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Moscovitz S, Glassner H, Wokam Njomgang RM, Aflalo ED, Ovadia O, Sagi A. Community composition of invasive, outbreak, and non-pest snail species along a source spring-to-fishpond gradient in a spatially structured aquacultural region. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119653. [PMID: 38070421 DOI: 10.1016/j.jenvman.2023.119653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 11/16/2023] [Accepted: 11/16/2023] [Indexed: 01/14/2024]
Abstract
Agricultural lands are integrated into and interact with natural areas. Such is the case of Emek HaMa'ayanot, northern Israel, comprising a springs-rich area characterized by multiple land-uses, including spring-water-based aquaculture, recreational springs, and nature reserves. Aquacultural farms suffer from pest snails that carry fish disease; in the study region, these species are invasive (Thiara scabra, Tarebia granifera, Pseudosuccinea columella) and outbreak endemic (Melanoides tuberculata). Previous snail control efforts have focused on individual fishponds without considering management on larger environmental scales in the waterways from the source springs to the fish farms. To broaden our understanding of the status of the pest snail problem in the study area prior to suggesting environmental managerial solutions, we quantified changes in the community composition of snail species along the springs-to-fishponds gradients in a spatially explicit system. We found a remarkable increase in pest snail abundances along these gradients, indicating that pest snails might be invading upstream towards the springs. There were always nearly 100% pest snails in the endpoint sites for water tracks that ended in fishponds. Moreover, pest snails dominated the site when it was used as a fishpond, even though the site was also a spring. In contrast, in a water track that does not end in a fish farm, the relative abundances of non-pest snail species was similar between the source spring and the downstream endpoint, in spite of an increase in pest snail abundance at a midpoint site. These results suggest that invasive pest snails are actively moving upstream and that the fishponds have a marked upstream effect on the ability of non-pest snails to resist pest species invasions. We suggest further investigation of possible strategies for biocontrol of the observed invasion of the snails into natural areas as a basis for environmental management efforts. Finally, the observations made during this study could have practical global implications for snail management in aquaculture and agriculture, and for the control of snails and snail vectors implicated in animal and human diseases.
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Affiliation(s)
- Sharon Moscovitz
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel
| | - Hanoch Glassner
- Eden Research Station, Mobile Post Beit Shean, 11710, Israel
| | | | - Eliahu D Aflalo
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel; Department of Life Sciences, Achva Academic College, Mobile Post Shikmim, 79800, Israel
| | - Ofer Ovadia
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel; Goldman Sonnenfeldt School of Sustainability and Climate Change, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel.
| | - Amir Sagi
- Department of Life Sciences, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel; National Institute for Biotechnology in the Negev (NIBN), Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva, 84105, Israel.
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Semakula HM, Liang S, Mukwaya PI, Mugagga F, Swahn M, Nseka D, Wasswa H, Kayima P. Determinants of malaria infections among children in refugee settlements in Uganda during 2018-2019. Infect Dis Poverty 2023; 12:31. [PMID: 37032366 PMCID: PMC10084630 DOI: 10.1186/s40249-023-01090-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 03/29/2023] [Indexed: 04/11/2023] Open
Abstract
BACKGROUND While 5% of 247 million global malaria cases are reported in Uganda, it is also a top refugee hosting country in Africa, with over 1.36 million refugees. Despite malaria being an emerging challenge for humanitarian response in refugee settlements, little is known about its risk factors. This study aimed to investigate the risk factors for malaria infections among children under 5 years of age in refugee settlements in Uganda. METHODS We utilized data from Uganda's Malaria Indicator Survey which was conducted between December 2018 and February 2019 at the peak of malaria season. In this national survey, household level information was obtained using standardized questionnaires and a total of 7787 children under 5 years of age were tested for malaria using mainly the rapid diagnostic test. We focused on 675 malaria tested children under five in refugee settlements located in Yumbe, Arua, Adjumani, Moyo, Lamwo, Kiryadongo, Kyegegwa, Kamwenge and Isingiro districts. The extracted variables included prevalence of malaria, demographic, social-economic and environmental information. Multivariable logistic regression was used to identify and define the malaria associated risk factors. RESULTS Overall, malaria prevalence in all refugee settlements across the nine hosting districts was 36.6%. Malaria infections were higher in refugee settlements located in Isingiro (98.7%), Kyegegwa (58.6%) and Arua (57.4%) districts. Several risk factors were significantly associated with acquisition of malaria including fetching water from open water sources [adjusted odds ratio (aOR) = 1.22, 95% CI: 0.08-0.59, P = 0.002], boreholes (aOR = 2.11, 95% CI: 0.91-4.89, P = 0.018) and water tanks (aOR = 4.47, 95% CI: 1.67-11.9, P = 0.002). Other factors included pit-latrines (aOR = 1.48, 95% CI: 1.03-2.13, P = 0.033), open defecation (aOR = 3.29, 95% CI: 1.54-7.05, P = 0.002), lack of insecticide treated bed nets (aOR = 1.15, 95% CI: 0.43-3.13, P = 0.003) and knowledge on the causes of malaria (aOR = 1.09, 95% CI: 0.79-1.51, P = 0.005). CONCLUSIONS The persistence of the malaria infections were mainly due to open water sources, poor hygiene, and lack of preventive measures that enhanced mosquito survival and infection. Malaria elimination in refugee settlements requires an integrated control approach that combines environmental management with other complementary measures like insecticide treated bed nets, indoor residual spraying and awareness.
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Affiliation(s)
- Henry Musoke Semakula
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda.
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, 2055 Mowry Rd, Gainesville, FL, 32610, USA.
| | - Song Liang
- Department of Environmental and Global Health, College of Public Health and Health Professions, University of Florida, 2055 Mowry Rd, Gainesville, FL, 32610, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Paul Isolo Mukwaya
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
| | - Frank Mugagga
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
| | - Monica Swahn
- Wellstar College of Health and Human Services, Kennesaw State University, Kennesaw, NW, USA
| | - Denis Nseka
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
| | - Hannington Wasswa
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
| | - Patrick Kayima
- Department of Geography, Geo-informatics and Climatic Sciences, Makerere University, P. O Box 7062, Kampala, Uganda
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Rinaldo A, Rodriguez-Iturbe I. Ecohydrology 2.0. RENDICONTI LINCEI. SCIENZE FISICHE E NATURALI 2022; 33:245-270. [PMID: 35673327 PMCID: PMC9165276 DOI: 10.1007/s12210-022-01071-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/27/2022] [Indexed: 11/23/2022]
Abstract
This paper aims at a definition of the domain of ecohydrology, a relatively new discipline borne out of an intrusion-as advertised by this Topical Collection of the Rendiconti Lincei-of hydrology and geomorphology into ecology (or vice-versa, depending on the reader's background). The study of hydrologic controls on the biota proves, in our view, significantly broader than envisioned by its original focus that was centered on the critical zone where much of the action of soil, climate and vegetation interactions takes place. In this review of related topics and contributions, we propose a reasoned broadening of perspective, in particular by firmly centering ecohydrology on the fluvial catchment as its fundamental control volume. A substantial unity of materials and methods suggests that our advocacy may be considered legitimate.
