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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 31  |  Issue : 3  |  Page : 963-969

Seroprevalence of Helicobacter pylori infection among school children in Al Qulubia governorate


1 Department of Pediatric, Faculty of Medicine, Menoufia University, Shebin El-Kom, Egypt
2 Department of Clinical Pathology, Faculty of Medicine, Menoufia University, Shebin El-Kom, Egypt
3 Department of Pediatric, Benha Hospital for Pediatric, Benha, Egypt

Date of Submission16-Oct-2016
Date of Acceptance07-Jan-2017
Date of Web Publication31-Dec-2018

Correspondence Address:
Marwa M Hessen
6, El Masaey Street, Quesna, Menoufia
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/mmj.mmj_548_16

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  Abstract 


Objective
The aim of this study was to determine the seroprevalence of Helicobacter pylori infection among apparently healthy Egyptian school children.
Background
H. pylori infection has a widespread distribution, but the prevalence varies between developed and developing countries.
Patients and methods
A series of 400 apparently healthy children attending basic schools were included in our study. Serum samples were withdrawn and assayed for the presence of anti-H. pylori antibody (immunoglobulin G) measured by the enzyme-linked immunosorbent assay test, and studied for the effect of age, sex, and socioeconomic background. The children's ages ranged from 6 to 13 years. All infected patients were treated successfully.
Results
The overall H. pylori seroprevalence in the study was 44% (176/400), and the frequency of seropositive cases increased highly significantly with advance in age. In a trial to study the risk factors for acquisition of H. pylori infection in our cases, we found a highly significant difference between seropositive and seronegative cases regarding socioeconomic status, family income, educational status of the parents, and occupational status of the parents (P = 0.001). On the other hand, we found no significant differences between seropositive and seronegative cases regarding sex and water supply (P = 0.304).
Conclusion
H. pylori is acquired in early childhood and the prevalence increases with age. The prevalence of H. pylori infection in Qulubia, Egypt, was substantially higher compared with developed countries and more or less within the range detected in developing countries, especially in African countries.

Keywords: children, Helicobacter pylori, seroprevalence


How to cite this article:
Deeb MM, Bahbah WA, Abou-Elela DH, Hessen MM. Seroprevalence of Helicobacter pylori infection among school children in Al Qulubia governorate. Menoufia Med J 2018;31:963-9

How to cite this URL:
Deeb MM, Bahbah WA, Abou-Elela DH, Hessen MM. Seroprevalence of Helicobacter pylori infection among school children in Al Qulubia governorate. Menoufia Med J [serial online] 2018 [cited 2019 Jun 16];31:963-9. Available from: http://www.mmj.eg.net/text.asp?2018/31/3/963/248750




  Introduction Top


Helicobacter pylori has been shown to infect more than 50% of the world's population, with an incidence up to 80% in developing countries[1].

H. pylori is a spiral-shaped, microaerophilic gram-negative bacterium biochemically characterized as catalase, oxidase, and urease positive[2].

The risk for infection acquisition is related to low socioeconomic status and poor living conditions early in life, such as density of housing, overcrowding, number of siblings, sharing a bed, and lack of running water. Childhood hygienic practices and level of education in the family are important risk factors[3].

The infection is acquired mainly in early life through fecal–oral or oral–oral route, and in the absence of antibiotic therapy it generally persists for life[4].

H. pylori infection causes chronic gastritis, which is considered a risk factor for the development of gastric and duodenal ulcer and the two gastric malignancies, mucosa-associated lymphoid tissue lymphoma and gastric adenocarcinoma[5].

The value of using immunoglobulin A (IgA) or IgM for H. pylori detection is controversial. However, neither was found to be an effective indicator in pediatric pylori infection. In addition, to study the effect of H. pylori on growth of the studied cases, only enzyme-linked immunosorbent assay (ELISA) based on IgG is recommended for children[6].

Several treatment regimens have been evaluated to be successful in H. pylori eradication. They are classified into first, second, and third lines of therapy[7].


  Patients and Methods Top


Patients

The study was approved by the ethical Committee of the hospital and the patient gave an informed consent. A series of 400 apparently healthy children from 400 different families – 218 boys, 182 girls – born and living in Qulubia Governorate and attending basic schools in Benha and the villages around it were included in this study conducted from July 2015 to August 2016. All approached patients agreed to participate in this study, and an informed consent was obtained from them. Children were selected in a random way and considered legible for entry into the study if they met the following criteria: age between 6 and 13 years, born and living in Qulubia Governorate, apparently healthy with no history of gastrointestinal tract troubles, not under specific treatment or had not been given antibiotics in the last month, and clinically free by general and local examination. Nonresponder cases; cases suffering from gastrointestinal tract, cardiac, chest, neurological, renal, hematological troubles by history, general, and local examination of all systems; those who were considered illegible for entry into the study, and cases who did not fulfill the previous inclusion criteria were excluded from the study. A letter explaining the purpose of the study was sent to the parents of each school child selected for the study; the letter included an appointment for the interview with parents 2 days later at school to complete the history sheet as regards name, age, sex, residence, the socioeconomic status including housing, slum, public housing, urban housing, the number of rooms, number of family members, and bed sharing to have an idea about the family crowding as a risk factor for H. pylori infection, also water supply, family income, educational status of parents, occupational status of parents. The protocol was approved by the school of Health Affairs in Qulubia Governorate.

