Abstract
Background: Most patients infected with Helicobacter pylori show no clinical symptoms. Nonetheless, approximately 10% to 20% of these patients will develop peptic ulcers and 1% will develop gastric cancer. The International Agency for Cancer Research has classified Helicobacter pylori as a Group 1 carcinogen. Materials and Methods: Drinking water samples from 20 cantons situated in areas of low and high incidence of gastric cancer in Costa Rica were analyzed. Water samples were concentrated and the nitrocellulose filter was cultivated for later molecular identification of Helicobacter pylori using the glmM marker. The tumor necrosis factor-alpha inducing protein (Tipalpha TNF-α) was used as a pathogenicity marker of the strains found followed by the sequencing of two products. Information on water management by aqueduct operators was collected in order to establish statistical relationships. Results: A total of 112 water samples were analyzed. Successful cultivation and molecular identification using the glmM marker was achieved in 39% of samples from areas of high incidence and in 7.5% of samples from areas of low incidence. Two glmM gene PCR products were sequenced and confirmed as true positives. Conclusions: The highest prevalence rate of Helicobacter pylori was found in water from areas with a high incidence of gastric cancer. Additionally, significant statistical correlations were established among environmental conditions, drinking water management and incidence of gastric cancer.
Highlights
Chronic infection with H. pylori in the human stomach can last decades resulting in persistent inflammation
In view of the high incidence of gastric cancer in the country and its potential relationship with Helicobacter pylori, the objective of this study was to determine the presence of this bacteria in sources of drinking water in areas of high and low incidence of gastric cancer in Costa Rica
In the second sampling of high incidence areas, 8 samples had residual chlorine and of these, 2 were positive using the glmM marker for Helicobacter pylori with residual chlorine values of 0.3 mg/L and 0.4 mg/L
Summary
Chronic infection with H. pylori in the human stomach can last decades resulting in persistent inflammation. The condition caused by Helicobacter pylori infection is the most common infectious disease affecting humans and an estimated 50% of the human population is infected [1] This condition can lead to persistent gastritis and is directly related to the development of peptic ulcers, gastric adenocarcinoma and lymphoma of the stomach’s mucous membrane [1]. According to the American Cancer Society [2], long-term infection with Helicobacter pylori is classified as a risk factor for gastric cancer. The latter is believed to be due to biological factors such as bacterial virulence factors, levels of pepsinogens and polymorphisms in humans [3]. Materials and Methods: Drinking water samples from 20 cantons situated in areas of low and high incidence of gastric cancer in Costa Rica were analyzed. Significant statistical correlations were established among environmental conditions, drinking water management and incidence of gastric cancer
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