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Siama A, Eteme Enama S, Kalmobe J, Abah S, Foutchou A, Njan Nloga AM. Abundance, Distribution, and Diversity of Freshwater Snail and Prevalences of Their Infection by Cercaria of Fasciola gigantica and Schistosoma spp at Mayo-Vreck River, Far North Region of Cameroon. J Trop Med 2023; 2023:9527349. [PMID: 37900305 PMCID: PMC10611546 DOI: 10.1155/2023/9527349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 09/14/2023] [Accepted: 09/28/2023] [Indexed: 10/31/2023] Open
Abstract
Malacological and parasitological studies were conducted from April 2020 to March 2021 to determine the abundance and distribution of molluscs and cercariae of Schistosoma spp and Fasciola gigantica. Collected molluscs are exposed to strong light to induce cercarial release. Mollusc densities were higher at station 1 (Gamak) than in station 8 (Patakai), with Bellamya unicolor and Biomphalaria pfeifferi more abundant and Bulinus truncatus, B. tropicus, and B. globosus less abundant. The overall prevalence of cercariae (19.87%) is higher in station 3 (Yaye orchard), station 9 (Gougni), station 4 (Madiogo), station 5 (Madiogo pasture), and station 6 (Ziam 3). It varies significantly between 15.76% in station 8 and 25.77% in station 3, between 8.48% in B. truncatus and 25.53% in B. globosus, and between 19.27% for cercariae of Schistosoma spp and 21.60% for those of F. gigantica. Cercarial emissions in L. natalensis and B. pfeifferi were higher in hot and cold dry seasons; on the other hand, cercarial emissions in B. globosus were higher in hot dry seasons (31.48%) and rainy seasons (23.38%). Emissions of cercariae from S. haematobium are related to areas of human activity and defecation, while those of F. gigantica in L. natalensis, Schistosoma haematobium in B. tropicus, and S. mansoni in B. pfeifferi are related to grazing areas. Mayo-Vreck is a site that favors the endemicity of fascioliasis and human schistosomiasis.
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Affiliation(s)
- Augustin Siama
- Department of Parasitology and Parasitic Pathology, School of Sciences and Veterinary Medicine, University of Ngaoundere, Ngaoundere, Cameroon
| | - Serges Eteme Enama
- Department of Animal Biology and Physiology, Faculty of Science, University of Yaounde I, Yaounde, Cameroon
| | - Justin Kalmobe
- Department of Parasitology and Parasitic Pathology, School of Sciences and Veterinary Medicine, University of Ngaoundere, Ngaoundere, Cameroon
| | - Samuel Abah
- Special Mission of Tse-Tse Flies Eradication, Ngaoundere, Cameroon
| | - Angele Foutchou
- Department of Biological Sciences, Faculty of Science, University of Ngaoundere, Ngaoundere, Cameroon
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Faiad SM, Williams MA, Goodman M, Sokolow S, Olden JD, Mitchell K, Andriantsoa R, Gordon Jones JP, Andriamaro L, Ravoniarimbinina P, Rasamy J, Ravelomanana T, Ravelotafita S, Ravo R, Rabinowitz P, De Leo GA, Wood CL. Temperature affects predation of schistosome-competent snails by a novel invader, the marbled crayfish Procambarus virginalis. PLoS One 2023; 18:e0290615. [PMID: 37703262 PMCID: PMC10499222 DOI: 10.1371/journal.pone.0290615] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 08/12/2023] [Indexed: 09/15/2023] Open
Abstract
The human burden of environmentally transmitted infectious diseases can depend strongly on ecological factors, including the presence or absence of natural enemies. The marbled crayfish (Procambarus virginalis) is a novel invasive species that can tolerate a wide range of ecological conditions and colonize diverse habitats. Marbled crayfish first appeared in Madagascar in 2005 and quickly spread across the country, overlapping with the distribution of freshwater snails that serve as the intermediate host of schistosomiasis-a parasitic disease of poverty with human prevalence ranging up to 94% in Madagascar. It has been hypothesized that the marbled crayfish may serve as a predator of schistosome-competent snails in areas where native predators cannot and yet no systematic study to date has been conducted to estimate its predation rate on snails. Here, we experimentally assessed marbled crayfish consumption of uninfected and infected schistosome-competent snails (Biomphalaria glabrata and Bulinus truncatus) across a range of temperatures, reflective of the habitat range of the marbled crayfish in Madagascar. We found that the relationship between crayfish consumption and temperature is unimodal with a peak at ~27.5°C. Per-capita consumption increased with body size and was not affected either by snail species or their infectious status. We detected a possible satiation effect, i.e., a small but significant reduction in per-capita consumption rate over the 72-hour duration of the predation experiment. Our results suggest that ecological parameters, such as temperature and crayfish weight, influence rates of consumption and, in turn, the potential impact of the marbled crayfish invasion on snail host populations.
