Trend of malaria prevalence in Wolkite health center: an implication towards the elimination of malaria in Ethiopia by 2030

Despite a rigorous effort done to prevent malaria, it is still a major public health challenge worldwide causing a significant burden of illness and mortality [1]. Globally, an estimated 219 million malaria cases and 435,000 death occurrence have been reported in 2017. African took a higher share from the global malaria burden and Plasmodium falciparum is the most predominant species, accounting for 99.7% [2]. The burden of malaria is more devastating in children and pregnant women [3]. Even though the expanded coverage of malaria prevention and case–control service reduced mortality and morbidity, malaria is a major threat especially to sub Saharan African countries including Ethiopia [4].

Around 68% of the Ethiopian population resides in the area below 2000 m altitude which is considered to be at risk of malaria. Thus, malaria is one of the public health challenges in Ethiopia impede the socio-economic development of the country [4, 5]. The transmission of malaria is highly seasonal throughout the country that depends on altitude and climatic variations [2]. Plasmodium falciparum and Plasmodium vivax are the most dominant malaria parasites in Ethiopia accounting for 60% and 40% of malaria cases respectively [5]. The major responsible vector for malaria transmission in Ethiopia is Anopheles arabiensis however in some other areas A. pharoensis, A. funestus, and A. nili are also responsible for the transmission of malaria [6].

Malaria prevention and control program in Ethiopia is guided by the National Malaria Strategic Plan (NMSP) in line with global Roll Back Malaria (RBM) [4]. The current vector control interventions implemented in Ethiopia include insecticide-treated mosquito nets (ITNs), indoor residual spraying (IRS) and mosquito larval source reduction [7]. As stated in the 2015 malaria indicator survey (MIS), above 70% of households in malaria-endemic areas were protected by ITN or IRS. The national malaria guidelines recommend Artemisinin-based combination therapies (ACTs) for the treatment of uncomplicated malaria caused by P. falciparum and for P. vivax treatment chloroquine remains efficacious in malaria-endemic areas. Whereas, Primaquine is recommended for radical cure of patients with P. vivax in non malarious area, however, to the best of author’s knowledge there was no published data that state the current Primaquine usage in Ethiopia [6, 8].

Ethiopia has recently targeted malaria elimination nationwide in 2030 aligned with the World Health Organization (WHO) Global Technical Strategy (GTS) through intensifying the existing malaria control activities [9]. Presently, Ethiopia is on track to achieve the 2020 milestone by reducing the incidence of malaria by 40% [2]. However, the emergence of insecticide resistance, migrant population, emerging chloroquine resistance for P. vivax, difficulty in control and elimination of P. vivax are the challenging factors for malaria elimination in Ethiopia and worldwide [5, 10].

According to the Gurage zone heath department, a higher prevalence of malaria was recorded in Wolkite, Abshge and Cheha woredas (district) in 2018 [11]. Analyzing the prevalence of malaria trends each year is important for expanding the prevention and control strategy as well as for designing new policies for appropriate intervention that could assist in the elimination of malaria in 2030. Thus, this study aimed to assess the trend of malaria prevalence in Wolkite health center in Gurage zone from 2015 to 2018. The findings may insight stakeholders to revise malaria control strategies in the study area.

In the present study, the overall microscopically confirmed malaria cases in Wolkite health center was 10,379 (8.56%) from 2015 to 2018. The maximum and minimum confirmed malaria case was reported in 2015 and 2018 respectively. However, the prevalence was lower than reported from other retrospective studies conducted in Adi Arkay health center (36.1%), Serbo health center (43.8%), Halaba special district (9.5%) and Wolaita zone (33.27%) [16‐19]. This variation might be due to climatic and altitude differences. In the previous study, endemic areas of Gurage zone had a good practice of malaria prevention measures accounted for 62% [20]. Moreover, according to 2018 Gurage zone health bureau report, the overall coverage of main malaria interventions, ITNs and IRS, has reached 88% in Gurage zone where Wolkite town accounted 95.6%, Abshge 87%, Kebena 95.5% which attributed for the reduction of malaria incidence [11]. In the study area, P. vivax was the dominant species among the Plasmodium species (69.7%) followed by P. falciparum (29.3%) during the last 4 years. This was similar to reports from Jimma and Butajira area, near the study area [21, 22]. The biological character of the Plasmodium species including the dormant stage of the parasite in the liver causing relapsing attribute to the predominance of P. vivax. In addition, the performance difference of the laboratory personnel regarding malaria species identification might be attributed to increased prevalence. However, despite emerging chloroquine resistance P. vivax has been reported in southern Ethiopia [10], chloroquine is an efficacious drug for the treatment of P. vivax malaria in the study area [23].

