Because antibodies to CagA remain positive longer than H. pylori IgG surface antibodies, relying on H. pylori IgG antibodies alone might misclassify a significant proportion of patients who once had the infection . In our study population,
the frequency of active and past infection with strains carrying CagA was very high—more than 70%. The results of other studies in Mexican population are consistent with ours [5, 40]. Longitudinal studies are required to understand the meaning of high prevalence of the virulence factor in these populations. Most of the epidemiological studies in adults have found an association between peptic learn more ulcers and gastric cancer, with H. pylori carrying CagA-positive strains [39, 41]. However, other factors may affect these associations. A study was carried out in two villages of the same country with high prevalence of CagA-positive strain but different gastric cancer risks. The study demonstrated that in subjects with CagA-positive and vacA s1 m1 strains, the ancestral origin of H. pylori strains was a strong predictor for gastric cancer risk. The European but not the African phylogeographic origin of the H. pylori strains was strongly associated with more advanced histological lesions and increased Cetuximab chemical structure DNA damage in gastric epithelial
cells . Another study concluded that iron depletion, in conjunction with the presence of H. pylori CagA-positive strains, should be considered a risk factor for the progression of gastric cancer because iron deficiency enhances H. pylori virulence and could represent a measurable biomarker to identify infected populations at higher risk for gastric cancer . Clinically, the UBT is useful to monitor the eradication of bacteria after receiving therapy because this test identified active infection. At the public health level, serological tests give a more complete representation of the percentage of individuals who have been exposed to H. pylori infection and of the prevalence of virulence factors. If the prevalence of H. pylori infection obtained using serological tests is compared to the prevalence by UBT, serological tests overestimate the prevalence
of H. pylori up to 30%. But serological tests based on immunoglobin G antibodies underestimate the percentage of infection that corresponds to active and acute infection in subjects MCE without detectable immune response to H. pylori whole-cell or Cag A-specific antigens but with positive UBT. In this study the percentage of underestimation was 4.9%. The results of our study confirm the association between factors related to low socioeconomic level and poor health conditions as iron deficiency and low height for age with H. pylori infection [4, 9, 21, 23], even in this low-income homogeneous population. H. pylori infection has been associated with ID or IDA in children in multiple studies. In clinical trials, higher response to iron supplementation has been observed with H.