Prevalence of helicobacter pylori infection among children living in a rural setting in Sub-Saharan Africa

Background Helicobacter pylori infection affects more than half of the world’s population. It is generally acquired during childhood with no symptoms but has long- term clinical sequelae. This study estimated the prevalence of H. pylori infection amongst children in a rural environment in Africa. Methods We conducted a cross-sectional study over a four (4)-month period within two rural communities. 240 asymptomatic children were tested using lateral flow immunochromatographic assay for the qualitative detection of H. pylori antigen in a fecal specimen. Statistical analysis and processing was done using Stata version 11. Results The mean age of the participants was 10.5 ± 2.7 years with the predominant age range being 8–10 years (34.6%), and a mean household size of 7.1 ± 1.7. The study population showed a female preponderance of 57.1%. 88% of the H. pylori positive children lacked pipe and borehole drinking water. All of the positive H. pylori children practiced open-air defecation. The overall prevalence of H. pylori infection among children in this study was at least 14.2%. Conclusion Our study demonstrated a high prevalence of H. pylori infection among children in a rural setting. Educational status of parents did not affect H. pylori prevalence but increasing household numbers, female gender, source of drinking water other than pipe and borehole, open-air defecation and younger age were associated with a higher H. pylori prevalence.


Background
Helicobacter pylori (H. pylori) is an important global infection with a worldwide prevalence of about 50 % [1,2]. This infection is mostly acquired during childhood through the fecal-oral and oral-oral route [3,4]. Initial infection with this organism is usually silent but symptoms and pathologic changes occur later in life. The clinical conditions and pathologic changes associated with H. pylori infection include gastritis, gastric and duodenal ulcers, gastric cancers, iron deficiency anaemia and idiopathic thrombocytopenic purpura (ITP) [5][6][7][8].
H. pylori infection exhibits a varied geographic distribution on both local and global scales. These variations are mostly socioeconomically driven; factors such as age, gender, genetic predisposition, ethnicity, educational level and sanitation determine the incidence and prevalence of this global infection [9][10][11].
The diagnosis of H. pylori infection is generally based on methods described as invasive or non-invasive approaches. The invasive methods are based on endoscopy and biopsy using modalities like culture, histology and rapid urease test. Non-invasive diagnostic methods include urea breath test (UBT), fecal antigen testing, serology and more recently polymerase chain reaction testing of feces. The sensitivities of the invasive and non-invasive tests are comparable and relevant in clinical practice [12,13]. This study used the lateral flow monoclonal immune-chromatographic testing (ICT) technique to determine the prevalence of H. pylori among children.
The primary objective of this study was to determine the prevalence of H. pylori infection among the pediatric population in a rural West African setting.
Additionally, we evaluated the sociocultural and demographic factors influencing the prevalence of this infection in the communities.

Study population and design
This cross-sectional study was conducted from December 2014 to March 2015 within two rural communities in the Upper West region of Ghana. The Upper West is located at the North western corner of Ghana with latitude 9.8°-11.0°north and longitude 1.6°-3.0°west, bounded to Burkina Faso to the north. A total of 240 children (≤16 years) were recruited for the study. This was done by assigning the students' numbers 1 and 2 with all those numbered 2 selected for this study. Informed consent was obtained through community leaders, teachers and parents of those who participated in the study.

Demographic details
The age, gender, type of toilet facility, source of drinking water, number of people in their household, number of siblings, and the educational level of the children as well as their parents were collected from all participants using a structured questionnaire.

Helicobacter pylori testing
Participants were given clean stool sample containers to provide fresh stool samples within 2 h in the sterilized containers provided.The children were asked to indicate the time and date of specimen collection. As an exclusion criteria, any specimen that lasted for more than 2 h before reaching us was discarded. All stool specimen were collected during their morning (7:00 am) assembly section and transported in a cold (−4°C) specimen carrier to the laboratory. Specimen that we anticipated will stay more than 2 h before processing (from time indicated on the container and the time of testing) in the laboratory were refrigerated at (−20°C). Eight samples in all were discarded with reference to the exclusion criteria defined in sample collection.
A lateral flow immunochromatographic assay for the qualitative detection of Helicobacter pylori antigen in human fecal specimen (OnSite H. pylori Ag Rapid Test, USA) was used.

Statistics
The data was captured using Microsoft excel, 2007 and exported to STATA version 11.0 for processing and analysis. Univariate and bivariate analysis were used to describe the results in the form of frequency and percentage distributions. Pearson's chi squared and Fisher's exact tests employed to test associations between various background characteristics of participants and the outcome of interest (H. pylori status) at p < 0.05 significance level.

