A geographic information system forecast model for strategic control of fasciolosis in Ethiopia
Identifieur interne : 000E35 ( Istex/Corpus ); précédent : 000E34; suivant : 000E36A geographic information system forecast model for strategic control of fasciolosis in Ethiopia
Auteurs : J. M Yilma ; J. B MaloneSource :
- Veterinary Parasitology [ 0304-4017 ] ; 1998.
Abstract
A geographic information system (GIS) forecast model based on moisture and thermal regime was developed to assess the risk of Fasciola hepatica, a temperate species, and its tropical counterpart, Fasciola gigantica, in Ethiopia. Agroecological map zones and corresponding environmental features that control the distribution and abundance of the disease and its snail intermediate hosts were imported from the Food and Agriculture Organization (FAO) Crop Production System Zones (CPSZ) database on east Africa and used to construct a GIS using ATLAS GIS 3.0 software. Base temperatures of 10°C and 16°C were used for F. hepatica and F. gigantica, respectively, to calculate growing degree days in a previously developed climate forecast system that was modified to allow use of monthly climate data values. The model was validated by comparison of risk indices and environmental features to available survey data on fasciolosis. Monthly Fasciola risk indices of four climatic regions in Ethiopia were used to project infection transmission patterns under varying climatic conditions and strategic chemotherapeutic fasciolosis control schemes. Varying degrees of F. hepatica risk occurred in most parts of the country and distinct regional F. hepatica transmission patterns could be identified. In the humid west, cercariae-shedding was predicted to occur from May to October. In the south it occurred from April to May and September to October, depending on the annual abundance of rain. In the north-central and central regions, risk was highest during heavy summer rains and pasture contamination with metacercariae was predicted to occur during August–September, except in wet years, when it may start as early as July and extend up to October. At cooler sites above altitude of 2800m, completion of an infection cycle may require more than a year. Fasciola gigantica risk was present in the western, southern and north-central regions of the country at altitudes of 1440–2560m. However, a transmission cycle could be completed in a single year only at elevations below 1700m. The greatest risk of F. gigantica infection was in the humid western region. Regional strategic chemotherapy schemes of two or three treatments per year were developed. Results suggest that the model can be extrapolated to all CPSZ in the country and adapted for use in control of other vector-borne diseases of economic and public health importance.
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DOI: 10.1016/S0304-4017(98)00136-8
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<record><TEI wicri:istexFullTextTei="biblStruct"><teiHeader><fileDesc><titleStmt><title>A geographic information system forecast model for strategic control of fasciolosis in Ethiopia</title><author><name sortKey="Yilma, J M" sort="Yilma, J M" uniqKey="Yilma J" first="J. M" last="Yilma">J. M Yilma</name><affiliation><mods:affiliation>Department of Pathology and Parasitology, Faculty of Veterinary Medicine, Addis Ababa University, P.O. Box 34Debre ZeitEthiopia</mods:affiliation></affiliation></author><author><name sortKey="Malone, J B" sort="Malone, J B" uniqKey="Malone J" first="J. B" last="Malone">J. B Malone</name><affiliation><mods:affiliation>Department of Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State UniversityBaton Rouge LA, 70803USA</mods:affiliation></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">ISTEX</idno><idno type="RBID">ISTEX:D193AD8DC9FC1EA54BA34500299F84D1BA34E02D</idno><date when="1998" year="1998">1998</date><idno type="doi">10.1016/S0304-4017(98)00136-8</idno><idno type="url">https://api.istex.fr/document/D193AD8DC9FC1EA54BA34500299F84D1BA34E02D/fulltext/pdf</idno><idno type="wicri:Area/Istex/Corpus">000E35</idno><idno type="wicri:explorRef" wicri:stream="Istex" wicri:step="Corpus" wicri:corpus="ISTEX">000E35</idno></publicationStmt><sourceDesc><biblStruct><analytic><title level="a">A geographic information system forecast model for strategic control of fasciolosis in Ethiopia</title><author><name sortKey="Yilma, J M" sort="Yilma, J M" uniqKey="Yilma J" first="J. M" last="Yilma">J. M Yilma</name><affiliation><mods:affiliation>Department of Pathology and Parasitology, Faculty of Veterinary Medicine, Addis Ababa University, P.O. Box 34Debre ZeitEthiopia</mods:affiliation></affiliation></author><author><name sortKey="Malone, J B" sort="Malone, J B" uniqKey="Malone J" first="J. B" last="Malone">J. B Malone</name><affiliation><mods:affiliation>Department of Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State