at Urbana-Champaign, 1816 South Oak Street, MC 652, Champaign, Illinois, 61820, USA
- Department of Ecology and Evolutionary Biology, University of Tennessee, 447 Hesler Biology Building, Knoxvillle, Tennessee, 37996-1610, USA
| | - Dina M Fonseca
- Center for Vector Biology, School of Environmental & Biological Sciences Rutgers, The State University of New Jersey, 178-180 Jones Ave, New Brunswick, New Jersey, 08901-8536, USA
| | - Nina H Fefferman
- Department of Ecology and Evolutionary Biology, University of Tennessee, 447 Hesler Biology Building, Knoxvillle, Tennessee, 37996-1610, USA
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