IgA antibodies in persisting Helicobacter pylori infection in Finnish adults

Performances of Four Helicobacter pylori Serological Detection Kits Using Stool Antigen Test as Gold Standard

The aim was to determine the performances of four Helicobacter pylori serological detection kits in different target groups, using Amplified IDEIA™ Hp StAR™ as gold standard. Kits studied were Rapid Immunochromatoghraphic Hexagon, Helicoblot 2.1, an EIA IgG kit and EIA IgA kit.

METHODS

Stool and blood samples were collected from 162 apparently healthy participants (control) and 60 Type 2 diabetes mellitus (T2DM) patients.

RESULTS

The performances of the four serological detection kits were found to be affected by gender, age, health status and ethnicity of the participants. In the control group, the Helicoblot 2.1 kit had the best performance (AUC = 0.85; p<0.05, accuracy = 86.4%), followed by EIA IgG (AUC = 0.75; p<0.05, accuracy = 75.2%). The Rapid Hexagon and EIA IgA kits had relatively poor performances. In the T2DM subgroup, the kits H2.1 and EIA IgG had best performances, with accuracies of 96.5% and 93.1% respectively. The performance of EIA IgG improved with adjustment of its cut-off value.

CONCLUSION

The performances of the detection kits were affected by various factors which should be taken into consideration.

Prevalence of Helicobacter pylori infection worldwide: a systematic review of studies with national coverage

The systematic assessment of large population-based surveys addressing the prevalence of Helicobacter pylori infection may provide robust evidence for understanding the trends in the exposure to this major risk factor across settings with distinct patterns of gastric cancer variation. Our aim was to describe the prevalence of H. pylori infection in different countries and periods, through systematic review of the literature. We searched PubMed from inception up to September 2013 to identify original studies reporting on the prevalence of H. pylori, and only those evaluating samples with national coverage were included. We identified 37 eligible studies including data for 22 countries. The prevalences were higher in Central/South America and Asia, and at least two-fold higher in countries with high gastric cancer incidence. In most countries presenting data for different time periods, the prevalences were usually lower in the most recent surveys. However, there was little variation in settings where prevalences were already low. Among countries with high prevalence of H. pylori infection there is an ample scope for reducing its burden in the next decades, whereas further declines in settings with already low prevalences will require more intensive efforts.

Apparent incidence of Helicobacter pylori in adulthood: to what extent do new infections reflect misclassification?

BACKGROUND

Helicobacter pylori infection is a key risk factor for a variety of gastrointestinal diseases. About half of the world population is infected. Most infections are acquired early in childhood, but the occurrence of new infections among adults has also been suggested.

METHODS

We review epidemiological studies providing estimates of incidence of H. pylori infection among adults and evaluate to what extent incidence estimates might have been affected by measurement error of infection status.

RESULTS

Thirty-two studies could be included in the review. Annual incidence was lower than 1.0 % in 17 studies; no correlation between length of follow-up and cumulative incidence was observed. Apparent cumulative incidences of the magnitudes observed in most studies would be expected, because of less than perfect sensitivity and specificity of the diagnostic tests, even in the absence of any true new infections. CONCLUSION/IMPACT: Apparent incidence rates of H. pylori infection among adults in Western populations should be interpreted with utmost caution.

Longitudinal analysis of serological responses of adults to Helicobacter pylori antigens

Because Helicobacter pylori persist for decades in the human stomach, the aim of this study was to examine the long-term course of H. pylori-specific serum immunoglobulin G (IgG) responses with respect to subclass and antigenic target. We studied paired serum samples obtained in 1973 and in 1994 in Vammala, Finland, from 64 healthy H. pylori-positive adults and from other healthy control subjects. H. pylori serum immunoglobulin A, IgG, and IgG subclass responses were determined by antigen-specific enzyme-linked immunosorbent assays. H. pylori-specific IgG1 and IgG4 subtype responses from 47 subjects were similar in 1973 and 1994, but not when compared with unrelated persons. H. pylori-specific IgG1:IgG4 ratios among the participants varied >1000-fold; however, 57 (89.1%) of 64 subjects had an IgG1:IgG4 ratio >1.0, consistent with a predominant IgG1 (Th1) response. Furthermore, ratios in individual hosts were stable over the 21-year period (r = 0.56; P < .001). The immune response to heat shock protein HspA was unchanged in 49 (77%) of the 64 subjects tested; of the 15 whose serostatus changed, all seroconverted and were significantly younger than those whose status did not change. These findings indicate that H. pylori-specific antibody responses are host-specific with IgG1:IgG4 ratios stable over 21 years, IgG1 responses predominating, and HspA seroconversion with aging.

Serum anti-Helicobacter pylori IgA and IgG antibodies in asymptomatic children in Serbia

The aim of this study was to determine the seroprevalence of Helicobacter pylori and the distribution of anti-H.pylori IgA and IgG antibodies in asymptomatic children aged between 7 and 18 y. We studied the serum samples of 283 children using the commercial ELISA test for the detection of anti-H. pylori IgA and IgG antibodies. The overall prevalence of anti-H. pylori antibodies was 36.4%. The seroprevalence was 35%, 28.3%, 37.5%, and 42.2% for the ages of 7, 10, 14 and 18 y, respectively. Serum IgG antibodies alone were detected in 88.3%, IgA alone in 4.9%, and both IgA and IgG antibodies were detected in 6.8% of samples. The mean levels of IgG antibodies to H. pylori increased with age. We concluded that the prevalence of H. pylori antibodies in Serbian children was high (36.4%), ranging from 35% to 42.2%. The detection of IgG antibodies is useful for the determination of seroprevalence in asymptomatic children.