UniversityBaton Rouge LA, 70803USA</mods:affiliation></affiliation></author></analytic><monogr></monogr><series><title level="j">Veterinary Parasitology</title><title level="j" type="abbrev">VETPAR</title><idno type="ISSN">0304-4017</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1998">1998</date><biblScope unit="volume">78</biblScope><biblScope unit="issue">2</biblScope><biblScope unit="page" from="103">103</biblScope><biblScope unit="page" to="127">127</biblScope></imprint><idno type="ISSN">0304-4017</idno></series><idno type="istex">D193AD8DC9FC1EA54BA34500299F84D1BA34E02D</idno><idno type="DOI">10.1016/S0304-4017(98)00136-8</idno><idno type="PII">S0304-4017(98)00136-8</idno></biblStruct></sourceDesc><seriesStmt><idno type="ISSN">0304-4017</idno></seriesStmt></fileDesc><profileDesc><textClass></textClass><langUsage><language ident="en">en</language></langUsage></profileDesc></teiHeader><front><div type="abstract" xml:lang="en">A geographic information system (GIS) forecast model based on moisture and thermal regime was developed to assess the risk of Fasciola hepatica, a temperate species, and its tropical counterpart, Fasciola gigantica, in Ethiopia. Agroecological map zones and corresponding environmental features that control the distribution and abundance of the disease and its snail intermediate hosts were imported from the Food and Agriculture Organization (FAO) Crop Production System Zones (CPSZ) database on east Africa and used to construct a GIS using ATLAS GIS 3.0 software. Base temperatures of 10°C and 16°C were used for F. hepatica and F. gigantica, respectively, to calculate growing degree days in a previously developed climate forecast system that was modified to allow use of monthly climate data values. The model was validated by comparison of risk indices and environmental features to available survey data on fasciolosis. Monthly Fasciola risk indices of four climatic regions in Ethiopia were used to project infection transmission patterns under varying climatic conditions and strategic chemotherapeutic fasciolosis control schemes. Varying degrees of F. hepatica risk occurred in most parts of the country and distinct regional F. hepatica transmission patterns could be identified. In the humid west, cercariae-shedding was predicted to occur from May to October. In the south it occurred from April to May and September to October, depending on the annual abundance of rain. In the north-central and central regions, risk was highest during heavy summer rains and pasture contamination with metacercariae was predicted to occur during August–September, except in wet years, when it may start as early as July and extend up to October. At cooler sites above altitude of 2800m, completion of an infection cycle may require more than a year. Fasciola gigantica risk was present in the western, southern and north-central regions of the country at altitudes of 1440–2560m. However, a transmission cycle could be completed in a single year only at elevations below 1700m. The greatest risk of F. gigantica infection was in the humid western region. Regional strategic chemotherapy schemes of two or three treatments per year were developed. Results suggest that the model can be extrapolated to all CPSZ in the country and adapted for use in control of other vector-borne diseases of economic and public health importance.</div></front></TEI><istex><corpusName>elsevier</corpusName><author><json:item><name>J.M Yilma</name><affiliations><json:string>Department of Pathology and Parasitology, Faculty of Veterinary Medicine, Addis Ababa University, P.O. Box 34Debre ZeitEthiopia</json:string></affiliations></json:item><json:item><name>J.B Malone</name><affiliations><json:string>Department of Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State UniversityBaton Rouge LA, 70803USA</json:string></affiliations></json:item></author><subject><json:item><lang><json:string>eng</json:string></lang><value>Fasciola hepatica</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Fasciola gigantica</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Fasciolosis</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Epidemiology</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Ethiopia</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Geographic information systems</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Climate</value></json:item><json:item><lang><json:string>eng</json:string></lang><value>Chemotherapy</value></json:item></subject><language><json:string>eng</json:string></language><originalGenre><json:string>Full-length article</json:string></originalGenre><abstract>A geographic information system (GIS) forecast model based on moisture and thermal regime was developed to assess the risk of Fasciola hepatica, a temperate species, and its tropical counterpart, Fasciola gigantica, in Ethiopia. Agroecological map zones and corresponding environmental