Schistosomiasis


The disease

Schistosomiasis, also known as bilharzia, is transmitted when people come into contact with water infected with the larval form of a parasitic blood fluke (flatworm) known as a schistosome. Water is contaminated with Schistosoma eggs when an infected person defecates or urinates into the water. The parasite uses freshwater snails as an intermediate host, such that when the eggs hatch in the water, they firstly enter snails, and once it has developed sufficiently within the snail, it emerges for the snail and swims around until it finds a person to infect. The parasite gets into the bloodstream via the skin, although it is so small the infected person will not feel anything. Most people don’t experience any initial symptoms and hence won’t know they are infected. There are two main forms of schistosomiasis: intestinal and urogenitory, with the infection type depending of the species of blood fluke that a person has been infected with. Symptoms of intestinal schistosomiasis include abdominal pain, diarrhoea, and blood in stools, whereas the main symptom of urogenital schistosomiasis is blood in urine, with less common symptoms including fibrosis of the bladder and kidney damage. In children, schistosomiasis infections are known to cause anaemia and stunted growth, and thus reduces school performance.

Disease control

Schistosomiasis is currently controlled by regularly treating all school-aged children within a high or moderate risk area with a anthelmintic (deworming) drug called praziquantel. Risk is assessed using prevalence surveys such that high risk areas are those with an estimated schistosomiasis prevalence (using parasitological diagnostic methods) above 50%, whereas moderate areas are those with prevalence between 10% and 50%.

Geographical distribution

Lai_schisto_prev

Predicted prevalence using survey data obtained from 2000 onwards, as published by Lai et al (2015)

Schistosomiasis is found in tropical and subtropical countries, with 90% of the cases occurring in sub-Saharan Africa. It is a highly focal disease, with its geographical distribution being largely influenced by water around which sanitation and hygiene practises are poor.

Factors influencing the geographical distribution

Schistosomiasis is found in areas where people have contact with waterbodies which are a good habitat for the snail host, and where sanitation and hygiene practises enable transmission to occur. Thus, when determining the geographical distribution of disease, factors affecting snail habitat, sanitation and hygiene, plus human water contact activities need to be taken into consideration. , or less frequently the geographical distribution of the intermediate host, the environmental factors researchers consider include precipitation, temperature, various soil properties, vegetation indices, landcover type, locations of waterbodies and water properties.

Spatial models of the geographical distribution

Spatial models associated with schistosomiasis tend to focus on mapping predictions of prevalence, as this measure is used to guide control strategies. The geographical factors included in these models include precipitation, temperature, various soil properties, vegetation indices, landcover type, and locations of waterbodies. See for example the papers by Manyangadze et al (2015) and Lai et al (2015) which review recently published spatial model publications, and predict prevalence across the sub-Saharan region respectively. Studies that focus on modelling schistosomiasis prevalence at the smaller geographical scale focus on more localised risk factors such as those influencing human water contact.

Models that focus on the spatial distribution of the intermediate host, the freshwater snail are less common than those of disease prevalence, as snail data is less abundant.  These models tend to focus on the type of habitat in and around freshwater plus water properties (temperature, pH, electro-conductivity and velocity).

Focus of the FOCAL-NTDs project

The overall objective of the FOCAL-NTDs project is to derive detailed risk maps for schistosomiais, and to extend our knowledge of appropriate sampling strategies for assessing disease risk in order to guide control and assist in determining the elimination status of the diseases. This work is being  undertaken in collaboration with Professor Russ Stothard, the director of the COUNTDOWN project.

