|Year : 2001 | Volume
| Issue : 2 | Page : 20-25
Anti - H. pylori IgG seroprevalence rates in asymptomatic children and adults from South India
V Kate , N Ananthakrishnan , C Ratnakar , S Badrinath
Department of Surgery (VK, NA), Pathology (CR), and Microbiology (SB). Jawaharlal Institute of Post graduate Medical Education and Research (JIPMER), Pondicherry- 605 006, India
Department of Surgery (VK, NA), Pathology (CR), and Microbiology (SB). Jawaharlal Institute of Post graduate Medical Education and Research (JIPMER), Pondicherry- 605 006, India
This study was undertaken to determine the seroprevalence of H.pylori in asymptomatic children and compare it with that seen in the asymptomatic adult population from south India. One hundred and five children and one hundred adults admitted to the wards for conditions other than gastrointestinal disorders were included for this study. H.pylori status was determined by ELISA for IgG. The prevalence of H.pylori in children of various ages varied from 44% to 46% with an overall prevalence of H.pylori in children of 45%. 67% of adults were infected with H.pylori which was significantly higher than children (P = 0.002). The prevalence of H.pylori increased markedly with age with the maximum colonization (74%) occurring in young adults (16-30 years). The antibody levels too followed a similar pattern. In conclusion, it was seen that almost half the children in south India acquire H.pylori infection early in life which increases slowly and steadily with a peak prevalence in the young adults. Gender does not affect the prevalence in children and adults. As age advances further there is a slight decline in the prevalence of H.pylori infection. The immune response reflected by the levels of the antibody levels also follows the same pattern.
|How to cite this article:|
Kate V, Ananthakrishnan N, Ratnakar C, Badrinath S. Anti - H. pylori IgG seroprevalence rates in asymptomatic children and adults from South India. Indian J Med Microbiol 2001;19:20-5
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Kate V, Ananthakrishnan N, Ratnakar C, Badrinath S. Anti - H. pylori IgG seroprevalence rates in asymptomatic children and adults from South India. Indian J Med Microbiol [serial online] 2001 [cited 2019 Jun 27];19:20-5. Available from: http://www.ijmm.org/text.asp?2001/19/2/20/6924
Helicobacter pylori is recognized as the most important etiological agent for chronic antral gastritis in humans, the major predisposing factor in the pathogenesis of duodenal and gastric ulcer as well as a probable cofactor in the development of gastric cancer.,, H.pylori infection, once acquired is believed to persist throughout life unless treated. The prevalence of H.pylori in children of developing countries is higher and begins at a younger age than children in developed countries.,, Even among the latter the prevalence varies among different ethnic and socioeconomic groups. ,,
The epidemiology of H.pylori in India suggests that infection occurs early in life and more than half of the population acquires the infection by early adult life. In our earlier study, sixty percent of asymptomatic adult population were colonized by this bacterium. As there is a strong evidence that infection is acquired in childhood, studies on children have become essential for understanding the role of H.pylori in this age group.  There are only few reports from this part of the country regarding the prevalence of H.pylori in children., This study was, therefore, undertaken to determine the seroprevalence of H.pylori in asymptomatic children and compare it with that seen in the asymptomatic adult population.
| ~ Material and Methods|| |
A total of two hundred and five subjects including 105 children and 100 adults admitted to the surgical and pediatric wards for conditions other than gastrointestinal disorders were included in the study from January 1997 to December 1998.
Blood for serology was obtained from children having blood tests for other reasons. It was difficult to get informed consent hence the number was limited. For the purpose of this study, subjects upto 15 years were considered as children and above 15 years as adults. The children were divided into three groups according to their age i.e. upto five years, six to ten years and eleven to fifteen years. The H.pylori status in these different age groups was noted. Gastrointestinal disorders in these children were ruled out by clinical examination only as endoscopic examination would have required general anaesthesia thus raising ethical issues in an apparently normal child.
One hundred adults without any gastrointestinal disorders were included in the study. An upper gastrointestinal endoscopy was done under topical anaesthesia in all these patients to rule out silent peptic ulcers or other upper gastrointestinal disorders.
Patients who had taken antibiotics, H2 blockers or proton pump inhibitors in the month preceding the presentation were excluded. Patients on chemotherapeutic or immunosuppressive drugs or with primary or secondary immunodepression were excluded. Informed consent was obtained from patients and/or legal guardians in case of children and ethical clearance from the Ethics Committee of the Institute was obtained.