features that control the distribution and abundance of the disease and its snail intermediate hosts were imported from the Food and Agriculture Organization (FAO) Crop Production System Zones (CPSZ) database on east Africa and used to construct a GIS using ATLAS GIS 3.0 software. Base temperatures of 10°C and 16°C were used for F. hepatica and F. gigantica, respectively, to calculate growing degree days in a previously developed climate forecast system that was modified to allow use of monthly climate data values. The model was validated by comparison of risk indices and environmental features to available survey data on fasciolosis. Monthly Fasciola risk indices of four climatic regions in Ethiopia were used to project infection transmission patterns under varying climatic conditions and strategic chemotherapeutic fasciolosis control schemes. Varying degrees of F. hepatica risk occurred in most parts of the country and distinct regional F. hepatica transmission patterns could be identified. In the humid west, cercariae-shedding was predicted to occur from May to October. In the south it occurred from April to May and September to October, depending on the annual abundance of rain. In the north-central and central regions, risk was highest during heavy summer rains and pasture contamination with metacercariae was predicted to occur during August–September, except in wet years, when it may start as early as July and extend up to October. At cooler sites above altitude of 2800m, completion of an infection cycle may require more than a year. Fasciola gigantica risk was present in the western, southern and north-central regions of the country at altitudes of 1440–2560m. However, a transmission cycle could be completed in a single year only at elevations below 1700m. The greatest risk of F. gigantica infection was in the humid western region. Regional strategic chemotherapy schemes of two or three treatments per year were developed. Results suggest that the model can be extrapolated to all CPSZ in the country and adapted for use in control of other vector-borne diseases of economic and public health importance.</abstract><qualityIndicators><score>8</score><pdfVersion>1.2</pdfVersion><pdfPageSize>466 x 681 pts</pdfPageSize><refBibsNative>true</refBibsNative><keywordCount>8</keywordCount><abstractCharCount>2430</abstractCharCount><pdfWordCount>6350</pdfWordCount><pdfCharCount>42542</pdfCharCount><pdfPageCount>25</pdfPageCount><abstractWordCount>372</abstractWordCount></qualityIndicators><title>A geographic information system forecast model for strategic control of fasciolosis in Ethiopia</title><pii><json:string>S0304-4017(98)00136-8</json:string></pii><genre><json:string>research-article</json:string></genre><host><volume>78</volume><pii><json:string>S0304-4017(00)X0051-9</json:string></pii><pages><last>127</last><first>103</first></pages><issn><json:string>0304-4017</json:string></issn><issue>2</issue><genre><json:string>journal</json:string></genre><language><json:string>unknown</json:string></language><title>Veterinary Parasitology</title><publicationDate>1998</publicationDate></host><categories><wos><json:string>science</json:string><json:string>veterinary sciences</json:string><json:string>parasitology</json:string></wos><scienceMetrix><json:string>health sciences</json:string><json:string>biomedical research</json:string><json:string>mycology & parasitology</json:string></scienceMetrix></categories><publicationDate>1998</publicationDate><copyrightDate>1998</copyrightDate><doi><json:string>10.1016/S0304-4017(98)00136-8</json:string></doi><id>D193AD8DC9FC1EA54BA34500299F84D1BA34E02D</id><score>0.049653433</score><fulltext><json:item><extension>pdf</extension><original>true</original><mimetype>application/pdf</mimetype><uri>https://api.istex.fr/document/D193AD8DC9FC1EA54BA34500299F84D1BA34E02D/fulltext/pdf</uri></json:item><json:item><extension>zip</extension><original>false</original><mimetype>application/zip</mimetype><uri>https://api.istex.fr/document/D193AD8DC9FC1EA54BA34500299F84D1BA34E02D/fulltext/zip</uri></json:item><istex:fulltextTEI uri="https://api.istex.fr/document/D193AD8DC9FC1EA54BA34500299F84D1BA34E02D/fulltext/tei"><teiHeader><fileDesc><titleStmt><title level="a">A geographic information system forecast model for strategic control of fasciolosis in Ethiopia</title></titleStmt><publicationStmt><authority>ISTEX</authority><publisher>ELSEVIER</publisher><availability><p>©1998 Elsevier Science B.V.</p></availability><date>1998</date></publicationStmt><notesStmt><note type="content">Fig. 1: Topographic map of Ethiopia showing variation in elevation, major geographic features and regions. Both thermal regime and rainfall are greatly influenced by elevation, making it possible to study a wide range of potential habitats for Fasciola hepatica and Fasciola gigantica in a relatively small geographic area.