References

  • [DOI] Danso-Appiah Tony. Schistosomiasis. In: Neglected tropical diseases – sub-saharan africa. Springer, 2016, 251-288.
    [Bibtex]
    @incollection{Danso-Appiah2016,
    author = {Danso-Appiah, Tony},
    booktitle = {Neglected Tropical Diseases - Sub-Saharan Africa},
    doi = {10.1007/978-3-319-25471-5_11},
    pages = {251--288},
    publisher = {Springer},
    title = {{Schistosomiasis}},
    url = {http://link.springer.com/10.1007/978-3-319-25471-5{\_}11},
    year = {2016}
    }
  • [DOI] Grimes Jack ET, Templeton Michael R. Geostatistical modelling of schistosomiasis prevalence.. The lancet. infectious diseases 2015;15(8):869-70.
    [Bibtex]
    @article{Grimes2015,
    author = {Grimes, Jack E T and Templeton, Michael R},
    doi = {10.1016/S1473-3099(15)00067-5},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Grimes, Templeton - 2015 - Geostatistical modelling of schistosomiasis prevalence.pdf:pdf},
    issn = {1474-4457},
    journal = {The Lancet. Infectious diseases},
    keywords = {Animals,Humans,Schistosomiasis,Schistosomiasis: epidemiology},
    month = {aug},
    number = {8},
    pages = {869--70},
    pmid = {26004858},
    title = {{Geostatistical modelling of schistosomiasis prevalence.}},
    url = {http://www.sciencedirect.com/science/article/pii/S1473309915000675},
    volume = {15},
    year = {2015}
    }
  • [DOI] Gurarie David, Yoon Nara, Li Emily, Ndeffo-Mbah Martial, Durham David, Phillips Anna E, Aurelio Osvaldo H, Ferro Josefo, Galvani Alison P, King Charles H. Modelling control of Schistosoma haematobium infection: predictions of the long-term impact of mass drug administration in Africa.. Parasites & vectors 2015;8(1):529.
    [Bibtex]
    @article{Gurarie2015,
    abstract = {BACKGROUND: Effective control of schistosomiasis remains a challenging problem for endemic areas of the world. Given knowledge of the biology of transmission and past experience with mass drug administration (MDA) programs, it is important to critically evaluate the likelihood that MDA programs will achieve substantial reductions in Schistosoma prevalence. In implementing the World Health Organization Roadmap for Neglected Tropical Diseases it would useful for policymaking to model projections of the status of Schistosoma control in MDA-treated areas in the next 5-10 years.
    METHODS: Calibrated mathematical models were used to project the effects of different frequency and coverage of MDA for schistosomiasis haematobia control in present-day endemic communities, taking into account uncertainties of parasite biology and input data. The modeling approach in this analysis was the Stratified Worm Burden model developed in our earlier works, calibrated using data from longitudinal S. haematobium control trials in Kenya.
    RESULTS: Model-based simulations of MDA control in typical low-risk and higher-risk communities indicated that infection prevalence can be substantially reduced within 10 years only when there is a high degree of community participation ({\textgreater}70 {\%}) with at least annual MDA. Significant risk for re-emergence of infection remains if MDA is suspended.
    CONCLUSIONS: In a stable (stationary) ecosystem, Schistosoma reproduction and transmission are sufficiently robust that the process of human infection continues, even under pressure from aggressive MDA. MDA alone is unlikely to interrupt transmission, and once mass treatment is suspended, the prevalence of human infection is likely to rebound to pre-control levels over a period of 25-30 years. MDA success in achieving very low levels of infection prevalence is highly dependent on treatment coverage and frequency within the local human population, and requires that both adults and children be included in drug delivery coverage. Ultimately, supplemental snail control and significant improvements in sanitation will be required to achieve full control of schistosomiasis by elimination of ongoing Schistosoma transmission.},
    author = {Gurarie, David and Yoon, Nara and Li, Emily and Ndeffo-Mbah, Martial and Durham, David and Phillips, Anna E and Aurelio, H Osvaldo and Ferro, Josefo and Galvani, Alison P and King, Charles H},
    doi = {10.1186/s13071-015-1144-3},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Gurarie et al. - 2015 - Modelling control of Schistosoma haematobium infection predictions of the long-term impact of mass drug admin(2).pdf:pdf},
    issn = {1756-3305},
    journal = {Parasites {\&} vectors},
    month = {jan},
    number = {1},
    pages = {529},
    pmid = {26489408},
    title = {{Modelling control of Schistosoma haematobium infection: predictions of the long-term impact of mass drug administration in Africa.}},
    url = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=4618728{\&}tool=pmcentrez{\&}rendertype=abstract},
    volume = {8},
    year = {2015}
    }
  • [DOI] Lai Ying-Si, Biedermann Patricia, Ekpo Uwem F, Garba Amadou, Mathieu Els, Midzi Nicholas, Mwinzi Pauline, N’Goran Eliézer K, Raso Giovanna, Assaré Rufin K, Sacko Moussa, Schur Nadine, Talla Idrissa, Tchuenté Louis-Albert Tchuem, Touré Seydou, Winkler Mirko S, Utzinger Jürg, Vounatsou Penelope. Spatial distribution of schistosomiasis and treatment needs in sub-Saharan Africa: a systematic review and geostatistical analysis.. The lancet. infectious diseases 2015;15(8):927-40.
    [Bibtex]
    @article{Lai2015,
    abstract = {BACKGROUND: Schistosomiasis affects more than 200 million individuals, mostly in sub-Saharan Africa, but empirical estimates of the disease burden in this region are unavailable. We used geostatistical modelling to produce high-resolution risk estimates of infection with Schistosoma spp and of the number of doses of praziquantel treatment needed to prevent morbidity at different administrative levels in 44 countries.
    METHODS: We did a systematic review to identify surveys including schistosomiasis prevalence data in sub-Saharan Africa via PubMed, ISI Web of Science, and African Journals Online, from inception to May 2, 2014, with no restriction of language, survey date, or study design. We used Bayesian geostatistical meta-analysis and rigorous variable selection to predict infection risk over a grid of 1 155 818 pixels at 5 × 5 km, on the basis of environmental and socioeconomic predictors and to calculate the number of doses of praziquantel needed for prevention of morbidity.
    FINDINGS: The literature search identified Schistosoma haematobium and Schistosoma mansoni surveys done in, respectively, 9318 and 9140 unique locations. Infection risk decreased from 2000 onwards, yet estimates suggest that 163 million (95{\%} Bayesian credible interval [CrI] 155 million to 172 million; 18{\textperiodcentered}5{\%}, 17{\textperiodcentered}6-19{\textperiodcentered}5) of the sub-Saharan African population was infected in 2012. Mozambique had the highest prevalence of schistosomiasis in school-aged children (52{\textperiodcentered}8{\%}, 95{\%} CrI 48{\textperiodcentered}7-57{\textperiodcentered}8). Low-risk countries (prevalence among school-aged children lower than 10{\%}) included Burundi, Equatorial Guinea, Eritrea, and Rwanda. The numbers of doses of praziquantel needed per year were estimated to be 123 million (95{\%} CrI 121 million to 125 million) for school-aged children and 247 million (239 million to 256 million) for the entire population.
    INTERPRETATION: Our results will inform policy makers about the number of treatments needed at different levels and will guide the spatial targeting of schistosomiasis control interventions.
    FUNDING: European Research Council, China Scholarship Council, UBS Optimus Foundation, and Swiss National Science Foundation.},