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Affiliation(s)
- Sara M. Faiad
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, United States of America
| | - Maureen A. Williams
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, United States of America
- Department of Biology, McDaniel College, Westminster, MD, United States of America
| | - Maurice Goodman
- Hopkins Marine Station, Dept. of Oceans and of Earth System Science, Doerr School of Sustainability, Stanford University, Stanford, CA, United States of America
| | - Susanne Sokolow
- Hopkins Marine Station, Dept. of Oceans and of Earth System Science, Doerr School of Sustainability, Stanford University, Stanford, CA, United States of America
- Marine Science Institute, University of California, Santa Barbara, Santa Barbara, CA, United States of America
| | - Julian D. Olden
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, United States of America
| | - Kaitlyn Mitchell
- Hopkins Marine Station, Dept. of Oceans and of Earth System Science, Doerr School of Sustainability, Stanford University, Stanford, CA, United States of America
| | - Ranja Andriantsoa
- Réseau International Schistosomiase Environnement Aménagement et Lutte (RISEAL) Madagascar, Madagascar
| | | | - Luciano Andriamaro
- Réseau International Schistosomiase Environnement Aménagement et Lutte (RISEAL) Madagascar, Madagascar
| | | | - Jeanne Rasamy
- Réseau International Schistosomiase Environnement Aménagement et Lutte (RISEAL) Madagascar, Madagascar
- Department of Zoology and Animal Biodiversity, University of Antananarivo, Antananarivo, Madagascar
| | - Tsilavina Ravelomanana
- Réseau International Schistosomiase Environnement Aménagement et Lutte (RISEAL) Madagascar, Madagascar
- Department of Zoology and Animal Biodiversity, University of Antananarivo, Antananarivo, Madagascar
| | - Salohy Ravelotafita
- Department of Zoology and Animal Biodiversity, University of Antananarivo, Antananarivo, Madagascar
| | - Ranaivosolo Ravo
- Department of Zoology and Animal Biodiversity, University of Antananarivo, Antananarivo, Madagascar
| | - Peter Rabinowitz
- Department of Environmental/Occupational Health Sciences, Global Health, University of Washington, Seattle, WA, United States of America
- Center for One Health Research (COHR), University of Washington, Seattle, WA, United States of America
| | - Giulio A. De Leo
- Hopkins Marine Station, Dept. of Oceans and of Earth System Science, Doerr School of Sustainability, Stanford University, Stanford, CA, United States of America
- Woods Institute for the Environment, Stanford University, Stanford, CA, United States of America
| | - Chelsea L. Wood
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, United States of America
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Matsumoto-Takahashi ELA, Kumagai T, Oyoshi K, Sasaki Y, Mizukami Y, Hongvanthong B, Brey PT, Kano S, Iwagami M. Impact of precipitation on the prevalence of schistosomiasis mekongi in Lao PDR: Structural equation modelling using Earth observation satellite data. One Health 2023; 16:100563. [PMID: 37363222 PMCID: PMC10288094 DOI: 10.1016/j.onehlt.2023.100563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 05/09/2023] [Accepted: 05/10/2023] [Indexed: 06/28/2023] Open
Abstract
Increasing attention is being given to the effect of climate change on schistosomiasis, but the impact is currently unknown. As the intermediate snail host (Neotricula aperta) of Schistosoma mekongi inhabits the Mekong River, it is thought that environmental factors affecting the area of water will have an impact on the occurrence of schistosomiasis mekongi. The aim of the present study was to assess the impact of precipitation on the prevalence of human schistosomiasis mekongi using epidemiological data and Earth observation satellite data in Khong district, Champasak province, Lao PDR. Structural equation modelling (SEM) using epidemiological data and Earth observation satellite data was conducted to determine the factors associated with the number of schistosomiasis mekongi patients. As a result, SEM identified 3 significant factors independently associated with schistosomiasis mekongi: (1) a negative association with mass drug administration (MDA); (2) negative association with total precipitation per year; and (3) positive association with precipitation during the dry season. Precisely, regardless of MDA, the increase in total yearly precipitation was suggested to decrease the number of schistosomiasis patients, whereas an increase in precipitation in the dry season increased the number of schistosomiasis patients. This is probably because when total precipitation increases, the water level of the Mekong River rises, thus decreasing the density of infected larvae, cercaria, in the water, and the frequency of humans entering the river would also decrease. In contrast, when precipitation in the dry season is higher, the water level of the Mekong River also rises, which expands the snail habitant, and thus water contact between humans and the snails would also increase. The present study results suggest that increasing precipitation would impact the prevalence of schistosomiasis both positively and negatively, and precipitation should also be considered in the policy to eliminate schistosomiasis mekongi in Lao PDR.
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Affiliation(s)
- Emilie Louise Akiko Matsumoto-Takahashi
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine (NCGM), Tokyo, Japan
- Graduate School of Public Health, St. Luke's International University, Tokyo, Japan
| | - Takashi Kumagai
- Department of Parasitology & Tropical Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kei Oyoshi
- Earth Observation Research Center (EORC), Space Technology Directorate I, Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan
| | - Yoshinobu Sasaki
- Earth Observation Research Center (EORC), Space Technology Directorate I, Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan
| | - Yousei Mizukami
- Earth Observation Research Center (EORC), Space Technology Directorate I, Japan Aerospace Exploration Agency (JAXA), Tsukuba, Japan
| | - Bouasy Hongvanthong
- Center of Malariology, Parasitology and Entomology (CMPE), Ministry of Health, Vientiane, Lao Democratic People’s Republic
| | - Paul T. Brey
- Institut Pasteur du Laos (IPL), Ministry of Health, Vientiane, Lao Democratic People’s Republic
| | - Shigeyuki Kano
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine (NCGM), Tokyo, Japan
- Parasitology Laboratory, Institut Pasteur du Laos (IPL), Ministry of Health, Vientiane, Lao Democratic People’s Republic
| | - Moritoshi Iwagami
- Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine (NCGM), Tokyo, Japan
- Parasitology Laboratory, Institut Pasteur du Laos (IPL), Ministry of Health, Vientiane, Lao Democratic People’s Republic
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Wang X, Juma S, Li W, Suleman M, Muhsin MA, He J, He M, Xu D, Zhang J, Bergquist R, Yang K. Potential risk of colonization of Bulinus globosus in the mainland of China under climate change. Infect Dis Poverty 2022; 11:52. [PMID: 35562755 PMCID: PMC9103089 DOI: 10.1186/s40249-022-00980-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 04/25/2022] [Indexed: 11/17/2022] Open
Abstract
Background Bulinus globosus, the main intermediate snail host of Schistosoma haematobium. The increased contacts between Africa and China could even lead to large-scale dissemination of B. globosus in China. Temperature is the key factor affecting fresh-water snail transmission. This study predicted potential risk of colonization of B. globosus in the mainland of China under climate change. Methods We investigated minimum and maximum temperatures for B. globosus eggs, juveniles and adult snails kept under laboratory conditions to find the most suitable range by pinpointing the median effective temperatures (ET50). We also assessed the influence of temperature on spawning and estimated the accumulated temperature (AT). The average air temperatures between 1955 and 2019 in January and July, the coldest and hottest months in China, respectively, were collected from national meteorological monitoring stations and investigated in a geographic information system (GIS) using empirical Bayesian Kriging to evaluate the theoretical possibility for distribution of B. globosus in southern China based on temperature. Results The effective minimum temperature (ET50min) for eggs, juveniles, adult snails and spawning were 8.5, 7.0, 7.0, 14.9 °C, respectively, with the corresponding maximum values (ET50max) of 36.6, 40.5, 40.2 and 38.1 °C. The AT was calculated at 712.1 ± 64.9 °C·d. In 1955, the potential B. globosus distribution would have had a northern boundary stretching from the coastal areas of Guangdong Province and Guangxi Autonomous Region to southern Yunnan Province. Since then, this line has gradually moved northward. Conclusions Annual regeneration of B. globosus can be supported by the current climate conditions in the mainland of China, and a gradual expansion trend from south to north is shown in the study from 2015 to 2019. Thus, there is a potential risk of colonization of B. globosus in the mainland of China under climate change. Graphical Abstract ![]()
