1. Introduction1.
1. Back ground of the study Malaria is avector-borne disease caused by protozoan parasites belonging to the genusPlasmodium and transmitted by the bite of infected female Anopheles species mosquitoes;about 60 species of the genus Anopheles can transmit malaria (Walker K,2002, Cox FE.2010). Until recently, five species of Plasmodium, namely: P.vivax, P.
falciparum, P. ovale (two sub species: P. ovale curtisi and P.ovale wallikeri), P.
malariae and P. knowlesi are known to causehuman disease (Cox-Singh J, 2010; Yusof R;,et al., 2014). The conditions of theparasite, vector and the human host are characterized by different factors,which are highlighted here. It is caused byPlasmodium parasites, is a blood-borne disease which is transmitted through thebite of an infected female Anopheles mosquito. It is a major public healthissue which affects the global population at large (Kumi-Boateng et al.,2015; Ahmed, 2014). Malaria is typically found in warmer regions of the world, i.
e.,the tropical and subtropical countries. Vectors (female Anopheles mosquitoes)require specific habitats with surface water for production, humidityfor adult mosquito survival and the development rate of both vector andparasite are dependent on temperature (Ahmed, 2014; Ashenafi, 2013). Malaria is essentially an environmentaldisease since the vectors require specific habitats with surface water forreproduction, humidity for adult mosquito survival and the development rates .
Theincrease in malaria prevalence is determined by several factors: mosquitoresistance to insecticides, parasite resistance to drugs, changes in land-usepatterns, and reductions in funding and manpower dedicated to controlactivities. Most of the determinants are heterogeneously distributed, changingover both space and time. Factors such as topography, temperature, rainfall,land use, population movements, and degree of deforestation have a profoundinfluence on the temporal and spatial distribution of malaria vectors andmalaria. (FMoH, 2009).
Globally, about half of theworld populations (3.3 billion) are at risk of malaria infection (WorldHealth Organization WHO 2011).Adult femalemosquitoes of the genus Anopheles are vectors for the Plasmodium parasites andare thus responsible for malaria transmission. There are 490 species in the genus Anopheles, and 70 of these arevectors of malaria. In sub-Saharan Africa, there are 140 Anopheles species ofwhich approximately 20 are known to transmit malaria parasites to human beings.Of these, Anopheles gambiae s.s, Anopheles arabiensis Patton, and Anophelesfunestus Giles are the most widely distributed and important malaria vectorspecies in tropical Africa (Gillies and Coetzee 1987, Foley et al.
2010). According to Kaya et al. (2002), malariaremains one of the greatest killers of human beings, particularly in thedeveloping countries. The World Health Organization (WHO,2012), estimated overone million malaria cases each year, where more than 80% of the cases are inSub-Saharan Africa countries. Malariais one of the main health problems in Ethiopia in which its cases are one ofthe highest and it is increasing in an alarming rate. Ethiopians live ataltitudes ranging from ?100 to >4220 m, the topography made a fertile groundfor the reproduction of the epidemic. More than 50 million (68%) of thepopulation live in areas below 2000 m above sea level are at risk of malaria.
With consequent variation in minimum and maximum temperatures. In general, themain reasons given for the increment are ecological and climatic changes. Thepeak of Malaria incidence follows the main rainfall season in July, August,September, October and November each year. (Negassi F., 2008).CurrentlyRemote Sensing techniques provide valuable information on such environmentalconditions. Several studies have used Remote Sensing imagery and GeographicalInformation System (GIS) techniques to map the distribution of vector speciesat different spatial scales such as the entire world, continent, national,regional, even at small village level.
According to Tran et al (2008),in endemic areas, mainly in tropical and subtropical regions, these vector mapsare designed to improve vector control, which is currently one of the essentialmethods in limiting the burden of important vector-borne diseases such asmalaria or dengue fever. In disease free areas, analyzing the link between theenvironment and potential vector distribution may help evaluate the risk ofemergence of the disease, and lead to better mitigation and control measure ofthe invasive vector species. In particular, the evolution of geographicinformation systems (GIS), the global positioning system (GPS), and remotesensing (RS) technologies has enabled the collection and analysis of field datain ways that were not possible before the advent of the computer(Milla et al.,2005).GIShas several applications to the study of mosquito biology and ecology (Eskinderetal., 2010), suggesting that GIS is the best or available method to answerquestions regarding mosquito ecologyas well studies of risk as a function ofdistance from known breeding sites and others are one common application ofGIS. GIS in combination with remote-sensing (RS) technology, has also beenemployed to predict areas of high productivity of mosquitoes and potentialmalaria epidemics based on the detection of proxy ecological variables (Hay etal., 2000).