Malaria prevalence trend showed consistent reduction during the last 4 consecutive years from 2015 to 2018 which was in agreement with a study reported in Kenya [24]. All Plasmodium species infections including mixed infection showed a decreasing trend throughout all 4 years. With the exception, a slight increment in the number of mixed malaria infection was recorded in 2018 compared to 2017. This shows continuous efforts were done in scaling up malaria prevention and control at the national and local levels. This might highlight the need for continuous efforts to eliminate malaria earlier than its plan.

In the present study, Plasmodium infection was nearly equal with only slight variation among males and females which was comparable with a study conducted in Wolaita zone [19]. This finding was in contrast with the majority of the study done in Ethiopia [25, 26] where males were highly affected by malaria than females. Both males and females are involved in outdoor activities especially males in the agricultural activities and most females travel to town for the market thus, they are exposed to the bite of Anopheles mosquitoes.

Regarding age, the highest affected age group was > 15 years accounted for 54% followed by 5–14 age group 23.5% while the least affected age group was < 1 year in both sexes and the most frequently reported species in all age groups were P. vivax. The highest malaria prevalence in the adult age group obtained was in agreement with other findings reported across Ethiopia [19, 22, 27, 28]. Whereas a finding from Arsi Negelle [29] showed that highly affected age group was 0–5 years followed by 16–20 years old. The reason for this variation might be the majority of the study participants were adults and as this age group is young and productive, they are actively engaged in an agricultural activity that might prone them for an anopheles mosquito bite. In addition, they travel far for schooling which exposes them to the infection.

The prevalence and magnitude of malaria transmission are mainly determined by environmental, climatic and seasonal factors. In highland-fringe areas, like Wolkite town, malaria transmission is seasonal and depends on altitude and rainfall. Thus, higher malaria transmission is recorded after the heavy rain of summer, September to December and the lowest in March to May after the light rains, which agrees with our findings. This was also in agreement with other studies done in the different parts of Ethiopia [26, 28]. Variability of rainfall and temperature in each season affects the availability of breeding habitats for mosquito vectors, the length of mosquito larvae development and the rate of growth of the malaria parasites inside the vector [30].

The distribution of Plasmodium infections across a community varies in a predictable pattern based on age and transmission intensity [31]. A higher prevalence of malaria infection was recorded in Wolkite town followed by Abeshge, Kebena and others. Plasmodium vivax was the predominant species in all residences. This variability in the prevalence of malaria among residences agrees with studies undertaken in Butajira [22], Tanzania [32] and Ghana [33]. This might be due to variation in the intervention of malaria prevention and control activities from one area to another. In the present study, there was a statistically significant association of Plasmodium infection with residence and age group. As Plasmodium infection varies between geographical setting and population, the control strategy must vary according to each area’s local epidemiology [31]. Thus, the national malaria control program should enhance the access of malaria prevention to high-risk populations and prioritize high-risk areas based on stratification.

Limitation of the study was poor management of patient data, 46 data were excluded from the study and only 4-year data were available during the data collection time. Since secondary data were used for analysis, it might affect the prevalence of malaria in the study area. However, the present study showed the trend of malaria prevalence in the study area and catchment areas which provides important information to strengthen the intervention of malaria control.

In general, the prevalence of malaria in Wolkite health center showed a consistent downward trend from the year of 2015–2018. Plasmodium vivax seemed to be overlooked even though there were hardly any known drug resistance has been reported in the study area for P. vivax [23]. In addition, a recent randomized trial has reported the effectiveness and safety of short-course usage of Primaquine for a radical cure in P. vivax endemic areas of Ethiopia [34]. Therefore, malaria prevention and control strategy should be reinforced particularly targeting adults and rural areas and also enhancing the capacity of laboratory personnel in malaria identification is very essential to reduce the prevalence of malaria in the study area.