Malaria is a public health problem in terms of morbidity and burden on health care facilities, accounting for the increasing percentage of outpatients in most health facilities in different regions in Ethiopia (4). The present study revealed that the average annual malaria prevalence was 7.7% (95% CI; 7.3–8.1). This finding was lower than the study conducted elsewhere in Kola Diba, North Gondar, Northwest Ethiopia (4), Adi Arkay, North Gondar, Northwest Ethiopia (12), Abeshge, south-central Ethiopia (6), Dembecha Health Center, West Gojjam Zone, Northwest Ethiopia (8) and Woreta Health Center, Northwest Ethiopia (13), and higher than other study findings conducted in of Felegehiwot referral Hospital catchment areas, Bahir Dar, northwest-Ethiopia Ethiopia(7) and Halaba special district, Southern Ethiopia (14). The difference might be due to variations in malaria diagnosis techniques and the skills of the laboratory personnel to detect and identify malaria parasites. Moreover, the implementation of malaria prevention and control activities might differ from one area to another. Besides, there might be demographic (sex, age) and geographic (attitude, temperature, rain fall) and economical activities differences that also had an effect on the prevalence of malaria.
The average annual trend of malaria revealed that there was slight increment malaria prevalence in the first two years (2015 and 2016) compare to the year of 2014, but statistically it was insignificant. However, in the last three years (2017, 2018 and 2019) the trend showed that significant reduction of malaria prevalence. The prevalence was reduced by 68%, 60% and 69% in the year of 2017, 2018 and 2019, respectively. The possible reasons for malaria reduction during this period (2017–2019) might be due to the increased attention to malaria control and preventive activities by different responsible bodies, increased awareness of the community on use of ITNs, insecticide spraying, drainage system of mosquito breeding sites and climate change at national and international level. Integrated control strategies are underway in the local area as part of the nationwide malaria control activities (15). However, the observed prevalence in this study is still considerable.
This study demonstrated that in average of the six years, P. vivax was the predominant species, although there was a species fluctuation from year to year. The proportion of P.vivax, P. falciparum and mixed infections was 47.2%, 45.6%, and 7.2%, respectively. This finding was consistent with the study conducted in Adama City, East Shoa Zone, Oromia, Ethiopia (15), Halaba health center Southern Ethiopia (14). The predominance of P. vivax might be due to relapse of dormant liver stages or increased treatment pressure against P. falciparum (16)and Southwest Ethiopia, around Gilgel gibe dam and 10 kilo Metter far from Gilgel gibe dam (3). However, this finding was disagreement with the study conducted at two health centers Gorgora and Chuahit in Dembia district (17), catchment areas of Felegehiwot referral Hospital (7) and Kola Diba, North Gondar, Northwest Ethiopia (4) which reported that P. falciparum was the predominant species. Moreover, the trend of P.vivax showed reduction whereas, P. falciparum showed increment trend. In the last three year of the six year periods, P. falciparum had become the predominant plasmodium species. The fluctuated proportion of plasmodium species might be attributed by heterogeneous parasite species and disease distribution include differences in genetic polymorphisms underlying parasite drug resistance and host susceptibility, mosquito vector ecology and transmission seasonality. Plasmodium species interact might have geographical differences and these interactions may even change from year to year in a given locale (18). The finding also revealed that there was fluctuated increment in the proportion of mixed infection.
The prevalence of malaria was varied among different seasons ranging from 6.6–8.8%, and these variation was statistically significant. The highest peak was observed in autumn (8.8%) and the lowest peak was observed in the winter season (6.6%). The malaria prevalence was reduced by 16% in the winter. However, where the sex and age were adjusted, the peak prevalence was observed in summer rather than autumn, in which the prevalence was increased by 32%. The reason might be due to climate change from year to year. In Ethiopia, summer is the season when the heavy rain fall is observed and it is not favorable season for vector spreading (15). However, there is rain fall variation from year to year (19). Changes in temperature, rainfall, and relative humidity due to climate change are estimated to influence malaria directly by modifying the behavior and geographical distribution of malaria vectors and by changing the length of the life cycle of the parasite. Climate change is also expected to affect malaria indirectly by changing ecological relationships that are important to the organisms involved in malaria transmission (the vector, parasite, and host) (20).
The current study revealed that males were more affected by malaria infection than females. The odds of malaria positivity rate among males were 1.41 times higher than females. The reason behind the high malaria cases in male might be due to the facts that males are involved in outdoor activities and are mobile to malaria-endemic areas seeking temporary employment, whereas females do not perform field activities rather they are cookers and stay at home which might reduce the risk of infection.
Age was also contributing factor for the prevalence of malaria. It was higher in younger age groups than the older age groups. The odds of malaria positivity rate among less than five years old children and 5–14 years old were 1.60 and 1.64 times higher than age group of greater than 55 year old, respectively. The reason might be these age groups may be less immune commutate than the older age groups (> 55 year old). This was supported by the world health organization report (21). The study also showed that the odds of malaria positivity rate among early working group (15–24) and primarily working groups (25–54) were, 2.45 and 1.82 times higher than age group of greater than 55 year old, respectively. The reason behind the high malaria cases in the mentioned age group of 15–24 and 25–54 years old might be the former one, that is males in this age group are involved in outdoor activities and are mobile to malaria-endemic areas seeking temporary employment, whereas the older age group do not perform field activities rather they are stay at home which might reduce the risk of infection.
The findings of this study might suffer from the fact that it is secondary data based on records; the reliability of the recorded data couldn’t be ascertained. Moreover, the collected data relayed on the laboratory logbook which lacks participants’ body temperature, clinical presentations and residence. It also lacks the information regarding to the weather conditions of the month, seasons and years.