Therefore, the aim of this study will be to assess the spatiotemporal variation of malaria in the study area 1.2. Statement of the of theproblemGlobally, about half of the world populations (3.3 billion) are atrisk of malaria infection (World Health Organization WHO2011). It has widely known impacts on theeconomic, social, and political sphere of the society As a result wide range ofmeasures were taken by national and international organizations to reduce theimpact of the epidemic but most of the efforts were invested on managing theresults than prevention.
Therefore, the cost of preventive plan and medicaltreatment becomes affect the GDP and as well as the individual economy due tothis infections.Anestimated numbers of billion peoples are at risk of this infections and 3000 to5000 million suffering a short period with the disease each year perhaps 90percent of these occur in tropic of Africa (WHO, 2012) Malaria kills between1.1 and 2.7 Million people per year. Of these deaths, approximately one millionare children in the tropic of Africa between the ages of 18 months and 5 years(Webb, 2009). Malaria risk becomes higherdeveloping countries (Donnelly, 2005).
According to Stratton, (2008) mentionedthe multiplicity of malaria causing factors in semi urban areas as the maincause of its prevalence as they are difficult to control at the same time. Due to its tropical location and availabilityof many rivers and lakes, Ethiopia is suitable for breeding of plasmodium (Womie,2008). As aresult it is a major public health problem in Ethiopia (FMoH, 2009).Accordingly its occurrence in most parts of the country is unstable mainly dueto the country’s topographical and climatic features. Inorder to reduce this impact of the epidemic disease, wide range of measureswere taken by national and international organizations. Preventive measures arecost and time effective.Oneof the Maine issues to be considered as preventive is to work on the mainfactors contributing for the development and expansion of the problem.
In thiscase Geographic Information System and Remote Sensing (GIS AND RS) application canbest fit to analyze the root problem both spatially and temporal variation. Forthis reason, understanding malaria epidemics using GIS and Remote Sensing databelieved to be essential by the researcher. Asa result, in the study area, the spatial variation of malaria risk level basedon environmental factors is not identified, which could facilitate the malariaprevention and control activities. To feel this gap, the researcher will tryapplying the application GIS, RS and MCDE based analysis to identify,classifying, and mapping areas vulnerable to malaria epidemic.1.3.Objective of the StudyThestudy will be carried out to achieve the following objectives.
1.3.1.
General objective Thisstudy aims to optimize the use of GIS and Remote Sensing (RS) technologies inmalaria control programme by examining the spatial distribution of vectors inmalaria endemic areas and determining the correlation between environmentalvariables and the distribution of larval in the breeding habitats.1.3.
2. Specific objective ü Toinvestigate the trends of malaria in the study area.ü To identify and integrates environmental(topographic) factors which make condition suitable for facilitating mosquitobreeding conditions. ü To analyze the spatial distribution of malariaepidemic in the study areaü To develop malaria risk map of the study area ü To compare malaria risk level of the selected weredas in the study area 1.
4. Research questionsConsideringthe above listed research objectives, the following research questions will beused as the fundamental basis for this study:1,Whatis the temporal change of malaria infestation in the study area?2,What are environmental factor which provides mosquito breeding conditions.3, Howthe malaria infestation is distributed over the space of the study area?4,Which parts of the the selected weredas have high, moderate and low malariarisk levels?1.5.Significant Of the StudyTheresult of this study could give important information on the spatio-temporaldistribution of malaria case in the study area.
The study will have also the ability of identifying risk areas usingGIS and remote sensing technique that greatly enhance the effectiveness ofprevention efforts and will contribute to cost-effective prevention method byproviding mechanism of efficiently targeting high risk areas, which helpnational and international organizations, medical geographers and any stakeholders working in the health and the selectedweredas of health sectors in organizing their effortstowards the fight against malaria efficiently and cost effectively.1.6. Scopeof the StudyThescope of this study is delimited both in geographical area and issue ofconcern. Geographically, it is delimited to the two selected woredas of Jimmazone which is Limmu seka and choraboter of Oromia national regional state.Regarding the area of concern, the main focus of the research will developing thespatioal variation of malaria risk map for the Woredas. Thus, this study isrestricted to develop GIS and remote sensing based malaria risk map of thestudy area using environmental factors.1.