    author = {Lai, Ying-Si and Biedermann, Patricia and Ekpo, Uwem F and Garba, Amadou and Mathieu, Els and Midzi, Nicholas and Mwinzi, Pauline and N'Goran, Eli{\'{e}}zer K and Raso, Giovanna and Assar{\'{e}}, Rufin K and Sacko, Moussa and Schur, Nadine and Talla, Idrissa and Tchuent{\'{e}}, Louis-Albert Tchuem and Tour{\'{e}}, Seydou and Winkler, Mirko S and Utzinger, J{\"{u}}rg and Vounatsou, Penelope},
    doi = {10.1016/S1473-3099(15)00066-3},
    issn = {1474-4457},
    journal = {The Lancet. Infectious diseases},
    keywords = {Adolescent,Africa South of the Sahara,Africa South of the Sahara: epidemiology,Animals,Bayes Theorem,Child,Child, Preschool,Health Services Needs and Demand,Humans,Morbidity,Mozambique,Praziquantel,Praziquantel: therapeutic use,Prevalence,Schistosoma haematobium,Schistosoma haematobium: drug effects,Schistosoma mansoni,Schistosoma mansoni: drug effects,Schistosomiasis,Schistosomiasis: drug therapy,Schistosomiasis: epidemiology},
    language = {English},
    month = {aug},
    number = {8},
    pages = {927--40},
    pmid = {26004859},
    publisher = {Elsevier},
    title = {{Spatial distribution of schistosomiasis and treatment needs in sub-Saharan Africa: a systematic review and geostatistical analysis.}},
    url = {http://www.thelancet.com/article/S1473309915000663/fulltext},
    volume = {15},
    year = {2015}
    }
  • [DOI] Lo Nathan C, Lai Ying-Si, Karagiannis-Voules Dimitrios-Alexios, Bogoch Isaac I, Coulibaly Jean T, Bendavid Eran, Utzinger Jürg, Vounatsou Penelope, Andrews Jason R. Assessment of global guidelines for preventive chemotherapy against schistosomiasis and soil-transmitted helminthiasis: a cost-effectiveness modelling study. The lancet infectious diseases 2015:74-84.
    [Bibtex]
    @article{Lo2015a,
    author = {Lo, Nathan C and Lai, Ying-Si and Karagiannis-Voules, Dimitrios-Alexios and Bogoch, Isaac I and Coulibaly, Jean T and Bendavid, Eran and Utzinger, J{\"{u}}rg and Vounatsou, Penelope and Andrews, Jason R},
    doi = {10.1016/S1473-3099(16)30073-1},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Lo et al. - 2015 - Assessment of global guidelines for preventive chemotherapy against schistosomiasis and soil-transmitted helminthiasi.pdf:pdf},
    journal = {The Lancet Infectious Diseases},
    number = {0},
    pages = {74--84},
    publisher = {Elsevier},
    title = {{Assessment of global guidelines for preventive chemotherapy against schistosomiasis and soil-transmitted helminthiasis: a cost-effectiveness modelling study}},
    volume = {0},
    year = {2015}
    }
  • [DOI] Makaula Peter, Sadalaki John R, Muula Adamson S, Kayuni Sekeleghe, Jemu Samuel, Bloch Paul. Schistosomiasis in Malawi: a systematic review.. Parasites & vectors 2014;7(1):570.
    [Bibtex]
    @article{Makaula2014,
    abstract = {IntroductionSchistosomiasis remains an important public health problem that undermines social and economic development in tropical regions of the world, mainly Sub-Saharan Africa. We are not aware of any systematic review of the literature of the epidemiology and transmission of schistosomiasis in Malawi since 1985. Therefore, we reviewed the current state of knowledge of schistosomiasis epidemiology and transmission in this country and identified knowledge gaps and relevant areas for future research and research governance.MethodsWe conducted computer-aided literature searches of Medline, SCOPUS and Google Scholar using the keywords: ¿schistosomiasis¿, ¿Bilharzia¿, ¿Bulinus¿ and ¿Biomphalaria¿ in combination with ¿Malawi¿. These searches were supplemented by iterative reviews of reference lists for relevant publications in peer reviewed international scientific journals or other media. The recovered documents were reviewed for their year of publication, location of field or laboratory work, authorship characteristics, ethics review, funding sources as well as their findings regarding parasite and intermediate host species, environmental aspects, geographical distribution, seasonality of transmission, and infection prevalence and intensities.ResultsA total of 89 documents satisfied the inclusion criteria and were reviewed. Of these, 76 were published in international scientific journals, 68 were peer reviewed and 54 were original research studies. Most of the documents addressed urinary schistosomiasis and about two thirds of them dealt with the definitive host. Few documents addressed the parasites and the intermediate hosts. While urinary schistosomiasis occurs in most parts of Malawi, intestinal schistosomiasis mainly occurs in the central and southern highlands, Likoma Island and Lower Shire. Studies in selected communities estimated prevalence rates of up to 94.9{\%} for Schistosoma haematobium and up to 67.0{\%} for Schistosoma mansoni with considerable geographical variation. The main intermediate host species are Bulinus globosus and Bulinus nyassanus for urinary schistosomiasis and Biomphalaria pfeifferi for intestinal schistosomiasis. Seasonality of transmission tends to vary according to geographical, environmental, biological and behavioural factors.ConclusionTransmission of schistosomiasis in Malawi appears to be highly focal, with considerable variation in space and time. Many locations have not been covered by epidemiological investigations and, thus, information on the transmission of schistosomiasis in Malawi remains fragmented. Functional infection risk assessment systems based on systematic investigations and surveillance are required for developing informed prevention and control strategies.},
    author = {Makaula, Peter and Sadalaki, John R and Muula, Adamson S and Kayuni, Sekeleghe and Jemu, Samuel and Bloch, Paul},
    doi = {10.1186/PREACCEPT-4336743301397410},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Makaula et al. - 2014 - Schistosomiasis in Malawi a systematic review(2).pdf:pdf},
    issn = {1756-3305},
    journal = {Parasites {\&} vectors},
    month = {dec},
    number = {1},
    pages = {570},
    pmid = {25490938},
    title = {{Schistosomiasis in Malawi: a systematic review.}},
    url = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=4288699{\&}tool=pmcentrez{\&}rendertype=abstract},
    volume = {7},
    year = {2014}
    }
  • Manyangadze Tawanda, Chimbari Moses John, Gebreslasie Michael, Mukaratirwa Samson. Application of geo-spatial technology in schistosomiasis modelling in Africa: a review. , 2015.
    [Bibtex]
    @misc{Manyangadze2015,
    abstract = {Schistosomiasis continues to impact socio-economic development negatively in sub-Saharan Africa. The advent of spatial technologies, including geographic information systems (GIS), Earth observation (EO) and global positioning systems (GPS) assist modelling efforts. However, there is increasing concern regarding the accuracy and precision of the current spatial models. This paper reviews the literature regarding the progress and challenges in the development and utilization of spatial technology with special reference to predictive models for schistosomiasis in Africa. Peer-reviewed papers identified through a PubMed search using the following keywords: geo-spatial analysis OR remote sensing OR modelling OR earth observation OR geographic information systems OR prediction OR mapping AND schistosomiasis AND Africa were used. Statistical uncertainty, low spatial and temporal resolution satellite data and poor validation were identified as some of the factors that compromise the precision and accuracy of the existing predictive models. The need for high spatial resolution of remote sensing data in conjunction with ancillary data viz. ground-measured climatic and environmental information, local presence/absence intermediate host snail surveys as well as prevalence and intensity of human infection for model calibration and validation are discussed. The importance of a multidisciplinary approach in developing robust, spatial data capturing, modelling techniques and products applicable in epidemiology is highlighted.},
