Abstract

Background and objectives: The Helicobacter pylori infection rate varies according to the age, location of the residence and socioeconomic status. The aim of the present study was to investigate the status of H. pylori infection among the asymptomatic Bangladeshi rural children and adolescents.

Material and methods: This cross-sectional study was carried out in a rural area under Pabna district about 150 km north-west of capital Dhaka. Asymptomatic and apparently healthy rural children and adolescents aged 6 to 18 years were enrolled in the study. A structured questionnaire was used to record the socio-demographic and clinical information. The rate of H. pylori infection was determined by the presence of H. pylori antigen in faeces and/or anti-H. pylori IgG and/or IgA antibodies in blood. H. pylori stool antigen was detected by lateral flow chromatographic immunoassay and serum anti-H. pylori IgG and IgA antibodies were estimated by ELISA method.

Results: A total number of 185 asymptomatic and apparently healthy children and adolescents were enrolled of which 34, 131 and 20 were in 6-10, 11-15 and 16-18 years age groups respectively. The overall H. pylori infection rate was 79.5% (95% CI: 0.729, 0.85) by positive stool antigen or by the presence of serum anti-H. pylori IgG/IgA antibodies. The rate of H. pylori infection significantly (p=0.05) increased with progress of age. H. pylori infection rate was 67.6%, 80.2% and 95% in 6-10, 11-15 and 16-18 years age groups respectively. The concentration of serum anti-H. pylori IgG/IgA antibodies did not differ across the age groups. The infection rate was significantly (p<0.05) higher among the children of illiterate parents compared to the children of literate parents.

Conclusion: The study demonstrated a high prevalence of H. pylori infection among children and adolescents in a rural setting. Gender and family history did not affect H. pylori prevalence but increasing age and poor educational status of parents were associated with a higher H. pylori prevalence.

IMC J Med Sci 2022; 16(2): 007. DOI: https://doi.org/10.55010/imcjms.16.017

*Correspondence: J. Ashraful Haq, Department of Microbiology, Ibrahim Medical College, 1/A, Ibrahim Sarani, Segunbagicha, Dhaka 1000, Bangladesh. Email: [email protected]

Introduction

Helicobacter pylori infection is one of the most chronic infections in humans [1]. It is associated with gastric diseases such as peptic ulcer, chronic gastritis, gastric adenocarcinoma and mucosa associated lymphoid tissue (MALT) lymphomas [2,3]. In addition, the infection has been associated with chronic diarrhea and malnutrition among infants and children [4,5]. In a meta-analysis, the overall global prevalence of H. pylori infection has been found as 44.3%, while it is 50.8% in developing countries and 34.7% in developed countries [6]. Previously, we reported low prevalence (38.9%, CI: 32.1, 46.2) of H. pylori infection in asymptomatic rural adults of Bangladesh [7].

H. pylori is most likely acquired in childhood [8-10]. In developed countries, the prevalence of H. pylori infection in children ranges from 10%–16.7% whereas it is 9%–78.6% in school children of developing countries [11-14]. In Bangladesh, the prevalence of H. pylori infection in peri-urban children has been reported as 82% [15]. However, the age group at greatest risk of infection is not clear yet [16]. Though the infection is clustered in families, it is not confirmed yet whether it is because of acquisition from person-to-person transmission or from common environmental source(s) [17-19]. Identifying the age group at greatest risk of H. pylori infection would be useful in determining the specific risk factors for infection and to plan preventive measure.

No previous study investigated the prevalence in rural children and adolescents in our country. Therefore, the primary aim of the present study was to find out the seroprevalence of H. pylori infection among asymptomatic rural children and adolescents in Bangladesh.

Materials and methods

The study was approved by the Institutional Research Review Board of Ibrahim Medical College and written informed consent was obtained from all adult participants and from the guardians of the children after explaining the nature and purpose of the study. Laboratory work was conducted at KA Monsur Research Laboratory at the Department of Microbiology, Ibrahim Medical College.

Study place and population: This cross-sectional study was carried out at Bhulbaria rural area of Santhia Upazilla (sub-district) under Pabna district in 2019. It is located about 150 km north-west of capital Dhaka. Apparently healthy rural school children and adolescents aged 6 to 18 years having no gastrointestinal symptoms, systemic infection, and malnutrition were enrolled in this study. A structured questionnaire (closed ended) was developed and used to record the socio-demographic information and clinical history. It was pretested and checked for applicability before it was finally launched at the field to interview for data collection from the respondents.

