This study was conducted to identify the prevalence of different parasite species and the related factors among the most vulnerable group in the community; school children. This will aid to identify the hot infection areas and proper application of control measures.
There were 239 school children have positive results for parasitic stool analysis representing an overall prevalence of 32.9%. Of those infected children, there were 143 (19.7%) mono-infected children, 71 (9.8%) double infected, and 25 (2.3%) triple infected. This indicates parasitic infections still represent a public health problem among school children who are forming a considerable proportion of the population. This can be attributed to the unsanitary environmental conditions and low level of public awareness . Egyptian studies conducted on school children revealed marked variability regarding the prevalence of IPIs with an infection range from 22.4 to 63.8% [15, 20,21,22,23,24,25,26,27,28,29,30,31].
The most prevalent parasitic species were E. histolytica (12.3%) and G. lamblia (8.5%). E. histolytica infection is strongly associated with drinking water sources contamination, poor personal hygiene, and lack of regular handwash habits . Also, G. lamblia was associated with open field defecation, poor hand washing, raw vegetables, and unwashed fruit consumption . This finding agreed with the findings of some Egyptian studies [20, 21, 24, 30] where E. histolytica was the most prevalent parasitic species with variable prevalence rates. However, other studies have shown variability regarding the most prevalent parasite where it was G. lambilia [15, 29], A. lumbricoides , and E.vermicularis [22, 26]. This variability regarding the overall prevalence of IPIs, type of infection, and parasite species can be attributed to different research settings and different characteristics of participants regarding socio-demographic, behavioral, and environmental characteristics. Also, the availability and quality of health services is an additional factor. Moreover, the different laboratory techniques used for parasitological diagnosis may have a role in this variable prevalence.
Also, variable findings were observed between studies conducted in Saudi Arabia [33,34,35] with prevalence rates 17.7%, 57.4%, and 5.3%, respectively. However, the most recent and powerful study  revealed a marked reduction in the prevalence of intestinal parasitic infection (5.3%) indicating improvement in the socio-economic and environmental conditions, personal hygiene and awareness, and the provided health services.
Similarly, much more variability was observed between Ethiopian studies [19, 32, 36,37,38,39] with prevalence rates ranging from 21.5 to 84.3%. Also, a systematic review and meta-analysis study  was conducted to identify the epidemiology of intestinal parasitic infection among preschool and school-aged children which included 83 studies from 1997 to 2019 and examined 56,786 stool specimens. It revealed that the prevalence of parasitic infection was 48% (95% CI: 42–53%) and the infection trend decreased by 17% (95% CI: 2.5–32%) every 6 consecutive years. This high prevalence of parasitic infection indicates bad environmental sanitary conditions and a low level of personal hygiene and awareness.
There were significant differences between infected and non-infected children regarding age, educational stage, residence, monthly family income, and mother’s educational level. Despite male students constitute most of the infected children (53.0%). However, there is no significant gender difference regarding IPIs (P=0.5). There were variable findings between Egyptian studies regarding gender differences where some studies [22, 23, 27, 28, 31] revealed similar findings with insignificant gender differences while other studies [21, 25, 29, 30] revealed significant gender differences. However, despite this variability, all of these studies except one  revealed a higher prevalence of IPIs among male students. This can be explained by their marked outdoor activity with more exposure to infectious pathogens. Also, insignificant gender differences were observed in studies conducted in Saudi Arabia [33,34,35] and in some Ethiopian studies [19, 36, 39].
Also, there is a highly significant difference between infected and non-infected children regarding their age. Children of the age group between 6 and 10 years have the highest prevalence of IPIs (46.6%) whereas other age groups (11–14 and 15–18 years) have lower prevalence (36.4% and 18.0%, respectively). This may be due to risky behavioral activities, little hygiene, and awareness of small age students about prevention and control measures in comparison with bigger age groups . Similar findings were observed in other Egyptian [20, 21, 25] and Ethiopian studies [38, 39]. Also, primary school children have a higher prevalence of IPIs (55.7%) than preparatory and secondary school children (28% and 16.3%, respectively) with highly significant differences. This finding agreed with the finding of Workneh et al.  and Dessie et al.  where there were significant associations between the grade level of children and IPIs with a higher probability of infection among low-grade children. They attributed this association to behavioral factors and little children’s understanding of disease processes. Also, lower grade students have less developed immunity towards parasitic infection. However, the effect of age as an additional and confounding variable cannot be excluded.
There is a highly significant difference between infected and non-infected children regarding residence where most of the infected children were rural residents (61.1%). Similar findings were observed in other Egyptian studies [15, 23, 31]. Rural children mostly have risky behavior such as walking poor footed, water and domestic animal contact, poor fingernails and hand hygiene, and defecation in the open agricultural field which consequently leads to more soil contamination with parasites .
Also, a highly significant difference was found between infected and non-infected children regarding family income where most of the infected children were belonging to families with a monthly income of fewer than 4000 L. E (73.7%). Low-income families mostly have poor housing conditions with overcrowded and unsanitary housing conditions, malnourished children, and less educated parents and consequently have less personal hygiene and little awareness of parasites prevention and control measures. A similar finding was found by Hailegebriel  where the probability of parasitic infection among low-income family children was six and half times children from high-income families. However, insignificant findings were observed in similar studies [35, 36]. This may be due to statistical reasons such as a small sample size or a little number of infected children which was insufficient to give statistically significant findings .
Concerning parental education, there is a significant difference in IPIs of children regarding mothers’ education only (P=0.02). This indicates that mothers are more influential in preventing parasitic infections among their children. This is due to a longer time of contact with their children contrary to fathers who spend most of their time outside doors. The educated mother has more awareness about parasitic infection prevention and control and their impact on their children and consequently more able to protect their children. A significant effect of the mother’s education was observed in similar studies [21, 25, 41]. However, some studies [20, 33] revealed significant differences between infected and non-infected children regarding both fathers’ and mothers’ educations while other studies [35, 37] have found no significant differences.
Regarding the behavioral and environmental factors, there were highly significant differences between infected and non-infected children regarding these factors with a considerable proportion of children having an unsanitary environment, little fingers hygiene, poor hand washing practice, and risky health behavior. These findings explain the high prevalence of parasitic infection among studied children which indicates improper implementation of prevention and control measures that are effective in reducing the IPIs such as the provision of safe drinking water, proper sewage and refuse disposal, improvement of personal hygiene and environmental sanitation, increased public health awareness, and community involvement activities .
There were highly significant differences between infected and non-infected children regarding the GIT disorder with much more prevalence among infected children and highly significant differences (p <0.00001). These findings agreed with findings of similar studies [19, 23, 28, 30]. However, the presence of GIT symptoms can be helpful for the early detection of parasitic infections.
The following limitations may be considered when interpreting the study findings: (i) the study was conducted in a single locality (Aga district) in Dakahlia governorate. So, the generalization of the findings to other localities of the governorate or overall Egypt must be taken with caution. However, to increase the power of the study and its repetitiveness we increase the sample size by approximately 100% of the calculated sample. Also, being a cross-sectional study conducted at one point of time, seasonal variation in the children’s IPIs cannot be detected. (ii) Diagnosis of children’s IPIs was carried out by taking a single stool sample from each child. However, stool samples were checked by an associate professor in the field of medical parasitology (second author) to minimize the possibility of misdiagnosis. (iii) Antigen test to differentiate between E. histolytica and E. dispar was not carried out.