    author = {Manyangadze, Tawanda and Chimbari, Moses John and Gebreslasie, Michael and Mukaratirwa, Samson},
    booktitle = {Geospatial Health},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Manyangadze et al. - 2015 - Application of geo-spatial technology in schistosomiasis modelling in Africa a review(3).pdf:pdf},
    issn = {1970-7096},
    keywords = {Africa,Earth observation,Geo-spatial technologies,Geographic information systems,Schistosomiasis modelling},
    language = {en},
    month = {nov},
    number = {2},
    title = {{Application of geo-spatial technology in schistosomiasis modelling in Africa: a review}},
    url = {http://geospatialhealth.net/index.php/gh/article/view/326},
    volume = {10},
    year = {2015}
    }
  • [DOI] Meurs Lynn, Mbow Moustapha, Boon Nele, {Van Den Broeck} Frederik, Vereecken Kim, Ndiaye Tandakha, Ye Diè, Abatih Emmanuel, Huyse Tine, Mboup Souleymane, Polman Katja. Micro-Geographical Heterogeneity in Schistosoma mansoni and S. haematobium Infection and Morbidity in a Co-Endemic Community in Northern Senegal. .
    [Bibtex]
    @article{Meurs,
    abstract = {Background: Schistosoma mansoni and S. haematobium are co-endemic in many areas in Africa. Yet, little is known about the micro-geographical distribution of these two infections or associated disease within such foci. Such knowledge could give important insights into the drivers of infection and disease and as such better tailor schistosomiasis control and elimination efforts. Methodology: In a co-endemic farming community in northern Senegal (346 children (0–19 y) and 253 adults (20–85 y); n = 599 in total), we studied the spatial distribution of S. mansoni and S. haematobium single and mixed infections (by microscopy), S. mansoni-specific hepatic fibrosis, S. haematobium-specific urinary tract morbidity (by ultrasound) and water contact behavior (by questionnaire). The Kulldorff's scan statistic was used to detect spatial clusters of infection and morbidity, adjusted for the spatial distribution of gender and age.},
    author = {Meurs, Lynn and Mbow, Moustapha and Boon, Nele and {Van Den Broeck}, Frederik and Vereecken, Kim and Ndiaye, Tandakha and Ye, Di{\`{e}} and Abatih, Emmanuel and Huyse, Tine and Mboup, Souleymane and Polman, Katja},
    doi = {10.1371/journal.pntd.0002608},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Meurs et al. - Unknown - Micro-Geographical Heterogeneity in Schistosoma mansoni and S. haematobium Infection and Morbidity in a Co-Ende.pdf:pdf},
    title = {{Micro-Geographical Heterogeneity in Schistosoma mansoni and S. haematobium Infection and Morbidity in a Co-Endemic Community in Northern Senegal}}
    }
  • [DOI] Moser Wendelin, Greter Helena, Schindler Christian, Allan Fiona, Ngandolo Bongo NR, Moto Daugla D, Utzinger Jürg, Zinsstag Jakob. The spatial and seasonal distribution of Bulinus truncatus, Bulinus forskalii and Biomphalaria pfeifferi, the intermediate host snails of schistosomiasis, in N’Djamena, Chad.. Geospatial health 2014;9(1):109-18.
    [Bibtex]
    @article{Moser2014,
    abstract = {There is a paucity of epidemiological and malacological data pertaining to schistosomiasis in Chad. In view of a recently articulated elimination agenda, a deeper understanding of the spatio-temporal distribution of schistosomiasis intermediate host snails is pivotal. We conducted cross-sectional malacological surveys during the dry season (April/May 2013) and after the short rainy season (October 2013) in N'Djamena, the capital of Chad. Snails were identified at the genus and species level using morphological keys and molecular DNA barcoding approaches. Those belonging to Bulinus and Biomphalaria were examined for cercarial shedding. Snail habitats were characterised and their predictive potential for the presence of schistosomiasis intermediate host snails explored. Seasonal patterns were studied using geographical information system and kriging in order to interpolate snail abundance data to make predictions at non-sampled locations across N'Djamena. Overall, 413 Bulinus truncatus, 369 Bulinus forskalii and 108 Biomphalaria pfeifferi snails were collected and subjected to cercarial shedding. During the dry season, one Bu. truncatus of 119 snails collected shed Schistosoma spp. cercariae (0.84{\%}), while S. mansoni was shed by one of 108 Bi. pfeifferi snails (0.93{\%}). None of the snails collected after the rainy season shed Schistosoma spp. cercariae. The abundance of Bu. truncatus and Bu. forskalii showed an inverse U-shape relationship with the square term of conductivity, i.e. low abundance at the lowest and highest levels of conductivity and high abundance at intermediate levels. Bi. pfeifferi showed a negative, linear association with pH in the dry seasons. It is planned to link these intermediate host snail data to infection data in human populations with the goal to draw a predictive risk map that can be utilised for control and elimination of schistosomiasis in N'Djamena.},
    author = {Moser, Wendelin and Greter, Helena and Schindler, Christian and Allan, Fiona and Ngandolo, Bongo N R and Moto, Daugla D and Utzinger, J{\"{u}}rg and Zinsstag, Jakob},
    doi = {10.4081/gh.2014.9},
    issn = {1970-7096},
    journal = {Geospatial health},
    month = {nov},
    number = {1},
    pages = {109--18},
    pmid = {25545929},
    title = {{The spatial and seasonal distribution of Bulinus truncatus, Bulinus forskalii and Biomphalaria pfeifferi, the intermediate host snails of schistosomiasis, in N'Djamena, Chad.}},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/25545929},
    volume = {9},
    year = {2014}
    }
  • [DOI] Ofulla Ayub V, Adoka Samson O, Anyona Douglas N, Abuom Paul O, Karanja Diana, Vulule John M, Okurut Tom, Matano Ally-Said, Dida Gabriel O, Jembe Tsuma, Gichuki John. Spatial distribution and habitat characterization of schistosomiasis host snails in lake and land habitats of western Kenya. Lakes & reservoirs: research & management 2013;18(2):197-215.
    [Bibtex]
    @article{Ofulla2013,
    author = {Ofulla, Ayub V. and Adoka, Samson O. and Anyona, Douglas N. and Abuom, Paul O. and Karanja, Diana and Vulule, John M. and Okurut, Tom and Matano, Ally-Said and Dida, Gabriel O. and Jembe, Tsuma and Gichuki, John},
    doi = {10.1111/lre.12032},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Ofulla et al. - 2013 - Spatial distribution and habitat characterization of schistosomiasis host snails in lake and land habitats of wes.pdf:pdf},
    issn = {13205331},
    journal = {Lakes {\&} Reservoirs: Research {\&} Management},
    keywords = {Biomphalaria and Bulinus snails,Lake Victoria basin,aquatic habitats,physicochemical parameters,phytoplankton,zooplankton},
    month = {jun},
    number = {2},
    pages = {197--215},
    title = {{Spatial distribution and habitat characterization of schistosomiasis host snails in lake and land habitats of western Kenya}},
    url = {http://doi.wiley.com/10.1111/lre.12032},
    volume = {18},
    year = {2013}
    }
  • [DOI] Pedersen Ulrik B, Stendel Martin, Midzi Nicholas, Mduluza Takafira, Soko White, Stensgaard Anna-Sofie, Vennervald Birgitte J, Mukaratirwa Samson, Kristensen Thomas K. Modelling climate change impact on the spatial distribution of fresh water snails hosting trematodes in Zimbabwe.. Parasites & vectors 2014;7:536.
    [Bibtex]
    @article{Pedersen2014a,