Definition of asymptomatic H. pylori infection: Asymptomatic H. pylori infection was defined if an apparently healthy individual was found positive for H. pylori stool antigen and or anti-H.pylori IgG and or IgA antibodies in blood without having any gastrointestinal symptoms.

Sample collection and preparation: Blood sample (about 2.5 ml) was collected aseptically from each participant by peripheral venipuncture. After collection, the serum was separated, aliquoted, refrigerated at 4⁰C and then transported to the microbiology laboratory in a cold box and stored at -20⁰C until tested. For stool antigen test, participants were asked to bring freshly passed stool (about 3-4 gm) in a sterile container and stored at 4⁰C until tested. Stool antigen test was performed within 3/4 hours of collection of stool.

Detection of H. pylori stool antigen: Stool samples were analyzed for H. pylori stool antigen using one step rapid lateral flow chromatographic immunoassay (ABON, Inverness Medical Innovation Hong Kong Limited). The test was performed as per manufacturer’s instruction. Small portions of stool from different parts of the collected stool were thoroughly mixed with extraction buffer and then vigorously agitated. Two drops of mixture were then put into the round window of the test cassette. Reading was made after 10 minutes of incubation at room temperature. Appearance of control (C) and test (T) lines across the central window of the cassette indicated positive test. Only one C line indicated negative result. The test was considered invalid if no line appeared in C line region.

Detection of serum anti-H. pylori IgG and IgA antibodies by ELISA: Serum samples were tested for the presence of anti-H. pylori IgG and IgA antibodies by ELISA method using DRG H. pylori IgG and IgA ELISA kit (DRG International Inc., USA). The test was performed according to the manufacturer’s instruction. The antibody concentration was expressed in optical density (OD) of the reactants.

Treatment of H. pylori stool antigen positive cases: H. pylori stool antigen positive individuals were treated with a proton pump inhibitor (PPI) and two antibiotics namely amoxicillin and metronidazole for 14 days for eradication of H. pylori according to the recommended dose schedule [20,21]. Stool samples were collected again and re-tested for H. pylori antigen one month after the completion of the treatment.

Results

A total number of 185 apparently healthy asymptomatic children and adolescents were enrolled in the study of which 34, 131 and 20 were in 6-10, 11-15 and 16-18 years age groups respectively. Socio-demographic variables of the participants are shown in Table-1. Almost equal number of male (51.4%) and female (48.6%) participated in the study. All were from middle socio-economic class. Of the enrolled children, 35.1% and 24.3% of their fathers and mothers were illiterate while remaining had access to academic education. Almost all (98.9%) used tube well water for drinking. Most of the participants (87%) used slab latrine. Though 81.6% washed hand with soap after defecation, only 37.3% washed hand with soap before meal. Around 48.1% had family history of gastritis whereas 51.9% had no such history. More than two third of individuals (71.4%) provided history of eating less spicy food. Most of the participants (96.8%) had no history of smoking.

Table-1: Socio-demographic characteristics of the study population (N=185)

Out of total 185 study population, 147 (79.5%; (95% CI: 0.729, 0.85) participants were positive for H. pylori infection either by positive stool antigen or by the presence of serum anti-H-pylori IgG/IgA antibodies (Table-2). Stool antigen, anti-H. pylori IgG and IgA antibody were positive in 24.9%, 64.9% and 55.1% participants respectively. The rate of H. pylori infection significantly (p=0.05) increased with the progress of age. H. pylori infection rate was 67.6%, 80.2% and 95% in 6-10, 11-15 and 16-18 years age groups respectively. Concentrations of anti-H. pylori IgG and IgA antibodies in different age groups were not significantly different as measured by OD (Table-3).

Table-2: Rate of H. pylori infection in different age groups of study population as determined by presence of stool antigen and serum anti-H. pylori IgG/IgA antibodies

Table-3: Anti-H. pylori IgG and IgA antibody concentration in different age groups of study population (N=185)

Significantly higher numbers of individuals were positive for anti-H. pylori IgG and IgA antibodies among stool antigen positive individuals compared to those who were stool antigen negative (p<0.001, 0.02 and p<0.009). Out of 46 H. pylori stool antigen positive cases, 91.3% were positive for IgG and/or IgA while out of 139 stool antigen negative individuals, 72.7% were also positive for anti-H. pylori IgG and/or IgA (Table-4).