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Affiliation(s)
- Andrea Rinaldo
- Accademia Nazionale dei Lincei, Rome, Italy
- Laboratory of Ecohydrology ENAC/IIE/ECHO, École Polytechinque Fédérale de Lausanne, Lausanne, Switzerland
- Dipartimento ICEA, Università degli studi di Padova, Padua, Italy
| | - Ignacio Rodriguez-Iturbe
- Department of Ocean Engineering, Texas A&M University, College Station, TX USA
- Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX USA
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Deka MA. Predictive Risk Mapping of Schistosomiasis in Madagascar Using Ecological Niche Modeling and Precision Mapping. Trop Med Infect Dis 2022; 7:15. [PMID: 35202211 PMCID: PMC8876685 DOI: 10.3390/tropicalmed7020015] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 01/10/2022] [Accepted: 01/13/2022] [Indexed: 01/27/2023] Open
Abstract
Schistosomiasis is a neglected tropical disease (NTD) found throughout tropical and subtropical Africa. In Madagascar, the condition is widespread and endemic in 74% of all administrative districts in the country. Despite the significant burden of the disease, high-resolution risk maps have yet to be produced to guide national control programs. This study used an ecological niche modeling (ENM) and precision mapping approach to estimate environmental suitability and disease transmission risk. The results show that suitability for schistosomiasis is widespread and covers 264,781 km2 (102,232 sq miles). Covariates of significance to the model were the accessibility to cities, distance to water, enhanced vegetation index (EVI), annual mean temperature, land surface temperature (LST), clay content, and annual precipitation. Disease transmission risk is greatest in the central highlands, tropical east coast, arid-southwest, and northwest. An estimated 14.9 million people could be at risk of schistosomiasis; 11.4 million reside in rural areas, while 3.5 million are in urban areas. This study provides valuable insight into the geography of schistosomiasis in Madagascar and its potential risk to human populations. Because of the focal nature of the disease, these maps can inform national surveillance programs while improving understanding of areas in need of medical interventions.
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Affiliation(s)
- Mark A Deka
- Centers for Disease Control and Prevention (CDC), 4770 Buford Hwy NE, Atlanta, GA 30341, USA
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Kadaleka S, Abelman S, Tchuenche JM. A Mathematical Model of the Transmission Dynamics of Bovine Schistosomiasis with Contaminated Environment. Acta Biotheor 2022; 70:9. [PMID: 35020068 DOI: 10.1007/s10441-021-09434-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 12/28/2021] [Indexed: 11/01/2022]
Abstract
Schistosomiasis, a vector-borne chronically debilitating infectious disease, is a serious public health concern for humans and animals in the affected tropical and sub-tropical regions. We formulate and theoretically analyze a deterministic mathematical model with snail and bovine hosts. The basic reproduction number [Formula: see text] is computed and used to investigate the local stability of the model's steady states. Global stability of the endemic equilibrium is carried out by constructing a suitable Lyapunov function. Sensitivity analysis shows that the basic reproduction number is most sensitive to the model parameters related to the contaminated environment, namely: shedding rate of cercariae by snails, cercariae to miracidia survival probability, snails-miracidia effective contact rate and natural death rate of miracidia and cercariae. Numerical results show that when no intervention measures are implemented, there is an increase of the infected classes, and a rapid decline of the number of susceptible and exposed bovines and snails. Effects of the variation of some of the key sensitive model parameters on the schistosomiasis dynamics as well as on the initial disease transmission threshold parameter [Formula: see text] are graphically depicted.
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Ossai EC, Eze AA, Ogugofor MO. Plant-derived compounds for the treatment of schistosomiasis: Improving efficacy via nano-drug delivery. Niger J Clin Pract 2022; 25:747-764. [DOI: 10.4103/njcp.njcp_1322_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Lund AJ, Wade KJ, Nikolakis ZL, Ivey KN, Perry BW, Pike HNC, Paull SH, Liu Y, Castoe TA, Pollock DD, Carlton EJ. Integrating genomic and epidemiologic data to accelerate progress toward schistosomiasis elimination. eLife 2022; 11:79320. [PMID: 36040013 PMCID: PMC9427098 DOI: 10.7554/elife.79320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Accepted: 08/11/2022] [Indexed: 11/13/2022] Open
Abstract
The global community has adopted ambitious goals to eliminate schistosomiasis as a public health problem, and new tools are needed to achieve them. Mass drug administration programs, for example, have reduced the burden of schistosomiasis, but the identification of hotspots of persistent and reemergent transmission threaten progress toward elimination and underscore the need to couple treatment with interventions that reduce transmission. Recent advances in DNA sequencing technologies make whole-genome sequencing a valuable and increasingly feasible option for population-based studies of complex parasites such as schistosomes. Here, we focus on leveraging genomic data to tailor interventions to distinct social and ecological circumstances. We consider two priority questions that can be addressed by integrating epidemiological, ecological, and genomic information: (1) how often do non-human host species contribute to human schistosome infection? and (2) what is the importance of locally acquired versus imported infections in driving transmission at different stages of elimination? These questions address processes that can undermine control programs, especially those that rely heavily on treatment with praziquantel. Until recently, these questions were difficult to answer with sufficient precision to inform public health decision-making. We review the literature related to these questions and discuss how whole-genome approaches can identify the geographic and taxonomic sources of infection, and how such information can inform context-specific efforts that advance schistosomiasis control efforts and minimize the risk of reemergence.