    abstract = {BACKGROUND Freshwater snails are intermediate hosts for a number of trematodes of which some are of medical and veterinary importance. The trematodes rely on specific species of snails to complete their life cycle; hence the ecology of the snails is a key element in transmission of the parasites. More than 200 million people are infected with schistosomes of which 95{\%} live in sub-Saharan Africa and many more are living in areas where transmission is on-going. Human infection with the Fasciola parasite, usually considered more of veterinary concern, has recently been recognised as a human health problem. Many countries have implemented health programmes to reduce morbidity and prevalence of schistosomiasis, and control programmes to mitigate food-borne fascioliasis. As these programmes are resource demanding, baseline information on disease prevalence and distribution becomes of great importance. Such information can be made available and put into practice through maps depicting spatial distribution of the intermediate snail hosts. METHODS A biology driven model for the freshwater snails Bulinus globosus, Biomphalaria pfeifferi and Lymnaea natalensis was used to make predictions of snail habitat suitability by including potential underlying environmental and climatic drivers. The snail observation data originated from a nationwide survey in Zimbabwe and the prediction model was parameterised with a high resolution Regional Climate Model. Georeferenced prevalence data on urinary and intestinal schistosomiasis and fascioliasis was used to calibrate the snail habitat suitability predictions to produce binary maps of snail presence and absence. RESULTS Predicted snail habitat suitability across Zimbabwe, as well as the spatial distribution of snails, is reported for three time slices representative for present (1980-1999) and future climate (2046-2065 and 2080-2099). CONCLUSIONS It is shown from the current study that snail habitat suitability is highly variable in Zimbabwe, with distinct high- and low- suitability areas and that temperature may be the main driving factor. It is concluded that future climate change in Zimbabwe may cause a reduced spatial distribution of suitable habitat of host snails with a probable exception of Bi. pfeifferi, the intermediate host for intestinal schistosomiasis that may increase around 2055 before declining towards 2100.},
    author = {Pedersen, Ulrik B and Stendel, Martin and Midzi, Nicholas and Mduluza, Takafira and Soko, White and Stensgaard, Anna-Sofie and Vennervald, Birgitte J and Mukaratirwa, Samson and Kristensen, Thomas K},
    doi = {10.1186/s13071-014-0536-0},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Pedersen et al. - 2014 - Modelling climate change impact on the spatial distribution of fresh water snails hosting trematodes in Zimbabw.pdf:pdf},
    issn = {1756-3305},
    journal = {Parasites {\&} vectors},
    pages = {536},
    pmid = {25498001},
    title = {{Modelling climate change impact on the spatial distribution of fresh water snails hosting trematodes in Zimbabwe.}},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/25498001 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=PMC4299310},
    volume = {7},
    year = {2014}
    }
  • [DOI] Schur Nadine, Hürlimann Eveline, Stensgaard Anna-Sofie, Chimfwembe Kingford, Mushinge Gabriel, Simoonga Christopher, Kabatereine Narcis B, Vounatsou Penelope. Spatially explicit Schistosoma infection risk in eastern Africa using Bayesian geostatistical modelling. Acta tropica 2013;128(2):365-377.
    [Bibtex]
    @article{Schur2013,
    abstract = {Schistosomiasis remains one of the most prevalent parasitic diseases in the tropics and subtropics, but current statistics are outdated due to demographic and ecological transformations and ongoing control efforts. Reliable risk estimates are important to plan and evaluate interventions in a spatially explicit and cost-effective manner. We analysed a large ensemble of georeferenced survey data derived from an open-access neglected tropical diseases database to create smooth empirical prevalence maps for Schistosoma mansoni and Schistosoma haematobium for a total of 13 countries of eastern Africa. Bayesian geostatistical models based on climatic and other environmental data were used to account for potential spatial clustering in spatially structured exposures. Geostatistical variable selection was employed to reduce the set of covariates. Alignment factors were implemented to combine surveys on different age-groups and to acquire separate estimates for individuals aged ≤20 years and entire communities. Prevalence estimates were combined with population statistics to obtain country-specific numbers of Schistosoma infections. We estimate that 122 million individuals in eastern Africa are currently infected with either S. mansoni, or S. haematobium, or both species concurrently. Country-specific population-adjusted prevalence estimates range between 12.9{\%} (Uganda) and 34.5{\%} (Mozambique) for S. mansoni and between 11.9{\%} (Djibouti) and 40.9{\%} (Mozambique) for S. haematobium. Our models revealed that infection risk in Burundi, Eritrea, Ethiopia, Kenya, Rwanda, Somalia and Sudan might be considerably higher than previously reported, while in Mozambique and Tanzania, the risk might be lower than current estimates suggest. Our empirical, large-scale, high-resolution infection risk estimates for S. mansoni and S. haematobium in eastern Africa can guide future control interventions and provide a benchmark for subsequent monitoring and evaluation activities.},
    author = {Schur, Nadine and H{\"{u}}rlimann, Eveline and Stensgaard, Anna-Sofie and Chimfwembe, Kingford and Mushinge, Gabriel and Simoonga, Christopher and Kabatereine, Narcis B. and Vounatsou, Penelope},
    doi = {10.1016/j.actatropica.2011.10.006},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Schur et al. - 2013 - Spatially explicit Schistosoma infection risk in eastern Africa using Bayesian geostatistical modelling.pdf:pdf},
    issn = {0001706X},
    journal = {Acta Tropica},
    number = {2},
    pages = {365--377},
    title = {{Spatially explicit Schistosoma infection risk in eastern Africa using Bayesian geostatistical modelling}},
    volume = {128},
    year = {2013}
    }
  • [DOI] Schur Nadine, Vounatsou Penelope, Utzinger Jürg. Determining treatment needs at different spatial scales using geostatistical model-based risk estimates of schistosomiasis.. Plos neglected tropical diseases 2012;6(9):e1773.
    [Bibtex]
    @article{Schur2012,
    abstract = {After many years of neglect, schistosomiasis control is going to scale. The strategy of choice is preventive chemotherapy, that is the repeated large-scale administration of praziquantel (a safe and highly efficacious drug) to at-risk populations. The frequency of praziquantel administration is based on endemicity, which usually is defined by prevalence data summarized at an arbitrarily chosen administrative level.},
    author = {Schur, Nadine and Vounatsou, Penelope and Utzinger, J{\"{u}}rg},
    doi = {10.1371/journal.pntd.0001773},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Schur, Vounatsou, Utzinger - 2012 - Determining treatment needs at different spatial scales using geostatistical model-based risk est(3).pdf:pdf},
    issn = {1935-2735},
    journal = {PLoS neglected tropical diseases},
    keywords = {Adolescent,Africa,Africa: epidemiology,Anthelmintics,Anthelmintics: therapeutic use,Chemoprevention,Chemoprevention: methods,Child,Child, Preschool,Female,Humans,Male,Praziquantel,Praziquantel: therapeutic use,Prevalence,Schistosomiasis,Schistosomiasis: drug therapy,Schistosomiasis: epidemiology,Schistosomiasis: prevention {\&} control,Topography, Medical},
    month = {jan},
    number = {9},
    pages = {e1773},
    pmid = {23029570},
    title = {{Determining treatment needs at different spatial scales using geostatistical model-based risk estimates of schistosomiasis.}},
    url = {http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3441409{\&}tool=pmcentrez{\&}rendertype=abstract},