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Affiliation(s)
- Xinyao Wang
- Jiangsu Institute of Parasitic Diseases, Wuxi, 214064, Jiangsu, China.,Key Laboratory On Technology for Parasitic Disease Prevention and Control, Jiangsu Provincial Key Laboratory On the Molecular Biology of Parasites, Ministry of Health, Wuxi, 214064, Jiangsu, China
| | - Saleh Juma
- Ministry of Health of Zanzibar, P.O. Box 236, Zanzibar, United Republic of Tanzania
| | - Wei Li
- Jiangsu Institute of Parasitic Diseases, Wuxi, 214064, Jiangsu, China.,Key Laboratory On Technology for Parasitic Disease Prevention and Control, Jiangsu Provincial Key Laboratory On the Molecular Biology of Parasites, Ministry of Health, Wuxi, 214064, Jiangsu, China
| | - Mchanga Suleman
- Ministry of Health of Zanzibar, P.O. Box 236, Zanzibar, United Republic of Tanzania
| | - Mtumweni Ali Muhsin
- Ministry of Health of Zanzibar, P.O. Box 236, Zanzibar, United Republic of Tanzania.,College of Medicine, Jiangnan University, Wuxi, 214122, Jiangsu, China
| | - Jian He
- Jiangsu Institute of Parasitic Diseases, Wuxi, 214064, Jiangsu, China.,Key Laboratory On Technology for Parasitic Disease Prevention and Control, Jiangsu Provincial Key Laboratory On the Molecular Biology of Parasites, Ministry of Health, Wuxi, 214064, Jiangsu, China
| | - Mingzhen He
- Changzhou Center for Disease Control and Prevention, Changzhou, Jiangsu, China
| | - Dacheng Xu
- Jintan Center for Disease Control and Prevention, Changzhou, Jiangsu, China
| | - Jianfeng Zhang
- Jiangsu Institute of Parasitic Diseases, Wuxi, 214064, Jiangsu, China.,Key Laboratory On Technology for Parasitic Disease Prevention and Control, Jiangsu Provincial Key Laboratory On the Molecular Biology of Parasites, Ministry of Health, Wuxi, 214064, Jiangsu, China
| | | | - Kun Yang
- Jiangsu Institute of Parasitic Diseases, Wuxi, 214064, Jiangsu, China. .,Key Laboratory On Technology for Parasitic Disease Prevention and Control, Jiangsu Provincial Key Laboratory On the Molecular Biology of Parasites, Ministry of Health, Wuxi, 214064, Jiangsu, China. .,College of Medicine, Jiangnan University, Wuxi, 214122, Jiangsu, China. .,School of Public Health, Nanjing Medical University, Nanjing, China.
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Yu A, Vannatta JT, Gutierrez SO, Minchella DJ. Opportunity or catastrophe? effect of sea salt on host-parasite survival and reproduction. PLoS Negl Trop Dis 2022; 16:e0009524. [PMID: 35202408 PMCID: PMC8870500 DOI: 10.1371/journal.pntd.0009524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 01/24/2022] [Indexed: 11/18/2022] Open
Abstract
Seawater intrusion associated with decreasing groundwater levels and rising seawater levels may affect freshwater species and their parasites. While brackish water certainly impacts freshwater systems globally, its impact on disease transmission is largely unknown. This study examined the effect of artificial seawater on host-parasite interactions using a freshwater snail host, Biomphalaria alexandrina, and the human trematode parasite Schistosoma mansoni. To evaluate the impact of increasing salinity on disease transmission four variables were analyzed: snail survival, snail reproduction, infection prevalence, and the survival of the parasite infective stage (cercariae). We found a decrease in snail survival, snail egg mass production, and snail infection prevalence as salinity increases. However, cercarial survival peaked at an intermediate salinity value. Our results suggest that seawater intrusion into freshwaters has the potential to decrease schistosome transmission to humans.
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Affiliation(s)
- Ao Yu
- Purdue University, West Lafayette, Indiana, United States of America
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Aula OP, McManus DP, Jones MK, Gordon CA. Schistosomiasis with a Focus on Africa. Trop Med Infect Dis 2021; 6:109. [PMID: 34206495 PMCID: PMC8293433 DOI: 10.3390/tropicalmed6030109] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 12/19/2022] Open
Abstract
Schistosomiasis is a common neglected tropical disease of impoverished people and livestock in many developing countries in tropical Africa, the Middle East, Asia, and Latin America. Substantial progress has been made in controlling schistosomiasis in some African countries, but the disease still prevails in most parts of sub-Saharan Africa with an estimated 800 million people at risk of infection. Current control strategies rely primarily on treatment with praziquantel, as no vaccine is available; however, treatment alone does not prevent reinfection. There has been emphasis on the use of integrated approaches in the control and elimination of the disease in recent years with the development of health infrastructure and health education. However, there is a need to evaluate the present status of African schistosomiasis, primarily caused by Schistosoma mansoni and S. haematobium, and the factors affecting the disease as the basis for developing more effective control and elimination strategies in the future. This review provides an historical perspective of schistosomiasis in Africa and discusses the current status of control efforts in those countries where the disease is endemic.
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Affiliation(s)
- Oyime Poise Aula
- School of Public Health, Faculty of Medicine, University of Queensland, Brisbane 4006, Australia;
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane 4006, Australia
| | - Donald P. McManus
- School of Public Health, Faculty of Medicine, University of Queensland, Brisbane 4006, Australia;
| | - Malcolm K. Jones
- School of Veterinary Sciences, University of Queensland, Gatton 4343, Australia;
| | - Catherine A. Gordon
- School of Public Health, Faculty of Medicine, University of Queensland, Brisbane 4006, Australia;
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Adekiya TA, Aruleba RT, Oyinloye BE, Okosun KO, Kappo AP. The Effect of Climate Change and the Snail-Schistosome Cycle in Transmission and Bio-Control of Schistosomiasis in Sub-Saharan Africa. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2019; 17:E181. [PMID: 31887979 PMCID: PMC6981654 DOI: 10.3390/ijerph17010181] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 12/17/2019] [Accepted: 12/19/2019] [Indexed: 01/30/2023]
Abstract
In the next century, global warming, due to changes in climatic factors, is expected to have an enormous influence on the interactions between pathogens and their hosts. Over the years, the rate at which vector-borne diseases and their transmission dynamics modify and develop has been shown to be highly dependent to a certain extent on changes in temperature and geographical distribution. Schistosomiasis has been recognized as a tropical and neglected vector-borne disease whose rate of infection has been predicted to be elevated worldwide, especially in sub-Saharan Africa; the region currently with the highest proportion of people at risk, due to changes in climate. This review not only suggests the need to develop an efficient and effective model that will predict Schistosoma spp. population dynamics but seeks to evaluate the effectiveness of several current control strategies. The design of a framework model to predict and accommodate the future incidence of schistosomiasis in human population dynamics in sub-Saharan Africa is proposed. The impact of climate change on schistosomiasis transmission as well as the distribution of several freshwater snails responsible for the transmission of Schistosoma parasites in the region is also reviewed. Lastly, this article advocates for modelling several control mechanisms for schistosomiasis in sub-Saharan Africa so as to tackle the re-infection of the disease, even after treating infected people with praziquantel, the first-line treatment drug for schistosomiasis.