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Affiliation(s)
- Andrea J Lund
- Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado AnschutzAuroraUnited States
| | - Kristen J Wade
- Department of Biochemistry & Molecular Genetics, University of Colorado School of MedicineAuroraUnited States
| | - Zachary L Nikolakis
- Department of Biology, University of Texas at ArlingtonArlingtonUnited States
| | - Kathleen N Ivey
- Department of Biology, University of Texas at ArlingtonArlingtonUnited States
| | - Blair W Perry
- Department of Biology, University of Texas at ArlingtonArlingtonUnited States
| | - Hamish NC Pike
- Department of Biochemistry & Molecular Genetics, University of Colorado School of MedicineAuroraUnited States
| | - Sara H Paull
- Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado AnschutzAuroraUnited States
| | - Yang Liu
- Sichuan Centers for Disease Control and PreventionChengduChina
| | - Todd A Castoe
- Department of Biology, University of Texas at ArlingtonArlingtonUnited States
| | - David D Pollock
- Department of Biochemistry & Molecular Genetics, University of Colorado School of MedicineAuroraUnited States
| | - Elizabeth J Carlton
- Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado AnschutzAuroraUnited States
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Ojo JA, Adedokun SA, Akindele AA, Olorunfemi AB, Otutu OA, Ojurongbe TA, Thomas BN, Velavan TP, Ojurongbe O. Prevalence of urogenital and intestinal schistosomiasis among school children in South-west Nigeria. PLoS Negl Trop Dis 2021; 15:e0009628. [PMID: 34314428 PMCID: PMC8345861 DOI: 10.1371/journal.pntd.0009628] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 08/06/2021] [Accepted: 07/05/2021] [Indexed: 01/25/2023] Open
Abstract
Background The risk of co-infection with Schistosoma haematobium and S. mansoni and the potential harmful effect on morbidity and control is enhanced by the overlapping distribution of both species in sub-Saharan Africa. Despite the reported high endemicity of both species in Nigeria, studies on the spread and effect of their mixed infection are limited. Therefore, a cross-sectional survey was conducted among school children in two communities in South-west Nigeria to investigate the prevalence of mixed human schistosome infection, intensity, and possible ectopic egg elimination. Methods Urine and stool samples were collected from consenting school children in Ilie and Ore communities of Osun State, Nigeria. Schistosoma haematobium eggs were detected in urine using the urine filtration technique, while S. mansoni eggs were detected in stool using the Kato–Katz thick smear technique. Results The study enrolled 466 primary and secondary school children (211; 45.3% males vs. 255; 54.7% females; mean age 11.6 ± 3.16 years). The overall prevalence of schistosomiasis was 40% (185/466), with 19% (89/466) recording single S. haematobium infection while 9% (41/465) had a single S. mansoni infection. The geometric mean egg count for S. haematobium was 189.4 egg/10ml urine; 95% CI: range 115.9–262.9, while for S. mansoni, it was 115.7 epg; 95% CI: range 78.4–152.9. The prevalence of ectopic S mansoni (S. mansoni eggs in urine) was 4.7%, while no ectopic S. haematobium (S. haematobium eggs in stool) was recorded. Mixed infection of S. haematobium/S. mansoni had a prevalence of 9.5% (44/466). More females (54.5%) presented with S. haematobium/S. mansoni co-infection. For both parasites, males had higher infection intensity, with a significant difference observed with S. haematobium (p = 0.0004). Hematuria was significant in individuals with single S. haematobium infection (p = 0.002), mixed ectopic S. haematobium/S. mansoni (p = 0.009) and mixed S. haematobium/S. mansoni/ectopic S. mansoni (p = 0.0003). Conclusions These findings suggest the probability of interspecific interactions between S. haematobium and S. mansoni. Scaling up of mass administration of praziquantel and control measures in the study areas is highly desirable. In sub-Saharan Africa, human schistosomiasis is a neglected disease of public health concern caused mostly by Schistosoma haematobium and Schistosoma mansoni. The overlapping range of both species in Africa considerably increases the chance of co-infection. School-aged children are the most vulnerable, as they participate in water contact activities that expose them to free-swimming cercariae released by infected snail species in freshwater. This study examined the probable mixed human Schistosoma infections and associated disease variables in school children in the communities of Ilie and Ore in southwest Nigeria. This study reveals a high prevalence of mixed S. haematobium and S. mansoni, and ectopic S. mansoni eggs (S. mansoni eggs in urine) elimination, highlighting the possible ongoing control challenges in this area. Furthermore, this study indicates that some form of inter-specific interaction exists between S. haematobium and S. mansoni, and may produce potentially significant consequences for developing morbidity in the study areas.
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Affiliation(s)
- Johnson A. Ojo
- Department of Medical Microbiology & Parasitology, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Samuel A. Adedokun
- Department of Medical Microbiology & Parasitology, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Akeem A. Akindele
- Department of Medical Microbiology & Parasitology, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Adedolapo B. Olorunfemi
- Department of Medical Microbiology & Parasitology, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Olawumi A. Otutu
- Department of Medical Microbiology & Parasitology, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
| | - Taiwo A. Ojurongbe
- Department of Mathematical Sciences, Osun State University, Osogbo, Nigeria
| | - Bolaji N. Thomas
- Department of Biomedical Sciences, College of Health Sciences and Technology, Rochester Institute of Technology, Rochester New York, United States of America
| | - Thirumalaisamy P. Velavan
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
- Vietnamese German Center for Medical Research (VG-CARE), Hanoi, Vietnam
| | - Olusola Ojurongbe
- Department of Medical Microbiology & Parasitology, Ladoke Akintola University of Technology, Ogbomoso, Nigeria
- * E-mail:
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Belizario VY, Delos Trinos JPCR, Lentejas N, Alonte AJ, Cuayzon AN, Isiderio ME, Delgado R, Tejero M, Molina VB. Use of geographic information system as a tool for schistosomiasis surveillance in an endemic Municipality in Eastern Samar, The Philippines. GEOSPATIAL HEALTH 2021; 16. [PMID: 34000789 DOI: 10.4081/gh.2021.957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Accepted: 03/03/2021] [Indexed: 06/12/2023]
Abstract
This study aimed to demonstrate the use of geographic information systems (GIS) in identifying factors contributing to schistosomiasis endemicity and identifying high-risk areas in a schistosomiasis- endemic municipality in the Philippines, which was devastated by Typhoon Haiyan in 2013. Data on schistosomiasis determinants, obtained through literature review, the Philippine Department of Health, and concerned local government units, were standardized and incorporated into a GIS map using ArcGIS. Data gathered included modifiable [agriculture, poverty, sanitation, presence of intermediate and reservoir hosts, disease prevalence and mass drug administration (MDA) coverage] and nonmodifiable (geography and climate) determinants for schistosomiasis. Results showed that most barangays (villages) are characterized by favourable conditions for schistosomiasis transmission which include being located in flood-prone areas, presence of vegetation, low sanitary toilet coverage, presence of snail intermediate host, high carabao (water buffalo) population density, previously reported ≥1% prevalence using Kato-Katz technique, and low MDA coverage. Similarly, barangays not known to be endemic for schistosomiasis but also characterized by the same favourable conditions for schistosomiasis as listed above and may therefore be considered as potentially endemic, even if not being high-risk areas. This study demonstrated the importance of GIS technology in characterizing schistosomiasis transmission. Maps generated through application of GIS technology are useful in guiding program policy and planning at the local level for an effective and sustainable schistosomiasis control and prevention.
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Affiliation(s)
- Vicente Y Belizario
- College of Public Health, University of the Philippines Manila, Manila, Philippines; Neglected Tropical Diseases Study Group, National Institutes of Health, University of the Philippines Manila, Manila.
| | - John Paul Caesar R Delos Trinos
- Neglected Tropical Diseases Study Group, National Institutes of Health, University of the Philippines Manila, Manila, Philippines; Kirby Institute, University of New South Wales Sydney, Sydney.
| | | | - Allen J Alonte
- Neglected Tropical Diseases Study Group, National Institutes of Health, University of the Philippines Manila, Manila.
| | - Agnes N Cuayzon
- Department of Health Centre for Health Development, Eastern Visayas.
| | | | | | | | - Victorio B Molina
- College of Public Health, University of the Philippines Manila, Manila.