    volume = {6},
    year = {2012}
    }
  • [DOI] Seto Edmund YW, Sousa-Figueiredo José C, Betson Martha, Byalero Chris, Kabatereine Narcis B, Stothard Russell J. Patterns of intestinal schistosomiasis among mothers and young children from Lake Albert, Uganda: water contact and social networks inferred from wearable global positioning system dataloggers.. Geospatial health 2012;7(1):1-13.
    [Bibtex]
    @article{Seto2012,
    abstract = {The establishment of a national control programme (NCP) in Uganda has led to routine treatment of intestinal schistosomiasis with praziquantel in the communities along Lake Albert. However, because regular water contact remains a way of life for these populations, re-infection continues to mitigate the sustainability of the chemotherapy-based programme. A six-month longitudinal study was conducted in one Lake Albert community with the aim of characterizing water contact exposure and infection among mothers and their young preschool-aged children as the latter are not yet formally included within the NCP. At baseline the cohort of 37 mothers, 36 preschool-aged children had infection prevalences of 62{\%} and 67{\%}, respectively, which diminished to 20{\%} and 29{\%}, respectively, at the 6-month post-treatment follow-up. The subjects wore global positioning system (GPS) datalogging devices over a 3-day period shortly after baseline, allowing for the estimation of time spent at the lakeshore as an exposure metric, which was found to be associated with prevalence at follow-up (OR = 2.1, P = 0.01 for both mothers and young children and odds ratio (OR) = 4.4, P = 0.01 for young children alone). A social network of interpersonal interactions was also derived from the GPS data, and the exposures were positively associated both with the number and duration of peer interaction, suggesting the importance of socio-cultural factors associated with water contact behaviour. The findings illustrate reduction in both prevalence and intensity of infection in this community after treatment as well as remarkably high rates of water contact exposure and re-infection, particularly among younger children. We believe that this should now be formally considered within NCP, which may benefit from more in-depth ethnographic exploration of factors related to water contact as this should provide new opportunities for sustaining control.},
    author = {Seto, Edmund Y W and Sousa-Figueiredo, Jos{\'{e}} C and Betson, Martha and Byalero, Chris and Kabatereine, Narcis B and Stothard, J Russell},
    doi = {10.4081/gh.2012.99},
    issn = {1970-7096},
    journal = {Geospatial health},
    month = {nov},
    number = {1},
    pages = {1--13},
    pmid = {23242675},
    title = {{Patterns of intestinal schistosomiasis among mothers and young children from Lake Albert, Uganda: water contact and social networks inferred from wearable global positioning system dataloggers.}},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/23242675},
    volume = {7},
    year = {2012}
    }
  • [DOI] Simoonga C, Utzinger J, Brooker S, Vounatsou P, Appleton CC, Stensgaard AS, Olsen A, Kristensen TK. Remote sensing, geographical information system and spatial analysis for schistosomiasis epidemiology and ecology in Africa.. Parasitology 2009;136(13):1683-93.
    [Bibtex]
    @article{Simoonga2009,
    abstract = {Beginning in 1970, the potential of remote sensing (RS) techniques, coupled with geographical information systems (GIS), to improve our understanding of the epidemiology and control of schistosomiasis in Africa, has steadily grown. In our current review, working definitions of RS, GIS and spatial analysis are given, and applications made to date with RS and GIS for the epidemiology and ecology of schistosomiasis in Africa are summarised. Progress has been made in mapping the prevalence of infection in humans and the distribution of intermediate host snails. More recently, Bayesian geostatistical modelling approaches have been utilized for predicting the prevalence and intensity of infection at different scales. However, a number of challenges remain; hence new research is needed to overcome these limitations. First, greater spatial and temporal resolution seems important to improve risk mapping and understanding of transmission dynamics at the local scale. Second, more realistic risk profiling can be achieved by taking into account information on people's socio-economic status; furthermore, future efforts should incorporate data on domestic access to clean water and adequate sanitation, as well as behavioural and educational issues. Third, high-quality data on intermediate host snail distribution should facilitate validation of infection risk maps and modelling transmission dynamics. Finally, more emphasis should be placed on risk mapping and prediction of multiple species parasitic infections in an effort to integrate disease risk mapping and to enhance the cost-effectiveness of their control.},
    author = {Simoonga, C and Utzinger, J and Brooker, S and Vounatsou, P and Appleton, C C and Stensgaard, A S and Olsen, A and Kristensen, T K},
    doi = {10.1017/S0031182009006222},
    issn = {1469-8161},
    journal = {Parasitology},
    month = {nov},
    number = {13},
    pages = {1683--93},
    pmid = {19627627},
    title = {{Remote sensing, geographical information system and spatial analysis for schistosomiasis epidemiology and ecology in Africa.}},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/19627627 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=PMC2789293},
    volume = {136},
    year = {2009}
    }
  • Sousa-Figueiredo José Carlos, Stanton Michelle C, Katokele Stark, Arinaitwe Moses, Adriko Moses, Balfour Lexi, Reiff Mark, Lancaster Warren, Noden Bruce H, Bock Ronnie, Stothard Russell J. Mapping of schistosomiasis and soil-transmitted helminths in Namibia: the first largescale protocol to formally include rapid diagnostic tests. Plos neglected tropical diseases 2015;9(7):e0003831.
    [Bibtex]
    @article{Sousa-Figueiredo,
    author = {Sousa-Figueiredo, Jos{\'{e}} Carlos and Stanton, Michelle C and Katokele, Stark and Arinaitwe, Moses and Adriko, Moses and Balfour, Lexi and Reiff, Mark and Lancaster, Warren and Noden, Bruce H and Bock, Ronnie and Stothard, J Russell},
    journal = {PLoS neglected tropical diseases},
    number = {7},
    pages = {e0003831},
    title = {{Mapping of schistosomiasis and soil-transmitted helminths in Namibia: the first largescale protocol to formally include rapid diagnostic tests}},
    volume = {9},
    year = {2015}
    }
  • [DOI] Sturrock Hugh JW, Gething Pete W, Ashton Ruth A, Kolaczinski Jan H, Kabatereine Narcis B, Brooker Simon. Planning schistosomiasis control: investigation of alternative sampling strategies for Schistosoma mansoni to target mass drug administration of praziquantel in East Africa.. International health 2011;3(3):165-75.
    [Bibtex]
    @article{Sturrock2011,
    abstract = {In schistosomiasis control, there is a need to geographically target treatment to populations at high risk of morbidity. This paper evaluates alternative sampling strategies for surveys of Schistosoma mansoni to target mass drug administration in Kenya and Ethiopia. Two main designs are considered: lot quality assurance sampling (LQAS) of children from all schools; and a geostatistical design that samples a subset of schools and uses semi-variogram analysis and spatial interpolation to predict prevalence in the remaining unsurveyed schools. Computerized simulations are used to investigate the performance of sampling strategies in correctly classifying schools according to treatment needs and their cost-effectiveness in identifying high prevalence schools. LQAS performs better than geostatistical sampling in correctly classifying schools, but at a cost with a higher cost per high prevalence school correctly classified. It is suggested that the optimal surveying strategy for S. mansoni needs to take into account the goals of the control programme and the financial and drug resources available.},