</note><note type="content">Fig. 2: Annual rainfall variation (mm) in Ethiopia based on 30-year average FAO databases.</note><note type="content">Fig. 3: 10-year average NDVI map of Ethiopia from the FAO-ARTEMIS NOAA AVHRR NDVI Image Bank for Africa, 1981–1991.</note><note type="content">Fig. 4: Thematic maps of Ethiopia showing annual forecast risk indices for Fasciola hepatica. The GIS forecast model was constructed based on monthly climate and agroecological zone databases from the FAO (Van Velthuizen et al., 1995). Base temperatures (minimum required for development of extramammalian stages) of 10°C and 16°C were used for F. hepatica and F. gigantica, respectively.</note><note type="content">Fig. 5: Thematic maps of Ethiopia showing annual forecast risk indices for F. gigantica. The GIS forecast model was constructed based on monthly climate and agroecological zone databases from the FAO (Van Velthuizen et al., 1995). Base temperatures (minimum required for development of extramammalian stages) of 10°C and 16°C were used for F. hepatica and F. gigantica, respectively.</note><note type="content">Fig. 6: Reported distribution of ruminant fasciolosis in Ethiopia based on prevalence surveys listed in Table 1. Survey data were not available for all areas.</note><note type="content">Fig. 7: Comparison of combined F. hepatica and F. gigantica forecast indices with ranked fasciolosis prevalence rates reported for Ethiopia</note><note type="content">Fig. 8: Comparsion of average Normalized Difference Vegetation Index (NDVI) with ranked fasciolosis prevalence rates reported for Ethiopia.</note><note type="content">Fig. 9: Monthly F. hepatica forecast for four regions in Ethiopia showing predicted periods of cercariae-shedding and recommended strategic curative/preventive treatment schemes for western Ethiopia. Two annual treatments are recommended for all regions, with an optional third treatment in high risk climate years in the western zone. The September–October curative and preventive treatment is considered most important in all regions if only one treatment can be given.</note><note type="content">Fig. 10: Monthly F. hepatica forecast for four regions in Ethiopia showing predicted periods of cercariae-shedding and recommended strategic curative/preventive treatment schemes for southern Ethiopia. Two annual treatments are recommended for all regions, with an optional third treatment in high risk climate years in the western zone. The September–October curative and preventive treatment is considered most important in all regions if only one treatment can be given.</note><note type="content">Fig. 11: Monthly F. hepatica forecast for four regions in Ethiopia showing predicted periods of cercariae-shedding and recommended strategic curative/preventive treatment schemes for north-central Ethiopia. Two annual treatments are recommended for all regions, with an optional third treatment in high risk climate years in the western zone. The September–October curative and preventive treatment is considered most important in all regions if only one treatment can be given.</note><note type="content">Fig. 12: Monthly F. hepatica forecast for four regions in Ethiopia showing predicted periods of cercariae-shedding and recommended strategic curative/preventive treatment schemes for central Ethiopia. Two annual treatments are recommended for all regions, with an optional third treatment in high risk climate years in the western zone. The September–October curative and preventive treatment is considered most important in all regions if only one treatment can be given.</note><note type="content">Table 1: Summary of reported prevalence rates of fasciolosis in different administrative regions in Ethiopia</note><note type="content">Table 2: Monthly forecast and cercariae-shedding patterns for F. hepatica in four selected agroclimatic regions in Ethiopia</note><note type="content">Table 3: Monthly forecast and cercariae-shedding patterns for F. gigantica in four selected agroclimatic regions in Ethiopia</note></notesStmt><sourceDesc><biblStruct type="inbook"><analytic><title level="a">A geographic information system forecast model for strategic control of fasciolosis in Ethiopia</title><author xml:id="author-1"><persName><forename type="first">J.M</forename><surname>Yilma</surname></persName><affiliation>Department of Pathology and Parasitology, Faculty of Veterinary Medicine, Addis Ababa University, P.O. Box 34Debre ZeitEthiopia</affiliation></author><author xml:id="author-2"><persName><forename type="first">J.B</forename><surname>Malone</surname></persName><note type="correspondence"><p>Corresponding author. Fax +504 346 5715; e-mail malone@vt8200.vetmed.lsu.edu</p></note><affiliation>Department of Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State UniversityBaton Rouge LA, 70803USA</affiliation></author></analytic><monogr><title level="j">Veterinary Parasitology</title><title level="j" type="abbrev">VETPAR</title><idno