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Spatial scales in human movement between reservoirs of infection. J Theor Biol 2021; 524:110726. [PMID: 33895180 PMCID: PMC8204271 DOI: 10.1016/j.jtbi.2021.110726] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 11/22/2022]
Abstract
Simple, yet flexible, model of human movement patterns. Analytic formalism which can be used to derive important spatial scales. Introduces a novel drift–diffusion approximation for stochastic reservoirs. A new critical spatial scale predicted for helminth reservoirs of infection. The necessary data needed to test these predictions is outlined in detail.
The life cycle of parasitic organisms that are the cause of much morbidity in humans often depend on reservoirs of infection for transmission into their hosts. Understanding the daily, monthly and yearly movement patterns of individuals between reservoirs is therefore of great importance to implementers of control policies seeking to eliminate various parasitic diseases as a public health problem. This is due to the fact that the underlying spatial extent of the reservoir of infection, which drives transmission, can be strongly affected by inputs from external sources, i.e., individuals who are not spatially attributed to the region defined by the reservoir itself can still migrate and contribute to it. In order to study the importance of these effects, we build and examine a novel theoretical model of human movement between spatially-distributed focal points for infection clustered into regions defined as ‘reservoirs of infection’. Using our model, we vary the spatial scale of human moment defined around focal points and explicitly calculate how varying this definition can influence the temporal stability of the effective transmission dynamics – an effect which should strongly influence how control measures, e.g., mass drug administration (MDA), define evaluation units (EUs). Considering the helminth parasites as our main example, by varying the spatial scale of human movement, we demonstrate that a critical scale exists around infectious focal points at which the migration rate into their associated reservoir can be neglected for practical purposes. This scale varies by species and geographic region, but is generalisable as a concept to infectious reservoirs of varying spatial extents and shapes. Our model is designed to be applicable to a very general pattern of infectious disease transmission modified by the migration of infected individuals between clustered communities. In particular, it may be readily used to study the spatial structure of hosts for macroparasites with temporally stationary distributions of infectious focal point locations over the timescales of interest, which is viable for the soil-transmitted helminths and schistosomes. Additional developments will be necessary to consider diseases with moving reservoirs, such as vector-born filarial worm diseases.
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Ntajal J, Evers M, Kistemann T, Falkenberg T. Influence of human-surface water interactions on the transmission of urinary schistosomiasis in the Lower Densu River basin, Ghana. Soc Sci Med 2020; 288:113546. [PMID: 33277069 DOI: 10.1016/j.socscimed.2020.113546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 10/17/2020] [Accepted: 11/19/2020] [Indexed: 10/22/2022]
Affiliation(s)
- Joshua Ntajal
- Department of Geography, University of Bonn, Germany; Center for Development Research, University of Bonn, Germany.
| | - Mariele Evers
- Department of Geography, University of Bonn, Germany
| | - Thomas Kistemann
- GeoHealth Centre, Institute for Hygiene and Public Health, University of Bonn, Germany
| | - Timo Falkenberg
- Center for Development Research, University of Bonn, Germany; GeoHealth Centre, Institute for Hygiene and Public Health, University of Bonn, Germany
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Hoover CM, Sokolow SH, Kemp J, Sanchirico JN, Lund AJ, Jones IJ, Higginson T, Riveau G, Savaya A, Coyle S, Wood CL, Micheli F, Casagrandi R, Mari L, Gatto M, Rinaldo A, Perez-Saez J, Rohr JR, Sagi A, Remais JV, De Leo GA. Modelled effects of prawn aquaculture on poverty alleviation and schistosomiasis control. NATURE SUSTAINABILITY 2020; 2:611-620. [PMID: 33313425 PMCID: PMC7731924 DOI: 10.1038/s41893-019-0301-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 04/26/2019] [Indexed: 05/23/2023]
Abstract
Recent evidence suggests that snail predators may aid efforts to control the human parasitic disease schistosomiasis by eating aquatic snail species that serve as intermediate hosts of the parasite. Potential synergies between schistosomiasis control and aquaculture of giant prawns are evaluated using an integrated bio-economic-epidemiologic model. Combinations of stocking density and aquaculture cycle length that maximize cumulative, discounted profit are identified for two prawn species in sub-Saharan Africa: the endemic, non-domesticated Macrobrachium vollenhovenii, and the non-native, domesticated Macrobrachium rosenbergii. At profit maximizing densities, both M. rosenbergii and M. vollenhovenii may substantially reduce intermediate host snail populations and aid schistosomiasis control efforts. Control strategies drawing on both prawn aquaculture to reduce intermediate host snail populations and mass drug administration to treat infected individuals are found to be superior to either strategy alone. Integrated aquaculture-based interventions can be a win-win strategy in terms of health and sustainable development in schistosomiasis endemic regions of the world.