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Affiliation(s)
- Tayo Alex Adekiya
- Biotechnology and Structural Biology Group, Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa; (R.T.A.); (B.E.O.)
| | - Raphael Taiwo Aruleba
- Biotechnology and Structural Biology Group, Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa; (R.T.A.); (B.E.O.)
| | - Babatunji Emmanuel Oyinloye
- Biotechnology and Structural Biology Group, Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa; (R.T.A.); (B.E.O.)
- Department of Biochemistry, Afe Babalola University, PMB 5454, Ado-Ekiti 360001, Nigeria
| | - Kazeem Oare Okosun
- Department of Mathematics, Vaal University of Technology, Vanderbijlpark 1900, South Africa;
| | - Abidemi Paul Kappo
- Biotechnology and Structural Biology Group, Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa; (R.T.A.); (B.E.O.)
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Mulero S, Rey O, Arancibia N, Mas-Coma S, Boissier J. Persistent establishment of a tropical disease in Europe: the preadaptation of schistosomes to overwinter. Parasit Vectors 2019; 12:379. [PMID: 31358021 PMCID: PMC6664521 DOI: 10.1186/s13071-019-3635-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 07/23/2019] [Indexed: 12/12/2022] Open
Abstract
Background Global changes promote the spread of infectious diseases worldwide. In this context, tropical urogenital schistosomiasis is now permanently established in Corsica since its first emergence in 2013. The local persistence of the tropical pathogens (schistosomes) responsible for urogenital schistosomiasis at such latitudes might be explained by (i) the presence of its intermediate host, the snail Bulinus truncatus, (ii) the recurrent local reseeding of schistosomes by their vertebrate hosts (either human or animal) every summer, and/or (iii) the maintenance and survival of schistosomes within their snail hosts over winter. Methods In this study we conducted an ecological experiment to assess the ability of temperate and tropical schistosome strains to survive in classical winter temperatures in Corsican rivers when infecting temperate (local) snail strains. We also quantified the ability of the schistosomes to complete their life-cycle post-overwintering when returned to classical summer water temperatures. Results Our results show that Mediterranean molluscs are locally adapted to winter conditions compared to tropical molluscs. Moreover, temperate and tropical schistosome strains equally survived the cold and produced viable offspring when returned to optimal temperatures. These results indicate that schistosomes can overwinter under temperate climates when infecting locally adapted snails and might partly explain the establishment and maintenance of schistosomes in Corsica from year to year. Conclusions The observed broader thermal range of schistosomes compared to that of their snail hosts was unexpected and clearly indicates that the spread and establishment of schistosomiasis in temperate countries relies primarily on the presence of the locally adapted snail host lineages, currently known to be present in France, Italy, Portugal, Spain and Greece.
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Affiliation(s)
- Stephen Mulero
- IHPE, University of Montpellier, CNRS, Ifremer, University of Perpignan Via Domitia, 66860, Perpignan, France
| | - Olivier Rey
- IHPE, University of Montpellier, CNRS, Ifremer, University of Perpignan Via Domitia, 66860, Perpignan, France
| | - Nathalie Arancibia
- IHPE, University of Montpellier, CNRS, Ifremer, University of Perpignan Via Domitia, 66860, Perpignan, France
| | - Santiago Mas-Coma
- Departamento de Parasitología, Facultad de Farmacia, Universidad de Valencia, Av. Vicent Andrés Estellés s/n, Burjassot, 46100, Valencia, Spain
| | - Jérôme Boissier
- IHPE, University of Montpellier, CNRS, Ifremer, University of Perpignan Via Domitia, 66860, Perpignan, France.
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Stensgaard AS, Vounatsou P, Sengupta ME, Utzinger J. Schistosomes, snails and climate change: Current trends and future expectations. Acta Trop 2019; 190:257-268. [PMID: 30261186 DOI: 10.1016/j.actatropica.2018.09.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 09/19/2018] [Accepted: 09/20/2018] [Indexed: 12/19/2022]
Abstract
The exact impact of climate change on schistosomiasis, a disease caused by a blood fluke that affects more than 250 million people mainly in tropical and subtropical countries, is currently unknown, but likely to vary with the snail-parasite species' specific ecologies and the spatio-temporal scale of investigation. Here, by means of a systematic review to identify studies reporting on impacts of climate change on the agents of schistosomiasis, we provide an updated synthesis of the current knowledge about the climate change-schistosomiasis relation. We found that, despite a recent increase in scientific studies that discuss the potential impact of climate change on schistosomiasis, only a handful of reports have applied modelling and predictive forecasting that provide a quantitative estimate of potential outcomes. The volume and type of evidence associated with climate change responses were found to be variable across geographical regions and snail-parasite taxonomic groups. Indeed, the strongest evidence stems from the People's Republic of China pertaining to Schistosoma japonicum. Some evidence is also available from eastern Africa, mainly for Schistosoma mansoni. While studies focused on the northern and southern range margins for schistosomiasis indicate an increase in transmission range as the most likely outcome, there was less agreement about the direction of outcomes from the central and eastern parts of Africa. The current lack of consensus suggests that climate change is more likely to shift than to expand the geographic ranges of schistosomiasis. A comparison between the current geographical distributions and the thermo-physiological limitations of the two main African schistosome species (Schistosoma haematobium and S. mansoni) offered additional insights, and showed that both species already exist near their thermo-physiological niche boundaries. The African species both stand to move considerably out of their "thermal comfort zone" in a future, warmer Africa, but S. haematobium in particular is likely to experience less favourable climatic temperatures. The consequences for schistosomiasis transmission will, to a large extent, depend on the parasites and snails ability to adapt or move. Based on the identified geographical trends and knowledge gaps about the climate change-schistosomiasis relation, we propose to align efforts to close the current knowledge gaps and focus on areas considered to be the most vulnerable to climate change.
