Although it is neglected disease in the developed world, GIH/STH infections are still remaining the major public health problem in developing countries, particularly in the tropics where appropriate parasitic growth factors exist. As a result, epidemiological study on the prevalence of GIH/STH infection in different region of the developing world is a primary objective to identify high-risk communities and formulate appropriate intervention [5, 8-10, 16-19]. In line with this view, the present study attempted to assess the prevalence of different GIH infections in primary school children in Dembi district (southwest Ethiopia).
In the current study, 30.9% overall prevalence of GIH which have public health importance were identified. Except 7.8% school children specimen samples showed double infection, most (92.2%) of the positive samples were identified single infection type. This was comparable with finding from elsewhere in Ethiopia and the world [13, 19-22]. For instance, the helminthic infection prevalence of 27.2% in Al-Ahsa (Saud Arabia), 31.8% in western city (Turkey), 34.0% in Kisumu city (Kenya), 35.6% in Hintallo-Wejerat (Ethiopia) and 36.5% Kathmandu valley (Nepal) reports were found to be almost in agreement with the current study (Table 4). However, the current study result has been found much higher (4.5 22.8%) than a report from Gondar  and Ambo  towns in Ethiopia and elsewhere in the world including Taiwan , Kenya , China  and Marshall Islands  (Table 4). Still, the present study prevalence was identified lower than study result from Tilili town (44.2%), Wolaita zone (72.2%), Azezo town (72.9%) and Chencha town (81.0%) in Ethiopia (Table 4). Comparatively, higher helminthic prevalence were also reported in Saud Arabia (45.4%) El Salvador (53.0%), Tanzania (57.1%), India (75.6%), China (86.0%), Nigeria (86.2%) and Malaysia (88.2%) (Table 4). The possible explanations for the discrepancy between the present and previous study findings might be the result of variation in the geographic location, socio-economy of the subjects, selection of study participants, sample size, method of parasitological examination, time of the study, access to health care facilities and awareness. Indeed, the comparative result shown in Table 4 is from different geographic locations (Africa, Asia, Middle East, Latin America and Europe) and participants from different population group (pre-/school children, rural community, patients from medical centers and hospitals). The number of participants (sample size) were also varies higher (n=6976) from northern Samar in Philippines  and lower (n=69) from Yunnan in southwest China .
In this study, a total of six intestinal parasitic worm was detected which could be comparable with study in Nepal  that was identified six parasitic worms. As shown in Table 4, our finding was also comparable to studies in Ethiopia (five parasites in Ambo town and seven parasites in Wolaita zone and Chencha) and elsewhere in the world (five parasites in Kisumu city, western Kenya and seven parasites in El Salvador). Relatively, small number (three) of parasitic worm infection (Table 4) was reported in Guizhou (southwest China), Peninsular Malaysia and Uttar Pradesh (India). In school children, four intestinal parasitic worms (Table 4) were also reported in Nairobi city (Kenya), Western city (Turkey), Tilili town (Ethiopia) and Yunnan (southwest China). Studies conducted in Saud Arabia  and Taiwan  were also reported 20 and 13 intestinal parasitic worm species using hospital patient, respectively which was higher than maximum number of parasitic species reported in school children (nine) in Gondar town (north Ethiopia)  and Majuro city (Marshall Islands) .
The majority of infections in the current and previous studies were single infection types (Table 4). In this study, single infection and double infections were accounted 96.7% and 2.4%, respectively. Compared to the current study, double infections were significantly higher in school children reported in Chencha town (26.5%) and Azezo town (47.3%) in Ethiopia, Makoko urban slum (45.7) and southwest (39.2%) in Nigeria, Nairobi city (33.3%) in Kenya, Majuro city (22.4%) in Marshall Islands and Yunnan (52.0%) in China. Compared to studies carried out with hospital and community participants, double infection has been found higher in most school age children studies (Table 4). This difference might be due to study population, environmental factors, investigation time and diagnosis method. It is obvious that the target population for the community and hospitals participants were at any age group and educational level, which was not true for school age children that have narrow age range and educational level.
In this study, STHs such as A. lumbricoides and hookworm infections were found the major public health problem. The prevalence of A. lumbricoides among school children in the current study area was found to be 43.3%. This prevalence of A. lumbricoides was higher than the national prevalence estimate (37%) in Ethiopia  and reports from other parts of the country such as 7.5% in northwest  and 28.9% south Gondar , 23.6% in Jimma , and 37.2% in Bushulo village . Lower prevalence value of A. lumbricoides also reported in Kenya  and Malaysia  with a prevalence of 4.9% and 23.8%, respectively. However, the current study A. lumbricoides prevalence result was much lower than a report from Wondogent (83.3%)  and Chencha town (60.5%)  in Ethiopia, Nigeria (57.2%)  and Nepal (57.9%) . There are several studies that mentioned STHs vary among localities due to variations in geographic location, socio-economic conditions and hygienic condition of the population under consideration. Of course, the higher prevalence of A. lumbricoides in the current study than the national estimates and elsewhere could be due to lack of drinking water source and latrine usage, which has been found significantly (Table 3) associated with STH infection in the current study area. Compared with sources of drinking water, students using stream water for drinking and food preparation have found a statistical significant difference for STHs than students using pipe water for similar purpose. This supports that the transmission of A. lumbricoides infection which is contracted through ingesting embryonic egg through water and food . In terms of gender, male students were identified more prevalent for A. lumbricoides than female students, which could be due to boys playing on soil and prefer to eat their food without proper hand washing (Table 2). Moreover, lower age (5 8 years) groups were found more prevalent to for A. lumbricoides than higher age groups (Table 2), which agrees with other studies that said lower age groups are more affected than higher age groups [16, 32]. As reported in other studies [1, 16], latrine usage has been found a significant risk factor for STH including A. lumbricoides (Table 3).
The prevalence of hookworm infection among primary school children of Dembi district was identified 26.7%, which is higher than the national hookworm infection prevalence (16.0%) in Ethiopia . The prevalence of this helminthic infection was also higher than a report from different areas of Ethiopia and other countries including 4.9% in Gamo area, south Ethiopia  and 12.9% in south Gonder , 6.1% in Kenya  and 17.8% in Nigeria . Infection by hookworm was much lower when compared to a report from southeastern Ethiopia  and Philippines  which revealed 60.5% and 28.4%, respectively. In fact, hookworm disease caused by two worm species (Ancylostoma duodenale and Necator americanus) has been reported one of the most common infections in SSA which affects around 198 million people in the region [4, 6]. It causes iron deficient anemia and protein malnutrition . Compared to age groups, hookworm infection has been found highest for older age groups (>12 years) than lower age groups (Table 2), which agrees with other studies [6, 26, 31]. For instance, Hotez and Kamath  mentioned that hookworm infection has steadily raised in the intensity during late childhood with either a peak or a plateau in adulthood.
The overall prevalence of T. trichiura, Teania species (6.7%), S.stercoralis (3.3%) and H.nana (3.3%) were found to be relatively very low. Interestingly, T. trichiura which is estimated 24% among STHs infection prevalence in Ethiopia from SSA prevalence proportion [4, 6], is found to be much lower (8.9%) among school children in Dembi district. This prevalence has also been lower than the previous school (23.1%) and community (57%) based study in Jimma/Ethiopia  and Peninsular Malaysia , respectively suggesting that relatively better toilet facilities, good hand washing habit and better awareness about health in the current study area.