type="pISSN">0304-4017</idno><idno type="PII">S0304-4017(00)X0051-9</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1998"></date><biblScope unit="volume">78</biblScope><biblScope unit="issue">2</biblScope><biblScope unit="page" from="103">103</biblScope><biblScope unit="page" to="127">127</biblScope></imprint></monogr><idno type="istex">D193AD8DC9FC1EA54BA34500299F84D1BA34E02D</idno><idno type="DOI">10.1016/S0304-4017(98)00136-8</idno><idno type="PII">S0304-4017(98)00136-8</idno></biblStruct></sourceDesc></fileDesc><profileDesc><creation><date>1998</date></creation><langUsage><language ident="en">en</language></langUsage><abstract xml:lang="en"><p>A geographic information system (GIS) forecast model based on moisture and thermal regime was developed to assess the risk of Fasciola hepatica, a temperate species, and its tropical counterpart, Fasciola gigantica, in Ethiopia. Agroecological map zones and corresponding environmental features that control the distribution and abundance of the disease and its snail intermediate hosts were imported from the Food and Agriculture Organization (FAO) Crop Production System Zones (CPSZ) database on east Africa and used to construct a GIS using ATLAS GIS 3.0 software. Base temperatures of 10°C and 16°C were used for F. hepatica and F. gigantica, respectively, to calculate growing degree days in a previously developed climate forecast system that was modified to allow use of monthly climate data values. The model was validated by comparison of risk indices and environmental features to available survey data on fasciolosis. Monthly Fasciola risk indices of four climatic regions in Ethiopia were used to project infection transmission patterns under varying climatic conditions and strategic chemotherapeutic fasciolosis control schemes. Varying degrees of F. hepatica risk occurred in most parts of the country and distinct regional F. hepatica transmission patterns could be identified. In the humid west, cercariae-shedding was predicted to occur from May to October. In the south it occurred from April to May and September to October, depending on the annual abundance of rain. In the north-central and central regions, risk was highest during heavy summer rains and pasture contamination with metacercariae was predicted to occur during August–September, except in wet years, when it may start as early as July and extend up to October. At cooler sites above altitude of 2800m, completion of an infection cycle may require more than a year. Fasciola gigantica risk was present in the western, southern and north-central regions of the country at altitudes of 1440–2560m. However, a transmission cycle could be completed in a single year only at elevations below 1700m. The greatest risk of F. gigantica infection was in the humid western region. Regional strategic chemotherapy schemes of two or three treatments per year were developed. Results suggest that the model can be extrapolated to all CPSZ in the country and adapted for use in control of other vector-borne diseases of economic and public health importance.</p></abstract><textClass><keywords scheme="keyword"><list><head>Keywords</head><item><term>Fasciola hepatica</term></item><item><term>Fasciola gigantica</term></item><item><term>Fasciolosis</term></item><item><term>Epidemiology</term></item><item><term>Ethiopia</term></item><item><term>Geographic information systems</term></item><item><term>Climate</term></item><item><term>Chemotherapy</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="1998">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><extension>txt</extension><original>false</original><mimetype>text/plain</mimetype><uri>https://api.istex.fr/document/D193AD8DC9FC1EA54BA34500299F84D1BA34E02D/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="Elsevier, elements deleted: ce:floats; body; tail"><istex:xmlDeclaration>version="1.0" encoding="utf-8"</istex:xmlDeclaration><istex:docType PUBLIC="-//ES//DTD journal article DTD version 4.5.2//EN//XML" URI="art452.dtd" name="istex:docType"><istex:entity SYSTEM="gr1" NDATA="IMAGE" name="gr1"></istex:entity><istex:entity SYSTEM="gr2" NDATA="IMAGE" name="gr2"></istex:entity><istex:entity SYSTEM="gr3" NDATA="IMAGE" name="gr3"></istex:entity><istex:entity SYSTEM="gr4" NDATA="IMAGE" name="gr4"></istex:entity><istex:entity SYSTEM="gr5" NDATA="IMAGE" name="gr5"></istex:entity><istex:entity SYSTEM="gr6" NDATA="IMAGE" name="gr6"></istex:entity><istex:entity SYSTEM="gr7" NDATA="IMAGE" name="gr7"></istex:entity><istex:entity SYSTEM="gr8" NDATA="IMAGE" name="gr8"></istex:entity><istex:entity SYSTEM="gr9" NDATA="IMAGE" name="gr9"></istex:entity><istex:entity SYSTEM="gr10" NDATA="IMAGE" name="gr10"></istex:entity><istex:entity SYSTEM="gr11" NDATA="IMAGE" name="gr11"></istex:entity><istex:entity SYSTEM="gr12" NDATA="IMAGE" name="gr12"></istex:entity></istex:docType><istex:document><converted-article version="4.5.2" docsubtype="fla"><item-info><jid>VETPAR</jid><aid>1421</aid><ce:pii>S0304-4017(98)00136-8</ce:pii><ce:doi>10.1016/S0304-4017(98)00136-8</ce:doi><ce:copyright year="1998" type="full-transfer">Elsevier Science B.V.