Retrospective trends of malaria prevalence
Out of 2,157 individuals who visited the two health facilities seeking treatment and suspected to have malaria, 22.4% (n= 484) were positive for malaria parasites (Table 1). Microscopic and RDT results indicated that19.4% (n=281) individuals in Arebiya and 28.7% (n= 203) individuals in Guramba Bata were infected with malaria parasites during the six-year period (2012-2017).
There were significant differences in malaria cases among the age groups in both health facilities (χ2=111.8, df =3, p=0.000; χ2=231.7, df =3, p=0.000). Malaria was more prevalent in individuals between the 18-64 age groups in both health facilities. Malaria parasites were detected in 28.5% (n= 226) individuals in Arebiya health post, and 67.1% (n= 143) individuals in Guramba Bata health centre in the 18-64 age group (Table 1). On the other hand, relatively low number of malaria cases was recorded in the 6-17 years age groups (7.2% in Arebiya health post and 9.3% in Guramba Bata health centre) (Table 1). The difference in malaria cases between sexes were statistically significant in both Arebiya health post (χ2= 102.3, df =1, p=0.000) and Guramba Bata study sites health centre (χ2= 21.7, df = 1, p= 0.000). Higher malaria cases were recorded in males (27.3% and 35.9%, respectively) than in females during the six-year period in both health facilities (Table 1). Furthermore, P. falciparum was detected in individuals of all age groups, but it was predominant in individuals between the 18-64 years age group (23.3% and 53.3% in Arebiya and Guramba Bata respectively). P.vivax was frequently recorded in children less than 5 years of age group in both study localities (Table 1).
The lowest malaria cases in Arebiya health post (10.9%; n= 31) were recorded in 2016, while the highest malaria cases (41.9%; n= 72) were encountered in 2017. Similarly, lower malaria cases (11.6%; n= 11) were detected in 2016 with highest (47.4%; n= 72) malaria cases were recorded in 2017 in Guramba Bata health centre (Figure 2).
Plasmodium falciparum was the predominant species in the study sites during the six year period (2012-2017) (Figure 3) with the highest P. falciparum malaria cases (35.8%; n= 116) recorded in 2017. P. vivax and mixed infections were recorded in relatively lower magnitude in both sites during the six-year period (Figure 3).
Prevalence of malaria parasites from blood sample examination
Out of the total 735 thick and thin blood smears taken from individuals who participated in the study, 3.5% (n= 26) were positive for malaria parasites. The results from the cross sectional survey indicate that there were no statistically significant difference in percent malaria prevalence between the two localities (χ2= 0.06, df =1, p=0.814). The prevalence of malaria infection in Guramba Bata and Arebiya study areas were 3.8% (n= 14) and 3.2% (n= 12) respectively (Table 2). Plasmodium falciparum was the predominant malaria parasite (2.3%, n= 17) in the study area, followed by P. vivax (0.7%, n=5), and mixed infections (0.5%, n= 4).
The frequency of malaria infection among the age groups was statistically significant in Arebiya study site (χ2= 8.3, df =3, p=0.040) (Table 2). Malaria was more prevalent in the age group> 15 years old at this study site (5.8%). Whereas, in Guramba Bata study site the age groups > 15 were more infected with malaria (5%) than the other, but it was not statistically significant (χ2=2.32, df =3, p= 0.509) (Table 2). Males were more infected with malaria in Arebiya (5%) and the difference in malaria case between sexes were statistically significant (χ2 = 4.3, df =1, p= 0.039) (Table 2). Similarly, in Guramba Bata study sites males were more infected with malaria (4.4%) than females, though the difference was not statistically significant (χ2= 0.31, df = 1, p= 0.579) (Table 2)
Socio-demographic data and Malaria risk factor analysis
Blood samples for microscopic examination were collected from 735 randomly selected individuals from the two study localities of which 50.3% (n= 370) were from Arebiya and 49.7% (n= 365) were from Guramba Bata. Males comprised 52% (n= 382) while females were 48% (n= 353) of individuals in the sample (Table 3). The age groups, below 15, 5-9, 10-14, and above 15 accounted for 7.3% (n= 54), 18.9% (n= 139), 17.8% (n= 131), and 55.9% (n= 411) of the study participants respectively. The majority of the study participants were farmers (86.7%; n= 637) and the rest (13.3%; n= 98) were merchants. Most of the study participants (45.9 %; n= 341) were not educated. All study participants were from rural areas (Table 3).
Bivariate and multivariate analysis indicated that risk factors such as sex, age, outdoor activity in the evening, awareness about malaria transmission, the frequency of LLIN distribution, and application of IRS were significantly associated with malaria prevalence (P<0.05). However, respondent’s occupation, educational level, the last time respondents received IRS were not significantly associated with malaria transmission (P>0.05; Table 4).
Males were 2.6 times more likely to be infected with malaria than females (AOR = 2.6, 95% CI: 1.04, 6.41) and individuals with high outdoor activity were 16.4 times more vulnerable than individuals with limited outdoor activities (AOR= 16.4, 95% CI: 1.82, 147.85). Respondents who are not aware of malaria transmission and control were highly infected with malaria than those who were aware of it (AOR=0.3, 95% CI: 0.12-0.82). The last time respondents received LLINs (before a year) was associated with a low level of malaria prevalence in the study area (Table 4).