Children are the most susceptible group of any population that can be infected by the parasites. They could also be asymptomatic carriers which may pose heightened danger and constitute particularly public health problems [15].
The prevalence of pinworm infection was 27.13% (137) among 505 children using the cellophane tape method. Our result was consistent with the prevalence of 29.8% in Erbil City recorded by [16] among primary school children and with the 29.4% prevalence rate reported by [17] in Turkey (Antakya) among children.
The prevalence observed in this study was lower than the 52.3% recorded by [18] among 2 to 12-years-old children in Baghdad and 86% in Turkey (Ankara) among 6 to 12-years-old children [19]. However, the result of this study was higher than the prevalence of 6.2% in Sri Lanka (Hambanatona district) [20], 7.1% in Iran (Mazandaran) [21], and 0.6% in Birbir town, southern Ethiopia [22].
The difference in the prevalence of E. vermicularis infection in different areas is often believed to be related to the age of children, behavioural patterns and area of the bedroom [23]. Personal hygiene, educational level among children, overcrowding, socioeconomic condition, and climate could be related to pinworm infection [24].
The relationship between the prevalence of E. vermicularis and sex in the current study showed that the risk of E. vermicularis infection was higher but not significant among female children using the adhesive tape method. These data support the findings other studies that have reported a higher prevalence of this helminth among female children: [15] in Mosul City and [25] in the Al- Mahmoudyia area in Baghdad, while in contrast to the present study, other studies reported a higher prevalence among male children [26] in Basrah and [27] in Egypt (Damietta governorate).
Although the infection rate among age groups in both infected and non-infected groups did not differ significantly, the highest rate was 27.42% in the younger age group (3–6 years old). This finding was supported by the reports of other studies done by [28] in Babylon Governorate and [29] in China (Guangdong). This finding was in contrast with those obtained by [30] in Sulaymaniy Governorate and [31] in Northern Thailand.
This difference in the rate of infection among age groups may be because the awareness of attention to personal hygiene is much lower among the small children in comparison to older children, as they spend more time outside the house. Therefore, they have more chances to play with dirt and have a greater frequency of physical contact with their friends than do younger children; thus, they have a higher risk of acquiring pinworm infection [3]. Additionally, the anal scratching habit (by the way hand-mouth transmission) is more frequent among small children, facilitating the autoinfection mode of transmission.
In relation to family size, the infection rate among children belonging to large families (12 persons) was 83.3%, i.e., higher than those found in smaller families. This result is in agreement with that found by [32] in Misan [33] in the Philippines (Albay), who reported that the rate of enterobiasis among children who belong to large families was higher than that of smaller families, so the infection among children increases with increasing family size.
Although enterobiasis is transmitted from one person to another directly and does not require any intermediate host, it is more likely to spread among members of the same family, especially overcrowded families. In addition, clinically mild cases and asymptomatic infected individuals may provide a hidden reservoir of infection in the family population [34]. Moreover, by increasing the number of family members, the possibility of bringing the infection from outside to inside of the home increases.
Immunoglobulin E has an important role in immune defence against most parasitic worms [35], and many researchers have observed a high level of IgE in parasitic infections [8, 36]. The present study found that patients infected with E. vermicularis had no significantly higher levels of serum total IgE in comparison with the enterobiasis-negative group. The serum total IgE level in the present study was in agreement with that recorded by [37] in Egypt and [36] in Turkey.
On the other hand, the mean serum vitamin B12 and folate levels in the enterobiasis-positive group were not significantly lower than those in the enterobiasis-negative group. These results were in accordance with those recorded by [14] in Spain and [38] in Iran (Kashan). The deficiency of vitamin B12 and folate are related to anaemia and cell divisions. Additionally, vitamin B12 is involved in the synthesis of DNA [6]. Several parasites inhabit the intestine and cause damage to the intestinal epithelium. Therefore, these parasites may lead to malabsorption and cause vitamin B12 and folate deficiency [39].
Intestinal parasites use food sources of the host, such as carbohydrates, minerals, vitamins and lipids, as essential energy sources for their life cycle. Minerals play an important role in the biochemical and physiological processes of the human body, particularly in growing children. Many studies have recorded that minerals such as magnesium, iron, copper, and zinc have a vital role in the growth and development of children [40, 41].
The mean serum phosphorus level in the enterobiasis-positive group was not significantly higher than that of the enterobiasis-negative group, and the serum phosphorus level in the present study was similar to that recorded by [42] in northern India.
The mean serum total protein and serum iron levels in the enterobiasis-positive group were significantly lower than those in the enterobiasis-negative group. This result is similar to that recorded by other investigators [43, 44]. Although the mean value of serum magnesium level decreased in the enterobiasis-positive group, statistically there was no significant difference between the enterobiasis-positive and enterobiasis-negative groups, which coincides with results found by [45] in Iran. Generally, the decrease in serum trace element levels is probably due to the loss of appetite that can be caused by pinworm infection.