Table-4: Comparison of stool antigen with the presence of serum anti-H. pylori IgG and IgA antibodies

No significant (p>0.05) association of H. pylori infection was observed with gender and family history of gastritis. The infection rate was significantly (p<0.05) higher among the children of illiterate parents than the children of parents having access to school (Table-5). Out of 46 stool antigen positive individuals, 34 (73.9%) became negative for H. pylori stool antigen when tested one month after the completion of scheduled treatment.

Table-5: Status of H. pylori infection according to the socio-demographic characteristics of the study population (N=185)

Discussion

This is the first study describing the H. pylori infection rate in rural children and adolescents in Bangladesh. In this study, H. pylori infection in an individual was defined as positive stool antigen and/or positive serum anti-H. pylori IgG and/or IgA antibodies. In the present study, we found the overall positivity rate as 79.5%; 67.6%, 80.2% and 95% in 6-10, 11-15 and 16-18 years age groups respectively. We found an increasing prevalence with age. This finding is comparable with other studies [22-24]. A plausible explanation might be increasing chance of exposure to H. pylori with advance of age due to consumption of H. pylori contaminated food/drinks from street vendors with poor hygienic condition. Children of lower age groups frequently consume antibiotics for other infections which might indirectly prevent infection by H. pylori infection [25].

Our study showed H. pylori IgG positivity rate of 64.9% in children and adolescents. In another developing country Benin, the rate was 68.3% in rural children [26]. In addition, in Vietnam, it was 41.4% in rural children [27]. On the other hand, the prevalence of H. pylori IgG antibodies in urban children of Benin was 78.3%. The lower rate of H. pylori infection in rural than urban population might be due to crowded accommodation, poor sanitation and exposure to unhygienic foods [26].

In the current study, the prevalence of H. pylori stool antigen in asymptomatic rural children and adolescents was 24.9%. It was 14.2% in African rural children [28]. Positive H. pylori stool antigen means active infection or individual is harboring the organism whereas positive H. pylori IgG antibodies represent current or previous H. pylori infection [29]. In our study, the H. pylori infection rate by serum anti-H. pylori IgG antibodies was 64.9% while the H. pylori stool antigen positivity rate was 24.9%. This difference suggests spontaneous resolution of infection in children. Auto-curability among black children aged 7-21 years in USA was 0.3% yearly and 5.5% per year in white children in the same cohort study [30]. Among Peruvian children, a spontaneous eradication of 7% monthly was reported [31]. The natural history of H. pylori infection in children continues to evolve. Further studies are needed to investigate whether re-infection or persistent infection occurs in antibody positives cases by detecting stool antigen or urea breath test or endoscopy.

We found no significant gender difference in the prevalence of H. pylori infection. It could be due to both boys and girls were equally exposed to same environment or sources in school as well as residence. Similar finding was observed in a meta-analysis of 10 studies conducted over the last 20 years in different countries [32]. However, few other studies reported significantly higher infection rates in boys than that of girls [33,34]. Our findings showed a significant association between higher rates of H. pylori infection in children of illiterate parents. It indicates that children of illiterate parents might have less knowledge regarding personal hygiene and good life style and that ultimately poses greater risk to be infected with H. pylori.

Our study revealed H. pylori infection was acquired in early childhood in rural Bangladeshi children. However, further study is necessary to understand the long term consequences of childhood H. pylori infection on the overall health of the population with the progress of age.

Acknowledgement

Authors gratefully acknowledge the support of Square Pharmaceuticals Ltd. for providing the accommodation during the field work.

Authors’ contributions

SM: sample/data collection, laboratory work, data entry and analysis and manuscript writing; FR: sample/data collection, laboratory work, data entry and analysis; FA: sample/data collection and data entry; RK and SA: sample/data collection; SPS: data entry; MSAJ: sample/data collection and data analysis; MAS and JAH: Idea generation, study design, data analysis and editing of manuscript.

Conflict of interest: The authors do not have any conflict of interest.

Financial support: The study was funded by research grant from Ibrahim Medical College, Dhaka, Bangladesh.

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Cite this article as:

Mazumder S, Rahman F, Akter F, Khatun R, Akter S, Saha SP, et al. Asymptomatic Helicobacter pylori infection among rural children and adolescents in Bangladesh. IMC J Med Sci. 2022; 16(2): 007. DOI: https://doi.org/10.55010/imcjms.16.017