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Shehata MA, Chama MF, Funjika E. Prevalence and intensity of Schistosoma haematobium infection among schoolchildren in central Zambia before and after mass treatment with a single dose of praziquantel. Trop Parasitol 2018; 8:12-17. [PMID: 29930901 PMCID: PMC5991037 DOI: 10.4103/tp.tp_32_17] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2017] [Indexed: 12/21/2022] Open
Abstract
Introduction Urinary schistosomiasis caused by Schistosoma haematobium is common in some parts of Lusaka Province, Zambia, where water contact activity is high and sanitation is poor. We conducted a longitudinal study in Ng'ombe Compound of Lusaka, between 2007 and 2015, to observe the prevalence and intensity of S. haematobium infection among community primary school children, before and after receiving a single dose of praziquantel. Materials and Methods A total of 975 (445 females and 530 males) pupils, aged 9-16 years, were tested for S. haematobium at baseline. After mass treatment with praziquantel in 2010, 1570 pupils (785 females and 785 males), aged 9-15 years, were examined for S. haematobium eggs, from 2011 to 2015. Results At baseline, 279 out of 975 of the children were infected, with light infections constituting 84.9% and 15.1% classified as heavy infection. After mass treatment with praziquantel, the prevalence rate dropped, slightly, to 20.3% (63 out of 310) in 2011. However, it increased the following years up to 38% (133 out of 350) in 2015, with prevalence rates higher in males than females. The average number of heavy infection cases increased to 24.3% (120 out of 494) after treatment, reducing cases of light infections to 75.7% (374 out of 494). Conclusion This study revealed that mass treatment with a single dose of praziquantel was not sufficient to significantly reduce the transmission of schistosomiasis. Further studies will need to evaluate whether multiple praziquantel treatments will be more therapeutically effective in limiting future incidences.
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Affiliation(s)
- Mohamed A Shehata
- Department of Biological Sciences, The University of Zambia, Zambia, United Kingdom
| | - Mubanga F Chama
- Department of Chemistry, School of Natural Sciences, The University of Zambia, Zambia, United Kingdom.,Tropical Gastroenterology and Nutrition Group, School of Medicine, The University of Zambia, Zambia, United Kingdom
| | - Evelyn Funjika
- Department of Chemistry, School of Natural Sciences, The University of Zambia, Zambia, United Kingdom.,Tropical Gastroenterology and Nutrition Group, School of Medicine, The University of Zambia, Zambia, United Kingdom.,Faculty of Life Sciences, The University of Manchester, Manchester, United Kingdom
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11
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Lu XT, Gu QY, Limpanont Y, Song LG, Wu ZD, Okanurak K, Lv ZY. Snail-borne parasitic diseases: an update on global epidemiological distribution, transmission interruption and control methods. Infect Dis Poverty 2018; 7:28. [PMID: 29628017 PMCID: PMC5890347 DOI: 10.1186/s40249-018-0414-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 03/27/2018] [Indexed: 12/30/2022] Open
Abstract
Background Snail-borne parasitic diseases, such as angiostrongyliasis, clonorchiasis, fascioliasis, fasciolopsiasis, opisthorchiasis, paragonimiasis and schistosomiasis, pose risks to human health and cause major socioeconomic problems in many tropical and sub-tropical countries. In this review we summarize the core roles of snails in the life cycles of the parasites they host, their clinical manifestations and disease distributions, as well as snail control methods. Main body Snails have four roles in the life cycles of the parasites they host: as an intermediate host infected by the first-stage larvae, as the only intermediate host infected by miracidia, as the first intermediate host that ingests the parasite eggs are ingested, and as the first intermediate host penetrated by miracidia with or without the second intermediate host being an aquatic animal. Snail-borne parasitic diseases target many organs, such as the lungs, liver, biliary tract, intestines, brain and kidneys, leading to overactive immune responses, cancers, organ failure, infertility and even death. Developing countries in Africa, Asia and Latin America have the highest incidences of these diseases, while some endemic parasites have developed into worldwide epidemics through the global spread of snails. Physical, chemical and biological methods have been introduced to control the host snail populations to prevent disease. Conclusions In this review, we summarize the roles of snails in the life cycles of the parasites they host, the worldwide distribution of parasite-transmitting snails, the epidemiology and pathogenesis of snail-transmitted parasitic diseases, and the existing snail control measures, which will contribute to further understanding the snail-parasite relationship and new strategies for controlling snail-borne parasitic diseases. Electronic supplementary material The online version of this article (10.1186/s40249-018-0414-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Xiao-Ting Lu
- School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Qiu-Yun Gu
- School of Public Health, Sun Yat-sen University, Guangzhou, 510080, China
| | - Yanin Limpanont
- Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Lan-Gui Song
- Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China.,Provincial Engineering Technology Research Center for Biological Vector Control, Guangzhou, 510080, China
| | - Zhong-Dao Wu
- Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China.,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China.,Provincial Engineering Technology Research Center for Biological Vector Control, Guangzhou, 510080, China
| | - Kamolnetr Okanurak
- Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400, Thailand
| | - Zhi-Yue Lv
- Fifth Affiliated Hospital, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, China. .,Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, 510080, China. .,Provincial Engineering Technology Research Center for Biological Vector Control, Guangzhou, 510080, China.
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12
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Rinaldo A, Bertuzzo E, Blokesch M, Mari L, Gatto M. Modeling Key Drivers of Cholera Transmission Dynamics Provides New Perspectives for Parasitology. Trends Parasitol 2017; 33:587-599. [PMID: 28483382 DOI: 10.1016/j.pt.2017.04.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 04/01/2017] [Accepted: 04/10/2017] [Indexed: 11/15/2022]
Abstract
Hydroclimatological and anthropogenic factors are key drivers of waterborne disease transmission. Information on human settlements and host mobility on waterways along which pathogens and hosts disperse, and relevant hydroclimatological processes, can be acquired remotely and included in spatially explicit mathematical models of disease transmission. In the case of epidemic cholera, such models allowed the description of complex disease patterns and provided insight into the course of ongoing epidemics. The inclusion of spatial information in models of disease transmission can aid in emergency management and the assessment of alternative interventions. Here, we review the study of drivers of transmission via spatially explicit approaches and argue that, because many parasitic waterborne diseases share the same drivers as cholera, similar principles may apply.