H.pylori prevalence was determined by serology as H.pylori specific serum IgG response is both highly specific (99%) and sensitive (96%) in detecting H.pylori colonization.,, Inspite of the fact that serology may under-estimate prevalence in adults due to fall in titres after ingestion of certain anti-H.pylori drugs administered for other indications, if still remains a valid epidemiological method since it is non-invasive.
Serology was done using a validated second generation Microwell ELISA assay using purified solid phase antigens (UBI Magiwell Helicobacter pylori IgG quantitative IA-601 Microwell ELISA supplied by United Biotech Inc., CA, USA).
The wells coated with purified antigens were used. 1:101 dilutions of test samples, negative, positive and calibrator were prepared by adding 5 mL of sample to 0.5 mL of sample of diluent in separate glass tubes. 100 mL of diluted control patient samples and sample diluent (as the blank ) were dispensed into each coated well. After incubation for 30 minutes at room temperature, the solution was discarded and the wells rinsed seven times with washing buffer. Thereafter 100 mL of enzyme conjugate (anti-human IgG conjugated with horse radish peroxidase) was dispensed to each well and incubated for 30 minutes at room temperature. The solution was discarded and the wells rinsed seven times with washing buffer. 100 mL of buffer solution containing hydrogen peroxide and 100 mL of tetramethylbenzidine were dispensed into each well. After incubation for 15 minutes at room temperature, the reaction was stopped by adding 50µL of 1 N sulphuric acid into each well. The optical density (OD) was read at 450 nm with a microwell reader. When the results in Elisa units (EU) /mL was less than 30 it was negative, 30 to 40 were considered equivocal and above 40 as positive. All equivocal results were repeated.
The analysis was done using Epi Info Software (Version 6.04). Chi-square (x2) for linear trend was used to evaluate the age related prevalence of H.pylori. X2 test and Fisher's exact test were used to correlate gender with H.pylori. Comparison of anti-H.pylori IgG titres was made with one-way ANOVA (Analysis of Variance). A calculated alpha value of less than 5 percent was considered significant.
| ~ Results|| |
A total of one hundred and five asymptomatic children and hundred adults were included in the study. Most of the children were admitted for disorders of the nervous or respiratory system. There were thirty seven children upto 5 years of age (Group I), thirty six between 6-10 years (Group II) and thirty two children from 11-15 years (Group III). The mean + SEM and the age range in Groups I, II and III were 2.59 + 0.22, range 2 months to 4˝ years, 7.11 + 0.21, range 6-10 years and 11.47 + 0.52, range 11-13 years respectively.
The H.pylori prevalence in Groups I, II and III was 46%, 44% and 44% respectively with no significant intergroup difference (P = 0.85). The overall prevalence in children was 45% (47/105). There was no significant difference in the IgG anti-H.pylori titres in the three groups (P = 0.53) [Table - 1]. All the three groups were comparable in gender and socioeconomic status. H.pylori was present in 37%, 57% and 47% male children in Groups I, II and III respectively. In female children, H.pylori was present as 55%, 27% and 38% in Groups I, II and III respectively. Although there is a slightly greater female preponderance seen in the under fives and a greater male preponderance in the 6-10 years group, these differences were not statistically significant. Overall, there was no difference in prevalence between the genders (P = 0.67).
In the adult asymptomatic population, there were one hundred subjects with a mean (+ SEM) age of 41.05 + 1.46 years. They ranged in age from 18 to 75 years. 82 were males and 18 were females. 63% (52/82) of males and 83% (15/18) of females were infected with H.pylori. The difference between the genders was not significant (P = 0.18). Overall H.pylori infection was present in 67% of adults. The prevalence increased with age being maximum (74%) between 16-30 years; thereafter there was a slight and steady decline with advancing age though a minimal rise was seen beyond 60 years [Table - 1]. This may be illusory due to very few patients being above 60 years of age in this study [Figure:1]. There was a significant difference in the prevalence between children and adult population with only 47/105 (45%) children being positive compared to 67/100 (67%) adults (P = 0.002). The age related prevalence also shows a significant rise in the level of infection in the young adults group with an odds ratio of 3.55 at 16-30 years (P = 0.001). The antibody levels too follow a similar pattern [Figure:1]. The mean + SEM titres in EU/mL upo 15 years was 39.47 + 2.8; it was 58.25 + 6.32 at 16-30 years, 64.98 + 7.78 at 31-45 years, 60.53 + 6.52 at 46-50 years and 50.54 + 9.75 above 60 years. The rise in titres in young adults and the middle age groups was significant (P = 0.0006) as seen in [Table - 1].