    author = {Sturrock, Hugh J W and Gething, Pete W and Ashton, Ruth A and Kolaczinski, Jan H and Kabatereine, Narcis B and Brooker, Simon},
    doi = {10.1016/j.inhe.2011.06.002},
    issn = {1876-3413},
    journal = {International health},
    month = {sep},
    number = {3},
    pages = {165--75},
    pmid = {24038366},
    title = {{Planning schistosomiasis control: investigation of alternative sampling strategies for Schistosoma mansoni to target mass drug administration of praziquantel in East Africa.}},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/24038366},
    volume = {3},
    year = {2011}
    }
  • [DOI] Vounatsou P, Raso G, Tanner M, N’goran EK, Utzinger J. Bayesian geostatistical modelling for mapping schistosomiasis transmission.. Parasitology 2009;136(13):1695-705.
    [Bibtex]
    @article{Vounatsou2009,
    abstract = {Progress has been made in mapping and predicting the risk of schistosomiasis using Bayesian geostatistical inference. Applications primarily focused on risk profiling of prevalence rather than infection intensity, although the latter is particularly important for morbidity control. In this review, the underlying assumptions used in a study mapping Schistosoma mansoni infection intensity in East Africa are examined. We argue that the assumption of stationarity needs to be relaxed, and that the negative binomial assumption might result in misleading inference because of a high number of excess zeros (individuals without an infection). We developed a Bayesian geostatistical zero-inflated (ZI) regression model that assumes a non-stationary spatial process. Our model is validated with a high-quality georeferenced database from western C{\^{o}}te d'Ivoire, consisting of demographic, environmental, parasitological and socio-economic data. Nearly 40{\%} of the 3818 participating schoolchildren were infected with S. mansoni, and the mean egg count among infected children was 162 eggs per gram of stool (EPG), ranging between 24 and 6768 EPG. Compared to a negative binomial and ZI Poisson and negative binomial models, the Bayesian non-stationary ZI negative binomial model showed a better fit to the data. We conclude that geostatistical ZI models produce more accurate maps of helminth infection intensity than the spatial negative binomial ones.},
    author = {Vounatsou, P and Raso, G and Tanner, M and N'goran, E K and Utzinger, J},
    doi = {10.1017/S003118200900599X},
    issn = {1469-8161},
    journal = {Parasitology},
    month = {nov},
    number = {13},
    pages = {1695--705},
    pmid = {19490724},
    title = {{Bayesian geostatistical modelling for mapping schistosomiasis transmission.}},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/19490724},
    volume = {136},
    year = {2009}
    }
  • [DOI] Walz Yvonne, Wegmann Martin, Leutner Benjamin, Dech Stefan, Vounatsou Penelope, N’Goran Eliézer K, Raso Giovanna, Utzinger Jürg. Use of an ecologically relevant modelling approach to improve remote sensing-based schistosomiasis risk profiling.. Geospatial health 2015;10(2):398.
    [Bibtex]
    @article{Walz2015b,
    abstract = {Schistosomiasis is a widespread water-based disease that puts close to 800 million people at risk of infection with more than 250 million infected, mainly in sub-Saharan Africa. Transmission is governed by the spatial distribution of specific freshwater snails that act as intermediate hosts and the frequency, duration and extent of human bodies exposed to infested water sources during human water contact. Remote sensing data have been utilized for spatially explicit risk profiling of schistosomiasis. Since schistosomiasis risk profiling based on remote sensing data inherits a conceptual drawback if school-based disease prevalence data are directly related to the remote sensing measurements extracted at the location of the school, because the disease transmission usually does not exactly occur at the school, we took the local environment around the schools into account by explicitly linking ecologically relevant environmental information of potential disease transmission sites to survey measurements of disease prevalence. Our models were validated at two sites with different landscapes in C{\^{o}}te d'Ivoire using high- and moderateresolution remote sensing data based on random forest and partial least squares regression. We found that the ecologically relevant modelling approach explained up to 70{\%} of the variation in Schistosoma infection prevalence and performed better compared to a purely pixelbased modelling approach. Furthermore, our study showed that model performance increased as a function of enlarging the school catchment area, confirming the hypothesis that suitable environments for schistosomiasis transmission rarely occur at the location of survey measurements.},
    author = {Walz, Yvonne and Wegmann, Martin and Leutner, Benjamin and Dech, Stefan and Vounatsou, Penelope and N'Goran, Eli{\'{e}}zer K and Raso, Giovanna and Utzinger, J{\"{u}}rg},
    doi = {10.4081/gh.2015.398},
    issn = {1970-7096},
    journal = {Geospatial health},
    month = {jan},
    number = {2},
    pages = {398},
    pmid = {26618326},
    title = {{Use of an ecologically relevant modelling approach to improve remote sensing-based schistosomiasis risk profiling.}},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/26618326},
    volume = {10},
    year = {2015}
    }
  • [DOI] Walz Yvonne, Wegmann Martin, Dech Stefan, Vounatsou Penelope, Poda Jean-Noël, N’Goran Eliézer K, Utzinger Jürg, Raso Giovanna. Modeling and Validation of Environmental Suitability for Schistosomiasis Transmission Using Remote Sensing.. Plos neglected tropical diseases 2015;9(11):e0004217.
    [Bibtex]
    @article{Walz2015a,
    abstract = {BACKGROUND: Schistosomiasis is the most widespread water-based disease in sub-Saharan Africa. Transmission is governed by the spatial distribution of specific freshwater snails that act as intermediate hosts and human water contact patterns. Remote sensing data have been utilized for spatially explicit risk profiling of schistosomiasis. We investigated the potential of remote sensing to characterize habitat conditions of parasite and intermediate host snails and discuss the relevance for public health.
    METHODOLOGY: We employed high-resolution remote sensing data, environmental field measurements, and ecological data to model environmental suitability for schistosomiasis-related parasite and snail species. The model was developed for Burkina Faso using a habitat suitability index (HSI). The plausibility of remote sensing habitat variables was validated using field measurements. The established model was transferred to different ecological settings in C{\^{o}}te d'Ivoire and validated against readily available survey data from school-aged children.
    PRINCIPAL FINDINGS: Environmental suitability for schistosomiasis transmission was spatially delineated and quantified by seven habitat variables derived from remote sensing data. The strengths and weaknesses highlighted by the plausibility analysis showed that temporal dynamic water and vegetation measures were particularly useful to model parasite and snail habitat suitability, whereas the measurement of water surface temperature and topographic variables did not perform appropriately. The transferability of the model showed significant relations between the HSI and infection prevalence in study sites of C{\^{o}}te d'Ivoire.