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Affiliation(s)
- Andrea Rinaldo
- Laboratory of Ecohydrology, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Dipartimento ICEA, Università di Padova, Padova, Italy.
| | - Enrico Bertuzzo
- Laboratory of Ecohydrology, School of Architecture, Civil and Environmental Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Department of Environmental Sciences, Informatics and Statistics, University Cà Foscari Venice, Venezia Mestre, Italy
| | - Melanie Blokesch
- Laboratory of Molecular Microbiology, School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Lorenzo Mari
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
| | - Marino Gatto
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy
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13
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Echaubard P, León T, Suwanatrai K, Chaiyos J, Kim CS, Mallory FF, Kaewkes S, Spear RC, Sripa B. Experimental and modelling investigations of Opisthorchis viverrini miracidia transmission over time and across temperatures: implications for control. Int J Parasitol 2017; 47:257-270. [PMID: 28237890 DOI: 10.1016/j.ijpara.2016.10.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 10/10/2016] [Accepted: 10/21/2016] [Indexed: 01/07/2023]
Abstract
Transmissibility is a significant factor in parasite fitness. The rate and magnitude of parasite transmission affect prevalence and infection intensity in individual hosts and are influenced by environmental factors. In this context, the objectives of this study were: (i) to experimentally assess Opisthorchis viverrini miracidia survival and infectivity over time and across temperatures; and (ii) to combine these experimental results with environmental data to build a key component of a transmission model, identifying seasonal windows of transmission risk in hyper-endemic northeastern Thailand. Five replicates of 50 O. viverrini eggs were randomly distributed and maintained under four temperature conditions (25°C, 30°C, 35°C, 40°C). Microscopic observations were performed on all experimental units over a period of 3months to record miracidia motility and mortality trends. Six infection trials were also conducted to assess infectivity of miracidia over time and across temperatures, using observations of egg hatching success and infection rates. Upon completion of experiments, data were integrated into a transmission model to create a transmission risk index and to simulate seasonal transmission risk. Miracidia survival rate and motility decreased steadily with 50% mortality observed after 2weeks. Hatching and infection success also decreased significantly after 3weeks. Temperatures over 30°C were associated with increased mortality and decreased infectivity. When incorporating local environmental parameters into our model, we observed low transmission risk during the dry season and increasing transmission risk at the onset of the rainy season, culminating with the highest risk in September. We believe that our results provide the first estimates of O. viverrini miracidia survival and transmission potential under variable temperature conditions and suggest that high temperature treatment (>40°C) of fecal waste could be an efficient control strategy.
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Affiliation(s)
- Pierre Echaubard
- Global Health Asia, Integrative Education and Research Programme, Faculty of Public Health, Mahidol University, Bangkok, Thailand; WHO Collaborative Center for Research and Control of Opisthorchiasis, Tropical Disease Research Laboratory, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; Department of Biology, Laurentian University, Sudbury, Ontario P3E 2C6, Canada.
| | - Tomas León
- WHO Collaborative Center for Research and Control of Opisthorchiasis, Tropical Disease Research Laboratory, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; School of Public Health, University of California, Berkeley, CA 94720, USA
| | | | - Jukkrid Chaiyos
- Department of Parasitology, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Christina S Kim
- WHO Collaborative Center for Research and Control of Opisthorchiasis, Tropical Disease Research Laboratory, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Frank F Mallory
- Department of Biology, Laurentian University, Sudbury, Ontario P3E 2C6, Canada
| | - Sasithorn Kaewkes
- Department of Parasitology, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Robert C Spear
- School of Public Health, University of California, Berkeley, CA 94720, USA
| | - Banchob Sripa
- WHO Collaborative Center for Research and Control of Opisthorchiasis, Tropical Disease Research Laboratory, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; Liver Fluke and Cholangiocarcinoma Research Center, Department of Parasitology, Khon Kaen University, Khon Kaen 40002, Thailand.
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14
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Stanton MC, Adriko M, Arinaitwe M, Howell A, Davies J, Allison G, LaCourse EJ, Muheki E, Kabatereine NB, Stothard JR. Intestinal schistosomiasis in Uganda at high altitude (>1400 m): malacological and epidemiological surveys on Mount Elgon and in Fort Portal crater lakes reveal extra preventive chemotherapy needs. Infect Dis Poverty 2017; 6:34. [PMID: 28162096 PMCID: PMC5292801 DOI: 10.1186/s40249-017-0248-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 01/19/2017] [Indexed: 01/24/2023] Open
Abstract
Background Intestinal schistosomiasis is of public health importance in Uganda but communities living above 1400 m are not targeted for control as natural transmission is thought unlikely. To assess altitudinal boundaries and at-risk populations, conjoint malacological and epidemiological surveys were undertaken on Mount Elgon (1139 m–3937 m), in Fort Portal crater lakes and in the Rwenzori Mountains (1123 m–4050 m). Methods Seventy freshwater habitats [Mount Elgon (37), Fort Portal crater lakes (23), Rwenzori Mountains (8) and Lake Albert (2)] were inspected for Biomphalaria species. Water temperature, pH and conductivity were recorded. A parasitological examination of 756 schoolchildren [Mount Elgon (300), Fort Portal crater lakes (456)] by faecal microscopy of duplicate Kato-Katz smears from two consecutive stool samples was bolstered by antigen (urine-CCA dipstick) and antibody (SEA-ELISA) diagnostic assays. Results Biomphalaria spp. was found up to 1951 m on Mount Elgon and 1567 m in the Fort Portal crater lakes. Although no snail from Mount Elgon shed cercariae, molecular analysis judged 7.1% of snails sampled at altitudes above 1400 m as having DNA of Schistosoma mansoni; in Fort Portal crater lakes three snails shed schistosome cercariae. Prevalence of intestinal schistosomiasis as measured in schoolchildren by Kato-Katz (Mount Elgon = 5.3% v. Fort Portal crater lakes = 10.7%), CCA urine-dipsticks (18.3% v. 34.4%) and SEA-ELISA (42.3% v. 63.7%) showed negative associations with increasing altitude with some evidence of infection up to 2000 m. Conclusions Contrary to expectations, these surveys clearly show that natural transmission of intestinal schistosomiasis occurs above 1400 m, possibly extending up to 2000 m. Using spatial epidemiological predictions, this now places some extra six million people at-risk, denoting an expansion of preventive chemotherapy needs in Uganda. Electronic supplementary material The online version of this article (doi:10.1186/s40249-017-0248-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michelle C Stanton
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Moses Adriko
- Vector Control Division, Ministry of Health, Kampala, P.O. Box 1661, Uganda
| | - Moses Arinaitwe
- Vector Control Division, Ministry of Health, Kampala, P.O. Box 1661, Uganda
| | - Alison Howell
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Juliet Davies
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Gillian Allison
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - E James LaCourse
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Edridah Muheki
