Prevalência de infecção por Helicobacter pylori em uma comunidade indígena em São Paulo e fatores associados: estudo transversalPrevalence of Helicobacter pylori infection in an indigenous community in São Paulo and associated factors: cross-sectional study

Helicobacter pylori exposure among the Awajún of the Peruvian Amazon: Prevalence and environmental, social, and biological associations

OBJECTIVES

Helicobacter pylori (H. pylori)-a gastric bacteria affecting almost 50% of the global population and leading to ulcers and cancer in severe cases-is a growing health concern among Indigenous populations who report a high burden of reported poor general health and gastrointestinal distress. We test hypothesized associations between H. pylori exposure patterns and environmental, social, and biological conditions among a sample of 212 Indigenous Awajún adults (112 males, 100 females, ages 18-65 years) living in the northern Peruvian Amazon.

MATERIALS AND METHODS

Dried blood spots were analyzed for H. pylori-specific IgG using a recently developed enzyme-linked immunosorbent assay. Resulting seropositivity rates and antibody concentrations, proxying past exposures to H. pylori were analyzed in relation to relevant environmental (toilet type, floor material, reported water quality), social (household size and education level), and biological (age, sex, BMI, blood pressure, immune and metabolic biomarkers) factors using multivariable regression analyses.

RESULTS

We found near ubiquitous seropositivity for H. pylori exposure in our sample (99.1% seropositive). In the regression analyses, elevations in H. pylori antibody concentrations were significantly higher among males compared to females (β = 0.36, p = 0.01). No associations were found with any other factors.

DISCUSSION

Anthropological research in the study communities suggests that the male bias in elevations of H. pylori antibody concentrations is related to cultural and biological factors. Future research is needed to further unravel these biocultural dynamics and determine whether elevations in H. pylori antibody concentrations have clinical relevance for gastrointestinal health outcomes in this population.

Prevalence of cagA, cagM, vacA and oipA genes in isolates of Helicobacter pylori obtained from hospital patients in Northeast Brazil

Helicobacter pylori is a major cause of gastrointestinal disorders such as chronic gastritis, peptic ulcers, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. It is estimated that around half of the world's population is infected with this pathogen, with underdeveloped countries reporting the highest frequencies. The genes cagA, cagM, vacA, and oipA are some of the most important virulence factors of H. pylori; however, there are no recent studies from Recife-PE demonstrating their frequency, and their relationship with severe gastric modifications. This work aims to use qualitative PCR to detect the virulence genes cagA, cagM, vacA, and oipA in H. pylori isolates obtained from patients in a public hospital in Recife (PE). We collected samples from the stomach's body and antrum of 147 patients, from which 71 (48%) tested positive for H. pylori. Among positive samples, the most frequently infected gender was female (44/71, 62%), and the most frequently infected age group was those above the age of 46 (31/71, 44%). Histological examination of H. pylori-positive samples revealed alterations other than chronic gastritis, including metaplasia and atrophy. The frequency of cagA, cagM, and oipA genes were identified in 84%, 56%, and 69% of the samples tested, respectively, as well as the vacA-s1m1 allelic combination (77%). However, there was no statistically significant variation in the occurrence of these genes, therefore they cannot be considered unique markers of severity in our setting. New research with larger samples and investigations of other genetic markers can aid uncover local risk factors and lead to a better understanding of H. pylori's pathogenesis.

[Cancer mortality among indigenous population in Acre State, Brazil]

The study aimed to estimate cancer mortality among indigenous peoples in Acre State, Brazil. This was a descriptive observational study based on the nominal bank of the Brazilian Mortality Information System for the period from January 1st, 2000, to December 31st, 2012. The study analyzed the distribution death frequencies by sex and age. Standardized mortality ratio (SMR) was calculated taking Goiânia (Goiás State), Acre State, and the North Region of Brazil as the references. A total of 81 deaths were identified, the majority in men (59.3%) and in individuals over 70 years of age. The five main sites in men were stomach, liver, colon and rectum, leukemia, and prostate. The five main sites in women were uterine cervix, stomach, liver, leukemia, and uterus. In indigenous men there was an excess of deaths from stomach cancer compared to the populations of Goiânia (SMR = 2.72; 2.58-2.87), Acre State (SMR = 2.05; 1.94-2.16) and North region (SMR = 3.10; 2.93-3.27). The same was observed for deaths from hepatic cell carcinomas referenced against Goiânia (SMR = 3.89; 3.66-4.14), Acre State (SMR = 1.79; 1.68-1.91), and the North of Brazil (SMR = 4.04; 3.77-4.30). Among indigenous women, there was an excess of cervical cancer in comparison to Goiânia (SMR = 4.67; 4.41-4.93), Acre State (SMR = 2.12; 2.00-2.24), and the North (SMR = 2.60; 2.45-2.75). The estimates show that preventable neoplasms such as cervical cancer and those linked to underdevelopment, such as stomach and liver cancer, account for 49.4% of deaths among indigenous peoples. Compared to the reference population, mortality from liver, stomach, and colorectal cancer and leukemias was more than twice as high in indigenous men; among indigenous women, cervical, stomach, and liver cancer and leukemias were 30% higher.