    CONCLUSIONS/SIGNIFICANCE: A predictive map of environmental suitability for schistosomiasis transmission can support measures to gain and sustain control. This is particularly relevant as emphasis is shifting from morbidity control to interrupting transmission. Further validation of our mechanistic model needs to be complemented by field data of parasite- and snail-related fitness. Our model provides a useful tool to monitor the development of new hotspots of potential schistosomiasis transmission based on regularly updated remote sensing data.},
    author = {Walz, Yvonne and Wegmann, Martin and Dech, Stefan and Vounatsou, Penelope and Poda, Jean-No{\"{e}}l and N'Goran, Eli{\'{e}}zer K and Utzinger, J{\"{u}}rg and Raso, Giovanna},
    doi = {10.1371/journal.pntd.0004217},
    file = {:C$\backslash$:/Users/michelle.stanton/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Walz et al. - 2015 - Modeling and Validation of Environmental Suitability for Schistosomiasis Transmission Using Remote Sensing(2).pdf:pdf},
    issn = {1935-2735},
    journal = {PLoS neglected tropical diseases},
    month = {nov},
    number = {11},
    pages = {e0004217},
    pmid = {26587839},
    publisher = {Public Library of Science},
    title = {{Modeling and Validation of Environmental Suitability for Schistosomiasis Transmission Using Remote Sensing.}},
    url = {http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0004217},
    volume = {9},
    year = {2015}
    }
  • [DOI] Wang Yong, Zhuang Dafang. A Rapid Monitoring and Evaluation Method of Schistosomiasis Based on Spatial Information Technology.. International journal of environmental research and public health 2015;12(12):15843-59.
    [Bibtex]
    @article{Wang2015,
    abstract = {Thanks to Spatial Information Technologies (SITs) such as Remote Sensing (RS) and Geographical Information System (GIS) that are being quickly developed and updated, SITs are being used more widely in the public health field. The use of SITs to study the characteristics of the temporal and spatial distribution of Schistosoma japonicum and to assess the risk of infection provides methods for the control and prevention of schistosomiasis japonica has gradually become a hot topic in the field. The purpose of the present paper was to use RS and GIS technology to develop an efficient method of prediction and assessment of the risk of schistosomiasis japonica. We choose the Yueyang region, close to the east DongTing Lake (Hunan Province, China), as the study area, where a recent serious outbreak of schistosomiasis japonica took place. We monitored and evaluated the transmission risk of schistosomiasis japonica in the region using SITs. Water distribution data were extracted from RS images. The ground temperature, ground humidity and vegetation index were calculated based on RS images. Additionally, the density of oncomelania snails, which are the Schistosoma japonicum intermediate host, was calculated on the base of RS data and field measurements. The spatial distribution of oncomelania snails was explored using SITs in order to estimate the area surrounding the residents with transmission risk of schistosomiasis japonica. Our research result demonstrated: (1) the risk factors for the transmission of schistosomiasis japonica were closely related to the living environment of oncomelania snails. Key factors such as water distribution, ground temperature, ground humidity and vegetation index can be quickly obtained and calculated from RS images; (2) using GIS technology and a RS deduction technique along with statistical regression models, the density distribution model of oncomelania snails could be quickly built; (3) using SITs and analysis with overlaying population distribution data, the range of transmission risk of schistosomiasis japonica of the study area can be quickly monitored and evaluated. This method will help support the decision making for the control and prevention of schistosomiasis and form a valuable application using SITs for the schistosomiasis research.},
    author = {Wang, Yong and Zhuang, Dafang},
    doi = {10.3390/ijerph121215025},
    issn = {1660-4601},
    journal = {International journal of environmental research and public health},
    month = {jan},
    number = {12},
    pages = {15843--59},
    pmid = {26703635},
    title = {{A Rapid Monitoring and Evaluation Method of Schistosomiasis Based on Spatial Information Technology.}},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/26703635},
    volume = {12},
    year = {2015}
    }
  • World Health Organization. Preventive chemotherapy in human helminthiasis. Geneva: 2006.
    [Bibtex]
    @techreport{WorldHealthOrganization2006a,
    address = {Geneva},
    author = {{World Health Organization}},
    title = {{Preventive chemotherapy in human helminthiasis}},
    year = {2006}
    }
  • World Health Organization. Report of an informal consultation on schistosomiasis control. 2013.
    [Bibtex]
    @techreport{WorldHealthOrganization,
    author = {{World Health Organization}},
    title = {{Report of an informal consultation on schistosomiasis control}},
    url = {http://apps.who.int/iris/bitstream/10665/78066/1/9789241505017{\_}eng.pdf},
    year = {2013}
    }
  • Yang Kun, Sun Le-Ping, Huang Yi-Xin, Yang Guo-Jing, Wu Feng, Hang De-Rong, Li Wei, Zhang Jian-Feng, Liang Yong-Sheng, Zhou Xiao-Nong. A real-time platform for monitoring schistosomiasis transmission supported by Google Earth and a web-based geographical information system.. Geospatial health 2012;6(2):195-203.
    [Bibtex]
    @article{Yang2012,
    abstract = {A basic framework for the rapid assessment of the risk for schistosomiasis was developed by combining spatial data from Google Earth{\textregistered} with a geographical information system (GIS) package, bundling the modules together with an Internet connection into a WebGIS platform. It operates through functions such as "search", "evaluation", "risk analysis" and "prediction" and is primarily aimed to be a dynamic, early-warning system (EWS) providing user-friendly, evidence-based, near real-time awareness of the status of an important endemic disease. It contributes to rapid information-sharing at all levels of decision-making, facilitating "point-of-care" response, i.e. treatment provided at newly discovered transmission sites. The experience using the platform is encouraging and it has the potential to improve support systems and strengthen schistosomiasis control activities, in particular with regard to surveillance and EWS. It can quickly and intuitively locate early, high-risk areas, retrieve all important data needed as well as provide detailed, up-to-date information on the performance of the control programme. This WebGIS, the first of its kind in the People's Republic of China, is not only applicable for schistosomiasis but can easily be adapted for improving control of any endemic disease in any geographical area.},
    author = {Yang, Kun and Sun, Le-Ping and Huang, Yi-Xin and Yang, Guo-Jing and Wu, Feng and Hang, De-Rong and Li, Wei and Zhang, Jian-Feng and Liang, Yong-Sheng and Zhou, Xiao-Nong},
    issn = {1970-7096},
    journal = {Geospatial health},
    keywords = {China,China: epidemiology,Computer Systems,Geographic Information Systems,Humans,Internet,Population Surveillance,Public Health,Public Health: instrumentation,Public Health: methods,Risk Assessment,Risk Assessment: methods,Schistosomiasis,Schistosomiasis: epidemiology,Schistosomiasis: prevention {\&} control,Schistosomiasis: transmission},
    month = {may},
    number = {2},
    pages = {195--203},
    pmid = {22639121},
    title = {{A real-time platform for monitoring schistosomiasis transmission supported by Google Earth and a web-based geographical information system.}},
    url = {http://www.ncbi.nlm.nih.gov/pubmed/22639121},
    volume = {6},
    year = {2012}
    }