- Vector Control Division, Ministry of Health, Kampala, P.O. Box 1661, Uganda
| | - Narcis B Kabatereine
- Vector Control Division, Ministry of Health, Kampala, P.O. Box 1661, Uganda.,Schistosomiasis Control Initiative, Imperial College London, London, W2 1PG, UK
| | - J Russell Stothard
- Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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15
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Kalinda C, Chimbari M, Mukaratirwa S. Implications of Changing Temperatures on the Growth, Fecundity and Survival of Intermediate Host Snails of Schistosomiasis: A Systematic Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2017; 14:ijerph14010080. [PMID: 28098789 PMCID: PMC5295331 DOI: 10.3390/ijerph14010080] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/04/2017] [Accepted: 01/09/2017] [Indexed: 12/27/2022]
Abstract
Climate change has been predicted to increase the global mean temperature and to alter the ecological interactions among organisms. These changes may play critical roles in influencing the life history traits of the intermediate hosts (IHs). This review focused on studies and disease models that evaluate the potential effect of temperature rise on the ecology of IH snails and the development of parasites within them. The main focus was on IH snails of schistosome parasites that cause schistosomiasis in humans. A literature search was conducted on Google Scholar, EBSCOhost and PubMed databases using predefined medical subject heading terms, Boolean operators and truncation symbols in combinations with direct key words. The final synthesis included nineteen published articles. The studies reviewed indicated that temperature rise may alter the distribution, optimal conditions for breeding, growth and survival of IH snails which may eventually increase the spread and/or transmission of schistosomiasis. The literature also confirmed that the life history traits of IH snails and their interaction with the schistosome parasites are affected by temperature and hence a change in climate may have profound outcomes on the population size of snails, parasite density and disease epidemiology. We concluded that understanding the impact of temperature on the growth, fecundity and survival of IH snails may broaden the knowledge on the possible effects of climate change and hence inform schistosomiasis control programmes.
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Affiliation(s)
- Chester Kalinda
- School of Nursing and Public Health, College of Health Sciences, Howard College Campus, University of KwaZulu-Natal, Durban 4001, South Africa.
| | - Moses Chimbari
- School of Nursing and Public Health, College of Health Sciences, Howard College Campus, University of KwaZulu-Natal, Durban 4001, South Africa.
| | - Samson Mukaratirwa
- School of Life Sciences, College of Agriculture, Engineering and Science, Westville Campus, University of KwaZulu-Natal, Durban 4001, South Africa.
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16
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Monde C, Syampungani S, van den Brink PJ. Natural and human induced factors influencing the abundance of Schistosoma host snails in Zambia. ENVIRONMENTAL MONITORING AND ASSESSMENT 2016; 188:370. [PMID: 27230422 PMCID: PMC4882361 DOI: 10.1007/s10661-016-5351-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 05/05/2016] [Indexed: 06/05/2023]
Abstract
Schistosomiasis remains a global public health problem affecting about 240 million people. In Zambia, 2 million are infected while 3 million live with the risk of getting infected. Research and interventions relating to schistosomiasis are mainly linked to disease epidemiology. Malacological and ecological aspects of the disease are superficially understood. Developing effective control measures requires an understanding of interacting environmental and socioeconomic factors of host snails vis-a-vis schistosomiasis. Therefore, the present work involved collecting social and environmental data in a large field study in two zones in Zambia that are different in terms of temperature and rainfall amounts. Social data collected through questionnaires included demographic, educational and knowledge of schistosomiasis disease dynamics. Environmental data included physicochemical factors, aquatic plants and snails. Gender (P < 0.001) significantly influences livelihood strategies, while age (P = 0.069) and level of education (P = 0.086) have a moderate influence in zone I. In zone III, none of these factors (age, P = 0.378; gender, P = 0.311; education, P = 0.553) play a significant role. Environmental parameters explained 43 and 41 % variation in species composition for zones I and III, respectively. Most respondents' (52 %, 87 %) perception is that there are more cases of bilharzia in hot season than in other seasons (rainy season 23 %, 7 %; cold season 8 %, 0 % and year round 17 %, 6 %) for zone I and zone III, respectively.
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Affiliation(s)
- Concillia Monde
- Department of Aquatic Ecology and Water Quality Management, Wageningen University and Research Centre, P.O. Box 47, 6700 AA, Wageningen, The Netherlands.
- Department of Zoology and Aquatic Sciences, Copperbelt University, P.O. Box 21692, Jambo Drive, Riverside, Kitwe, Zambia.
| | - Stephen Syampungani
- Department of Plant and Environmental Sciences, Copperbelt University, P.O Box 21692, Jambo Drive, Riverside, Kitwe, Zambia
| | - Paul J van den Brink
- Department of Aquatic Ecology and Water Quality Management, Wageningen University and Research Centre, P.O. Box 47, 6700 AA, Wageningen, The Netherlands
- Alterra, Wageningen University and Research Centre, P.O. Box 47, 6700 AA, Wageningen, The Netherlands
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17
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McCreesh N, Nikulin G, Booth M. Predicting the effects of climate change on Schistosoma mansoni transmission in eastern Africa. Parasit Vectors 2015; 8:4. [PMID: 25558917 PMCID: PMC4297451 DOI: 10.1186/s13071-014-0617-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 12/19/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Survival and fitness attributes of free-living and sporocyst schistosome life-stages and their intermediate host snails are sensitive to water temperature. Climate change may alter the geographical distribution of schistosomiasis by affecting the suitability of freshwater bodies for hosting parasite and snail populations. METHODS We have developed an agent-based model of the temperature-sensitive stages of the Schistosoma mansoni and intermediate host snail lifecycles. The model was run using low, moderate and high warming climate projections over eastern Africa. For each climate projection, eight model scenarios were used to determine the sensitivity of predictions to different relationships between air and water temperature, and different snail mortality rates. Maps were produced showing predicted changes in risk as a result of increasing temperatures over the next 20 and 50 years. RESULTS Baseline model output compared to prevalence data indicates suitable temperatures are necessary but not sufficient for both S. mansoni transmission and high infection prevalences. All else being equal, infection risk may increase by up to 20% over most of eastern Africa over the next 20 and 50 years. Increases may be higher in Rwanda, Burundi, south-west Kenya and eastern Zambia, and S. mansoni may become newly endemic in some areas. Results for 20-year projections are robust to changes in simulated intermediate host snail habitat conditions. There is greater uncertainty about the effects of different habitats on changes in risk in 50 years' time. CONCLUSIONS Temperatures are likely to become suitable for increased S. mansoni transmission over much of eastern Africa. This may reduce the impact of control and elimination programmes. S. mansoni may also spread to new areas outside existing control programmes. We call for increased surveillance in areas defined as potentially suitable for emergent transmission.