Association between Helicobacter pylori, Epstein-Barr virus, human papillomavirus and gastric adenocarcinomas

AIM

To correlate Helicobacter pylori (H. pylori), Epstein-Barr virus (EBV) and human papillomavirus (HPV) with gastric cancer (GC) cases in Pará State, Brazil.

METHODS

Tissue samples were obtained from 302 gastric adenocarcinomas. A rapid urease test was used to detect the presence of H. pylori, and the presence of the cagA gene in the HP-positive samples was confirmed by PCR. An RNA in situ hybridization test designed to complement Eber1 RNA was used to detect the presence of EBV in the samples, and the L1 region of HPV was detected using nested PCR. Positive HPV samples were genotyped and analyzed for E6 and E7 viral gene expression. Infections were also correlated with the clinical and pathological characteristics of the patients.

RESULTS

The majority of the 302 samples analyzed were obtained from men (65%) aged 55 years or older (67%) and were classified as the intestinal subtype (55%). All three pathogens were found in the samples analyzed in the present study (H. pylori: 87%, EBV: 20%, HPV: 3%). Overall, 78% of the H. pylori-positive (H. pylori⁺) samples were cagA+ (H. pylori-cagA⁺), and there was an association between the cytotoxic product of this gene and EBV. Coinfections of H. pylori-cagA⁺ and EBV were correlated with the most advanced tumor stages. Although only 20% of the tumors were positive for EBV, infection with this virus was associated with distant metastasis. Only the HPV 16 and 18 strains were found in the samples, although no expression of the E6 and E7 oncoproteins was detected. The fundus of the stomach was the region least affected by the pathogens.

CONCLUSION

HPV was not involved in gastric tumorigenesis. Prophylactic and therapeutic measures against H. pylori and EBV may prevent the development of GC, especially the more aggressive forms.

Development and validation of a whole-cell ELISA for serologically diagnosing Helicobacter pylori infection in Brazilian children and adults: a diagnostic accuracy study

BACKGROUND

Serological tests are practical, with low cost, but no noninvasive tests are available for diagnosing Helicobacter pylori (H. pylori) infection in Brazil. The aim here was to develop and validate enzyme-linked immunosorbent assay (ELISA) serological tests to detect anti-H. pylori immunoglobulin G antibodies, based on cultured strains from Brazilian patients.

DESIGN AND SETTING

Cross-sectional, diagnostic accuracy study comparing a locally developed and validated ELISA and invasive tests among dyspeptic patients at two public hospitals in São Paulo, Brazil.

METHODS

An ELISA test was prepared using whole-cell antigen from 56 strains. After genotypic characterization, it was standardized and optical density (OD) cutoffs were determined based on the serum antibody response of 100 H. pylori-negative samples, compared with 82 H. pylori-positive samples. Validation was performed on 174 symptomatic patients.

RESULTS

The optimal OD cutoffs established (for monoclonal and polyclonal tests, respectively) were 0.167 and 0.164; overall ELISA sensitivity: 84.3%, 78.9%; specificity: 88.6%, 90.6%; positive predictive value (PPV): 75.4%, 80%; negative predictive value (NPV): 93.1%, 81.8%; accuracy: 87.3%, 86.2%; child and adolescent ELISA sensitivity: 74.2%, 81.8%; specificity: 90.8%, 86.7%; PPV: 66.6%, 84.3%; NPV: 95.8%, 84.8%; accuracy: 88.5%, 84.6; adult ELISA sensitivity: 84.4%, 75%; specificity: 86.9%, 93%; PPV: 81.8%, 78.3%; NPV: 88.9%, 91.8%; accuracy: 85.9%, 88.5%.

CONCLUSION

The polyclonal serological test developed using local strains presented better diagnostic performance among children and adolescents, while the monoclonal test was better among adults. The results from both tests suggest that these in-house serological tests could be used to detect anti-H. pylori antibodies in our population, for screening purposes.