Methods

Sample collection

Four hundred blood samples were obtained from legible cases and serum collected was assayed for anti-H. pylori IgG antibodies measured by an ELISA test, using the commercially available Biotest anti-H. pylori IgG ELISA (Euro Diagnostic Company, Malmo, Sweden).

Test explanation (immunoglobulin G)

Principle of assay

ELISA relies on the ability of antigens to adsorb to plastic surfaces such as polystyrene (solid phase). When antigens bound to the solid phase are brought into contact with the patient's serum, antigen-specific antibody, if present, will bind to the antigen on the solid phase forming antigen–antibody complex. Excess antibody is removed by washing. This is followed by addition of goat antihuman IgG conjugated with horseradish peroxidase (HRP), which then binds to the antigen–antibody complexes. The excess conjugate is removed by washing, followed by addition of chromogenic/substrate, tetramethylbenzidine (TMB). If specific antibody to the antigen is present in the patient's serum, a blue color develops. When the enzymatic reaction is stopped with one-normal sulfuric acid (1 N H2 SO4), the contents of wells turn yellow.

Assay procedure

Reagent preparation: All reagents (including unsealed microstrips) should be allowed to reach room temperature (18–25°C) before use. All regents should be mixed by gentle inversion or overtaxing before use. Foam formation should be avoided. It is recommended to spin down shortly the vials with calibrators on low-speed centrifuge. Prepare washing solution from the 26× concentrate BUF WASH by 26 dilutions in distilled water.

Procedural note: It is recommended that pipetting of all calibrators and samples should be completed within 3 min. Put the desired number of microstrips into the frame; allocate four wells for control samples, control− and control+ (three and one wells, respectively), and two wells for each unknown sample. Do not remove the adhesive sealing tape from unused strips. Pipet 90 μl of EIA sample buffer into each well. Pipet 10 μl of control samples, control− and control+, and unknown samples into the wells by using the plate adhesive tape (included into the kit). Incubate 30 min at 37°C. Prepare washing solution by 26× dilution of washing solution concentrate BUF WASH 26× with distilled water. Minimal quantity of washing solution should be 250 μl/well. Wash the strips three times. Dispense 100 μl of CONJ HRP into the wells. Cover the wells by plate adhesive tape. Incubate 30 min at 37°C. Wash the strips five times. Dispense 10 μl of SUBS TMB into the wells. Incubate 10–20 min at 18–25°C. Dispense 100 μl of STOP solution into the wells. Measure optical density (OD) at 450 nm. Set the photometer blank on air.

Calculation of results: the mean absorbance values (OD450) for control−, in triplicates, and each pair of samples were calculated. The cutoff value was calculated as: (mean OD450 for control−)+0.3. Positive index (PI) for each sample was calculated as: mean OD450 (sample)/cutoff. Expected values: if PI value is greater than 1.1, the result is positive; if PI value is less than 0.9, the result is negative; and if PI value is between 0.9 and 1.1, the result is equivocal. Such samples should be retested.

Statistical analysis

Standard computer program SPSS Inc. Released 2007. SPSS for Windows, Version 16.0. (SPSS Inc., Chicago) was used for data entry and analysis. All numeric variables were expressed as mean ± SD. Comparison of different variables in various groups was done using Student's test. The c2-test was used to compare frequency of qualitative variables among the different groups. For all tests a P value less than 0.05 was considered statistically significant. Graphic presentation of some results was also done. When P value was greater than 0.05, it was considered statistically nonsignificant. When P value was less than 0.05, it was considered statistically significant. When P value was less than 0.001, it was statistically highly significant.


  Results Top


The overall H. pylori IgG seropositive cases in children from 6 to 13 years were 44% (176/400) compared with 56% (244/400) for H. pylori IgG seronegative cases [Table 1] and [Figure 1].
Table 1: Seroprevalence of Helicobacter pylori infection among studied group

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Figure 1: Seroprevalence of Helicobacter pylori infection among studied group.