</ce:copyright></item-info><head><ce:title>A geographic information system forecast model for strategic control of fasciolosis in Ethiopia</ce:title><ce:author-group><ce:author><ce:given-name>J.M</ce:given-name><ce:surname>Yilma</ce:surname><ce:cross-ref refid="AFF1">a</ce:cross-ref></ce:author><ce:author><ce:given-name>J.B</ce:given-name><ce:surname>Malone</ce:surname><ce:cross-ref refid="AFF2">b</ce:cross-ref><ce:cross-ref refid="CORR1">*</ce:cross-ref></ce:author><ce:affiliation id="AFF1"><ce:label>a</ce:label><ce:textfn><ce:hsp sp="0.25"></ce:hsp>Department of Pathology and Parasitology, Faculty of Veterinary Medicine, Addis Ababa University, P.O. Box 34Debre ZeitEthiopia</ce:textfn></ce:affiliation><ce:affiliation id="AFF2"><ce:label>b</ce:label><ce:textfn><ce:hsp sp="0.25"></ce:hsp>Department of Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State UniversityBaton Rouge LA, 70803USA</ce:textfn></ce:affiliation><ce:correspondence id="CORR1"><ce:label>*</ce:label><ce:text>Corresponding author. Fax +504 346 5715; e-mail malone@vt8200.vetmed.lsu.edu</ce:text></ce:correspondence></ce:author-group><ce:date-received day="8" month="4" year="1997"></ce:date-received><ce:date-accepted day="23" month="2" year="1998"></ce:date-accepted><ce:abstract><ce:section-title>Abstract</ce:section-title><ce:abstract-sec><ce:simple-para>A geographic information system (GIS) forecast model based on moisture and thermal regime was developed to assess the risk of <ce:italic>Fasciola hepatica</ce:italic>, a temperate species, and its tropical counterpart, <ce:italic>Fasciola gigantica</ce:italic>, in Ethiopia. Agroecological map zones and corresponding environmental features that control the distribution and abundance of the disease and its snail intermediate hosts were imported from the Food and Agriculture Organization (FAO) Crop Production System Zones (CPSZ) database on east Africa and used to construct a GIS using ATLAS GIS 3.0 software. Base temperatures of 10°C and 16°C were used for <ce:italic>F. hepatica</ce:italic> and <ce:italic>F. gigantica,</ce:italic> respectively, to calculate growing degree days in a previously developed climate forecast system that was modified to allow use of monthly climate data values. The model was validated by comparison of risk indices and environmental features to available survey data on fasciolosis. Monthly <ce:italic>Fasciola</ce:italic> risk indices of four climatic regions in Ethiopia were used to project infection transmission patterns under varying climatic conditions and strategic chemotherapeutic fasciolosis control schemes. Varying degrees of <ce:italic>F. hepatica</ce:italic> risk occurred in most parts of the country and distinct regional <ce:italic>F. hepatica</ce:italic> transmission patterns could be identified. In the humid west, cercariae-shedding was predicted to occur from May to October. In the south it occurred from April to May and September to October, depending on the annual abundance of rain. In the north-central and central regions, risk was highest during heavy summer rains and pasture contamination with metacercariae was predicted to occur during August–September, except in wet years, when it may start as early as July and extend up to October. At cooler sites above altitude of 2800<ce:hsp sp="0.25"></ce:hsp>m, completion of an infection cycle may require more than a year. <ce:italic>Fasciola gigantica</ce:italic> risk was present in the western, southern and north-central regions of the country at altitudes of 1440–2560<ce:hsp sp="0.25"></ce:hsp>m. However, a transmission cycle could be completed in a single year only at elevations below 1700<ce:hsp sp="0.25"></ce:hsp>m. The greatest risk of <ce:italic>F. gigantica</ce:italic> infection was in the humid western region. Regional strategic chemotherapy schemes of two or three treatments per year were developed. Results suggest that the model can be extrapolated to all CPSZ in the country and adapted for use in control of other vector-borne diseases of economic and public health importance.