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Affiliation(s)
- Nicky McCreesh
- School of Medicine, Pharmacy and Health, Durham University, Durham, DH1 3LE, UK.
| | - Grigory Nikulin
- Swedish Meteorological and Hydrological Institute, Rossby Centre, Norrköping, SE-601 7, Sweden.
| | - Mark Booth
- School of Medicine, Pharmacy and Health, Durham University, Durham, DH1 3LE, UK.
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18
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McCreesh N, Arinaitwe M, Arineitwe W, Tukahebwa EM, Booth M. Effect of water temperature and population density on the population dynamics of Schistosoma mansoni intermediate host snails. Parasit Vectors 2014; 7:503. [PMID: 25388819 PMCID: PMC4234839 DOI: 10.1186/s13071-014-0503-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 10/26/2014] [Indexed: 11/24/2022] Open
Abstract
Background Mathematical models can be used to identify areas at risk of increased or new schistosomiasis transmission as a result of climate change. The results of these models can be very different when parameterised to different species of host snail, which have varying temperature preferences. Currently, the experimental data needed by these models are available for only a few species of snail. The choice of density-dependent functions can also affect model results, but the effects of increasing densities on Biomphalaria populations have only previously been investigated in artificial aquariums. Methods Laboratory experiments were conducted to estimate Biomphalaria sudanica mortality, fecundity and growth rates at ten different constant water temperatures, ranging from 13-32°C. Snail cages were used to determine the effects of snail densities on B. sudanica and B. stanleyi mortality and fecundity rates in semi-natural conditions in Lake Albert. Results B. sudanica survival and fecundity were highest at 20°C and 22°C respectively. Growth in shell diameter was estimated to be highest at 23°C in small and medium sized snails, but the relationship between temperature and growth was not clear. The fecundity of both B. sudanica and B. stanleyi decreased by 72-75% with a four-fold increase in population density. Increasing densities four-fold also doubled B. stanleyi mortality rates, but had no effect on the survival of B. sudanica. Conclusions The optimum temperature for fecundity was lower for B. sudanica than for previously studied species of Biomphalaria. In contrast to other Biomphalaria species, B. sudanica have a distinct peak temperature for survival, as opposed to a plateau of highly suitable temperatures. For both B. stanleyi and B. sudanica, fecundity decreased with increasing population densities. This means that snail populations may experience large fluctuations in numbers, even in the absence of any external factors such as seasonal temperature changes. Survival also decreased with increasing density for B. stanleyi, in contrast to B. sudanica and other studied Biomphalaria species where only fecundity has been shown to decrease. Electronic supplementary material The online version of this article (doi:10.1186/s13071-014-0503-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nicky McCreesh
- School of Medicine, Pharmacy and Health, Durham University, Durham, DH1 3LE, UK.
| | - Moses Arinaitwe
- Vector Control Division, Ministry of Health, Plot 15 Bombo Road, Kampala, Uganda.
| | - Wilber Arineitwe
- Vector Control Division, Ministry of Health, Plot 15 Bombo Road, Kampala, Uganda.
| | - Edridah M Tukahebwa
- Vector Control Division, Ministry of Health, Plot 15 Bombo Road, Kampala, Uganda.
| | - Mark Booth
- School of Medicine, Pharmacy and Health, Durham University, Durham, DH1 3LE, UK.
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19
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McCreesh N, Booth M. The effect of increasing water temperatures on Schistosoma mansoni transmission and Biomphalaria pfeifferi population dynamics: an agent-based modelling study. PLoS One 2014; 9:e101462. [PMID: 24987963 PMCID: PMC4079709 DOI: 10.1371/journal.pone.0101462] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 06/06/2014] [Indexed: 11/26/2022] Open
Abstract
Introduction There is increasing interest in the control and elimination of schistosomiasis. Little is known, however, about the likely effects of increasing water-body temperatures on transmission. Methods We have developed an agent-based model of the temperature-sensitive stages of the Schistosoma and intermediate host snail life-cycles, parameterised using data from S. mansoni and Biomphalaria pfeifferi laboratory and field-based observations. Infection risk is calculated as the number of cercariae in the model, adjusted for their probability of causing infection. Results The number of snails in the model is approximately constant between 15–31°C. Outside this range, snail numbers drop sharply, and the snail population cannot survive outside the range 14–32°C. Mean snail generation time decreases with increasing temperature from 176 days at 14°C to 46 days at 26°C. Human infection risk is highest between 16–18°C and 1 pm and 6–10 pm in calm water, and 20–25°C and 12–4 pm in flowing water. Infection risk increases sharply when temperatures increase above the minimum necessary for sustained transmission. Conclusions The model suggests that, in areas where S. mansoni is already endemic, warming of the water at transmission sites will have differential effects on both snails and parasites depending on abiotic properties of the water-body. Snail generation times will decrease in most areas, meaning that snail populations will recover faster from natural population reductions and from snail-control efforts. We suggest a link between the ecological properties of transmission sites and infection risk which could significantly affect the outcomes of interventions designed to alter water contact behaviour – proposing that such interventions are more likely to reduce infection levels at river locations than lakes, where infection risk remains high for longer. In cooler areas where snails are currently found, increasing temperatures may significantly increase infection risk, potentially leading to new, high-intensity foci of infection.
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Affiliation(s)
- Nicky McCreesh
- School of Medicine, Pharmacy and Health, Durham University, Durham, United Kingdom
- * E-mail:
| | - Mark Booth
- School of Medicine, Pharmacy and Health, Durham University, Durham, United Kingdom
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