The study results indicated, of the total 260 study participants, 107 (41.1%) of the symptomatic children were infected with one or more intestinal parasites. It is comparable with study done by Unasho in southern Ethiopia, where 170 (41.9%) children were found to have single and double intestinal parasitic infections , but higher than study conducted in Gondar where the observed prevalence of intestinal parasites was 34.2%  and the study conducted in Gamo area where 342 (39.9%) study subjects were found positive for at least one intestinal parasite . Our study prevalence result was lower compared with reports of other similar studies, 72.9% in Gondar, Azezo , 83% in Jimma  and 83.8% in South East of Lake Langano . These variations in prevalence might be due to differences in climatic conditions, environmental sanitation, economic and educational status of parents and study subjects, and previous control efforts. The low prevalence of intestinal parasite in this study compared to the other previous studies in Jimma (5) and elsewhere in the country (7) could be due to increased awareness of the community about personal and environmental hygiene from the continuous awareness creation and interventions made by the health science students from Jimma University during their practical training conducted in the field as well as in different health institutions.
Among helminthiasis, Ascaris lumbricoid (11.5%) was the most prevalent parasite and followed by H. nana and T.trichiura, whereas giardiasis was the leading infection among protozoan infections. Though the rate of prevalence is different the dominancy of A. lumbricoides is in line with the study result by Abayne in south Ethiopia  and with previous studies done in Assedabo (Jimma, Ethiopia), where Ascaris lumbricoides was the leading (56.4%) . But different with study conducted in Gondar  where the dominant parasite was H. nana. The difference could be mainly difference in climatic condition.
Many studies had already demonstrated the high prevalence of parasitic infections among Ethiopian children in various parts of the country [5, 27–29]. In this study, A. lumbricoides (3.5%) and T. trichiura (3.1%) were found to be the dominant soil transmitted helminthes. Studies done by Ali et al. (1999) and Roma and Solomon (1997) reported higher rates of A. lumbricoides (54.6% vs. 75.2%) and T. trichiura (21% vs. 24.4%) respectively [5, 29]. Our study data showed comparable prevalence rate with reported by Tadesse (2005) where the prevalence rate of A. lumbricoides and T. trichiura were 3.6% and 3.9%, respectively . A prevalence rate of 3% for H. nana is higher than earlier findings, which were 1.1% in Wondogenet, Ethiopia , 1.3% in south Wollo  and lower than with the findings of Tadesse, (2005) and Haileamlak (2005) with frequency rate of 10.1% and 4.3% respectively [27, 30].
Except in the early stage/age (where mostly rely on breast feeding), parasitic infections were decreasing as the age of the children increases, which could be due to acquired immunity as they are exposed more and more to infections as well as developing awarness to personal hygiene. In this study multiple parasitic infections were seen in 19 children (7.3%) from the total 260 study subjects and 17.8% among children who were infected with parasites and this result is higher than the study conducted in Gondar, where multiple infections (polyparasitism) occurred in 14 individuals or 4.6% of the total examined subjects and 13.5% of those who had intestinal parasites . The difference could be due to geographical location or variation in study subject sample size.
Comparison with previous study results conducted in different parts of Ethiopia is difficult since the parasite prevalence varies with agro-ecozone, altitude and other environmental factors which are not studied here. Shigellosis is primary a pediatric disease, with more than half of all infections occurring in children between six month to 10 years of age as observed in previous Ethiopian study . The isolation of Shigella species (2.3%) in this study is lower than (5%) reported by Mache, 2001  (20.1%) from the same study subjects and area.
Even though, the study was conducted in different age groups, our prevalence rate of 2.3% lowers than that a report by Ashenafi, 1983 (9%)  and 11.7% isolation rate reported by Asrat et al. 1999 at Tikur Anbessa, Ethio-Swedish children’s hospital , a report by Ayalu (6.7%) in Harar  and a report 15.6% by Hiruy in Gondar . The low isolation of Shigella in this study compared to the previous study in Jimma (14) could be due to increased awareness of the community about personal and environmental hygiene from the continuous interventions made by the health science students form Jimma University during their filed practice.
Epidemiological investigation of salmonellosis in developing countries like Ethiopia is difficult because of the very limited scope of the studies and lack of coordinated surveillance systems. The overall prevalence of Salmonella in this study was 6.2%. This is comparable with studies conducted in Ethiopia at different times, 4.5% in Addis Ababa , 6.4% in Addis Ababa , 4.5% in Addis Ababa  and higher than the findings reported by Asrat et al. 1999 (3.8%) in Addis Ababa  but lower than reported in Jimma (15%) . Antibiotic susceptibility data to Shigella isolates showed that all isolates were resistance to ampicillin, amoxacillin, and cotrimoxazole. Similarly a study conducted in Awassa showed that all isolates were resistant to amoxacillin and ampicillin (12). The development of high resistance of Shigella species against the commonly used antibiotics was witnessed by other investigators in different periods. In Hawassa high rate of resistance of Shigella species to ampicillin (93%), erythromycin (90%), tetracycline (90%) and cotrimoxazole (56%) was reported by Roma et al, in Gondar, high antibiotic resistance was documented against ampicillin (79.9%), tetracycline (86%), and cotrimoxazole (73.4%) by Yismaw et al.. Asrat reported isolation of Shigella species with high resistance to erythromycin (100%), Tetracycline (97.3%), and ampicillin (78.7%) in Addis Ababa . High resistance against amoxicillin (100%) and ampicillin (100%) was also reported by Reda et al. in Harar . Our Shigella isolates were highly susceptible to ceftriaxone, ciprofloxacin and gentamicin. Comparatively high rate of resistance to ciprofloxacin (8.3%) was reported in Gondar. In parallel to our result lower (2%) resistance rate was reported from Gondar . Comparable to the study conducted by Daniel  in Addis Ababa where all Shigella isolates were susceptible to gentamicin. The low resistant rate of isolates to chloramphenicol (18.8%), could be that physicians stopped to prescribe the drug before long time a go and once again the strains started to become sensitive. All Shigella isolates were MDR (resistant to two or more drugs). Similar findings were seen in other studies in Ethiopia [12, 38].
Infection with non-typhoidal Salmonella in infants and children commonly produces self-limited diarrhoea. Studies have indicated that antimicrobial treatment for uncomplicated gastroenteritis does not shorten the duration and severity of symptoms; in contrast, it may prolong fecal excretion, increase the risk of relapse, and result in the emergence of antibiotic resistance . Nevertheless, if extra-intestinal complications occur, effective antimicrobial treatment is essential. Multidrug resistant phenotypes have been increasingly described among Salmonella species worldwide, according to the infectious disease report released by the WHO in 2000 .
In this study, Salmonella isolates showed high re resistant to ampicillin and amoxicillin which is comparable with previous study done in Harar, Ethiopia where the highest level of resistance was detected to ampicillin (100%) and amoxicillin (100%) . a relatively similar pattern of resistance (74 to 97.3%) was reported from other parts of the country  and outside . Our study findings showed that all Salmonella species were susceptible to ceftriaxone and ciprofloxacin, which is inline with recently study results conducted in Nigeria where all isolates were susceptible to ciprofloxacin, and ceftriaxone . Un like most previous study findings, in this study Shigella and Salmonella species showed low resistance level to chloramphenicol, this could be due abandoning of prescribing the drug by the responsible health personnel before a long time ago.