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:keywords class="keyword"><ce:section-title>Keywords</ce:section-title><ce:keyword><ce:text><ce:italic>Fasciola hepatica</ce:italic></ce:text></ce:keyword><ce:keyword><ce:text><ce:italic>Fasciola gigantica</ce:italic></ce:text></ce:keyword><ce:keyword><ce:text>Fasciolosis</ce:text></ce:keyword><ce:keyword><ce:text>Epidemiology</ce:text></ce:keyword><ce:keyword><ce:text>Ethiopia</ce:text></ce:keyword><ce:keyword><ce:text>Geographic information systems</ce:text></ce:keyword><ce:keyword><ce:text>Climate</ce:text></ce:keyword><ce:keyword><ce:text>Chemotherapy</ce:text></ce:keyword></ce:keywords></head></converted-article></istex:document></istex:metadataXml><mods version="3.6"><titleInfo><title>A geographic information system forecast model for strategic control of fasciolosis in Ethiopia</title></titleInfo><titleInfo type="alternative" contentType="CDATA"><title>A geographic information system forecast model for strategic control of fasciolosis in Ethiopia</title></titleInfo><name type="personal"><namePart type="given">J.M</namePart><namePart type="family">Yilma</namePart><affiliation>Department of Pathology and Parasitology, Faculty of Veterinary Medicine, Addis Ababa University, P.O. Box 34Debre ZeitEthiopia</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">J.B</namePart><namePart type="family">Malone</namePart><affiliation>Department of Microbiology and Parasitology, School of Veterinary Medicine, Louisiana State UniversityBaton Rouge LA, 70803USA</affiliation><description>Corresponding author. Fax +504 346 5715; e-mail malone@vt8200.vetmed.lsu.edu</description><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="research-article" displayLabel="Full-length article"></genre><originInfo><publisher>ELSEVIER</publisher><dateIssued encoding="w3cdtf">1998</dateIssued><copyrightDate encoding="w3cdtf">1998</copyrightDate></originInfo><language><languageTerm type="code" authority="iso639-2b">eng</languageTerm><languageTerm type="code" authority="rfc3066">en</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType></physicalDescription><abstract lang="en">A geographic information system (GIS) forecast model based on moisture and thermal regime was developed to assess the risk of Fasciola hepatica, a temperate species, and its tropical counterpart, Fasciola gigantica, in Ethiopia. Agroecological map zones and corresponding environmental features that control the distribution and abundance of the disease and its snail intermediate hosts were imported from the Food and Agriculture Organization (FAO) Crop Production System Zones (CPSZ) database on east Africa and used to construct a GIS using ATLAS GIS 3.0 software. Base temperatures of 10°C and 16°C were used for F. hepatica and F. gigantica, respectively, to calculate growing degree days in a previously developed climate forecast system that was modified to allow use of monthly climate data values. The model was validated by comparison of risk indices and environmental features to available survey data on fasciolosis. Monthly Fasciola risk indices of four climatic regions in Ethiopia were used to project infection transmission patterns under varying climatic conditions and strategic chemotherapeutic fasciolosis control schemes. Varying degrees of F. hepatica risk occurred in most parts of the country and distinct regional F. hepatica transmission patterns could be identified. In the humid west, cercariae-shedding was predicted to occur from May to October. In the south it occurred from April to May and September to October, depending on the annual abundance of rain. In the north-central and central regions, risk was highest during heavy summer rains and pasture contamination with metacercariae was predicted to occur during August–September, except in wet years, when it may start as early as July and extend up to October. At cooler sites above altitude of 2800m, completion of an infection cycle may require more than a year. Fasciola gigantica risk was present in the western, southern and north-central regions of the country at altitudes of 1440–2560m. However, a transmission cycle could be completed in a single year only at elevations below 1700m. The greatest risk of F. gigantica infection was in the humid western region. Regional strategic chemotherapy schemes of two or three treatments per year were developed. Results suggest that the model can be extrapolated to all CPSZ in the country and adapted for use in control of other vector-borne diseases of economic and public health importance.</abstract><note type="content">Fig. 1: Topographic map of Ethiopia showing variation in elevation, major geographic features and regions. Both thermal regime and rainfall are greatly influenced by elevation, making it possible to study a wide range of potential habitats for Fasciola hepatica and Fasciola gigantica in a relatively small geographic area.</note><note type="content">Fig. 2: Annual rainfall variation (mm) in Ethiopia based on 30-year average FAO databases.</note><note type="content">Fig. 3: 10-year average NDVI map of Ethiopia from the FAO-ARTEMIS NOAA AVHRR NDVI Image Bank for Africa, 1981–1991.</note><note type="content">Fig. 4: Thematic maps of Ethiopia showing annual forecast risk indices for Fasciola hepatica. The GIS forecast model was constructed based on monthly climate and agroecological zone databases from the FAO (Van Velthuizen et al., 1995). Base temperatures (minimum required for development of extramammalian stages) of 10°C and 16°C were used for F. hepatica and F. gigantica, respectively.