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Affiliation(s)
- Christopher M. Hoover
- Division of Environmental Health Sciences, University of California, Berkeley School of Public Health, Berkeley, CA 94720 USA
| | - Susanne H. Sokolow
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950 USA
- Woods Institute for the Environment and Center for Innovation in Global Health, Stanford University, Stanford, CA 94305 USA
| | - Jonas Kemp
- Program in Human Biology, Stanford University, Stanford, CA 94305 USA
| | - James N. Sanchirico
- Department of Environmental Science and Policy, University of California, Davis, Davis, CA 95616 USA
| | - Andrea J. Lund
- Emmett Interdisciplinary Program in Environment and Resources, School of Earth, Energy and Environmental Sciences, Stanford University, Stanford, CA 94305 USA
| | - Isabel J. Jones
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950 USA
| | - Tyler Higginson
- Middlebury Institute of International Studies at Monterey, Monterey, CA 93940 USA
| | - Gilles Riveau
- Biomedical Research Center EPLS, Saint Louis, Senegal
| | - Amit Savaya
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Shawn Coyle
- Kentucky State University, Aquaculture Division, Aquaculture Research Center, Frankfort, KY 40601 USA
| | - Chelsea L. Wood
- University of Washington, School of Aquatic and Fishery Sciences, Seattle, WA 98195 USA
| | - Fiorenza Micheli
- Hopkins Marine Station and Center for Ocean Solutions, Stanford University, Pacific Grove, CA 93950 USA
| | - Renato Casagrandi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Lorenzo Mari
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Andrea Rinaldo
- Laboratory of Ecohydrology, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Switzerland
| | - Javier Perez-Saez
- Laboratory of Ecohydrology, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Switzerland
| | - Jason R. Rohr
- Department of Biological Sciences, Eck Institute of Global Health, Environmental Change Initiative University of Notre Damea, Notre Dame, IN, 46556 USA
- Department of Integrative Biology, University of South Florida, Tampa, FL, 33620 USA
| | - Amir Sagi
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben Gurion University of the Negev, Beer Sheva, Israel
| | - Justin V. Remais
- Division of Environmental Health Sciences, University of California, Berkeley School of Public Health, Berkeley, CA 94720 USA
| | - Giulio A. De Leo
- Department of Biology, Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950 USA
- Woods Institute for the Environment and Center for Innovation in Global Health, Stanford University, Stanford, CA 94305 USA
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13
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Tiruneh A, Kahase D, Zemene E, Tekalign E, Solomon A, Mekonnen Z. Identification of transmission foci of Schistosoma mansoni: narrowing the intervention target from district to transmission focus in Ethiopia. BMC Public Health 2020; 20:769. [PMID: 32448159 PMCID: PMC7245888 DOI: 10.1186/s12889-020-08904-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/12/2020] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Schistosoma mansoni (S. mansoni) infection is a significant public health problem in Ethiopia, and has wide distribution in the country. The impact of the disease is particularly high on school-age children. Nationwide 385 endemic districts were identified, whereby control and elimination interventions are underway using school-based annual mass drug administration (MDA) with praziquantel. The national elimination program targets endemic districts as a whole. The aim of this study was to identify the transmission foci of Schistosoma mansoni and determine prevalence of soil-transmitted helminths (STHs) in Abeshge district. METHODS The study was conducted from April to May, 2019 among school-age children randomly selected from public elementary schools in Abeshge district, South-central Ethiopia. Demographic information and data on risk factors of S. mansoni infection were gathered using pre-tested questionnaire. Moreover, a stool sample was collected from each child and examined using Kato-Katz thick smear technique. The data were analyzed using STATA_MP version 12. RESULTS A total of 389 school-age children from five public elementary schools were included in the study. The overall prevalence of S. mansoni and STHs was 19.3% (75/389) and 35% (136/389), respectively. The prevalence of S. mansoni was 60.6% in Kulit Elementary school, while it was zero in Geraba. The prevalence of S. mansoni was significantly higher among males (AOR = 2.6, 95% CI 1.3-5.1), those with habit of swimming and/or bathing in rivers (AOR = 2.9, 95%CI 1.3-5.1) and involved in irrigation activities (AOR = 2.9, 95% CI 1.0-8.3). Overall, the prevalence of S. mansoni was significantly higher among school children attending Kulit Elementary School compared to those attending the remaining schools (AOR = 12.5, 95%CI 6.2-25.1). CONCLUSION A wide variation of S. mansoni prevalence was observed among the school children in the different schools. Control interventions better identify and target foci of S. mansoni transmission, instead of targeting the district homogenously.
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Affiliation(s)
- Abebaw Tiruneh
- School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Daniel Kahase
- Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Wolkite University, Wolkite, Ethiopia
| | - Endalew Zemene
- School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Eyob Tekalign
- Department of Medical Laboratory Sciences, College of Health Sciences, Mizan-Tepi University, Mizan-Tepi, Ethiopia
| | - Absra Solomon
- Department of Medical Laboratory Sciences, College of Medicine and Health Sciences, Wolkite University, Wolkite, Ethiopia
| | - Zeleke Mekonnen
- School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
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14
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Gatto M, Bertuzzo E, Mari L, Miccoli S, Carraro L, Casagrandi R, Rinaldo A. Spread and dynamics of the COVID-19 epidemic in Italy: Effects of emergency containment measures. Proc Natl Acad Sci U S A 2020; 117:10484-10491. [PMID: 32327608 PMCID: PMC7229754 DOI: 10.1073/pnas.2004978117] [Citation(s) in RCA: 576] [Impact Index Per Article: 144.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The spread of coronavirus disease 2019 (COVID-19) in Italy prompted drastic measures for transmission containment. We examine the effects of these interventions, based on modeling of the unfolding epidemic. We test modeling options of the spatially explicit type, suggested by the wave of infections spreading from the initial foci to the rest of Italy. We estimate parameters of a metacommunity Susceptible-Exposed-Infected-Recovered (SEIR)-like transmission model that includes a network of 107 provinces connected by mobility at high resolution, and the critical contribution of presymptomatic and asymptomatic transmission. We estimate a generalized reproduction number ([Formula: see text] = 3.60 [3.49 to 3.84]), the spectral radius of a suitable next-generation matrix that measures the potential spread in the absence of containment interventions. The model includes the implementation of progressive restrictions after the first case confirmed in Italy (February 21, 2020) and runs until March 25, 2020. We account for uncertainty in epidemiological reporting, and time dependence of human mobility matrices and awareness-dependent exposure probabilities. We draw scenarios of different containment measures and their impact. Results suggest that the sequence of restrictions posed to mobility and human-to-human interactions have reduced transmission by 45% (42 to 49%). Averted hospitalizations are measured by running scenarios obtained by selectively relaxing the imposed restrictions and total about 200,000 individuals (as of March 25, 2020). Although a number of assumptions need to be reexamined, like age structure in social mixing patterns and in the distribution of mobility, hospitalization, and fatality, we conclude that verifiable evidence exists to support the planning of emergency measures.
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Affiliation(s)
- Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy;
| | - Enrico Bertuzzo
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari Venezia, 30172 Venezia-Mestre, Italy
- Science of Complexity Research Unit, European Centre for Living Technology, 30123 Venice, Italy
| | - Lorenzo Mari
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Stefano Miccoli
- Dipartimento di Meccanica, Politecnico di Milano, 20133 Milano, Italy
| | - Luca Carraro
- Department of Aquatic Ecology, Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8057 Zurich, Switzerland
| | - Renato Casagrandi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Andrea Rinaldo
- Laboratory of Ecohydrology, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland;
- Dipartimento di Ingegneria Civile, Edile e Ambientale, Università di Padova, 35131 Padova, Italy
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15
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Influences of Land-Use Dynamics and Surface Water Systems Interactions on Water-Related Infectious Diseases—A Systematic Review. WATER 2020. [DOI: 10.3390/w12030631] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Human interactions with surface water systems, through land-use dynamics, can influence the transmission of infectious water-related diseases. As a result, the aim of our study was to explore and examine the state of scientific evidence on the influences of these interactions on water-related infectious disease outcomes from a global perspective. A systematic review was conducted, using 54 peer-reviewed research articles published between 1995 and August 2019. The study revealed that there has been an increase in the number of publications since 2009; however, few of these publications (n = 6) made explicit linkages to the topic. It was found that urban and agricultural land-use changes had relatively high adverse impacts on water quality, due to high concentrations of fecal matter, heavy metals, and nutrients in surface water systems. Water systems were found as the common “vehicle” for infectious disease transmission, which in turn had linkages to sanitation and hygiene conditions. The study found explicit linkages between human–surface water interaction patterns and the transmission of water-based disease. However, weak and complex linkages were found between land-use change and the transmission of water-borne disease, due to multiple pathways and the dynamics of the other determinants of the disease. Therefore, further research studies, using interdisciplinary and transdisciplinary approaches to investigate and enhance a deeper understanding of these complexities and linkages among land use, surface water quality, and water-related infectious diseases, is crucial in developing integrated measures for sustainable water quality monitoring and diseases prevention.
