Malaria is a haemoparasitic disease caused by obligate intracellular protozoan parasites of plasmodium species which are transmitted by infected female anopheline mosquito. Among the five types of plasmodium parasites that cause malaria, Plasmodium vivax and Plasmodium falciparum are widely distributed in Ethiopia and worldwide [1].
Irrespective of the promising strives made so far, to reduce malaria-related mortality and morbidity, malaria is the third leading cause of mortality next to HIV/AIDS and TB among infectious diseases. Therefore, malaria is considered one of the still existing health threats causing a considerable amount of mortality, morbidity and economic burden affecting all parts of the sub-Saharan African countries in which the problem is aggravated [2].
As indicated in the World malaria report of 2018, a promising effort was made to combat malaria. The success to tackle the disease was lowered during the years of 2015 through 2017 in which, in 2017 a total of 219 million and 435000 malaria cases and malaria attributed deaths were reported respectively [3].
Ethiopia is among the countries with a large burden of malaria with the peak transmission rate in the world. According to the survey of indicators' of malaria taken in Ethiopia in 2015, overall malaria parasite prevalence is 0.5 % in a population residing in malarious areas and a total of 2,174,707 malaria cases were detected and (63.7%) of these cases were Plasmodium falciparum [4].
More than half (60%) of Ethiopia's population lives in malarious areas, and 68 percent of the country's landmass is favorable for malaria transmission. Malaria transmission occurs throughout the year with the highst transmission period from June to September which is considered as a major transmission season in the country [4].
Transmission is mostly geo-spatially heterogeneous throughout the year and among the years. Malaria epidemics occur every five to eight years in the country. Social and natural factors mark the transmission scheme of malaria. Temperature, relative humidity, and rainfall are the key natural features that influence the breeding character of mosquito and malaria parasites [5,6].
Malaria parasite favor's increased humidity indices for completion of its major life cycle phases. Researches addressing prevalence helps to assess malaria status within a given locality and has an important indication to value the overall effectiveness of prevention strategies being implemented in the area [6,7].
About half of a population living in areas of an altitudinal range of 1,500 and 2,500 m above sea level are more likely to get malaria and these areas experience hit in malaria outbreak in Ethiopia Some studies from high altitude zones identified age, the proximity of households to potential mosquito breeding sites, sharing of houses with cattle, presence of windows and open attics as malaria risk factors. In addition to this, malaria is also related to factors like altitude, rainfall, and temperature. Thus, interventions focus on both the households and the surrounding environment [5,7].
In Africa, members of Anopheles gambiae complex and Anopheles funestus are widely distributed and are causes for the spread of malaria in the region. Anopheles gambiaes.s is the most anthropophagic species of malaria vector with characteristic indoor and outdoor resting. Anopheles arabiensis and Anopheles quadriannulatus species are one of the species of the Anopheles gambiae complex that are found in Ethiopia [8].
Entomological findings conducted so far indicated the presence of 42 anopheles in Ethiopia. Despite the presence of all these, only Anopheles arabiensis is known to play a major contribution in the spread of malaria in the country. Others like Anopheles funestus and Anopheles pharoensis playing a secondary role, while Anopheles nili involves transmission in localized areas [9].
WHO has initiated strategies to control malaria in 1992. Since that time, emphasis on malaria control has shifted from vector eradication to increased case detection and treatment Efforts to control malaria include environmental management, insecticide sprays and use of Insecticide-treated nets (ITNs) [6,10]. In Ethiopia, the key malaria control strategies are prompt diagnosis and immediate treatment of cases. Besides these, there are other strategies like outbreak investigation and arrest, mosquito vector control and environmental management. Indoor residual sprays and insecticide-treated nets are also used at a large [10].
Unstable malaria transmission occurs in Ethiopia and makes the country vulnerable to focal and multifocal devastating malaria outbreaks. Malaria is most of Ethiopia is mainly characterized by its seasonality. The transmission intensity and prevalence pattern variably differs with ranging altitude, temperature, and social mobility. Control of the disease is stepped on key universal strategies, such as prompt and proper case management, intermittent preventive treatment (IPT) during pregnancy and integrated vector management (IVM) encompassing the use of insecticide-treated nets (ITN), indoor residual spraying (IRS), and environmental management [2].
According to the retrospective trend analysis of malaria cases done in Ataye District Hospital, 31,810 blood films examined from malaria suspected patients from January 2013 to December 2017. Among these blood films, 2,670 (8.4%) were microscopically ascertained malaria cases. In 2016, a higher number (8,066) of malaria suspected patients were examined and 863 (10.7%) of them 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 soared during the years 2013 through 2016 and declined in 2017 [11].
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 diagnosed malaria parasites recorded which gives an average of 603.6 malaria cases. No year reported zero malaria cases. The lowest rate (1.6%) malaria cases recorded in 2008 and the highest (31.2%) in 2004, followed by 2010, 2005 at a prevalence of 13.7% and 13%, respectively. Furthermore, malaria rose in all months of the year with different fluctuation rate in which, the highest peak was in June at a prevalence rate of 18.9%, followed by May, November, and July with a prevalence of 13.3%, 13.2%, and 11.2%, respectively [12].
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 help provide 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.