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The percentage of the seropositive cases was 30.4% (74/243) at the age of 6 to 1 years, which increased to 65% (102/157) at the age of 10 to 13 years; the frequency of seropositive cases increased highly significantly with advances of age (P = 0.001) [Table 2].
Table 2: Relation between age and Helicobacter pylori infection among studied group

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The study included 218 boys (54.5%) and 182 girls (45.5%); there was no significant difference in the seroprevalence of IgG antibody for H. pylori infection as regards to sex (P = 0.67) [Table 3].
Table 3: Relation between sex and Helicobacter pylori infection among studied group

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Data collected from the questionnaire concerning the socioeconomic status (the residence area, family crowding, number of family members, number of rooms, bed sharing, and water supply) was plotted

No significant difference was found in the seroprevalence of IgG antibody for H. pylori infection in relation to water supply (P = 0.304) [Table 4].
Table 4: Relation between demographic data and Helicobacter pylori infection among studied group

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On the other hand, we found a highly significant difference between seropositive and seronegative cases regarding family crowding, number of family members, number of rooms and bed sharing, and residence area (P = 0.001), denoting that cases with higher family crowding and those residing in slums had a higher prevalence of infection [Table 4].

The seropositive results in high-income families was 10.5% (8/76), which increased to 11.2% (13/116) in middle-income families to reach the highest increase of 74.5% (155/208) in low-income families, with a highly significant difference (P = 0.001), denoting that the seroprevalence of H. pylori infection increased with the lowering of the family income [Table 5].
Table 5: Relation between socioeconomic status and Helicobacter pylori infection according to yearly income per family person among studied group

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The percentage of seropositive cases concerning fathers' and mothers' education was 4.5% (5/111) and 4.2% (4/98), respectively, for high education level, increasing to 40.9 (45/110) and 50% (49/98) for secondary education level to reach the highest percentage of 75.8% (25/33) and 74.5% (35/47) for illiterate parents. There was a highly significant difference regarding the educational status of parents (P = 0.001 for fathers and P = 0.063 for mothers) between seropositive and seronegative cases, denoting that the seroprevalence of H. pylori infection increased with lowering the educational status of parents [Table 6].
Table 6: Relation between educational level and Helicobacter pylori infection among studied group

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The percentage of seropositive cases concerning fathers' and mothers' occupation was 11.3% (7/62) and 4% (4/96), respectively, for white collar workers and 28.3% (41/145) and 46.9% (30/64) for blue collar workers, to reach the highest percentage of 66.8% (129/193) and 59.7% (141/236) for farmers. From the above observation it was realized that H. pylori prevalence was highly significant higher among cases of farmers (P = 0.001 for fathers and P = 0.001 for mothers) than among cases and white collar workers (P = 0.001 for fathers and P = 0.001 for mothers); moreover, cases from white collar families had the lowest risk for being positive for H. pylori infection [Table 7].
Table 7: Relation between occupation and Helicobacter pylori infection among studied group

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  Discussion Top


H. pylori is the most common chronic bacterial infection in humans. It has been demonstrated worldwide and in individuals of all ages. Although infection rates are falling in the developed and developing countries, H. pylori is still widespread in the world[8].

Conservative estimates suggest that 50% of the world's population is affected. The prevalence of H. pylori differs significantly both between and within countries. Estimated prevalence is almost 70% in developing countries and 30–40% in the industrialized countries[9].

The present study was designed to examine the prevalence of H. pylori seropositivity in a population of apparently healthy children of both sexes and variable ages, born and residing in Al Qulubia Governorate; furthermore, the effects of age, sex, socioeconomic status, water supply, family income, educational status of parents, and occupational status of parents were also studied.

In our study the prevalence of H. pylori in asymptomatic children aged 6–13 years, of different sex and various socioeconomic standards, was assayed using the ELISA technique. Out of the 400 samples collected, 176 cases were seropositive for H. pylori antibody. The overall prevalence was 44% (176/400). This prevalence is quite close to that reported by Elin et al.[10], who found that the prevalence of H. pylori was 44.3%. A study carried out in apparently healthy Kenyan children, using serological tests, found a prevalence of 45.6%. Langat et al.[11] and Yilmaz et al.[12] found a prevalence of 43.9%, which was lower that recorded by Altuglu et al.[13], who found a prevalence of 53%. Sherif et al.[14] demonstrated a prevalence 46% in Egyptian children aged 2–17 years. Mahmoud et al.[15] found infection among Egyptian school children aged 6–15 years, which increased up to 70%. In Turkey, 64.4% of children aged 6–17 years were infected, as reported by Selimoglu et al.[16]. In Algeria, Ivory Coast, Gambia, 45–90% of children were infected during the first decade of life, as reported by Prieto et al.[17].

In contrast, in developed countries the prevalence was much lower. As per the findings of Chong et al.[18], prevalence in the USA was 12.1%. In Sweden the prevalence rate was 13.6% and decreased with age to reach 3% at the age of 11 years. There were no confirmed cases between 4 and 11 years of age, as reported by Granstrom et al.[19].