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16
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Shao X, Fang Y, Jawitz JW, Yan J, Cui B. River network connectivity and fish diversity. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 689:21-30. [PMID: 31260896 DOI: 10.1016/j.scitotenv.2019.06.340] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 06/14/2019] [Accepted: 06/21/2019] [Indexed: 06/09/2023]
Abstract
Frequent and severe disruptions of natural river flows associated with human activities significantly alter hydrological connectivity in large river networks, with deleterious effects on fish diversity. Understanding the relationship between fish diversity and river network connectivity is fundamental to ensuring species persistence, ecosystem integrity, and human well-being. Here, we provide a review of the mechanisms by which river network connectivity (RNC) affects fish diversity. We review the relationships between forms, systems and types of RNC and fish diversity, based on more than 100 previous studies. In summary, sustaining RNC promotes fish diversity in longitudinal and lateral axes, and species sorting, dispersal dynamics, and habitat availability are the main factors driving the distribution of fish diversity, followed by nutrition and trophic dynamics. Our work highlights the effects of RNC on fish diversity, and provides a mechanistic understanding of how RNC affects fish diversity across river basins, thus providing scientific guidance for protecting fish biodiversity and improving the health of river network ecosystems.
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Affiliation(s)
- Xiaojing Shao
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Yu Fang
- State Key Laboratory of Hydroscience and Engineering, Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, China
| | - James W Jawitz
- Soil and Water Sciences Department, University of Florida, Gainesville, FL, USA
| | - Jiaguo Yan
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China
| | - Baoshan Cui
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, People's Republic of China.
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17
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Lund AJ, Sam MM, Sy AB, Sow OW, Ali S, Sokolow SH, Bereknyei Merrell S, Bruce J, Jouanard N, Senghor S, Riveau G, Lopez-Carr D, De Leo GA. Unavoidable Risks: Local Perspectives on Water Contact Behavior and Implications for Schistosomiasis Control in an Agricultural Region of Northern Senegal. Am J Trop Med Hyg 2019; 101:837-847. [PMID: 31452497 PMCID: PMC6779182 DOI: 10.4269/ajtmh.19-0099] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 06/24/2019] [Indexed: 12/31/2022] Open
Abstract
Human schistosomiasis is a snail-borne parasitic disease affecting more than 200 million people worldwide. Direct contact with snail-infested freshwater is the primary route of exposure. Water management infrastructure, including dams and irrigation schemes, expands snail habitat, increasing the risk across the landscape. The Diama Dam, built on the lower basin of the Senegal River to prevent saltwater intrusion and promote year-round agriculture in the drought-prone Sahel, is a paradigmatic case. Since dam completion in 1986, the rural population-whose livelihoods rely mostly on agriculture-has suffered high rates of schistosome infection. The region remains one of the most hyperendemic regions in the world. Because of the convergence between livelihoods and environmental conditions favorable to transmission, schistosomiasis is considered an illustrative case of a disease-driven poverty trap (DDPT). The literature to date on the topic, however, remains largely theoretical. With qualitative data generated from 12 focus groups in four villages, we conducted team-based theme analysis to investigate how perception of schistosomiasis risk and reported preventive behaviors may suggest the presence of a DDPT. Our analysis reveals three key findings: 1) rural villagers understand schistosomiasis risk (i.e., where and when infections occur), 2) accordingly, they adopt some preventive behaviors, but ultimately, 3) exposure persists, because of circumstances characteristic of rural livelihoods. These findings highlight the capacity of local populations to participate actively in schistosomiasis control programs and the limitations of widespread drug treatment campaigns. Interventions that target the environmental reservoir of disease may provide opportunities to reduce exposure while maintaining resource-dependent livelihoods.
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Affiliation(s)
- Andrea J. Lund
- Emmett Interdisciplinary Program in Environment and Resources, Stanford University, Stanford, California
| | | | - Alioune Badara Sy
- Centre de Recherche Biomédicale – Espoir Pour la Santé, Saint Louis, Sénégal
| | | | - Sofia Ali
- Stanford University, Stanford, California
| | | | - Sylvia Bereknyei Merrell
- Department of Surgery, Stanford Surgery Policy Improvement Research & Education Center (S-SPIRE), School of Medicine, Stanford University, Stanford, California
| | - Janine Bruce
- Pediatric Advocacy Program, Department of Pediatrics, School of Medicine, Stanford University, Stanford, California
| | - Nicolas Jouanard
- Centre de Recherche Biomédicale – Espoir Pour la Santé, Saint Louis, Sénégal
- Station d’Innovation Aquacole, Saint Louis, Senegal
| | - Simon Senghor
- Centre de Recherche Biomédicale – Espoir Pour la Santé, Saint Louis, Sénégal
| | - Gilles Riveau
- Centre de Recherche Biomédicale – Espoir Pour la Santé, Saint Louis, Sénégal
| | - David Lopez-Carr
- Department of Geography, University of California, Santa Barbara, Santa Barbara, California
| | - Giulio A. De Leo
- Hopkins Marine Station, Stanford University, Pacific Grove, California
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18
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Vegvari C, Truscott JE, Kura K, Anderson RM. Human population movement can impede the elimination of soil-transmitted helminth transmission in regions with heterogeneity in mass drug administration coverage and transmission potential between villages: a metapopulation analysis. Parasit Vectors 2019; 12:438. [PMID: 31522681 PMCID: PMC6745807 DOI: 10.1186/s13071-019-3612-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 07/08/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Soil-transmitted helminth (STH) infections affect predominantly socio-economically disadvantaged populations in sub-Saharan Africa, East Asia and the Americas. Previous mathematical modelling studies have evaluated optimal intervention strategies to break STH transmission in clusters of villages. These studies assumed that villages are closed independent units with no movement of people in or out of communities. Here we examine how human population movement, for example, of seasonal migrant labourers, affect the outcome of mass drug administration (MDA) programmes. RESULTS We used a stochastic individual-based metapopulation model to analyse the impact of human population movement at varying rates on STH elimination efforts. Specifically, we looked at seasonal clumped movement events of infected individuals into a village. We showed that even if on average 75% of the entire resident population within a village are treated, an annual rate of 2-3% of the population arriving from an untreated source village can reduce the probability of STH elimination to less than 50% in high-prevalence settings. If a village is infection-free, an annual movement rate of 2-3% from an infected source village imposes a risk of re-introduction of STH of 75% or higher, unless the prevalence in the source village is less than 20%. Even a single arrival of 2-3% of the population can impose a risk of re-introducing STH of 50% or greater depending on the prevalence in the source village. The risk of re-introduction also depends on both the age group of moving individuals and STH species, since the pattern of cross-sectional age-prevalence and age-intensity profiles of infection in the human host are species-specific. CONCLUSIONS Planning for STH elimination programmes should account for human mobility patterns in defined regions. We recommend that individuals arriving from areas with ongoing STH transmission should receive preventive chemotherapy for STHs. This can most easily be implemented if migration is seasonal and overlaps with treatment rounds, e.g. seasonal migrant labour. Moreover, transmission hotspots in or near treatment clusters should be eliminated, for example, by implementing appropriate water, sanitation and hygiene (WASH) measures and targeting treatment to individuals living in hotspots.
