Malaria is a haemoparasitic disease caused by obligate intracellular protozoan parasites of plasmodium species which are transmitted by infected female anopheline mosquito. There are five species of plasmodium parasites which infect humans and cause malaria, of which Plasmodium falciparum and Plasmodium vivax have broad distribution which holds true for the case of Ethiopia as well .
In the last decade, although much progress has been made in reducing malaria morbidity and mortality, next to HIV/AIDS and TB, malaria still remains the third leading cause of death. It is still considered as a major public health problem, causing considerable amount of mortality, morbidity and economic burden affecting all parts of the sub Saharan African countries , in which the problem is aggravated.
World Malaria Report 2018  indicated that after an unprecedented period of success in global malaria control, progress has stalled. Data from 2015–2017 highlight that no significant progress in reducing global malaria cases was made in this period. There were an estimated 219 million cases and 435 000 related deaths in 2017.
Ethiopia bears a particularly large burden, having among the highest rates of transmission worldwide. According to the national malaria indicator survey taken in 2015  , malaria parasite prevalence by microscopy was 0.5 percent among all age groups residing in malarious areas and a total of 2,174,707 malaria cases were detected and (63.7%) of these cases were Plasmodium falciparum. More than half (60%) of Ethiopia’s population lives in malarious areas, and 68 percent of the country’s land mass is favorable for malaria transmission . Transmission takes place all year round with a seasonal peak extending from June to September which is considered as a major transmission season in the country. Malaria transmission tends to be highly heterogeneous geo-spatially within each year as well as between years. Additionally, malaria in Ethiopia is characterized by widespread epidemics occurring every five to eight years .
Many factors affect the dynamics of malaria transmission and infection, ranging from social to natural. Rainfall and temperature can be considered as the major natural risk factors affecting the life cycle of malaria parasite and mosquito breeding. Relative humidity plays a role in the life span of the mosquito. In the presence of high relative humidity values, the malaria parasite would complete the necessary life cycle in order to increase transmission of the infection to humans. Studies on prevalence of malaria are important not only to assess the problem of malaria in a given region, but also to analyze the effectiveness of strategies for primary and secondary prevention as well as its quality and impact.
About half of the total population living between altitudes of 1,500 and 2,500 m above sea level is at risk of malaria and the areas experience epidemics in Ethiopia . Some studies  from high-altitude areas identified age, nearness of houses to breeding places, sharing of houses with animals, presence of windows and open eaves as malaria risk factors. In addition to this, malaria is associated with environmental factors such as altitude; rainfall, and temperature. Thus, malaria interventions target both households and environment.
In Africa, members of Anopheles gambiae complex and Anopheles funestus are widely distributed and are responsible for the transmission of malaria in the region. Anopheles gambiae s.s is the most anthropophagic species in the complex and the most important, probably the world’s most efficient malaria vector with characteristic indoor and outdoor resting. Anopheles arabiensis and An. quadriannulatus sp. B are among the species of the An. gambiae complex that are found in Ethiopia .Even though entomological findings conducted so far indicated the presence of 42 anophelines in Ethiopia, only An. arabiensis is known to play a crucial role in malaria transmission in the country. Others such as An. funestus and An. pharoensis playing secondary role, while An. nili involves transmission in localized areas .
Efforts to control malaria include environmental management, insecticide sprays and use of insecticide‐treated nets (ITNs) .Since the development of the Global Malaria Control Strategy by the World Health Organization in 1992, emphasis in malaria control has shifted from vector eradication to increased case detection and treatment of malaria .The main malaria control strategies in Ethiopia include: early diagnosis and prompt treatment, selective vector control, epidemic management and control, environmental management and personal protection through the use of insecticide-treated bed nets . Unstable malaria transmission patterns make Ethiopia prone to focal and multifocal epidemics that have on occasion caused catastrophic public health emergencies. Malaria is seasonal in most parts of Ethiopia, with variable transmission and prevalence patterns affected by the large diversity in altitude, rainfall, and population movement. Control of malaria is hinged on key global strategies, which include prompt and effective case management, intermittent preventive treatment (IPT) of malaria in pregnancy and integrated vector management (IVM) comprising the use of insecticide-treated nets (ITN), indoor residual spraying (IRS), and environmental management .
According to retrospective trend analysis of malaria cases done in Ataye District Hospital , a total of 31,810 blood films were examined from malaria suspected patients from January 2013 to December 2017. Of the examined blood films, 2,670 (8.4%) were microscopically confirmed malaria cases. In 2016, higher number (8,066) of malaria suspected patients were examined and 863 (10.7%) of them were became microscopically confirmed cases. On the other hand, out of 6,172 malaria suspected patients, the least number of cases, 358 (5.8%), were recorded in 2017. Generally, malaria cases showed an increment from 2013 to 2016 whereas there was a decrease in malaria cases in 2017. A ten year retrospective malaria trend analysis conducted in Sibu-Sire, western Ethiopia from 2004 -2013 , demonstrated that among a total of 30,070 blood films requested for malaria diagnosis, 6,036 (20.07%) microscopically confirmed malaria cases were reported with mean malaria cases of 603.6. In this area malaria was reported in all years with the lowest (1.6%) malaria cases reported in 2008 and the highest (31.2%) in 2004, followed by 2010, 2005 with the prevalence rate of 13.7% and 13%, respectively. Furthermore, malaria aroused in all months of the year with different fluctuation rate in which, the highest peak was in June with a prevalence rate of 18.9%, followed by May, November, and July with a prevalence rate of 13.3%, 13.2%, and 11.2%, respectively .
To our knowledge level, the present study is the first community based malaria survey in the vicinity and can be considered as a baseline survey which would be helpful in providing information and fill the knowledge gap regarding malaria prevalence, predictors of malaria prevalence and the fluctuating trend of malaria observed over the years around the area. Thus this study was designed to assess the prevalence of malaria and its associated factors in and around Arjo Didhessa sugar factory, Western, Ethiopia.