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Background: The prevalence of Helicobacter pylori including strains with putatively virulent genotypes is high, whereas the H. pylori-associated disease burden is low, in Africa compared to developed countries. In this study, we investigated the prevalence of virulence-related H. pylori genotypes and their association with gastroduodenal diseases in The Gambia. Methods and Findings: DNA extracted from biopsies and H. pylori cultures from 169 subjects with abdominal pain, dyspepsia or other gastroduodenal diseases were tested by PCR for H. pylori. The H. pylori positive samples were further tested for the cagA oncogene and vacA toxin gene. One hundred and twenty one subjects (71.6%) were H. pylori positive. The cagA gene and more toxigenic s1 and m1 alleles of the vacA gene were found in 61.2%, 76.9% and 45.5% respectively of Gambian patients harbouring H. pylori. There was a high prevalence of cagA positive strains in patients with overt gastric diseases than those with non-ulcerative dyspepsia (NUD) (p = 0.05); however, mixed infection by cagA positive and cagA negative strains was more common in patients with NUD compared to patients with gastric disease (24.5% versus 0%; p = 0.002). Conclusion: This study shows that the prevalence of H. pylori is high in dyspeptic patients in The Gambia and that many strains are of the putatively more virulent cagA+, vacAs1 and vacAm1 genotypes. This study has also shown significantly lower disease burden in Gambians infected with a mixture of cag-positive and cag-negative strains, relative to those containing only cag-positive or only cag-negative strains, which suggests that harbouring both cag-positive and cagnegative strains is protective. [ABSTRACT FROM AUTHOR]

Background: Helicobacter pylori is an important agent of gastroduodenal disease in Africa and throughout the world. We sought to determine an optimum method for genotyping H. pylori strains from children and adults in The Gambia, West Africa. Results: Virulence genes were amplified in 127 of 190 cases tested (121 adults and 6 children); each of 60 bacterial cultures, and 116 from DNA extracted directly from biopsies. The proportion of biopsies that were cagA+, the ratio of vacAs1/s2, and vacAm1/m2, and the proportion of mixed strain populations in individual subjects changed with age. Strains lacking virulence cagA and vacA genes and with apparently homogeneous (one predominant strain) infections were more common among infants than adults. Conclusions: In order to detect the range of bacterial genotypes harbored by individual patients, direct PCR proved slightly superior to isolation of H. pylori by biopsy culture, but the techniques were complementary, and the combination of both culture and direct PCR produced the most complete picture. The seemingly higher virulence of strains from adult than infant infections in The Gambia merits further analysis. [ABSTRACT FROM AUTHOR]

ABSTRACTBackground.Helicobacter pylori infection is very common in Africa, yet peptic ulcer disease and gastric malignancy are rare. Aim.The aim of this study was to quantify mucosal responses to H. pylori in Gambian adults and children and to estimate the prevalence of antibodies to bacterial virulence factors (cagA and vacA ) in a symptomatic population. Patients and methods.Adults (mean 36 SD 12 years) with dyspepsia and children (mean 1.4 years SD 0.4 years) with malnutrition underwent gastroscopy with biopsy. Blood was simultaneously drawn for cagA and vacA antibody status. Histopathological scoring used the modified Sydney classification. Results.Both adults (n = 45) and children (n = 37) mainly demonstrated chronic mild antral inflammation. Only 2/83 cases of focal atrophy (GA) and 4/83 cases of intestinal metaplasia (IM) were observed. Adults tended to demonstrate more frequent acute (AI) and chronic inflammation (CI) (38% compared with 18% and 85% compared with 72%, respectively). Sixty-seven percent of children were cagA IgG+ and 21%vacA IgG+ and 93% of adults were IgG cagA + and 86%vacA +. There were no differences in mucosal responses between those who were cagA or vacA positive compared with those who were negative. Conclusion.Gambian adults and children mount a CI response to H. pylori but GA, IM and AI are uncommon. cagA and vacA are commonly expressed in Gambian strains of H. pylori . Further studies are needed in order to confirm that GA and IM are not late findings in old age. [ABSTRACT FROM AUTHOR]