According to this study, the total prevalence of malaria cases over six-years was 11.3%. This result was noticeably lower than 48%, 36.1%, 33.8%, 21.8% and 17% reported from the nearby localities of Woreta town, northwest Ethiopia ; Addi Arkay health center, northwest Ethiopia; and Abeshge, South-central Ethiopia; Gondar, northwest Ethiopia; Metema hospital northwest Ethiopia, respectively [18–22]. On the other hand, it was higher than the studies conducted in Ataye, North Shoa, Ethiopia (8.4%), Bahirdar city (5%) and kombolcha town (7.5%) [16, 23, 24].The differences might be due to time variations of the studies, the difference of malaria prevention and control implementation activities, variations in geographical locations and difference in insecticide application in the areas.
According to this study, the number of confirmed malaria cases was steady increased from 2015 to 2016which indicates that the area needs attention to intensify the existing interventions to enhance malaria elimination efforts. However, slightly decreasing trend in number of confirmed malaria cases was observed from 2016 to2019. This reduction of malaria cases over three year was due to the Bati health district was consistently implemented malaria prevention and control including distribute Insecticide Treated Net (ITN), create health awareness about malaria prevention and control to the community. This reduction is also due to effective malaria control and prevention strategies which are being implemented by Federal Ministry of Health in the whole malaria areas by giving emphasis to reduce malaria cases to zero.
Regarding to distribution of plasmodium species in the study area, Plasmodium falciparum was the dominant species which accounted 57.6% followed by P. viva 42.4%. This result was similar with the retrospective studies conducted in Raya Azebo which accounted Plasmodium falciparum(56.9%) and P. viva43.1% [23] and around Gilgel Gibe Hydroelectric Dam (GGHD), which accounts Plasmodium falciparum (54.6%) and Plasmodium vivax(41.6%)[24]. As compare to the studies, this finding is agreement with malaria species distribution in several parts of Ethiopia such as Kola Diba, North Gondar; Raya Azebo Northern Ethiopia; Butajira, Southern Ethiopia; Jimma, Southwest Ethiopia [2, 23, 25, 26]. On other hand, the prevalence of p. falciparum was slightly less than a result reported from a retrospective study reported in Kola Diba health center (75%)[26].This is mainly due to the implementation of malaria prevention and control activities which might differ from one area to another showing that the interventions in our study area might have been stronger.
The numbers of confirmed malaria cases were varied from season to season and also year to year. In fact, the prevalence and magnitude of malaria transmission are mainly determined by environmental, climatic, seasonal factors and behavioral factors. In this study, the highest malaria cases were reported during summer season (47.2%). This result was in agreement with the retrospective studies conducted in Kombolcha, Ethiopia; Ataye Northshoa; Northwest Gondar, Ethiopia[16, 20, 27]. This might be due to the similarity of climate condition and altitude difference. This is also true as explained by federal democratic republic of Ethiopia ministry of health national strategic plan for malaria prevention there two peak malaria transmission seasons are from September to December and following the rainy season from June to September. However, in this study, malaria cases were high at summer season. This is may be due to relapsing behavior of malaria parasite and irregular rain-full in the area[9].
According to this study, malaria was detected in all age groups. In current study, the highest prevalence of malaria was observed among ≥15 age groups (57.2%) followed by 5 to 15 age groups (24.5%) and under five children (18.3%). This results was similar to the findings of studies conducted in Raya Azebo; Addi Arkay health center; Ataye Northshoa; and Abeshge, South-central Ethiopia; Northwest Gondar[20–22, 27, 28].This might be due to the fact that productive age groups often engaged in farm activities in the fields.