It has been estimated that more than 230 million (43%) of all preschool children in the developing world are stunted in their growth because of malnutrition caused by lack of food and by disease including parasitic infection [23
]. In this study, despite the occurrence of a very high prevalence rate of intestinal parasitic infection among the school children, younger children with lower body weight and lower height were more infected with intestinal parasites than children with higher anthropometric parameters (P
0.05). Reports have indicated that because parasitic infections such as soil transmitted helminthic infections cause anorexia and poor absorption of nutrients and promote the deviation of nutrients to the organism’s defense mechanisms; thereby contributing to the onset or exacerbation of weight and height deficits, as well as to specific nutritional deficiencies [24
]. A number of earlier studies have shown that in the acute phase, these helminthic infections induce an immune response and the production of cytokines [25
], which can directly affect the process of bone formation and remodeling required for the growth of long bones [27
Intestinal parasites are highly prevalent among schoolchildren (55.6%-72.9%) in Northwest Ethiopia [28
]. The present study however showed a relatively low prevalence of parasitosis (22.7%) comparable to the report from the study conducted in Babile town, eastern Ethiopia [30
]. The difference could be due to variability in the prevalence of these infections, low sensitivity of the diagnostic method, the use of single stool sample and environmental contamination could partly explain the observed difference.
Although the prevalence rates of individual parasites vary considerably with altitude in different parts of the country, A. lumbricoides
, H. nana
and Hook worm were found to be the most prevalent parasites in this study. This finding was in agreement with reports of previous studies conducted in Ethiopia [30
]; however, the prevalence of H. nana
was higher than that of the study in Mexico and Pakistan [33
]. The high rate of H. nana
observed in this study indicates that hygienic practices of the schoolchildren in the study area are poor and that it is an important factor for auto-infection and transmission to others [35
]. Unlike geo-helminths, H. nana
does not require the external environment for maturation of eggs, which means the lifecycle of this parasite cannot be affected. The high prevalence might therefore be due to its high transmission.
Several studies have documented a positive association between BMI and allergy. Positive association between overweight and asthma was reported in black and Hispanic children [36
]. In addition, in Taiwanese girls, a positive association was reported between the highest BMI quartile and risk for asthma symptoms, atopy and rhinitis [37
]. Another study reported that a baseline BMI greater than 30 kg/m2
was a significant predictor of asthma incidence in women [38
]. In the present study we evaluated several categorical (weight-for-age, height-for-age, BMI-for-age) and continuous (weight, height) anthropometric values, but only low height-for-age were related with allergy in boys. The present findings seem to be consistent with other research which found children with food allergies had weight-for-age and height-for-age Z scores lower than controls (0.1 versus 0.6 and 0.2 versus 0.8, respectively) [39
Moreover, boys with allergy were younger than boys without allergy while girls with allergy were relatively older than girls without allergy. It is difficult to explain this result; hence, further research is needed to identify factors that contribute to such differences of this condition and to assess whether a similar pattern is also observed elsewhere.
In the present study, we evaluated total IgE responses, which are important components of host defense mechanisms against helminthic parasites in children and with differing degrees of malnutrition. In this study, high level of total IgE was observed; however, IgE concentration was not associated either with the presence of parasitic infection or history of allergy. The results are consistent with previous studies in Israeli-Ethiopian children and Vietnamese school children which found no significant difference in mean serum IgE between the stool parasite-positive group and the parasite-negative school children [40
]. This also accords with our earlier observations, which showed that elevated IgE levels in diarrheic patients irrespective of HIV and/or intestinal parasitic infection [42
A possible explanation for the high level of IgE observed irrespective of parasitic infection and history of allergy might be as is well established, malnutrition affects the immune response and increases the susceptibility to parasitic infection. On this regard, studies suggested that malnutrition and infectious agents that are frequent in malnourished children potentiates the polyclonal stimulation of IgE synthesis induced by helminths. As specific IgE antibody has been implicated in the resistance to helminthic infection, and the polyclonal stimulus diminishes this response, these factors may increase the susceptibility of malnourished children to such parasites [43
]. Another possible contributing factor is a race-associated genetic mechanism; it was previously shown that IgE levels are higher in blacks than in Caucasians [45
]. The effect of anti-helmintic treatment on the total serum IgE and specific IgE antibody response need to be elucidated in children with different nutritional status.
Undernutrition continues to be a cause of ill health and premature mortality among children in developing countries including Ethiopia [46
]. This problem is not only associated with serious long-term consequences for the child but also adversely related to the economic development of a nation [47
]. In the present study, the overall prevalence of underweight, stunting and thinness/wasting was 15.1%, 25.2% and 8.9% respectively. These prevalence rates of malnutrition indicated that the school children of this study area were in a better condition compared to malnutrition reported by a number of other studies [29
Although the prevalence rates of malnutrition computed from the anthropometric measurements of the study children were not very severe compared to the national figure in 2005 which showed that underweight, wasted and stunted were 35.7, 9.7 and 51.3%, respectively [48
], the prevalence of malnutrition remain substantial, demanding the attention of the responsible bodies.
The relationship of malnutrition and intestinal parasitic infection has been well established [9
]. Different reports showed a close association between intestinal parasitism and malnutrition [53
] which was not the case with this study.
A possible explanation for this might be that both malnutrition and parasitic infections exist to a level of public health significance in the area, probably interacting synergistically and with other socio-economic and dietary factors [56
This study has some limitations. First, the study was carried out in only urban schools of Northwest Ethiopia, and thus further investigation in suburban and rural areas is still needed. Second, the definition of allergy, which relies on self-reported physician diagnosed allergy. Third, there was no detailed information on socioeconomic status and non-availability of data on dietary intake. However, to our knowledge this article is the first of its type to look the relationship between allergy and nutritional status and, intestinal infection among school children in Ethiopia.