</note><note type="content">Fig. 5: Thematic maps of Ethiopia showing annual forecast risk indices for F. gigantica. The GIS forecast model was constructed based on monthly climate and agroecological zone databases from the FAO (Van Velthuizen et al., 1995). Base temperatures (minimum required for development of extramammalian stages) of 10°C and 16°C were used for F. hepatica and F. gigantica, respectively.</note><note type="content">Fig. 6: Reported distribution of ruminant fasciolosis in Ethiopia based on prevalence surveys listed in Table 1. Survey data were not available for all areas.</note><note type="content">Fig. 7: Comparison of combined F. hepatica and F. gigantica forecast indices with ranked fasciolosis prevalence rates reported for Ethiopia</note><note type="content">Fig. 8: Comparsion of average Normalized Difference Vegetation Index (NDVI) with ranked fasciolosis prevalence rates reported for Ethiopia.</note><note type="content">Fig. 9: Monthly F. hepatica forecast for four regions in Ethiopia showing predicted periods of cercariae-shedding and recommended strategic curative/preventive treatment schemes for western Ethiopia. Two annual treatments are recommended for all regions, with an optional third treatment in high risk climate years in the western zone. The September–October curative and preventive treatment is considered most important in all regions if only one treatment can be given.</note><note type="content">Fig. 10: Monthly F. hepatica forecast for four regions in Ethiopia showing predicted periods of cercariae-shedding and recommended strategic curative/preventive treatment schemes for southern Ethiopia. Two annual treatments are recommended for all regions, with an optional third treatment in high risk climate years in the western zone. The September–October curative and preventive treatment is considered most important in all regions if only one treatment can be given.</note><note type="content">Fig. 11: Monthly F. hepatica forecast for four regions in Ethiopia showing predicted periods of cercariae-shedding and recommended strategic curative/preventive treatment schemes for north-central Ethiopia. Two annual treatments are recommended for all regions, with an optional third treatment in high risk climate years in the western zone. The September–October curative and preventive treatment is considered most important in all regions if only one treatment can be given.</note><note type="content">Fig. 12: Monthly F. hepatica forecast for four regions in Ethiopia showing predicted periods of cercariae-shedding and recommended strategic curative/preventive treatment schemes for central Ethiopia. Two annual treatments are recommended for all regions, with an optional third treatment in high risk climate years in the western zone. The September–October curative and preventive treatment is considered most important in all regions if only one treatment can be given.</note><note type="content">Table 1: Summary of reported prevalence rates of fasciolosis in different administrative regions in Ethiopia</note><note type="content">Table 2: Monthly forecast and cercariae-shedding patterns for F. hepatica in four selected agroclimatic regions in Ethiopia</note><note type="content">Table 3: Monthly forecast and cercariae-shedding patterns for F. gigantica in four selected agroclimatic regions in Ethiopia</note><subject><genre>Keywords</genre><topic>Fasciola hepatica</topic><topic>Fasciola gigantica</topic><topic>Fasciolosis</topic><topic>Epidemiology</topic><topic>Ethiopia</topic><topic>Geographic information systems</topic><topic>Climate</topic><topic>Chemotherapy</topic></subject><relatedItem type="host"><titleInfo><title>Veterinary Parasitology</title></titleInfo><titleInfo type="abbreviated"><title>VETPAR</title></titleInfo><genre type="journal">journal</genre><originInfo><dateIssued encoding="w3cdtf">19980731</dateIssued></originInfo><identifier type="ISSN">0304-4017</identifier><identifier type="PII">S0304-4017(00)X0051-9</identifier><part><date>19980731</date><detail type="volume"><number>78</number><caption>vol.</caption></detail><detail type="issue"><number>2</number><caption>no.</caption></detail><extent unit="issue pages"><start>79</start><end>160</end></extent><extent unit="pages"><start>103</start><end>127</end></extent></part></relatedItem><identifier type="istex">D193AD8DC9FC1EA54BA34500299F84D1BA34E02D</identifier><identifier type="DOI">10.1016/S0304-4017(98)00136-8</identifier><identifier type="PII">S0304-4017(98)00136-8</identifier><accessCondition type="use and reproduction" contentType="copyright">©1998 Elsevier Science B.V.</accessCondition><recordInfo><recordContentSource>ELSEVIER</recordContentSource><recordOrigin>Elsevier Science B.V., ©1998</recordOrigin></recordInfo></mods></metadata><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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