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