7.Organization of the paperThe study will have five chapters the first chapter containsintroduction, statement of the problem, objectives, and research question: inthe second part theoretical literature will reviewed and the third chaptercontains methodology and description of the study area. The fourth chapterdeals with result and discussion, in the last chapter conclusion andrecommendation will be forwarded. CHAPTER TWO2.
LITERATURE REVIEW 2.1. Global Concepts and Distribution of MalariaMalariais an ancient disease caused by parasites of the genus Plasmodium andtransmitted by several species of female anopheles mosquitoes. The term’malaria’ originates from malaria (Italian) signifying ‘bad air’ or miasmasarising from marshes (Shumbullo, 2013). Protozoanparasites of the genus Plasmodium are responsible for human malaria, of whichfour species are primarily involved, plasmodium falciparum, Plasmodium vivax,Plasmodium malaria, and Plasmodium ovale. Recent reports have suggested thepossibility of a fifth species, Plasmodium Knowles, as an important and commonemerging zoonotic pathogen responsible for human infections in Southeast Asia(Cox-Singh et al.
, 2008). Globally,P.falciparumis the most common cause of malarial infection, responsible forapproximately 80% of all cases and 90% of the deaths. Plasmodium transmissionfrom Anopheles vector to humanism accomplished through direct injection of theparasite contained in salivary gland fluid during blood feeding. Of the484recognized species of Anopheles (Harbach, 2004), only about 20% orless aregenerally involved in malaria transmission (Bruce-Chwatt, 1980). Anophelesfemales become infected by imbibing sexually mature gametocytes present in theperipheral blood of the host. In the mosquito midgut fertilization produces theookinete which traverses the mosquito gut and forms oocytes under the outermost layer of the gut wall.
After repeated multiplication, each oocysteventually ruptures releasing hundreds of sporozoites into the mosquito bodycavity, a proportion of which will invade the salivary glands awaiting theopportunity to infect another human upon the next blood feeding by themosquito. Thissporogonic cycle (ookinete–oocyst–sporozoite) within the mosquitotakes on average 10–14 days depending on the ambient temperature and Plasmodiumspecies. Infective female mosquitoes will generally remain infectious duringtheir entire life which is spent repeating a cycle of blood feeding, developingand lying eggs every two to three days per gonotrophic cycle. Accordingto WMR (2009), the global numbers of malaria cases in 2008 were an estimated243 million. The vast majority of cases (85percent) were in the African Region,followed by the South-East Asia (10percent) and Eastern Mediterranean Regions(4percent). And it accounted for an estimated 863,000 deaths, of which89percent were in the African Region, followed by the Eastern Mediterranean(6percent) and the South-East Asia Regions (5percent). Each parasite has adistinctive appearance under the microscope, and produces a somewhat differentpattern of symptoms (NIAID, 2007). Their description is given as.
The infection can develop suddenlyand produce several life threatening complications. With prompt, effectivetreatment, however, it is almost always curable (NIAID, 2007). Plasmodium vivax: the mostgeographically widespread of the species, produces less severe symptoms.Relapses, however, can occur forup to 3 years, and chronic disease is debilitating. Once common in temperateclimates, Plasmodium vivax is now found mostly in the tropics,especially throughout Asia (NIAID, 2007).
A person asymptomatic (no symptoms) Plasmodiummalaria, however, can 8 infect others, either through blood donation ormosquito bites. Plasmodium malaria has been wiped out from temperateclimates, but it persists in Africa (NIAID, 2007). Plasmodium ovale: is rare, can cause relapses, and generallyoccurs in West Africa (NIAID, 2007)2.2. Globaldistribution of malariaMalariais one of the world’s most common and serious tropical diseases.
However, on the globe, it extends up to 60° north and40° south of latitudes. Its distribution in the world is not uniform. Differentspecies of Plasmodium are found in different countries.
According World MalariaReport of 2012, about 70-90 per cent of the risk of malaria is considered dueto environmental factors which in turn influence the abundance and survival ofthe vectors. Thishas motivated the World Health Organization to pursue the development of newtechniques and models in which the role of environmental is fundamental.Spatial technology helps systematic and regular monitoring of the earth’senvironmental conditions furnishing large amounts of spatial and temporal data.Such information together with appropriate field studies can prove veryfruitful for early detection and timely response to disease management.