| ~ Discussion|| |
It is difficult for investigators on H.pylori to have sufficient number of adults and children without gastrointestinal disorders to establish normal prevalence in the “well” population. The only available non-invasive test, the breath test, is very expensive. Of less invasive test serology is most convenient. Urine-elisa tests are not yet freely available and stool examination by PCR involves prohibitive cost. In this study, since the aim was only to establish baseline age-related prevalence rates no attempt was made to relate prevalence to epidemiological factors. Hospital based controls were used so that blood for ELISA could be drawn when drawing samples for other investigations without having to subject the patient to vein puncture merely for research purposes.
The prevalence of H.pylori infection varies worldwide, but higher colonization rates are seen in developing countries compared to developed countries. H.pylori has been considered as an infection acquired in childhood that will last most, if not all of the individual's life and eventually in some subjects due to other co-existing risk factors will contribute to the development of stomach and duodenal diseases. As one of the major risk factors for acquiring this infection is low socioeconomic status it is widely prevalent in India. In Western countries, H.pylori infection is rare in patients less than 5 years of age.  This prevalence increases with age and more than 50% of individuals above fifty years have serologic evidence of infection. Prietto et al. reported a prevalence of 10% in the first decade of life from Spain. In France, 3.5% patients were infected in the first decade. On the contrary, in countries such as Algeria, Ivory Coast and Gambia 45% to 90% of children are infected during the first decade of life., Fiedorek et al studied 245 healthy children (under 20 years) in Arkansas, USA, for serologic evidence of H.pylori infection. 31% of these were infected with H.pylori with the frequency in blacks being twice as high as whites (50% vs 25%).
Age related studies documenting H.pylori infection from India show the same trend seen in developing countries i.e. occurrence of infection at an earlier age. Dore et al reported a high prevalence of H.pylori infection (82%) in school children using C urea breath test. In a study from Mumbai, age related prevalence of H.pylori in 82 control subjects in the age groups 10-19 years, 20-29 years, 30-39 years, 40-49 years and 50 years and above was 44%, 55%, 58%, 36% and 33% respectively. In our study too, children less than 5 years had a relatively high prevalence of H.pylori (46%) compared to their Western counterparts. Although, 4 out of 8 children under one year of age were serologically positive it is difficult without testing the mothers to exclude transplacental transfer of IgG. The prevalence was almost same through the different age groups of 6-10 years and 10-15 years suggesting a steady colonisation rate compared to young adults where it rises significantly to 74% (P = 0.001). Our study reflects a similar pattern of H.pylori infection as seen in Mumbai showing a steady rise upto 30 years and thereafter, a slight decline in the later years of life [Figure:1].
The mean titres of antibodies to H.pylori in different age groups shows a correlation with the prevalence rate at different age groups. The IgG titres level were significantly higher in adults compared to children (P = 0.0006).
Gill et al reported H.pylori seroprevalence rates of 22%, 56% and 87% in 0-4, 5-9 and 10-19 age groups. Though their prevalence in the under fives was low compared to our study, it was higher in older children. The difference in the under fives prevalence compared to our study could be due to use of crude whole cell preparations of H. pylori based kits by them. As the older children were included upto 19 years, a higher prevalence compared to the present study might have resulted. Kang et al in a report from south India, found 57% of subjects between 6 months to 4 years positive for IgG antibodies for H. pylori. There was an increasing prevalence with age to a maximum of 90% above 60 years of age. Sharma et al too reported a 50% seropositivity for H. pylori in children below 10 years of age. In a study from Chennai in an urban upper class population, a 21.1% prevalence rate was seen in individuals between 12-20 years of age. This study showed a trend of rising prevalence with age with a maximum prevalence of 76.2% in those older than 75 years. The authors noted that individuals belonging to larger families had a higher risk of infection. [Table - 2] shows the high prevalence of H.pylori infection in children from developing countries compared to the low infection rates from developed countries.
In conclusion, almost half the children in south India acquire H.pylori infection early in life which increases slowly and steadily peaking in young adults. Thereafter, there is a slight decline as age advances but still more than two-thirds of the adult population remains colonized by this bacterium. The immune response reflected by the levels of anti-H.pylori antibody titres also follows the same pattern.
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