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Affiliation(s)
- Carolin Vegvari
- Department of Infectious Disease Epidemiology, Imperial College London, London Centre for Neglected Tropical Disease Research (LCNTDR), St Mary's Campus, Praed Street, London, W2 1PG, UK.
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, Praed Street, London, W2 1PG, UK.
| | - James E Truscott
- Department of Infectious Disease Epidemiology, Imperial College London, London Centre for Neglected Tropical Disease Research (LCNTDR), St Mary's Campus, Praed Street, London, W2 1PG, UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, Praed Street, London, W2 1PG, UK
- The DeWorm3 Project, The Natural History Museum of London, London, SW7 5BD, UK
| | - Klodeta Kura
- Department of Infectious Disease Epidemiology, Imperial College London, London Centre for Neglected Tropical Disease Research (LCNTDR), St Mary's Campus, Praed Street, London, W2 1PG, UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, Praed Street, London, W2 1PG, UK
| | - Roy M Anderson
- Department of Infectious Disease Epidemiology, Imperial College London, London Centre for Neglected Tropical Disease Research (LCNTDR), St Mary's Campus, Praed Street, London, W2 1PG, UK
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, St Mary's Campus, Praed Street, London, W2 1PG, UK
- The DeWorm3 Project, The Natural History Museum of London, London, SW7 5BD, UK
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19
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Mari L, Casagrandi R, Bertuzzo E, Rinaldo A, Gatto M. Conditions for transient epidemics of waterborne disease in spatially explicit systems. ROYAL SOCIETY OPEN SCIENCE 2019; 6:181517. [PMID: 31218018 PMCID: PMC6549988 DOI: 10.1098/rsos.181517] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 03/12/2019] [Indexed: 05/06/2023]
Abstract
Waterborne diseases are a diverse family of infections transmitted through ingestion of-or contact with-water infested with pathogens. Outbreaks of waterborne infections often show well-defined spatial signatures that are typically linked to local eco-epidemiological conditions, water-mediated pathogen transport and human mobility. In this work, we apply a spatially explicit network model describing the transmission cycle of waterborne pathogens to determine invasion conditions in metacommunities endowed with a realistic spatial structure. Specifically, we aim to define conditions under which pathogens can temporarily colonize a set of human communities, thus triggering a transient epidemic outbreak. To that end, we apply generalized reactivity analysis, a recently developed methodological framework for the study of transient dynamics in ecological systems subject to external perturbations. The study of pathogen invasion is complemented by the detection of the spatial signatures associated with the perturbations to a disease-free system that are expected to be amplified the most over different time scales. Understanding the drivers of waterborne disease dynamics over time scales that are relevant to epidemic and/or endemic transmission is a crucial, cross-disciplinary challenge, as large portions of the developing world still struggle to cope with the burden of these infections.
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Affiliation(s)
- Lorenzo Mari
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
- Author for correspondence: Lorenzo Mari e-mail:
| | - Renato Casagrandi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Enrico Bertuzzo
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca’ Foscari Venezia, 30170 Venezia Mestre, Italy
| | - Andrea Rinaldo
- Laboratory of Ecohydrology, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Dipartimento ICEA, Università di Padova, 35131 Padova, Italy
| | - Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
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20
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Antoszczak M, Steverding D, Huczyński A. Anti-parasitic activity of polyether ionophores. Eur J Med Chem 2019; 166:32-47. [DOI: 10.1016/j.ejmech.2019.01.035] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/08/2019] [Accepted: 01/15/2019] [Indexed: 02/04/2023]
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21
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Mari L, Casagrandi R, Rinaldo A, Gatto M. Epidemicity thresholds for water-borne and water-related diseases. J Theor Biol 2018; 447:126-138. [PMID: 29588168 DOI: 10.1016/j.jtbi.2018.03.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 02/02/2018] [Accepted: 03/16/2018] [Indexed: 12/18/2022]
Abstract
Determining the conditions that favor pathogen establishment in a host community is key to disease control and eradication. However, focusing on long-term dynamics alone may lead to an underestimation of the threats imposed by outbreaks triggered by short-term transient phenomena. Achieving an effective epidemiological response thus requires to look at different timescales, each of which may be endowed with specific management objectives. In this work we aim to determine epidemicity thresholds for some prototypical examples of water-borne and water-related diseases, a diverse family of infections transmitted either directly through water infested with pathogens or by vectors whose lifecycles are closely associated with water. From a technical perspective, while conditions for endemicity are determined via stability analysis, epidemicity thresholds are defined through generalized reactivity analysis, a recently proposed method that allows the study of the short-term instability properties of ecological systems. Understanding the drivers of water-borne and water-related disease dynamics over timescales that may be relevant to epidemic and/or endemic transmission is a challenge of the utmost importance, as large portions of the developing world are still struggling with the burden imposed by these infections.
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Affiliation(s)
- Lorenzo Mari
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano 20133, Italy.
| | - Renato Casagrandi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano 20133, Italy
| | - Andrea Rinaldo
- Laboratory of Ecohydrology, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland; Dipartimento ICEA, Università di Padova, Padova 35131, Italy
| | - Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano 20133, Italy
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Rinaldo A, Gatto M, Rodriguez-Iturbe I. River networks as ecological corridors: A coherent ecohydrological perspective. ADVANCES IN WATER RESOURCES 2018; 112:27-58. [PMID: 29651194 PMCID: PMC5890385 DOI: 10.1016/j.advwatres.2017.10.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 10/05/2017] [Accepted: 10/06/2017] [Indexed: 05/14/2023]
Abstract
This paper draws together several lines of argument to suggest that an ecohydrological framework, i.e. laboratory, field and theoretical approaches focused on hydrologic controls on biota, has contributed substantially to our understanding of the function of river networks as ecological corridors. Such function proves relevant to: the spatial ecology of species; population dynamics and biological invasions; the spread of waterborne disease. As examples, we describe metacommunity predictions of fish diversity patterns in the Mississippi-Missouri basin, geomorphic controls imposed by the fluvial landscape on elevational gradients of species' richness, the zebra mussel invasion of the same Mississippi-Missouri river system, and the spread of proliferative kidney disease in salmonid fish. We conclude that spatial descriptions of ecological processes in the fluvial landscape, constrained by their specific hydrologic and ecological dynamics and by the ecosystem matrix for interactions, i.e. the directional dispersal embedded in fluvial and host/pathogen mobility networks, have already produced a remarkably broad range of significant results. Notable scientific and practical perspectives are thus open, in the authors' view, to future developments in ecohydrologic research.