Characteristics of study population
The participant characteristics are as presented in Table  1. The mean age of the participants was 10.5 ± 2.7 years. The predominant age range was 8-10 years constituting 34.6%. However, the age group with the highest incidence of H. pylori infection was 5-7 years that had 19.5% positivity. The age group with the least H. pylori infection rate was 14-16 years with prevalence of 11.9%. The study population showed a female: male ratio of 1.3:1, with a higher proportion of females having H. pylori infection compared to males [16.8% (females) vs 10.7% (males)]. Table 2 stratifies the study participants with regards to H. pylori infection and its association with educational level of parents and household size. The educational level of either parent was not significantly associated with H. pylori infection rate. The mean household size of the study participants was 7.1 ± 1.7. Interestingly, participant household size was significantly associated with the prevalence of H. pylori infection (p = 0.000; Fisher's exact test).

Discussion
H. pylori infection affects more than half of the world's population including children. Because of the fecal-oral mode of transmission it is more prevalent in poor socioeconomic environments. H. pylori is described in current medical literature as a group 1 carcinogen but the health implications of infection in children remains uncertain [2]. This may be problematic particularly in African children who may harbor more virulent strains. The long term sequelae of H. pylori infection was ignored because of what has been described as "African enigma" [6]. It has however been shown that all complications including carcinoma do occur in the African population [6,14]. Our study used a noninvasive method to qualitatively detect H. pylori antigen in human fecal specimen. We acknowledge the limitation in testing as the H. pylori stool antigen testing was not compared with any gold standard diagnostic method. However, the ethical and feasibility challenges of upper gastrointestinal endoscopy as a screening tool in an asymptomatic pediatric population was strongly considered [15].
The global prevalence of H. pylori infection is generally higher in developing countries than the developed world [16,17]. Transmission of H. pylori infection is rapidly decreasing in the developed countries predictably because of improvement in the sanitation [18,19]. There  is infrequent H. pylori infection during childhood in the developed countries with the United States reporting less than 5% in under five years and up to 10% by adolescent age. However in developing countries the story is different with about 50% of children under five infected and as high as 90% in some adult populations [20,21]. We demonstrated a prevalence of at least 14.2% among asymptomatic children between the ages of 5-16 years living in a rural setting in sub-Saharan Africa (SSA). Our finding in terms of prevalence of H. pylori infection among children was not consistent with the developing countries data [22][23][24]. This could be attributed to the differences in the study design, population dynamics, as well as the specificities of techniques employed in the studies. Antibody testing procedures for H. pylori detection are used in some studies but is unable to differentiate active infection from a previous in the early weeks of follow up after eradication therapy. Our study employed H. pylori stool antigen testing methods because of its non-invasive nature especially in a children population. Our study had a female preponderance of 57.1% with higher H. pylori prevalence among females (16.8%) than males (10.7%). The gender effect on prevalence of H. pylori infection in many populations is varied. Woodward and colleagues reported a higher prevalence in men than women [20,23] whiles others reported no difference. A meta-analysis reported a male predominance in adults but not in children [19,25,26]. Our study in children demonstrated a higher prevalence in females with no plausible explanation.
The age effect on prevalence is well documented in H. pylori epidemiology with a positive correlation between age and prevalence [27,28]. Our study showed higher prevalence in the younger age group and decreasing prevalence with advancing age. This is a reverse of the pattern in most population studies. Educational status has been used as a proxy marker of socioeconomic status and an important determinant of H. pylori prevalence in developed and resource limited settings [29][30][31]. The educational status of parents in our study did not affect the prevalence significantly. Crowding in households and increasing household contact have been linked as risk factors of H. pylori infection [32,33]. As the number of people in a household increased the prevalence of H. pylori also increased [34]. Source of drinking water other than pipe and borehole increased the prevalence of H. pylori infection as well as open-air defecation. Water is an important source of H. pylori spread and many studies have actually confirmed it. Therefore, handling of water and poor sanitation will be a good milieu for the spread of this infection. Our study support this assertion as we also realized that source of water other than pipe and borehole and open air defecation were associated with higher prevalence of H. pylori infection [35,36].
In our environment, poverty and poor socioeconomic status are associated with higher household numbers. It is therefore not surprising giving the mode of transmission that prevalence in our study increased with increasing household numbers. Proper hand washing and waste disposing systems will help

Conclusion
Our study demonstrated a high prevalence of H. pylori infection among children in a rural setting. Educational status of parents did not affect H. pylori prevalence but increasing household numbers, female gender, younger age, open-air defecation and source of drinking water other than pipe and borehole were associated with a higher prevalence.