About90% of all malaria deaths in the world today occur in Sub Sahara Africacountries. This is because the majority of infections in Africa are caused by Plasmodiumfalciparum, the most dangerous malaria species of the four types. It is themost widespread in Africa and the most difficult to control.
About one millionpeople in Africa die from malaria each year, where most of them are childrenunder 5 years old (WHO, 2011). Accordingto World Malaria Report of WHO, 2012, the global malaria distribution hasprogressively been reduced since the mid 19thAccording to World MalariaReport of WHO, 2012, the global malaria distribution has progressively beenreduced since the mid 19th century, especially from 1945 to 1977,when 37 countries were freed of malaria thanks to the efforts of the globaleradication programme. Success in malaria elimination occurred mainly incountries in Europe and North America, where malaria transmission was lower.Even today, the 11 countries which are aiming at malaria elimination have lowmalaria transmission and are placed at the limits of the global map of malariadistribution (NIAID, 2015).
Century, especially from 1945 to 1977, when37 countries were freed of malaria thanks to the efforts of the globaleradication programme. Success in malaria elimination occurred mainly incountries in Europe and North America, where malaria transmission was lower.Even today, the 11 countries which are aiming at malaria elimination have lowmalaria transmission and are placed at the limits of the global map of malaria distribution(NIAID, 2015).2.3. Distribution ofmalaria in EthiopiaTheexistence of malaria in Ethiopia is unquestionable due to its tropicallocation. Besides its tropical location, 75% of the area that lies below 2000 ma.s.
l elevation, where about two-third of the population is living on is alsoprovides favorable natural environment for the occurrence of malaria and henceit is malarious (Woime, 2008). InEthiopia, the estimated incidence rate for malaria (i.e., the estimatedprobability of contracting the disease in a year) is 15%, which is low relativeto the rest of sub-Saharan Africa (Where the average incidence rate is 0.
33),but higher than any other country outside of sub-Saharan Africa, Panama, Laos,Myanmar, and the Solomon Islands (WHO, 2012). Despitethe somewhat low incidence rate, this country is an appealing place to do astudy on malaria for at least two reasons. First, malaria is still a veryimportant public health problem: Ethiopia is thought to experience some 10million cases per year, the fourth highest case numbering sub-Saharan Africa(behind Nigeria, the DRC, Tanzania, and Uganda (WHO, 2012).
The second reasonfor considering malaria in Ethiopia is that, unlike most other Africancountries, there is extensive local variation in malaria incidence. Amongplasmodium species, Plasmodium falciparum and Plasmodium vivax arethe most dominant malaria parasites in Ethiopia, distributed all over thecountry and accounting for 60% and 40% of malaria cases, respectively. Plasmodiummalaria accounts for less than 1% and Plasmodium ovale is rarelyreported. The parasite is principally transmitted by the major mosquito vectorknown as Anopheles arabinoses. Insome areas, Anopheles pharoensis, Anopheles funestus and Anophelesnili also transmit the disease (Adugna, 2011). InEthiopia, malaria has a personality, geographic character, and impact quitedifferent from other parts of Africa and global malaria (Getachew et al.,2010)they put forward, Ethiopia’s malaria is unstable-the high seasonal fluctuationsin temperature and moisture result in malaria appearing in epidemic form andwith great variation across landscapes. The instability of Ethiopia’s malariameans that populations in most areas have never attained a significant level ofprotective immunity (ashas been the case in endemic areas of West Africa) andthus a higher rate of death and morbidity among adults.
Ineach of those early to mid-twentieth-century analyses medical fieldobservations confirmed Ethiopians’ own folk epidemiology about malaria as an endemicdisease of the moist lowlands and river valleys and its highly seasonalcharacter that followed closely the annual life cycle of its mosquito vectors(FMoH 2009). The malaria landscape followed closely elevation, slope and theseasonal cycle of temperature and moisture (Getachew et al., 2010). Ethiopia’s malaria is also distinctive in thedominance of the parasite P.
falciparum, a particularly deadly form, andparticularly the prevalence of the mosquito vector A.arabiensis, aspecies of anopheles mosquito that has over time and changing ecologies adaptedits behavior and habitat preference for the high seasonal variation of EastAfrica andsahelian zones where unstable malaria is the dominant form (Asnakew,2002).