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Affiliation(s)
- Andrea Rinaldo
- Laboratory of Ecohydrology ECHO/IIE/ENAC, École Polytechinque Fédérale de Lausanne, Lausanne, CH, Switzerland
- Dipartimento ICEA, Università di Padova, Padova, IT, Italy
| | - Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano IT, Italy
| | - Ignacio Rodriguez-Iturbe
- Department of Ocean Engineering, Department of Civil Engineering and Department of Biological and Agricultural Engineering, Texas A & M University, College Station (TX), USA
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Sokolow SH, Wood CL, Jones IJ, Lafferty KD, Kuris AM, Hsieh MH, De Leo GA. To Reduce the Global Burden of Human Schistosomiasis, Use 'Old Fashioned' Snail Control. Trends Parasitol 2018; 34:23-40. [PMID: 29126819 PMCID: PMC5819334 DOI: 10.1016/j.pt.2017.10.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 09/30/2017] [Accepted: 10/16/2017] [Indexed: 12/27/2022]
Abstract
Control strategies to reduce human schistosomiasis have evolved from 'snail picking' campaigns, a century ago, to modern wide-scale human treatment campaigns, or preventive chemotherapy. Unfortunately, despite the rise in preventive chemotherapy campaigns, just as many people suffer from schistosomiasis today as they did 50 years ago. Snail control can complement preventive chemotherapy by reducing the risk of transmission from snails to humans. Here, we present ideas for modernizing and scaling up snail control, including spatiotemporal targeting, environmental diagnostics, better molluscicides, new technologies (e.g., gene drive), and 'outside the box' strategies such as natural enemies, traps, and repellants. We conclude that, to achieve the World Health Assembly's stated goal to eliminate schistosomiasis, it is time to give snail control another look.
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Affiliation(s)
- Susanne H Sokolow
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA; Marine Science Institute, University of California, Santa Barbara, CA 93106, USA.
| | - Chelsea L Wood
- School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA 98195-5020, USA
| | - Isabel J Jones
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - Kevin D Lafferty
- U.S. Geological Survey, Western Ecological Research Center, c/o Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
| | - Armand M Kuris
- Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
| | - Michael H Hsieh
- Children's National Health System, Washington DC, 20010, USA; The George Washington University, Washington DC, 20037, USA; Biomedical Research Institute, Rockville, MD 20850, USA
| | - Giulio A De Leo
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
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Mari L, Ciddio M, Casagrandi R, Perez-Saez J, Bertuzzo E, Rinaldo A, Sokolow SH, De Leo GA, Gatto M. Heterogeneity in schistosomiasis transmission dynamics. J Theor Biol 2017; 432:87-99. [PMID: 28823529 PMCID: PMC5595357 DOI: 10.1016/j.jtbi.2017.08.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 06/30/2017] [Accepted: 08/15/2017] [Indexed: 01/30/2023]
Abstract
Transmission dynamics of schistosomiasis presents multiple heterogeneity sources. A comprehensive framework for heterogeneous disease transmission is proposed. Heterogeneous multigroup communities can be more prone to parasite transmission. Presence of multiple water sources can hinder parasite transmission. Spatial and temporal heterogeneities can have nontrivial implications for endemicity.
Simple models of disease propagation often disregard the effects of transmission heterogeneity on the ecological and epidemiological dynamics associated with host-parasite interactions. However, for some diseases like schistosomiasis, a widespread parasitic infection caused by Schistosoma worms, accounting for heterogeneity is crucial to both characterize long-term dynamics and evaluate opportunities for disease control. Elaborating on the classic Macdonald model for macroparasite transmission, we analyze families of models including explicit descriptions of heterogeneity related to differential transmission risk within a community, water contact patterns, the distribution of the snail host population, human mobility, and the seasonal fluctuations of the environment. Through simple numerical examples, we show that heterogeneous multigroup communities may be more prone to schistosomiasis than homogeneous ones, that the availability of multiple water sources can hinder parasite transmission, and that both spatial and temporal heterogeneities may have nontrivial implications for disease endemicity. Finally, we discuss the implications of heterogeneity for disease control. Although focused on schistosomiasis, results from this study may apply as well to other parasitic infections with complex transmission cycles, such as cysticercosis, dracunculiasis and fasciolosis.
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Affiliation(s)
- Lorenzo Mari
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy.
| | - Manuela Ciddio
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Renato Casagrandi
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
| | - Javier Perez-Saez
- Laboratory of Ecohydrology, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Enrico Bertuzzo
- Dipartimento di Scienze Ambientali, Informatica e Statistica, Università Ca' Foscari Venezia, 30170 Venezia Mestre, Italy
| | - Andrea Rinaldo
- Laboratory of Ecohydrology, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland; Dipartimento ICEA, Università di Padova, 35131 Padova, Italy
| | - Susanne H Sokolow
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA; Marine Science Institute, University of California, Santa Barbara, CA 93106, USA
| | - Giulio A De Leo
- Hopkins Marine Station, Stanford University, Pacific Grove, CA 93950, USA
| | - Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, 20133 Milano, Italy
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25
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Big-data-driven modeling unveils country-wide drivers of endemic schistosomiasis. Sci Rep 2017; 7:489. [PMID: 28352101 PMCID: PMC5428445 DOI: 10.1038/s41598-017-00493-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 02/27/2017] [Indexed: 11/09/2022] Open
Abstract
Schistosomiasis is a parasitic infection that is widespread in sub-Saharan Africa, where it represents a major health problem. We study the drivers of its geographical distribution in Senegal via a spatially explicit network model accounting for epidemiological dynamics driven by local socioeconomic and environmental conditions, and human mobility. The model is parameterized by tapping several available geodatabases and a large dataset of mobile phone traces. It reliably reproduces the observed spatial patterns of regional schistosomiasis prevalence throughout the country, provided that spatial heterogeneity and human mobility are suitably accounted for. Specifically, a fine-grained description of the socioeconomic and environmental heterogeneities involved in local disease transmission is crucial to capturing the spatial variability of disease prevalence, while the inclusion of human mobility significantly improves the explanatory power of the model. Concerning human movement, we find that moderate mobility may reduce disease prevalence, whereas either high or low mobility may result in increased prevalence of infection. The effects of control strategies based on exposure and contamination reduction via improved access to safe water or educational campaigns are also analyzed. To our knowledge, this represents the first application of an integrative schistosomiasis transmission model at a whole-country scale.
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