Helicobacter pylori Seropositivity in Institutionalized Children With Down Syndrome

Abstract

To the Editors: Helicobacter pylori is usually acquired in early infancy and probably persists throughout the life.1 Host genetic background, environment, and bacterial determinants contribute to the development of H. pylori-associated diseases.2 Poor living and socioeconomic conditions as well as overcrowding are among the main risk factors for infection during childhood.3 Children with Down syndrome (DS) have multiple immunologic defects.4 It remains controversial whether abnormality of immune responses in such children increases the propensity to infections. We undertook a study to find H. pylori seropositivity among children with DS compared with age- and gender-matched children having other intellectual disabilities with similar nutritional regimen and living and hygienic environment. Peripheral blood samples were collected from 24 children with DS and 24 children with other intellectual disabilities who were residents of 3 institutes for intellectually disabled children in Tehran. The paired match of each DS case was selected from other intellectual disabilities cases of the same institute, so the matched cases had similar living conditions. Serum H. pylori-specific immunoglobulin G (IgG) antibody was measured using ELISA (enzyme-linked immunosorbent assay) method, according to manufacturer's instructions (IMMUNOLAB GmbH, Germany). The results were considered positive if H. pylori IgG titer were >0.1 U/mL. For statistical analysis, χ2 test and nonparametric tests (Mann-Whitney and Kruskal–Wallis tests) were used. A P value of ≤0.05 was considered statistically significant. The DS and other intellectual disabilities groups each consisted of 13 females and 11 males, ranging in age from 1 to 15 years, and the mean age ± SD was 5.75 ± 4.35. H. pylori-specific IgG was detected in 17 of 24 (70.8%) DS children with a median titer of 30.09 U/mL. Among other intellectual disabilities children, 15 of 24 (62.5%) were seropositive with a median IgG of 34.34 U/mL. The seroprevalence of H. pylori infection in children with DS did not significantly differ from that in children suffering from other intellectual disabilities (odds ratio: 1.45; 95% confidence interval: 0.43–4.87). In the current small groups, seropositivity rates were similar in DS and other intellectual disabilities children in relation to age. More than half of seropositive children in DS (52.9%) and other intellectual disabilities (60%) groups were younger than 6 years, and this difference was not statistically significant. The median duration of institutionalization was 30 months (range, 6–96 months) for DS group and 24 months (range, 7–96 months) for other intellectual disabilities group. The antibody response against H. pylori was not associated with gender and duration of institutionalization. The current study demonstrated high seropositivity for H. pylori in DS children. The high seropositivity may be attributed to the fact that overcrowding, sanitary conditions, and dietary regimen in childhood affect the route of H. pylori transmission and infection.3 No significant difference was found in the risk of H. pylori seropositivity between children with DS and those with other intellectual disabilities. Two studies have reported H. pylori seropositivity in children with DS with lower rates. Jaber5 assessed 24 children with DS in Saudi Arabia and found a 29.2% seropositivity rate. A study of 46 children with DS by Failla et al6 showed that 19.5% of cases were seropositive. Both studies were of noninstitutionalized children with DS, whereas we examined children reside permanently in the institutes. Hence, the higher seropositivity of H. pylori infection might be explained by institutionalization and sanitary conditions as major risk factors. On the other hand, children with DS did not show a significantly higher susceptibility to H. pylori infection than children with other intellectual disabilities. It seems that host response against H. pylori infection is similarly influenced by environmental conditions in DS versus other intellectually disabled cases. Masoumeh Douraghi, PhD Department of Microbiology Shahid Beheshti University of Medical Sciences Division of Microbiology Department of Pathobiology School of Public Health Tehran University of Medical Sciences Tehran, Iran Hossein Goudarzi, MD, PhD Department of Microbiology Shahid Beheshti University of Medical Sciences [email protected] Mahmoud Nateghi Rostami, PhD Department of Public Health Qom University of Medical Sciences Qom, Iran Elnaz Sadat Mirsamadi, MSc Department of Microbiology Shahid Beheshti University of Medical Sciences Tehran, Iran