From the above observation it was realized that H. pylori infection has a widespread distribution, but the prevalence varies between developed and developing countries. If we compare our results with the above results, we can observe that the prevalence rate of 44% was much higher than the values detected in developed countries and quite close to the values recorded in developing countries.

When studied cases were divided into two groups (group I: 6–9 years old and group II: 10–13 years old) according to Yilmaz et al.[12], we found that the frequency of seropositive cases increased highly significantly with advance in the age (P = 0.001), denoting that the older age group had a higher prevalence of infection. This finding was exactly similar to that reported by Yilmaz et al.[12].

This was in agreement with other studies that showed that the prevalence of infection steadily increases with age among children[20],[21].

However, this is in contrast to with Mahmud et al.[22] and Naji et al.[23] who stated that the prevalence of H. pylori is not influenced by age. The low seroprevalence between the ages older than 6 and 9 years (30.4%) as compared with the second group between the ages older than 9 to 13 years (65%) means a low incidence of infection at this age group, as stated by Gold et al.[24]. This can be explained by low incidence of infection and also the frequent uses of antibiotic in this age group, which leads to some clearance of infection.

In this study we had also specified the seroprevalence positive results in both sexes (boys 45%, girls 42.9%); no significant difference was found in relation to sex (P = 0.67). In reviewing the available reference in this field, we found that our results were in agreement with similar studies by Jafar et al.[25] and Goodman et al.[26].

In contrast to a few studies that found a significant difference between males and females, Naji et al.[23] found a higher prevalence in females than in males. Hestvik et al.[20] found a higher prevalence in males than in females, and El-Samed El-Hewala et al.[27] found a higher prevalence in females than in males.

Socioeconomic status appears to be the other major epidemiologic factor in H. pylori infection. In the present study we found a highly significant difference between seropositive and seronegative cases regarding family crowding, number of family members, number of rooms and bed sharing, and residence area (P = 0.001), denoting that the cases with higher family crowding and residence in slums had a higher prevalence of infection. These results are in agreement with Queiroz et al.[28] and Elin et al.[10]. However, our findings contradict the findings of Qu et al.[29], who stated that seroprevalence did not differ according to the number of people living in the same house or living area. Regarding the relation between prevalence of H. pylori and water supply, we found no significant difference (P = 0.304), which was in agreement with Yilmaz et al.[12].

In the present study, the family income was classified into three categories, low, middle, and high according to yearly income per family person, as proposed by Abdollah et al.[30].

In our study we found a highly significant difference between seropositive and seronegative cases regarding family income (P = 0.001), and the prevalence of the infection was much higher among cases from low-income families compared with high-income families.

These results were in agreement with Yilmaz et al.[12], but in contrast to the findings of Elitsur et al.[31], who stated that the prevalence of H. pylori is not influenced by family income.

Regarding the relation between the prevalence of H. pylori and educational status of parents, in our study we found a highly significant difference between seropositive and seronegative cases (P = 0.001 for both fathers and mothers), denoting that the seroprevalence of H. pylori infection increased with lowering the educational status of parents. These results were in agreement with Yilmaz et al.[12], but in contrast to the findings of Selimoglu et al.[16], who reported no significant difference between children of parents with different educational statuses.

Occupational statuses of parents were classified into three categories, white collar workers, blue collar workers, and farmers, according to Patrizia et al.[32].

Regarding the relation between the prevalence of H. pylori and occupational status of parents, in our study we found that H. pylori prevalence was highly significant higher among farmers (66.8% for fathers and 59.7% for mothers) (P = 0.001 for both fathers and mothers) than among blue collar workers (28.3% for fathers and 46.9% for mothers) (P = 0.001 for fathers and P = 0.613 for mothers); moreover, cases from white collar families had a highly significant lower risk for being positive for H. pylori infection (11.3% for fathers and 4% for mothers) (P = 0.001). These results were in agreement with Patrizia et al.[32], who stated that children whose parents were blue collar workers or farmers had a significantly increased risk for H. pylori infection compared with children of white collar workers.


  Conclusion Top


H. pylori is acquired in early childhood and there is a gradual seraconversion cumulative sera conversion as the prevalence increased with age. The prevalence of H. pylori infection in Qulubia, Egypt, was substantially higher than that in developed countries and more or less within the range detected in developing countries, especially in African countries. There were many risk factors influencing the prevalence of H. pylori infection but other factors requiring wider scale studies for conformation. H. pylori infection could be one of the environmental causes of growth delay. Mechanisms by which H. pylori might influence growth are unknown, although a direct effect cannot be excluded.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

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    Tables

  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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